Tag: Rain

Another Cold Snap in Southern Manitoba

Brad Leave a comment

Moderately miserable, categorically cold; the weather leading into this weekend will be fairly miserable as a large low pressure system moving through Ontario exerts its influence over southern Manitoba causing strong northwesterly winds as the coldest shot yet of Arctic air plunges southwards into the United States.

Friday
5°C / -1 to 2°C
Cloudy with showers. Flurries possible in the morning. Strong NW wind to 50km/h.

Saturday
7°C / 0–2°C
Clearing except cloudy in the lee of the lakes

Sunday
9°C / 3°C
Mixed skies with a slight chance of isolated showers or drizzle

Friday: A Miserable Fall Storm

The Red River Valley will be under the grip of a miserable fall storm lifting northwards through Northern Ontario today, driven by a massive push of cold Arctic air sweeping through Manitoba. We’ll see a very cold start to the morning with temperatures hovering around 2–3°C, strong northerly winds at 40–50km/h with gusts as high as 70–75km/h and a band of rain stretching north-south through the region. Embedded within the band will likely be some convection, significant since increased precipitation intensity could mean that in addition to the rain, we might see brief bursts of snow as well.

The precipitation should taper off by early afternoon, but we’ll still be left with a strong northerly wind and temperatures struggling to get to our high of 5°C. If the sun manages to poke out at all, we may eke out a 6°C for a high, but that looks quite unlikely.

The RDPS clearly shows Winnipeg nestled between two bands of lake-effect precipitation on Friday night.
The RDPS clearly shows Winnipeg nestled between two bands of lake-effect precipitation on Friday night.

Winds will begin to taper off tonight to around 20km/h. Combined with the cold air, the lake-effect machine will likely start up again, producing lake-effect showers or snow through the overnight period across regions in the lee of the lakes. At this point it looks like Winnipeg will remain safely between the two bands of lake-effect precipitation. The overnight low will be anywhere from –1 to 2°C, depending on exactly how much cloud remains in the area. Here in Winnipeg we should end up on the colder end of things under clearing skies.

A Chilly Weekend

It will be a chilly weekend in Winnipeg with temperatures on Saturday and Sunday both climbing only into the mid-to-upper single digits. Saturday should be a fairly nice day with mainly sunny skies in Winnipeg, but just to our west and east, lake-effect cloud (and likely precipitation) will be ruining a few people’s day. Temperatures will dip to the 0 to 2°C range Saturday night with just a few clouds. Again, lake-effect cloud will be present in the lee of the lakes.

Sunday will bring mixed skies as the whole storm system begins backing into Northern Manitoba from Ontario. Rain or snow will push through Central Manitoba into the Interlake through the day, spreading cloud ahead of it. Winds don’t look too bad this time – only around 20–30km/h – and precipitation should hold off in Winnipeg until overnight. Temperatures will drop to around 3–4°C on Sunday night, heading into a cool and showery Monday.

Fall-like Weather Returns

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After a week of summer-like weather, conditions will return to reality. More fall-like temperatures are expected this week along with some rain.

Cool conditions will dominate our weather on Monday
Cool conditions will dominate our weather on Monday

Monday

Monday
12°C / 8°C
Mainly cloudy

Today will be mainly cloudy with a chance of an isolated shower or drizzle. Low-level moisture under a strong ridge of high pressure will be responsible for the cloud. We may see some clearing late in the day, but that won’t change the day’s expected temperatures. High temperatures today will be in the low teens, with a light easterly to south-easterly wind.

Tuesday

Tuesday
16°C / 10°C
Mainly cloudy

Tuesday will remain on the cool side, with temperatures in the low to mid teens. Despite the fact that these temperatures may seem cool, especially compared to last week, they are actually near normal for this time of year. Our next chance for rain will begin on Tuesday night as a compact, but intense, low pressure system spreads rain over southern Manitoba.

Wednesday

Wednesday
18°C / 8°C
Periods of rain

The aforementioned low pressure system will be the dominant weather feature on Wednesday. It is expected to bring light to moderate rainfall to southern Manitoba for most of Wednesday. It is too early to predict how much rain will fall, but at this point 5-10 mm looks most probable.

Long Range

The long range forecast looks very fall-like. Current modelling suggests we will see normal to below-normal weather as we move into October. That means temperatures in the low teens, plus or minus a few degrees.

Mild Weather Moderating; Rain Returns Sunday

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Temperatures will remain well above normal for two more days before seasonal air begins pushing back into the province through the weekend as a cold front gradually progresses southeastwards. A chance for showers returns to southern Manitoba on Sunday as a disturbance developing in North Dakota causes the cold front to stall out over our area.

Friday
28°C / 16°C
Fog patches in the morning, then hot and humid

Saturday
26°C / 12°C
Chance of morning fog, then mainly sunny and warm

Sunday
⇘ 10°C / 6°C
Cloudy with rain likely

First the good news: after we burn off a little fog that developed overnight, today will be another beautiful, summer-like day with highs in the upper 20’s and surprisingly humid conditions for late September. Strong southerly winds at 40–50km/h with gusts as high as 70km/h will be tapping into a pool of moisture in the Northern Plains and drawing it northwards. Dewpoint values will sit near 17–19°C through much of the southern portions of the province.

