First, was the tornado outbreak over the United States a couple of weeks ago, and in particular, a F3 tornado that went through Michigan and actually crossed an ice-covered lake where it appears to pull up ice. If you haven’t seen the video, I would highly recommend taking a look.

The second item has been the record-shattering heat over a good chunk of the western and central U.S. I don’t have room to go into all the details, but a heat dome brought record temperatures for March to many locations with some of them seeing temperatures that would have broken April all-time records. With persistent arctic high pressure to our north, these extreme temperatures have been kept south of the border, but southern Minnesota did see a record high of 31 C.

Last on our list is an article that came out indicating that there is a good chance we will see the development of El Niño conditions across the Pacific later this year and it could be a very strong El Niño. We will look at that topic in April.

OK, now on to our main topic.

In our last article we looked at the composition of the atmosphere, breaking it down into a heterosphere and homosphere. Then we looked at the atmosphere from a temperature point of view and proceeded to break it down into four regions or layers — the thermosphere, mesosphere, stratosphere, and troposphere. We finished off by saying that one of these layers is responsible for most, if not all, of our weather. So, in this issue we will get back on track and extend our understanding of weather and the atmosphere by beginning our look at the atmosphere and surface energy balances.

To begin to understand how solar energy is spent as it reaches the Earth’s surface, and thus understand our surface energy budget, we need to look at the pathways in which solar energy can travel once it reaches the Earth’s surface.

Where the rays go

Earth receives energy from the Sun in the form of shortwave radiation. When this energy is turned into heat, it takes on the form of long-wave radiation. A good portion of both of these types of radiation passes through our atmosphere in the process known as transmission. When we are looking at shortwave radiation reaching the Earth’s surface, we call it insolation, and it is this insolation that is the driving force behind all of our weather.

Insolation is comprised of shortwave radiation that is transmitted directly to the ground, along with diffused or scattered radiation (indirect radiation). As shortwave radiation travels through our atmosphere some of it interacts with gas, dust, pollutants, water droplets and water vapour, changing the direction of the shortwave radiation — or scattering it. This scattering is what causes the sky to be blue during the day and why sunsets and sunrises take on a reddish hue.

The principle behind why we see these colours is known as Rayleigh scattering; named after the English physicist Lord Rayleigh, who came up this principle back in 1881. The principle relates wavelength to the size of the particles that are causing the scattering.

The general rule is: the shorter the wavelength, the greater the scattering; the longer the wavelength, the less the scattering.

Small gas molecules will scatter shorter wavelengths (remember with visible light, blues and violets have the shortest wavelengths, while oranges and reds have the longest wavelengths). So, since short waves are scattered the most and the molecules in our atmosphere scatter short waves, we end up having the lower atmosphere dominated by scattered blue waves.

At sunrise and sunset, the angle of the Sun is such that the insolation has to travel through much more atmosphere than during the day. The short blue wave lengths are still scattered, but now they encounter so much scattering only the longer orange and red wave lengths are left to reach our eyes — so we tend to see these colours.

Action and refraction

Another thing that happens to shortwave radiation as it enters the atmosphere is that it refracts. Refraction is the bending of light as it passes from one medium to the next. In this case, it is passing from the virtual vacuum of space to our dense atmosphere.

We have all seen examples of refraction. Rainbows are created when light passes through dense water drops causing the different wavelengths of light to refract at different rates. Mirages are another example of refraction. Most of us have experienced mirages on warm days along a highway when you stare down the highway and see what appears to be something floating above the road. In this case, it is the hot air above the highway that causes the light to be refracted.

One interesting note about refraction is that without it, the amount of daylight we receive would be about eight minutes less each day. When the sun sets or rises, the light refracts as it passes from space into our atmosphere. This refraction allows us to “see” the Sun when it is actually below the horizon. In the morning we see the sun rise four minutes before it actually moves above the horizon and at sunset we continue to see the Sun for four minutes after it has actually dropped below the horizon.

Next we will take a break from learning about the weather and take a look back at our extended winter to see how the numbers stacked up.

The post Why is the sky blue? appeared first on Manitoba Co-operator.

Many of our most memorable fall and winter storms, whether they bring heavy snow, strong winds or a sudden drop in temperature, originate from areas of low pressure that form immediately to the east of the Rocky Mountains.

One of these development zones sits over Alberta, producing what we fondly call an “Alberta clipper,” while another forms farther south over Colorado, responsible for the infamous “Colorado low.”

So, let’s revisit why the lee of the Rockies is such a breeding ground for storm systems and why certain lows grow into major weather makers while others barely organize at all.

We’ve previously discussed how the jet stream, with its sweeping curves and shifting speed, helps shape regions of rising and sinking air. When the jet accelerates, rising motion and low pressure often develop beneath it. When it slows, sinking air and high pressure tend to form. While this plays a supporting role, it doesn’t fully explain why lows so often take shape immediately east of the mountains.

To understand that, meteorologists talk about vorticity, a measure of how much spin an air parcel has. There are several types — absolute, relative and the Earth’s own vorticity — but the fine details can be complicated enough to test anyone’s patience. Instead, we’ll focus on the main ideas needed to understand how lee-side lows develop.

