Major Cool Down Begins

A significant change in the weather is underway today as Arctic air blasts southwards, pushing out the pleasant, above normal temperatures we’ve had lately and replacing it with cloudy, cool, windy weather. I hope you enjoyed the last few days, because you probably won’t enjoy the next few.

850mb Temperatures from the GFS

850mb temperatures valid this morning from the GFS model. Warm and cold fronts are depicted.

A cold front, tied to a powerful low pressure system moving through central Manitoba, swept across the Red River Valley overnight, ushering out the warmer temperatures aloft that have given us pleasant temperatures the past few days. In it’s wake is a dramatically different pattern than we’ve seen lately.

Upper troughing will dominate the Prairies as a secondary low, currently spinning up over Montana/Wyoming tracks eastwards and pulls more cold air southwards. This will establish us into a much cooler pattern where cooler, Arctic air is entrenched over the region and it’s significantly harder for us to get those nice warm breaks.

Today we’ll see winds begin to pick up out of the north as temperatures climb to only around 13°C. We’ll get cloudier as the day goes on, and by the late afternoon into the evening some showers will push into the southern regions of the Red River Valley. Further north, we’ll see a chance of showers, however it will be more difficult for any organized precipitation to develop over the northern Red River Valley.

As the aforementioned US low tracks through South Dakota, winds will shift to the north-northeast over the RRV, which when combined with the cooler air being dragged southwards, will bring lake-effect showers into the central Red River Valley. Current model solutions hint that Winnipeg may be in the path of these, however, as usual, the exact wind direction will be crucial in determining where the showers will fall. Temperatures will drop to around +3°C tonight.

Thursday will be a cool day, with northerly winds persisting, cloudy skies and a high of only 7 or 8°C. Lake effect showers will persist in the lee of the lakes, and scattered showers will likely be found throughout the entire Red River Valley. Cold air continues to pour southwards and we’ll drop to near 0°C. Precipitation is…complicated for Thursday night. The GEM-GLB & GFS models are forecasting only around 5mm of rain for Thursday evening over SE Manitoba, including the Steinbach region. Other models, such as the NAM, have a much worse forecast. The NAM spins up the low over the states into a very powerful storm system, which taps into some Gulf moisture over the east-central States and lifts it northwest and slams it into a deformation zone oriented north-south over the Red River Valley. In this outcome, 1-2 inches of precipitation is forecast to fall, some as rain, however much of it as snow. Should we believe the NAM, it would result in many communities east of the Red River waking to find over a foot of snow on the ground! Ensemble forecasts suggest that this is an outlier; most solutions favour a quicker track to the low with less precipitation over the Red River Valley. We’ll keep a close eye on this as it develops, but you should be prepared for the potential for poor travelling conditions on Friday.

Things calm down on Friday as this system leaves the region and we’ll be left with cloudy skies and a high around 10°C. Things look to improve a little bit for the weekend (e.g. we may see the sun), but temperatures will remain locked in the high single digits to low teens as cold, arctic air remains entrenched over the region.

Two More Nice Days

A couple more nice days are in store for the Red River Valley before a significant change in the weather occurs for the second half of the week.

850mb Temperatures valid Tuesday Morning

850mb temperatures valid Tuesday morning showing the baroclinic wave (warm and cold front) that will be tracking into Manitoba.

The Red River Valley will see a beautiful day today as temperatures climb to the 20C mark under sunny skies and light winds. A major low pressure system will begin to track across the Prairies on Tuesday, which will bring a major weather change to us, but not before we sneak one more nice day in. Temperatures will climb into the low 20’s on Tuesday with mainly sunny skies. Winds will increase out of the south to 40km/h with gusts near 60km/h in the morning, however they’ll let up in the afternoon as a weak trough passes through.

We’ll be under the influence of this major low pressure system for the second half of the week, which will bring cold, cloudy, very windy weather. We’ll have more details on what to expect bright and early on Wednesday morning. We’ll also have a complete summary of September’s weather within the next week. I hoped to have it ready for today, however circumstances have prevented me from being able to get it all together just yet.

Get out there and enjoy the nice weather while it lasts!

Elsewhere in Weather News: September 29, 2012

Typhoon Jelawat Forecast to Weaken Before Impacting Japan

Typhoon Jelawat remains at very strong intensity despite weakening from its previous status as a super typhoon. Earlier this week Jelawat had maximum sustained winds of 220km/h near its centre, which would classify it as a category four hurricane by north american standards. The storm currently has maximum sustained winds of 145km/h (as of Friday afternoon), the equivalent of a category two hurricane.

Satellite image of Jelawat on Thursday morning when it was heading toward Taiwan with 155mph sustained winds

Satellite image of Jelawat on Thursday morning when it was heading toward Taiwan with 155mph sustained winds. (JMA/NOAA) – via Washington Post (see sources)

Jelawat is presently located near Okinawa and is moving in a north-easterly direction toward Japan, weakening the further north it moves. According to the Japanese Meterological Agency Jelawat will impact the Ryukyu Islands, including Okinawa, today before moving toward the Japanese mainland late today into Sunday.

Jelawat's Forecast track by the JMA

Jelawat’s Forecast track by the JMA

Thus far Jelawat has not caused any devastating damage, owing to the fact that it has not yet impacted any large land masses. Some damage was reported on Lanyu (Orchid Island), located just off Taiwan’s south-eastern coast. No casualties have been reported on Lanyu, but the harbor, gas station, and supermarket were reportedly destroyed. There may be more damage as this typhoon moves over the more heavily populated Ryukyu Islands this weekend.


Beautiful Weekend Ahead

The Red River Valley will receive a second shot of summer this weekend as warm air floods over the Prairies underneath an upper ridge.

500mb Winds valid Friday evening

500mb wind speeds valid this evening. A large upper ridge will bring warm weather to the Eastern Prairies.

Temperatures aloft continue to climb as an upper ridge advances eastwards across the Prairies. As a result, we’ll see a beautiful weekend ahead across the whole Red River Valley. Sunshine will dominate the skies over the next few days as temperatures climb into the low-to-mid 20’s. We’ll see highs near 23 or 24°C across the Red River Valley today, while things will really heat up tomorrow with highs closer to 26 or 27°C. Some cloud will begin to move into our region on Sunday ahead of an incoming system, which will limit our high to the lower 20’s, probably around 22 or 23°C.

Enjoy a nice summer-like break this weekend to our fall weather.