Today will bring abnormally high late-September humidity to Southern Mantioba.
Today will bring abnormally high late-September humidity to Southern Mantioba.

Yesterday I erroneously tweeted that our dewpoint of 17.6°C broke the previous record of 16.8°C set in 2008 and that it had been the latest on record[1] such high humidity had been seen in Winnipeg. Rob’s Obs did a little digging and found that the actual record is still held by October 8, 1997 when the dewpoint climbed to 18.6°C. Whoops. I apologize for missing that.

That being said, today will give that record a run for its money; multiple models forecast our dewpoint to climb to 19°C, which if it happens would be the latest 19°C dewpoint on record.

Saturday will be a beautiful day in Winnipeg with a high in the mid–20’s and more comfortable humidity as a cold front gradually approaching begins flushing out some of the moisture in the region. There’s a chance of fog again in the morning and we may see a few clouds around, but the bulk of the day should be mainly sunny. Winds don’t look to be an issue.

This simulated RADAR image from the NAM shows a band of rain stretching across Southern Mantioba on Sunday afternoon.
This simulated RADAR image from the NAM shows a band of rain stretching across Southern Mantioba on Sunday afternoon.

Things change on Sunday as the cold front that was approaching on Saturday stalls out as a disturbance in North Dakota develops. A band of rain is expected to develop along the stalled out front, spreading from SW Manitoba eastwards through the afternoon until a band of rain stretches across the whole province. Temperatures will start off cool and only drop from there as the rain cools things off a little further and northerly winds at 20–30km/h continue to tap cooler air and bring it into the region. The rain should taper off late in the evening here in Winnipeg with anywhere from 5–15mm falling depending on the exact timing and speed of the system. Temperatures will dip down to around 6°C.

Unsettled Week Ahead Leading to A Cold Snap

Long-range forecasts don’t look particularly great. The first couple days of the week look seasonal temperature-wise. A series of Colorado Lows look to develop mid-to-late week which will bring a chance for showers, but more significantly, begin drawing down much cooler air from the Arctic. The end of the week looks like it will end with an Arctic outbreak bringing another shot of below-normal temperatures and brisk northwesterly winds.

  1. Records for seasonal dewpoint values go start in 1953.  ↩

Another Storm on the Way

Brad Leave a comment

Wednesday will be a brief reprieve from the showery weather before a fairly potent low pressure system spreads more rain & thunderstorm activity across Southern Manitoba tonight into tomorrow morning and brings dreary weather for Thursday with strong northwesterly winds.

Wednesday
23°C / 13°C
A few sunny breaks; rain overnight.

Thursday
19°C / 6°C
Rain and drizzle tapering off mid-day. Risk of a thunderstorm. Windy.

Friday
19°C / 5°C
Mainly sunny.

Today will be a fairly pleasant day with mostly cloudy skies and a high near 23°C or so. There’s a slight chance of an isolated shower or three through the Red River Valley, including Winnipeg, but for now it looks like the activity should mainly remain to our west over southern Saskatchewan and southwest Manitoba.

Tonight, an inverted trough extending NW from a low pressure system moving through the Dakotas will spread rain with the risk of thunderstorms eastwards into the Red River Valley. Rain will likely start sometime after 1AM and persist until mid-morning Thursday. The temperature will dip to around 13°C.

The Canadian RDPS is one of the models rather bullish on higher precipitation amounts Wednesday night.
The Canadian RDPS is one of the models rather bullish on higher precipitation amounts Wednesday night.

Rainfall totals for tonight are still uncertain; the general agreement is for between 10–20mm, however if substantial elevated convection develops as much as local amounts of 40–50mm may be possible. The low end of precipitation forecasts produce only around 5mm of rain.

I feel fairly comfortable with 10–20mm of rain tonight, but we’ll reassess the elevated convection potential later today and update if necessary. We’ll try and have an update fairly early this afternoon.

Unpleasant Thursday

Thursday will be quite an unpleasant day as Winnipeg moves onto the back side of the low pressure system lifting northeastwards into Ontario. The bulk of the rain should taper off mid-day, but brisk northwesterly winds building to 30–40km/h will accompany cloudy skies and a high struggling to climb into the upper teens. It’s also fairly likely drizzle will persist after the main area of rain moves out, making for a generally dreary day.

Skies will clear out for the evening, although there may be some cloudy periods through the first half of the night with some cloud moving off of Lake Manitoba, and temperatures will drop to a chilly 5 or 6°C.

Fall-Like Friday

Friday will be fairly pleasant, albeit cool, with mainly sunny skies and a high near 19 or 20°C. Winds will be fairly light through the day.

Friday night should bring clear skies and a low near 5 or 6°C.

A Look Ahead to the Weekend

The upcoming weekend is looking fairly good with unpleasant weather staying to our north. It’s looking like plenty of sun is in store with daytime highs in the ballpark of the seasonal 21°C mark and overnight lows moderating by the end of the weekend.