As you move closer to the equator, the Earth’s vorticity decreases. Relative vorticity, meanwhile, refers to the air parcel’s own spin — counterclockwise rotation adds positive vorticity and clockwise rotation adds negative.

The important concept is that absolute vorticity, which combines both the Earth’s vorticity and the parcel’s relative vorticity, stays constant unless something forces it to change. So, if an air parcel moves southward and the Earth’s vorticity drops, the parcel must gain relative vorticity to maintain the balance. If it moves northward, the opposite happens. Increasing vorticity encourages cyclonic (low pressure) development, while decreasing vorticity promotes anticyclonic (high pressure) behaviour.

Upward bound

Now imagine Pacific air flowing eastward toward the Rockies. When it reaches the mountains, it is forced upward. At the same time, the tropopause acts like a rigid ceiling, preventing the air from expanding upward as much as it would like. The result is that the atmospheric column becomes squeezed vertically and must, in turn, spread out horizontally. When the column becomes shallower, its absolute vorticity decreases. Because the Earth’s vorticity hasn’t changed at that moment, the parcel’s relative vorticity also has to decrease. This gives the air an anticyclonic, or southeastward, turn as it flows over the mountains and spills down their eastern slopes.

Once the air begins drifting southeast of the Rockies, however, it is now entering a region of lower Earth vorticity. To compensate, its relative vorticity must increase. This creates a cyclonic bend in the flow, turning the air northeastward. Put together, these shifts form a trough of low pressure stretching along the lee of the mountains — a crucial first step in the development of an Alberta clipper or Colorado low.

The next question is why some of these troughs intensify dramatically while others fade. The Rockies themselves play a major part. These are among the tallest mountains on the continent, and their height forces a dramatic squeeze on the air column. The stronger the squeeze, the more the vorticity must adjust, and the deeper the resulting trough. But a trough alone is not enough to guarantee a storm. If it were, we would be dealing with a constant conveyor belt of major lows sweeping across the Prairies all winter long.

Other factors at play

To develop into a significant system, several additional ingredients must align. Cold arctic air often slides southward along the mountains, while warmer, moister air waits to the south. When the developing low taps into both air masses, a strong temperature gradient forms which is a key source of energy for strengthening storms. The moisture adds even more fuel as it rises and condenses, releasing heat that intensifies the system. When these ingredients line up perfectly, an Alberta clipper can quickly spin up and race eastward, bringing snow, wind, and rapid temperature changes.

Colorado lows, meanwhile, owe much of their punch to their southern position. Like clippers, they draw cold air from the north, but they also have access to warm, moisture-rich air from the Gulf of Mexico. Because the Gulf is one of the most reliable moisture sources for the continent, these systems sometimes tap into deep, sustained humidity. As this warm moist air rises and condenses, it releases a tremendous amount of heat, fueling rapid development. This is why Colorado lows can grow into sprawling, slow-moving storms capable of affecting vast regions at once.

Still, not every setup produces a major event. A storm might have abundant moisture but lack arctic air, limiting snowfall and reducing the system’s strength. A promising low might start strengthening only after it has moved east of us, missing the Prairies entirely. Other times, a lack of cold air shifts the storm track farther west, producing more rain than snow or allowing the system to slide too far south to have much impact.

With so many moving parts like the jet stream position, mountain effects, temperature contrasts, moisture supply and timing, it’s no surprise that forecasting these systems can be challenging.

Whether all the ingredients will come together for a major storm this winter remains an open question, but one thing is certain: the unique geography of the Rockies will continue shaping our storm season, just as it has for generations.

The post The lowdown on winter storms on the Prairies appeared first on Manitoba Co-operator.

From heat that pushed cities to their limits, to fire seasons that refused to end, to water arriving all at once or not at all, the planet delivered a steady stream of reminders about how quickly conditions can shift. What we are going to look at is a broad, worldwide view at some of the major weather themes of 2025.

Tinderbox conditions

Persistent heat was the headline almost everywhere. Long, unbroken stretches of high temperatures settled across Europe, the Middle East, Southeast Asia, and parts of North America. It seemed like summer arrived early, stayed late, and left little room for relief.

In several regions, temperatures climbed high enough that energy grids were stressed, and outdoor workers were pushed to their limits. What stood out wasn’t just the intensity of the heat, but how far it reached. Places accustomed to heat struggled just as much as regions that normally expect a break between hot spells. The message was simple: extreme heat is becoming a fixture, not a visitor.

Several major fire zones flared up early, and many burned long past their traditional endpoints. Canada and parts of Europe found themselves once again under thick smoke as sprawling fires worked their way through forests dried out by months of below-average rainfall.

Fire crews often battled a combination of high winds and low humidity, making suppression difficult. Smoke travelled thousands of kilometres, dimming skies far from the fires’ origin. At one point, Americans were getting mad at us for sending smoke their way.

Rain, rain, go away

On the opposite end of the spectrum, several countries had to navigate severe flooding. Monsoon rains in parts of South Asia were stronger than usual, pushing rivers into surrounding farmland and communities. Elsewhere, short-lived but powerful storm systems triggered flash floods that swept through urban corridors and mountain valleys. Some areas spent part of the year in deep drought and later dealt with swollen waterways.

