Sunday, September 14, 2014

Warming trend this week

After an early taste of fall like weather, temperatures will be returning to more normal values this week over southern Manitoba as a large cool airmass pushes east out of the Prairies. In its place, a moderating trend will become established over much of the Prairies as a zonal upper flow develops, allowing milder air from western Canada to spread east across the Prairies into southern Manitoba. This will allow temperatures to climb into the upper teens over the next few days and lower 20s later this week, which is near or even a bit above normal for this time of year (normal high for Winnipeg is now 18C)  High temperatures Wednesday may dip into the mid teens as we get sideswiped by a cold front pushing through the Interlake into NW Ontario, but then temperatures should rebound quickly for late week into the weekend and next week.  In addition, the weather should remain generally dry this week over southern Manitoba until Friday when a system will bring the next main threat of showers. The upcoming warmer and drier weather pattern will be most welcome by farmers looking to ramp up harvesting activities after an unsettled first week and cool second week of September.  

8 comments:

  1. "Backdoor" cold front has slipped through Winnipeg and northern RRV this afternoon as very cool airmass over northern Manitoba pushes into Interlake, This airmass is currently producing snow in Flin Flon today with afternoon temperatures only in the low teens over the Interlake. We're going to get sideswiped by this airmass tonight into Wednesday, as the coldest core pushes into NW Ontario.. so look for high temperatures only around 13-15C Wednesday for Winnipeg.. cooler to the NE of us and warmer to the SW where the cool outflow will be weaker. Temps rebound again for Thursday back into upper teens/low 20s.. then mid 20s possible Friday as we warm sector with low pressure trough moving across. Cooler on Saturday and then another rebound next week, with temperatures rising back into the 20s. Nice outlook! Sure hope it pans out!

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  2. We're well into that cold airmass today with single digit temps this morning, overcast skies and a NE breeze. Satellite imagery shows an extensive deck of low level cloud covering all of southern Manitoba into eastern and central SK, a common feature with these back door cold fronts in the fall. Hopefully, we can get some breaks in the cloud cover this afternoon, but often these clouds don't clear out until we get a more southerly or westerly wind. If so, don't be surprised if these clouds hang in all day into tonight before clearing out overnight. Looking much better tomorrow with southerly winds flushing out that cold air we're getting today and temps rebounding back to the 20C mark.

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  3. Area of low clouds finally eroding.. with SW portions of the city starting to warm up a bit. Overall, very bad timing.. with highs not even reaching double digits - temperatures do not have far to drop to near freezing.

    As such, a tricky forecast for overnight lows. Flow turns SE around midnight and starts advecting 7-10 C dewpoints just south of the border. If clearing does occur - areas with sandy soils east of the RRV stand a chance of seeing near freezing to below freezing temperatures around 12- 2 am. Will have to monitor cloud trends until sunset, and for redevelopment as low level moisture starts creeping north again in the latter part of the overnight period.

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  4. Cloud band lifted north of the city relatively early in the night.. leading to extensive near to slightly below freezing temperatures over SE Manitoba back into the western RRV. Only areas of the southern interlake were spared likely due to lingering cloud, along with urban areas like Winnipeg.

    Not to be negative, but EC unfortunately did not have a good handle on the forecast. Given the much cooler than expected afternoon temperatures, the steady erosion of low clouds, and only weak warm advection progged.. the potential was at least there for radiative cooling to overcome any moisture return and yield below freezing temperatures in some areas.

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    1. Actually EC did issue a frost advisory last evening at 9:45 pm for areas north and east of Winnipeg to the Ontario border, and added a risk of frost elsewhere. Perhaps it was a bit late.. but they did jump on the frost potential once they were satisfied the low cloud was clearing out. Luckily it wasn't a major freeze. No frost tonight though! Gusty winds and clouds keeping us in the double digits all night, along with a threat of showers and maybe even a thunderstorm in spots!

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    2. Yeah, dewpoints a bit too high, and just enough wind to keep temperatures from dropping appreciably below zero in the RRV, a bit colder to the east.

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  5. Good drying noted behind main wave and area of steady rain.. but a trailing disturbance off the our NW is generating an area of showers around Dauphin that will likely drop down over us before dark.

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  6. Cloudy skies and fog patches this morning will give way to sunny periods this afternoon with a gradual clearing trend by evening. Then the rest of the week is looking fabulous with mainly sunny, warm and dry conditions and temperatures in the mid 20s! Great start to fall!

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