Last week’s forecast was pretty spot on for the first half, but things started to fall apart over the last few days. To give the weather models some credit, they stuck to their forecast of warm weather during the first half of the week for a long time before a last-minute switch, thanks to weaker-than-expected Gulf of Alaska lows.
For this forecast period, it is going to be a battle between strong ridging to our west and a deep trough of low pressure to our east. If we go with history on this type of setup, the colder trough will probably win out. With that said, here is what the weather models are forecasting.
Starting on Wednesday, Sept. 30, the weather models show a very strong area of low pressure winding up over James Bay. The counter-clockwise flow around this low will help to open the door for arctic high pressure to dive southeastward. For our region this will mean partly to mostly cloudy skies on Wednesday with the chance of afternoon showers, especially over eastern areas. This will then transition to sunny starts to the day with afternoon clouds from Thursday to Saturday. Temperatures will be seasonable, but will feel cool with moderate northerly to northwesterly winds. Expect daytime highs to be around 14 C with overnight lows around +3 C.
By Sunday or Monday, we may see a short warm-up as a weak area of low pressure crosses the central Prairies. Unfortunately, behind this low, another arctic high is forecast to drop southward, bringing cooler temperatures, with daytime highs forecasted to be in the 10 to 12 C range and overnight lows falling into the 0 to -3 C range. Looking further ahead, the models are hinting that the western upper ridge will push eastward for the Thanksgiving long weekend, bringing sunny skies and nice warm temperatures.
Usual temperature range for this period: Highs, 10 to 21 C; lows, -1 to +8 C.