These quick swings highlighted how modern flood risk increasingly depends on short-duration extremes rather than just long seasonal trends.

Tropical cyclone activity in 2025 delivered more intensity than volume. Some basins came in near or even a touch below their usual storm counts, yet the systems that did develop really packed a punch.

In the Atlantic, the season finished with 13 named storms and five hurricanes, and an impressive four of those reached major-hurricane strength. The standout was Hurricane Melissa, a powerful Category 5 that tore across Jamaica late in the season, and was the strongest tropical cyclone anywhere in the world in 2025.

Melting away

Farther north, the Arctic continued down its long-term trajectory of ice loss. Winter’s peak ice coverage set yet another record low, and by the end of summer, the melt season had carved out one of the smallest minimums. With less ice comes warmer water, which means more open ocean for weather systems to draw energy from. This, in turn, results in subtle but meaningful bends in the jet stream, which eventually impacts our weather in ways we are just trying to figure out.

Northern communities felt the effects of the ice loss first-hand, with eroding shorelines, and shifting wildlife habits.

Human impact

Another issue that impacted the planet was air quality, with smoke, dust, heat and industrial pollution dragging it down. Cities on multiple continents issued repeated advisories, asking residents to limit outdoor activity when possible. Even regions far from wildfire zones experienced haze from distant burns. The growing overlap between heat waves and poor air quality emerged as one of the more troubling health storylines this year.

One of the new sciences that started to get recognized in 2025 was the rapid event-attribution groups. This is a science that analyzes major heat and rainfall extremes to determine how much human-driven warming influenced them. Several high-profile studies concluded that some of the year’s worst episodes would have been far less likely in a cooler world. These findings added scientific weight to what many people already sensed: The background climate is shifting, and that shift is shaping the extremes we see.

Wild weather year

Taken together, the weather stories of 2025 paint a picture of a planet adjusting to a new rhythm, one marked by sharper extremes, quicker transitions and narrower margins. Heat waves that would have once been once-in-a-generation events are showing up every few years. Fire seasons behave less like defined “seasons” and more like extended periods of risk. Water arrives suddenly or not at all.

I once used an analogy of a blender. When you turn the blender on, the pattern remains fairly constant until you hit the next power level. Everything then jumps and becomes chaotic, eventually a new different pattern then emerges. I think we are starting to hit the next power level jump, we are seeing the chaotic weather patterns developing.

The question is, how long until a new stable pattern develops, and just what will be that pattern?

While the hope is always for a quieter year ahead, the lessons of 2025 will carry forward: awareness matters, preparation matters, and the stories we track now will help shape how we respond to whatever unfolds next.

The post YEAR IN REVIEW: 2025 a year of weather extremes appeared first on Manitoba Co-operator.

The big question at this time of year always turns to whether or not we’ll have perfect Christmas weather, but in reality, the real million-dollar question — just what is perfect Christmas weather?

For those of you who have followed my articles, it’s probably no secret that my perfect Christmas weather is to have a nice big snowstorm that keeps everyone at home for a couple of days.

I know that a big storm at this time of the year would cause all sorts of problems and hardships. But deep down inside, it is the idea of being stuck at home for a few days, no pressure to go anywhere because you can’t, plenty of food available, family around you, and hopefully something new to play with, just sounds perfect to me.

Basically, a perfect time to be forced to sit back and just relax and get away from all the holiday bustle.

That’s my holiday weather wish but I am sure there are others out there who would prefer no snow and record warmth, or daytime highs right around zero with great big lazy snowflakes falling — or maybe even clear skies and frigid cold!

All I know is, it takes all kinds to make the world go round and what is perfect for one person is not perfect for another.

According to Environment Canada, perfect Christmas weather means there is already snow on the ground and at some point during Christmas Day there is measurable snowfall. So, what are the chances of this happening somewhere across the Prairies?

The first table shows the probability of having snow on the ground for Christmas along with having snow fall during the day. It breaks the data down into two periods to try and show how our winters seem to be becoming warmer with less snow.

Looking at this data it seems that if you want a white Christmas, then Winnipeg is your best bet. If you want Environment Canada’s version of a perfect Christmas, then Regina is your best bet.

If we look at the current snow cover across these locations (I am writing this in mid-December due to holiday deadlines) it’s going to be a close call as to whether this will be a white or a green Christmas. In Manitoba, both Winnipeg and Brandon are reporting three centimetres of snow on the ground and there’s a forecast for some above-freezing temperatures before the big day. With the low sun angle, I don’t think these locations will lose their snow cover.

In Saskatchewan, both Regina and Saskatoon are reporting only one centimetre of snow on the ground. With a few above freezing days, it is going to be close between a green or white Christmas.

In Alberta, Calgary is currently the snowiest location with six centimetres on the ground, but there’s a good chance that could all melt away before Christmas. Up in Edmonton, there’s only one centimetre of snow on the ground, so it’s in the same situation as Saskatoon and Regina, too close to call.

If your version of a perfect Christmas is to have record breaking warm or heck, even cold temperatures, then table two shows the warmest, coldest and snowiest Christmas periods on record for two major centres in each of the three Prairie provinces.

These records are based on the full set of data that each of these cities has, which means they go back to the late 1800s. While some might argue that these old records are not valid, I personally think they are and should be included.

