Category: Forecasts

Beautiful Weekend Ahead

Brad Leave a comment

The massive warm-up alluded we discussed on Wendesday is in full swing with warm air aloft surging over Southern Manitoba. Rapid snow melt and swelling rivers will be the name of the game this weekend as temperatures soar into the mid-to-upper teens with overnight lows dipping only into the mid-single digits.

Friday

11°C / 0°C
Mainly sunny.
Saturday

16°C / 7°C
Mix of sun and cloud.
Sunday

15°C / 0°C
Slight chance of a morning shower then clearing.

Today we’ll see the warmest day of the year so far here in Winnipeg with temperatures climbing towards the low teens this afternoon under mainly sunny skies. Winds will be out of the southwest at about 20km/h. This warmth is thanks to a southwest flow that has developed aloft which has displaced the northwest flow that has been locked over us for far too long.

850mb Temperatures from the GFS

850mb temperatures for Saturday night from the GFS model.

Temperatures at 850mb[1] are forecast to push towards 12–14°C over the weekend, almost 20°C warmer than the temperatures at 850mb over Winnipeg on Wednesday morning. Typically temperatures that warm would result in daytime highs approaching 20°C but our extensive snow cover over the Red River Valley will drag temperatures down somewhat. The big question mark is to what extent the snow cover will be able to maintain the layer of cold air near the surface, especially since winds aren’t expected to be too strong. The snow should be able to hold our temperatures back the most today; the warm air will still be working it’s way in and the winds will be fairly light through the lower levels; our high of 11°C will probably be reached later in the afternoon in most places.

By Saturday, though, the warm air will be surging into Southern Manitoba and not even the snow-cover will be able to hold our temperatures back. Many models have the temperature up to nearly 15°C by lunch on Saturday. Temperatures won’t climb too much above that, but assuredly that will dramatically impact the remaining snowpack over the Valley. If we can reach that temperature so early in the day, it’ll be almost a guarantee that little to no snow will be left over in the Valley by the end of the weekend.

With such warm temperatures aloft on the weekend, our overnight low will only dip to around 7 or 8°C on Saturday night. There will be a very slight chance of a shower or two on Sunday morning as a low pressure system passes to our north; the temperature should be able to climb back up to around 15 or 16°C before a cold front pushes through drops our temperature back towards around 12°C in the afternoon.

Next Week

Next week looks a little unsettled; we should see another warm day on Monday and Tuesday as a warm return flow sets up ahead of another low pressure system. That system currently looks quite strong. The GFS is forecasting for it to move through on Tuesday into Tuesday night and will likely bring snowfall warnings through portions of Northern Manitoba while some rain moves through the Red River Valley long the cold front late Tuesday. This system will usher in cool air which will drop us back into a below-to-near-normal regime, but not nearly as bad as of late. Daytime highs through the second half of the week look to sit near 8°C. We’ll see how things develop; one thing is for sure, though: the massive erosion of snow cover this weekend will make it substantially easier to warm up from here on out!

  1. About 1.5km above sea level.  ↩

Massive Warm-Up On The Way

Brad Leave a comment

After what will be going down in the record books as one of the coldest, if not the coldest, April on record, the weather is poised to dramatically shift gears. After being stuck in “March” for far too long, it looks like we’re poised to skip right over “April” and shift into “May” in very short order.

850mb Temperatures for Saturday Morning from the GFS

850mb temperatures from the NAM show temperatures approaching 15°C advecting into Southern Manitoba on Saturday morning.

Southern Manitoba has been locked in March-like weather temperatures routinely 8–12°C below normal as a persistent northwest flow aloft has continually reinforced the Arctic air mass sitting over the region. This has led to some impressive new records including the latest date in the year that Winnipeg[1] has hit it’s first +5°C temperature. This has led to a substantial snowpack remaining through the Red River Valley and we’re on our way to the latest flood peak for the Red River; in Winnipeg the Red is expected to peak in late-May, 1–2 weeks later than the previous latest-peak on record which was May 19, 1950.

We’re set to bust out of the cold, though, as a huge shift in the upper-level pattern is on the way.


2°C / -10
Scattered flurries in the morning. Mix of sun & cloud.

Today will continue our trend of cool weather as yet more cold air will be descending southwards through the province. A cold front will pass through Winnipeg in the morning and through the Southern Red River Valley in the afternoon. The cold front will likely have some scattered flurries along it as it pushes through in the morning and then develop more organized, heavier convective flurries along it in the afternoon, south and east of Winnipeg. There will be a very slight chance of some light flurry activity behind the cold front, but that will be minimal as the atmosphere quickly stabilizes behind the front despite daytime heating. Skies will clear out through the afternoon and we’ll be headed to a chilly –9 or –10°C tonight.

Thursday & Friday

A huge change is on the way for the end of the week. The high over low block we mentioned last week will finally break down as the cold low associated with the feature ventures towards the Central Plains of the United States. The upper ridge begins to collapse over the Eastern Pacific and the upper flow rapidly breaks down and becomes zonal, dramatically shifting storm tracks. By Wednesday evening, a new low will already be moving into Northern Alberta. Over the past few weeks, stuck in a northwest flow, such lows would generally slice SE through Saskatchewan and push into the States before reaching Manitoba. Under this new flow regime, though, this low will push through Central Manitoba instead, helping pull warmer air into southern portions of the province. Just how warm, you ask?

