Friday, April 08, 2016

Windy, cool, unsettled weekend.. then FINALLY!.. pattern change to warmer weather beginning next week

500 mb pattern so far in April has featured a stubborn
Arctic vortex and trof over Hudson Bay into Great Lakes
It's been a cold start to April across much of central and eastern North America with a persistent pattern of below normal temperatures and occasional snowfall since the beginning of the month. A stubborn Arctic vortex and long wave trof digging unseasonably deep into the eastern US has been responsible for the winter like start to April over southern MB and Ontario, while the western Prairies and west coast have basked under above normal warmth.  This pattern will remain in place over the weekend as another clipper system tracks through southern MB and reinforces cool air behind it, but there are finally signs that this stubborn pattern will be changing by the middle to end of next week bringing more seasonable, and even above seasonable temperatures to southern MB.

Surface prog valid Saturday evening shows next
clipper system tracking through interlake region
But first, we have to get through this weekend which will feature another clipper system tracking through southern MB bringing strong southerly winds and a chance of snow ahead of it on Saturday, some rain or snow Saturday night, then blustery and cool conditions Sunday. Model guidance is indicating this clipper system will track north of Winnipeg through the Interlake region this weekend, bringing heavier snow accumulations of 10 cm or more through the northern Interlake and central MB. Further south, Winnipeg/RRV will see a band of light snow moving through ahead of the system Saturday morning along with strong south to southeast winds gusting to 70 km/h by midday and afternoon. Temperatures will only struggle to +4C or so, still below normal for this time of year (normal highs now +8C) and feeling even cooler with those strong winds. As the clipper system tracks through the interlake Saturday night, scattered rain or snow showers are expected over southern MB with steadier snow through the northern interlake regions. On Sunday, blustery NW winds will bring in a reinforcing shot of below normal temperatures again over southern MB along with occasional flurries or snow, and afternoon temperatures only around +2C or so.

CPC outlook for Apr 14 -19 finally gives hope for
a return to warmer weather over southern MB
The good news is that this weekend storm system should finally be the last of the clipper systems for a while with a trend to warmer and more settled conditions next week. Below normal temperatures but dry conditions are expected over southern MB for Monday and Tuesday, but then a long awaited pattern change is expected to bring in warmer air by Wednesday with near seasonal temperatures, and even above normal temperatures in the mid to upper teens possible by the end of the week into next weekend.  So hang in there folks... warmer weather is on the way!

8 comments:

  1. Hey Rob, GFS model is now showing another storm system that could affect us next weekend with snowfall. Thoughts? I really dislike and doubt that this will happen.

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    1. At this point, it looks too warm for any precip next weekend to fall as snow over us.. but a significant rainfall is possible. Unfortunately, long range models are starting to show that our long awaited warmup late next week may be a wet one as a frontal boundary sits over southern MB and waves of precip run along it Friday and Saturday. Warmest air would be shunted south over North Dakota, while we stay on the wet and cool side north of the frontal boundary. Hopefully models back off on that scenario and shift that frontal boundary further west, but at this point, it's starting to look like our warmup later this week won't be as warm or dry as first hoped.

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    2. The good news is that models show us rebounding nicely after Saturday, with dry weather and above normal temps again by early next week.. so hopefully, that Friday/Saturday setback is a temporary blip on an otherwise overall warming trend into next week.

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  2. Terribly frustrating April so far.. unseasonably cold for the first 11 days, then when we finally get into a warmer pattern, we get drenched with rain along a stalled front that keeps the warmest air to our south. Can't seem to win this month. Hopefully pattern smartens up for the latter half of April and gets us into a nice May. Seems like we rarely get dry warm spring patterns here anymore..

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    1. What really annoys me is that southern MB will yet again find itself in the transition zone between two contrasting airmasses over the continent. Up to now, the warmer air has been west of us with colder air to the east.. no benefit for southern MB in the transition zone between the two. Now we have a pattern change coming up with the warmer air shifting east into Ontario, while cooler air settles over the west. But once again, the transition zone between these two airmasses is right over southern Manitoba, with no benefit for us (except more unsettled variable weather). Is it too much to ask for a blocking pattern that favours southern MB?

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  3. Friday looking interesting.. models agreeing that there will a sharp warm frontal zone extending across southern MB from western ND into NW Ontario. Trouble is, they disagree where this front will end up across southern MB, which will mean the difference between a warm 20C day south and east of the front, to a cool wet 7C north of it. General consensus is that the front will end up somewhere from the Modern area through Winnipeg to Pinawa with a sharp thermal gradient across it, and most of the rain along and northwest of the frontal zone. This means the southern RRV and SE MB have the best chance of seeing warmer and drier weather Friday (possibly 20C), while SW MB and the interlake will be cooler and wetter.

    Winnipeg is close to the frontal zone, so watch for big swings in Friday's forecast as models try to resolve the position of this frontal zone across southern MB.

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  4. Models such as the NAM are now also hinting at thunderstorms for the day Thursday overnight into Friday for the Winnipeg area. Thoughts??? https://spotwx.com/products/grib_index.php?model=nam_awphys&lat=49.90983&lon=-97.23655&tz=America/Winnipeg

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    1. Thunderstorms certainly possible in this setup.. good southerly low level jet riding over warm front across the MB/ND border tapping some good moisture south of the border with dewpoints in the low teens. That may be what is driving the areas of heavy rain on the long range models late week.

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