If you’re looking for a place to go on the Prairies where you might experience a really warm Christmas, then Calgary would be the place for you. While all of the other centres have seen some nice warm Christmases in the past, not one of the major centres comes close to Calgary’s recorded highs.

If you want a chance at seeing some really cold weather during this period, then you could pick pretty much any place, as they have all seen Christmases colder than -35 C, although Winnipeg comes out the winner here, with a bone-chilling -47.8 C on Christmas Eve in 1879.

Interestingly, when you examine the precipitation records for these three days you’ll notice that the Christmas period has been a relatively dry, storm-free period, but there are a few exceptions. Winnipeg did see a heavy dump of 30.5 cm of snow on Boxing Day back in 1916, but the record for biggest Christmas snowstorms has to go to Edmonton. Back in 1938, Edmonton recorded over 25 cm of snow on Christmas Eve and then a further 18 cm of snow on Christmas day, for a total of 43 cm of snow. Looking at the other snowfall records, it seems like 1938 was a snowy Christmas right across the Prairies.

Whatever weather you do end up with I hope it is what you wanted, if not, then remember the season and try to make the best of it!

The post What is perfect Christmas weather? appeared first on Manitoba Co-operator.

Highlights

• A strong Alberta clipper is forecasted to track across the southern Prairies, but the strength and track of the system remains to be seen.
• Alberta can widespread snow to southern and central regions on Wednesday and into Wednesday night. Friday could bring another quick shot of snow.
• Saskatchewan looks set for blizzard conditions later on Wednesday.
• Manitoba can expect blizzard conditions to set in late Wednesday and into Thursday morning.
• Cold temperatures are expected to build in behind the lows in time for the weekend.

Overview

Well, so much for a quieter pattern. While we did see a short window of quieter weather last weekend, the parade of storm systems coming in off the Pacific continued. This was thanks in part to an upper atmospheric river, which brought copious moisture to the Pacific coast.

Looking back, the weather models were not that far off, but when we are talking about weather, a couple hundred kilometers can make a big difference.

Up until the weekend things went pretty well. Cold Arctic air settled in. This brought the coldest air of the season to parts of Saskatchewan and Manitoba. After that it started to fall apart a bit.

The area of low pressure, which was forecasted to move in off the Pacific and then track across the northern Prairies, developed as forecasted. However, it was a a bit stronger than expected and it also tracked further south. This brough snow and freezing rain to the central Prairies early this week along with the forecasted mild temperatures.

In fact, the temperatures ended up being significantly warmer than expected with daytime highs pushing +5 C. However, most regions saw less than 12 hours of above freezing temperatures.

More weather coverage: Predicting Manitoba winter snowfall

Now we come to the current situation across the Prairies. This looks to be a potentially difficult forecast period.

Currently a strong Alberta Clipper has developed and is forecasted to track across the southern Prairies. The weather models are still bouncing back and forth on both the strength of the system and its exact track. Latest model runs have the low tracking from around Calgary on Wednesday morning and then into northeastern North Dakota by early Thursday morning.

Most of the precipitation will fall in a narrow band just to the north of the low track, so the exact track of the low is important. The strength of the low is also important as to how windy it will be and how weather systems will behave after the low passes by. Strong areas of low pressure can alter the overall weather pattern, which makes it difficult to accurately forecast what will happen once they pass by.

With that said, the weather models are showing a second, but weaker, area of low-pressure tacking across the southern and central Prairies on Friday. This should bring another quick round of snow.

Over the weekend, Arctic high pressure will build in. This will bring a return to below average temperatures, especially over the central and eastern Prairies.

In the days leading up to Christmas, the weather models are showing a couple of weak areas of low pressure tracking across the south-central Prairies. These may bring more clouds than sun, seasonable temperatures, along with the chance of flurries or light snow.

Alberta

This forecast period will start with a strong area of low pressure moving in from southern B.C. This low looks to bring widespread snow to southern and central regions on Wednesday and into Wednesday night. Currently it looks like southern regions could see up to 5 cm with amounts further north possibly pushing 20 cm before the system moves out.

A second area of low pressure is forecasted to push in from the west on Friday. This low looks to take a more northerly route, which will result in central and northern regions seeing a quick 5 cm of snow as it zips though.

Behind this low, cool Arctic air will push southwards bringing a return to slightly below average temperatures.

Early next week the weather models are showing a couple of weak areas of low pressure pushing in from the Pacific over central regions.

Confidence in these systems is low. Should they materialize, expect partly to mostly-cloudy skies in the days leading up to Christmas with occasional flurries or periods of light snow with seasonable temperatures.

Saskatchewan and Manitoba

Just like Alberta, these regions are starting this forecast period off with a strong area of low pressure moving in from southern Alberta. Snow is forecasted to develop in a narrow band along a warm front, which is stretching eastwards from the low.

Across Saskatchewan, expect snow to develop around noon over central regions while southern regions may be warm enough for either wet snow or rain.

The precipitation will transition to all snow later in the day as the main area of low pressure moves through. Latest model indications are for central regions to see upwards of 20 to 25 centimeters of snow with southern regions seeing 5 to 15 cm. Winds look to be strong with blizzard conditions very likely.