Thursday

8°C / -2°C
Mainly sunny.
Friday

15°C / 3°C
Sunny.

Temperatures will soar over the next few days as warm air that not even the snowpack can fight against floods it’s way northward. We’ll see temperatures climb to 7 or 8°C Thursday as the southwest flow sets up and the warm air is able to start pushing into Southern Manitoba and then see temperatures be close to double that on Friday as we get deep into the warm air. No precipitation is expected either day.

Long-Range

It looks, more or less, like warmer air is here to stay. Warm air will continue to build into the province through the weekend pushing temperatures closer and closer to the 20°C mark. We’ll likely have a couple nights with lows well above 0°C. A disturbance will return cooler air to the province at the start of next week, but it’s not expected to stick around for too long.

Flood Concerns

Flooding concerns will arrive en masse with the warmer weather. The dramatic and intense warm-up, combined with a high likelihood of overnight lows above 0°C this weekend mean that the remaining snowpack will undergo rapid melting. Some overland flooding should be expected, and anybody living near rivers or streams should expect them to swell quickly this weekend into the beginning of next week. In Fargo, the Red River is expected to rise from 20’ on Friday night to around 32’ by Monday morning. The Red River isn’t expected to peak in Winnipeg until late May, but one thing is for sure: the water will be flowing by the end of the weekend all over the Red River Valley, so be sure to take adequate precaution when around swollen rivers or streams.

  1. The observing site CYWG at the Richardson Int’l Airport.  ↩

Week to Start Cool, but is Spring Coming?

Brad Leave a comment

This week will start out well below normal, but there are signs that we may begin to warm up towards week’s end. Is Spring finally set to arrive?

Monday and Tuesday

Monday
image
Mix of sun and cloud. Chance of flurries.
-3°C / -8°C
Tuesday
image
Mainly sunny.
2°C / -8°C

Monday will be a cold day by April standards. High temperatures are generally not expected to exceed the freezing mark in Southern Manitoba (except in cities and forests), which will make the day some 15 degrees below our normal high of 13C. There may be some isolated flurries on Monday, as weak low-level instability develops during the day.

Tuesday will be a bit warmer than Monday, but not by much. Temperatures should climb just above zero in most areas, but that will still put as well below normal.

Wednesday

Wednesday
image
Mainly cloudy. Chance of flurries.
2°C / 2°C

Wednesday should be another above freezing day in Southern Manitoba, but we could see more snow as well. Flurries look to plague us for much of the day as the atmosphere once again destabilizes behind a passing weather system. Accumulations look to be minimal, but I doubt that will make the snow any more pleasant.

Long Range

image

Forecast high temperatures on Friday

There are signs that we may finally see a return to near normal or just below normal conditions by late this week or into the weekend. Models are in fairly good agreement that temperatures will rise up into the high single digits or low DOUBLE digits by later in the week/weekend. Of course we have seen forecasts like this fall apart before this spring, but hopefully this time things will be different.

Pleasant Weekend With Stormy End

Brad Leave a comment

Although temperatures will remain well below normal, we’ll see a pleasant weekend ahead when compared to the weather we’ve had as of late.

Friday

4°C / -14°C
Sunny.
Saturday

2°C / -4°C
Increasing cloudiness in the afternoon.
Sunday

2°C / -3·C
Cloudy; rain or snow beginning midday.

The next two days will be fairly nice despite the cool air that remains entrenched over the province. Both Friday and Saturday will provide plenty of sunshine and daytime highs climbing a few degrees above zero. We should see substantial snow-melt here in Winnipeg over the next two days thanks to that increasingly strong April sun. We’ll see a cooler night tonight as winds lighten up allowing us to radiate more heat away than the past couple nights. Temperatures will likely drop into the minus teens tonight while cloud cover will keep us substantially warmer on Saturday night.

Stormy Sunday

Precipitation totals for the daytime period on Sunday from the 00Z April 19 GDPS model.

For Sunday, an Alberta Clipper will make it’s way across Southern Manitoba and while many aspects of the system look to be relatively innocuous, it looks poised to pack a punch precipitation-wise. Snow will push into the Red River Valley midday, but the afternoon brings a particular challenge. Warm air will be advected northwards in the southeast flow ahead of this system, slowly warming the lower-levels of the atmosphere. Some indications are that preciptiation will switch over to rain in the afternoon, especially for the central Red River Valley and areas eastwards. It’s a very challenging problem and the phase of the precipitaiton will make a significant impact: around 10mm of liquid-equivalent precipitation and if it ends up falling as snow, that could quickly amount to another 6-10cm of the stuff. It’s almost a certainty that areas east of the Red River Valley will see mainly rain and areas west of the Red River Valley will see mainly snow.

At this point I think we’ll end up seeing a mix here in Winnipeg, with predominantly snow in heavier areas of precipitation. I’m not going to wager too much on accumulations right now; it’s likely that much of the snow will melt on contact with the ground as temperatures will likely remain just over the freezing mark. The system will move off overnight leaving clearing skies on Monday morning.