Conditions look to improve overnight Wednesday with sunny skies moving on Thursday as arctic high pressure briefly builds in.

Across Manitoba, the snow looks to move in by late in the afternoon on Wednesday. Where the heaviest snow will set up is still up in the air. Currently indications are it will be slightly north of the Trans-Canada highway but any small nudge to the storms track will change that.

More weather coverage: Prairie winter snowfall forecast 2025-2026

Snow looks to continue overnight Wednesday and into Thursday morning. This is expected to bring around 5 cm of snow near the border, increasing to 20+ cm under the main storm track. As with Saskatchewan, winds look to become very strong with blizzard conditions developing during the evening and lasting possibly into Thursday morning.

A second weaker area of low pressure is forecasted to track across the central Prairies on Saturday. Most of the snow from this system will be over central regions of both Saskatchewan and Manitoba but southern regions will likely see another couple of centimeters. Cold Arctic high pressure will then build in behind this low bring below average temperatures and clearing skies over the weekend.

For the first half of next week, the weather models are showing two weak areas of low-pressure tracking across the central Prairies. Confidence in this part of the forecast is low, but should it materialize, these regions can expect partly to mostly cloudy skies, near average temperatures, and a chance of some flurries or occasional periods of light snow.

The post Prairie forecast: First blizzard of the year, then quiet? appeared first on Manitoba Co-operator.

We will start off with probabilities, as lately I have been constantly reminded of how our weather memories tend to grow over time, but long-term climate records give a clearer picture, which is something that often surprises people.

What is ‘normal’ snowfall?

Environment and Climate Change Canada’s climate normals make it possible to compare snowfall behaviour across the region, without analyzing each province separately. Despite differences in terrain and storm tracks, the Prairie provinces show remarkably similar snowfall probabilities. Manitoba and Alberta align closely, while Saskatchewan tends to be slightly drier, recording fewer days with total snowfall above five centimetres.

To understand how much snow typically falls, we first look at single-day snowfall. In Winnipeg, a strong representative station thanks to its long period of record, there is a 90 per cent chance of seeing around 30 snowfall days per winter. About half of winters see closer to 45, and only once in roughly 100 years will that number reach 70. A snowfall day simply means any measurable amount.

On those days, about 90 per cent produce at least a light dusting (0.2 cm). Roughly half exceed two centimetres, which means half fall short of that mark. Days with five centimetres or more occur only five to 10 per cent of the time, while 10-centimetre days show up once or twice in a typical winter. A single-day snowfall over 30 cm is extremely rare — around a 0.1 per cent probability, or once every 20 to 40 years.

But single-day totals don’t tell the whole story. Many Prairie storms extend across several days, so looking at snowfall events — defined as snow falling on two or more consecutive days — gives a better idea of what we experience on the ground. Winnipeg averages about 20 such events per winter, with around half of winters reaching the upper-20s. Only about once per century would an area see 40 or more snowfall events.

Most multi-day events remain small. Ninety per cent bring at least half a centimetre, and about half exceed two centimetres. When we move into higher totals, probabilities shift noticeably compared to single-day snowfall. About 30 per cent of multi-day events exceed five cm. Totals of 10 cm or more appear roughly 10 per cent of the time — usually once or twice per winter. These are the systems that commonly disrupt travel and require extended cleanup.

The largest events, multi-day accumulations of more than 30 cm, are still uncommon, but less rare than 30-plus cm in a single day. They occur roughly once every 200 events, or about once every decade. These storms tend to be remembered not because of a dramatic single burst, but because of steady snow, drifting, and lingering impacts.

It’s important to remember that these figures represent long-term averages. Statistics don’t prevent several large storms from happening in one season, nor do they guarantee one will occur within a decade. Weather clusters naturally, and our memories often exaggerate past extremes.

Winter follows warm November

Now on to our monthly weather review and our look ahead to see what the next couple of months might have in hold for us. November was a warm month right across the Prairies with temperatures ranging between 1.6 C above-average in Edmonton to 3.8 C above-average in Winnipeg. The warm spot was Calgary with an actual mean monthly temperature of -0.4 C with the cold spot going to Peace River at -5.4 C.

Looking at precipitation for the month, Manitoba, eastern Saskatchewan, and northwestern Alberta saw a dry month. The driest location was Brandon with only 2.7 mm of water equivalent precipitation reported. The wet spot was Calgary which reported 16.7 mm, about four mm above the long-term average.

Looking back at the different weather forecasts or predictions, both the Old Farmers’ Almanac, and Canadian CanSIPS model predicted a warmer than average start to the winter. Unfortunately, neither of these forecasts got the precipitation forecast correct as the Old Farmers’ Almanac called for above average amounts and the CanSIPS model called for near average amounts.

Winter snow predictions

Looking at the latest predictions and model runs, and as usual starting off with the almanacs, the Old Farmers’ Almanac is calling for a warmer than average December and January with above average precipitation. The Canadian Farmers’ Almanac, which unfortunately will no longer be with as after next year, is calling for cold and snowy over the next couple of months, with clipper systems and a late January blizzard.

Next up, the weather models. The CFS model is calling for a brief warm-up to start December with colder than average temperatures moving in during the second half of the month. These cold temperatures are then forecasted to moderate as we move into January with most locations expected to see near to slightly above average temperatures. Its precipitation forecasts is calling for near average amounts in both months, with western Alberta having the greatest chance of seeing above average amounts.

Looking at the CanSIPS model, it is calling for near to slightly below average temperatures across the eastern Prairies in December with western regions seeing above average values. January is forecasted to be cold with all areas expected to see well below average temperatures. Precipitation is forecasted to be near average right across the Prairies in both months. The European model or ECMWF is calling for near average temperatures over the next two months with above average precipitation. NOAA is also calling for above average precipitation over the next two months but is predicting below average temperatures.

Lastly, my two cents. I think we are going to see near average temperatures and precipitation in December followed by below average temperatures and above average precipitation in January.

Now, as usual, we have to sit back and see what Mother Nature will throw at us.

The post Predicting Manitoba winter snowfall appeared first on Manitoba Co-operator.

The losses to crops such as cotton and soybean are expected to slow agricultural growth, boost farmers’ debt and cap rural consumption, which had been set to rise after New Delhi slashed taxes on hundreds of consumer items.

“We had hoped to harvest 10 to 12 quintals of soybean per acre, but now we’ll be lucky to get 2 to 3 quintals — and even that will require significant additional expenses,” said farmer Kishore Hangargekar. A quintal is a unit equivalent to 100 kg (220 lb).

He was speaking after two days of unrelenting rain flooded his fields and submerged his crops in the district of Dharashiv in the western state of Maharashtra.

Related: India and Canada agree on new roadmap for relations.

Until then, the soybean crop had been thriving, and farmers were readying for harvest.

The reduction in yields from excessive rainfall is likely to halve agricultural growth to three per cent to 3.5 per cent in the December quarter, down from 6.6 per cent a year earlier, said Garima Kapoor, economist at Mumbai-based Elara Securities.

Summer-sown crops such as soybean, cotton, rice, pulses and vegetables mature from September, a month that saw rains of 15 per cent above average this year, with some regions getting as much as 115 per cent more than normal.

While agriculture contributes just 18 per cent to India’s economy of nearly US$4 trillion, almost half its population of 1.4 billion relies on farming to earn a living.

No respite from rain

Now farmers are scrambling to harvest summer crops ahead of winter sowing set to begin next month, but more untimely rain forecast this week could delay planting and damage late-maturing summer crops.

The rain-damaged crops are earning prices well below the government’s minimum support price, as quality has deteriorated.

“Traders are buying the damaged crops for throwaway prices, and we have no choice but to sell,” said farmer Sachin Nanaware, who sold his soybean at a rate of 3,200 rupees ($50.62) for 100 kg, below the government-fixed rate of 5,328 rupees.

Nanaware said he had hoped to buy a motorcycle and a television, but is now worried about repaying his bank loan.

The excessive rain has boosted soil moisture for winter-sown crops such as wheat, rapeseed and chickpea, but many farmers say they lack funds for seeds and fertilisers.

“We need money to buy seeds and fertilisers and to prepare the land,” said farmer Chaya Jawale as she collected cotton bolls brought down from plants prematurely by the rain.

“So, we have no choice but to mortgage our gold jewellery.”

Damage to soybean and cotton crops is expected to boost India’s vegetable oil imports in the marketing year from November by 1.5 million tons to a record 18 million, says industry analyst Thomas Mielke of Oil World.

— Additional reporting by Ira Dugal

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One weather model was not ready at that time, and that was the Canadian CanSIPS model. Its latest forecast is calling for near- to above-average temperatures in September and October, with western regions being the warmest compared to average and eastern regions being the coolest compared to average. November temperatures are predicted to be near-average.

Their precipitation forecast calls for near-average amounts across all three months, with northern Alberta seeing below-average amounts in September.

In this issue we are going to wrap up our look at extreme rainfall by looking at the different weather patterns that tend to be associated with these rainfall events. We’ll also examine how changing weather patterns may contribute to these events.

Extreme or heavy rainfall can happen from many conditions, but often it is a combination of specific conditions that leads to record breaking rainfalls. For example, you could have training thunderstorms, but if there is not much available moisture then you will not get extreme rainfall. You could have a strong area of low pressure, with lots of moisture and plenty of instability — but it if is moving fast then rainfall totals will not be that extreme.

Looking at all the one-day rainfall records, they all occur in either June, July or August, which just happens to be thunderstorm season. Thunderstorms that bring extreme rainfall usually have several conditions that come together to produce extreme rainfall. There will be plenty of moisture, atmospheric instability, some form of front providing lift, and then slow speeds or training of storms.

The two main conditions that are almost always needed to be present for extreme rainfall are plenty of moisture and slow movement of systems.

With changes that our atmosphere is currently undergoing due to a warming planet, these two conditions look to become more prevalent. A warmer atmosphere and ocean is leading to an increase in the available atmospheric moisture. Now this doesn’t mean we won’t have dry conditions. Sure, a warmer atmosphere can hold more moisture, but if the atmosphere is dry that means the increased heat will be able to pullmore moisture out of a region through evapotranspiration.

Overall, it looks like the atmosphere can and will hold more moisture and that moisture will be available to produce rainfall. There is also emerging evidence that a warming planet is leading to a slowing down of weather systems and the development of more blocking patterns. Blocking patterns are when certain configurations of highs and lows develop that tend to not move much, or they block the movement of weather systems — thus the term blocking pattern.

We often remember blocking patterns when they bring long periods of warm dry weather, but they can also bring long periods of cool wet weather. It all depends on where you are in relationship to the block.

Why the slow down? To put it into simple terms, as the planet warms, the poles warm significantly faster than the equatorial regions. This lessens or weakens the temperature gradient between these two regions. It is this temperature gradient that is the driving force behind most of the atmospheric circulations such as the jet stream. As they weaken systems will move slower and the pattern become more meandering.

Think of a river. If it is flowing down a steep hill it tends to stay relatively straight, when it is flowing slowly across a flat region, like the Prairies, it meanders. The same thing happens with the flow of the atmosphere and when it gets curvy it can get stuck in that curve until that curve breaks off — much like rivers and oxbow lakes.

Are we going to continue to see a continuation of the slowdown and more meandering and blocking patterns in the future? I think so. Chances are we will see more of the shifting between dry and wet patterns. Sometimes it will be within short time frames — dry one month and wet the next — and other times over longer periods where we will see a season or year or two that are dry, followed by just as long wet periods.

This is what is making long-range weather forecasts much more difficult. Weather models rely partially on past experience — what happened in the past when a certain weather pattern was present. The problem now is that the atmosphere is not behaving the same way as it did in the past, and in my opinion things are going to get more uncertain over the next few decades.

In upcoming issues I’d like to explore fall frosts, as a few regions have already experienced their first, and will revisit the topic of folklore and what it might tell us about the upcoming winter.

If you have questions about either topic, I’d be glad to hear from you. Feel free to email me: dmgbezte@gmail.com. I’d love to hear from you, about these or any other weather topics you’d like me to cover.

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In particular, training thunderstorms brought upwards of 100 millimetres of rain to parts of southern Manitoba.

Recipe for rain

There are several factors that need to come together for an extreme rainfall event to take place. Sometimes you need more than just one factor, other times, if the factor is strong enough, you just need one.

The first factor is atmospheric moisture. If we are going to get heavy rain, there needs to be a significant supply of moisture in the atmosphere.

When warm, moist air masses interact with cooler air, it can lead to the condensation of water vapour and the formation of clouds and precipitation. Across the Prairies we experience the influx of moisture-laden air from different directions, such as from the Gulf of Mexico or the Pacific, which can contribute to the potential for heavy rain. For really extreme rainfall events, we need the atmospheric moisture to be deep, that is, a large portion of the atmosphere is moist.

This deep moisture is referred to as precipitable water and is measured by stating the amount of rainfall that would occur if all the moisture over a region fell as rain all at once. When there is a lot of deep moisture across our region, we can typically see this value in the 50 mm range, but that doesn’t mean this is the greatest amount of rain that we can see.

We can have plenty of moisture in place but still not see heavy or extreme rainfall. The second key component or factor is atmospheric instability.

Atmospheric instability refers to the condition in which warm, moist air at the surface is overlaid by cooler, drier air aloft. This creates an environment conducive to the development of thunderstorms and heavy rainfall.

As the sun warms the surface it heats the surrounding air, and it begins to rise. This rising air will cool, but if it cools at a slower rate than that of the atmosphere around it, then the air will continue to rise, eventually cooling to the point that condensation will occur.

Remember the total precipitable water? Well, as that air rises, new air moves in horizontally that is also full of moisture. That air will eventually rise bringing even more moisture into the upper atmosphere to condense. This is why you can get much more rainfall that what the precipitable water value is.

Impact of Manitoba’s landscape

The next factor is confined to certain parts of the Prairies such as the Manitoba escarpment and further west to the Rocky Mountains, and it is topography and orographic lift.

While the Prairies are generally flat, there can still be variations in terrain that influence the behavior of storm systems. Even subtle changes in elevation, such as low hills or ridges, can play a role in enhancing rainfall. When moist air is forced to rise over elevated features, a process known as orographic lift occurs. As the air is lifted, it cools and condenses, leading to cloud formation and precipitation. This effect can enhance rainfall over certain areas of the Prairies that are situated in the path of prevailing winds.

We can see this in Manitoba around the Dauphin/Riding Mountain region, but it is especially evident in Alberta when easterly winds push up against the mountains. This is one of the leading reasons behind the epic flooding that hit southwestern Alberta back in 2013.

Bringing the storm

Besides moisture and instability, the next biggest factor that contributes to heavy or extreme rainfall is storm dynamics. This is basically how a storm system behaves. Rainfall events come from different types of storm systems, such as fronts, areas of low pressure, and convective thunderstorms. Each of these storm systems have the potential to produce heavy or extreme rainfall, depending on their dynamics or how they behave.

The behaviour that contributes the most to extreme rainfall events is the speed at which they are moving. Simply stated, the slower the system, the greater chance of heavy rain. When a front or an area of low-pressure moves slowly, or even stops moving, which we refer to as stalling out, then the mechanism in place for producing rainfall just stays over one region.

Normally most rain producing systems have the potential to bring heavy rain; they just don’t stay over one place long enough. Even convective thunderstorms can stall out but that usually does not create conditions that create heavy rain, as a stalled-out storm will usually self-destruct over a short period of time. What is dangerous with convective thunderstorms is when “training” occurs, as Manitoba recently saw.

Primed for rain

Training is when a series of thunderstorms form and move over the same region. One storm will develop and bring heavy rain, as it starts to move off and self-destruct a second storm then quickly develops and moves in to replace the first storm, and so on. From the ground it will often seem like it is just one big storm that keeps on going. Heavy rain develops, there is a short lull and then it picks up again. Training thunderstorms can and have resulted in some of the heaviest amounts of rain across the Prairies.

The last factor that we are going to examine is convergence zones. These are similar to topography and orographic lift as they are areas where winds from different directions come together, or converge, forcing air to rise. They can form nearly anywhere when winds of opposing directions meet. These zones can act as focal points for storm development and can lead to the formation of heavy rain-producing thunderstorms.

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The two phenomena we’ll examine are often overlooked, but both have warnings and advisories associated with them — rainfall and humidity, or what is otherwise known as humidex.

Humidity, by its simplest definition, is the amount of water vapour that is in the air. The warmer the air, the greater the distance between air molecules and therefore, the greater the holding capacity of the air for water vapour. Due to this relationship, warm air has the capacity to hold much more water than cold air.

The most common way in which humidity is reported is relative humidity. Unfortunately, it is probably one of the most misunderstood terms used in trying to describe the weather.

Relative humidity is a ratio of the amount of water vapour that is in the air, compared to the maximum that it could hold under those same conditions, and is expressed as a percentage.

For example, if we had an air temperature of 10 degrees Celsius and had eight grams of water vapour per kilogram of air, our relative humidity would be 100 per cent, since air at 10 C can hold a maximum of eight grams of water vapour. If this same air was warmed up to a temperature of 30 C and the amount of water vapour in the air didn’t change, the relative humidity would now be around 29 per cent, as air at 30 C can hold 28 grams.

This is where the misunderstanding begins to develop. When the air temperature was 10 C and the relative humidity was 100 (per cent), people would say that it is humid out, but once the temperature has warmed up to 30 C and the relative humidity dropped to 29 per cent, people would say that it is very dry out, but in reality, the amount of water vapour in the air has not changed, only the temperature has.

A better way to measure humidity is by using the dew point temperature, which we simply refer to as the dew point. This measurement is a fairly simple way of telling us exactly how much moisture is in the air no matter how the temperature changes during the day. The dew point is the temperature that we would have to cool the air down to for condensation (or dew) to begin forming.

In other words, it is the temperature that the air would have to be to give us 100 per cent relative humidity. For example, if it is 18 C outside early in the morning and the dew point is 18 C, the relative humidity would be 100 per cent. By the afternoon, as the air warms up, the dew point would still be around 18 C if no additional water vapour was added or removed from the air, but the relative humidity would now have dropped into the 50 per cent range.

The best way to look at humidity and determine how humid it is outside is as follows:

Dew points that are less than 10 C, the atmosphere is fairly dry.

Dew points in the 10-15 C range are comfortable.

Dew points in the 15-20 C range are humid, starting to feel uncomfortable.

Dew points over 20 C are getting very humid, start to feel very uncomfortable.

Dew point over 25 C, extremely humid and conditions will be very uncomfortable and can even be dangerous.

This illustrates why dew point is a better measure than relative humidity. If the dew point was 25 C we know it is very humid out no matter what the temperature is, but if the temperature was, let’s say 35 C, the relative humidity would only be around 55 per cent. That would make some people think that it’s not very humid, despite the enormous amount of water the atmosphere held. So, remember, if it’s a hot summer day with dew points in the low twenties, even if the relative humidity is only 50 per cent, it is still humid.

Now on to the one thing about severe summer weather that we tend not to think about until it creeps up on us — heavy or extreme rainfall.

When you look at the impact of heavy rain and the resultant flooding, it by far outweighs most of the other summer severe weather events.

Just what is a heavy or extreme rainfall event? According to Environment Canada rainfall warnings are issued according to the following criteria.

If it is going to be a short duration event, such as a thunderstorm, you need to expect upwards of 50 mm of rain in one hour before a rainfall warning will be issued, at least across the Prairies. It is actually lower over the east and west coasts. While this might not make sense at first, if you think about it, they rarely get the intense thunderstorms that the inland areas of Canada receive.

If the rainfall event is expected to be a longer-term event, then the criterion for a warning is when 50 mm of rain is expected within 24 hours or 75 mm of rain is expected within 48 hrs. Sometimes, due to the nature of summer storms, you can have both types of warnings going on at the same time.

If you listen to or read the news over the last couple of years, there has been plenty of talk connecting extreme rainfall events and global warming. It is not just the air temperature that is getting warmer but also the oceans. Combine warmer oceans with warmer air and you get an increase in atmospheric moisture levels, or humidity. This does not mean we will always see higher humidities but it does mean that the atmosphere can hold more water vapour and will receive more water vapour.

All this water vapour must go somewhere. If you remember the water cycle, the moisture in the air will eventually fall in some form of precipitation. The more water vapour available, the greater the chance the precipitation falling will be an extreme event.

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