Category: Forecasts

GFS Forecast Precipitation Type/Rate valid 06Z Thursday October 26, 2017

Mild Fall Temperatures On The Way Out

Brad Leave a comment

The first half of the week will bring seasonal conditions Winnipeg, but the writing is on the wall: a big pattern shift will usher in significantly cooler conditions for the second half of the week and into the next.

The cooler weather begins to arrive today in Winnipeg, drawn southwards across the province behind a low pressure system that passed through overnight. A few remaining showers and cloud will clear out this morning, leaving Winnipeg with mixed skies for the afternoon. Winds will be fairly breezy out of the northwest as a ridge of high pressure builds into the province; light morning winds will build to 40 gusting 60 km/h for the afternoon. Temperatures today will barely budge from this morning, remaining steady near 6 or 7°C through the day. Expect partly cloudy skies overnight with winds diminishing to around 20-30 km/h and a low dipping down to the freezing mark.

Tuesday will be a pleasant and crisp fall day with plenty of sunshine and a high near 9°C in Winnipeg. Winds will be much calmer out with a morning breeze out of the northwest at around 20 km/h diminishing to light midday. Some cloud will spread into Winnipeg later in the afternoon, announcing the approach of the low that will usher in a dramatic change in the general weather pattern.1 Temperatures will drop to a low near 4°C overnight as northwesterly winds move back in and usher cooler air into the region once again.

RDPS 2m Temperature Forecast valid 00Z Wednesday October 25, 2017
A low pressure system moving across northern Manitoba will draw warm air eastwards into the southern half of the province for Wednesday.

Wednesday will be the last day of mild conditions before things take a dive on Thursday. Temperatures will climb to a high near 10°C as skies become cloudy for the afternoon. Northwesterly winds around 15-25 km/h in the morning will taper off to light for the afternoon. As the low pressure system begins pushing into Manitoba in the late afternoon, the chance for showers will increase as an area of rain slumps southeastwards from central Saskatchewan. Temperatures will dip to a low near 2-3°C early Thursday morning as rain moves in overnight.

Long Range Outlook

Thursday looks rather unpleasant with rain likely changing over to snow in the morning as significantly colder air floods southwards behind a strong low moving across southern Manitoba. Temperatures will reach a high in the low single digits with a brisk northerly wind – likely reaching 40-50 km/h – as the snow tapers off in the afternoon.

GFS 850mb Temperature Forecast valid 00Z Thursday October 26 to 00Z Friday October 27, 2017
This animation of 850mb temperatures – approximately 1.5km above the ground – very clearly depicts the colder air moving into the region through the day

The remainder of the week looks quite cool with highs in the low single digits and overnight lows dipping below the freezing mark each night well into next week. The one saving grace will be the cloud cover, ranging from mixed skies to overcast, that will help moderate the temperatures from getting too cold.

This pattern of cooler conditions will continue through much of next week as a persistent west-coast ridge, eastern Canada trough pattern sustains a generally northwesterly flow over the eastern Prairies.

Winnipeg’s seasonal daytime high is currently 7°C while the seasonal overnight low is -3°C.

  1. Some cloud will likely be around in the Red River Valley through much of the day as it comes off of Lake Manitoba and Winnipeg in the northwest wind. Whether Winnipeg sees any of it will depend on the exact wind direction, but it will likely remain outside the city. ↩

Potential Record-Breaking Warmth Friday Leads Into A Seasonably Mild Weekend

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Temperatures will soar into the low 20’s today and challenge a long-standing daily record high . Temperatures will then cool for the weekend as a low pressure system tracks through the region, but will still remain seasonably mild with daytime highs in the mid-teens.

Today will be a gorgeous day with temperatures soaring towards record values as very mild air – shown well by 850 mb temperature anomalies of 15 to 20°C above seasonal – moves into southern Manitoba. This mild air is being drawn northwards by a broad area of low pressure strengthening over Alberta. In addition to the warmth, strong southerly winds will develop across the Red River Valley today, reaching a peak near 40 gusting to 60 km/h through the afternoon.

850mb temperatures are forecast to be over 15°C above normal over southern Manitoba.

The southerly winds and mild temperatures aloft will result in daytime highs climbing into the low 20’s today; in Winnipeg, the high should reach 23°C, or perhaps a tad warmer, challenging the current record daily high of 23.9°C set in 1958. Clouds will build into the region through the day, going from sunny skies this morning to mixed skies this afternoon. Tonight should bring variable cloudiness and a low near 15°C. While the overnight low will likely remain higher than the record warmest daily minimum temperature of 12.2°C set in 1953, Winnipeg won’t break a record due to this morning’s chillier low near 7°C.

Winnipeg will see more cloud on Saturday with mixed skies in the morning giving way to mainly cloudy conditions in the afternoon as a low pressure system moves through. Temperatures will be cooler than Friday, but still much warmer than seasonal as highs climb to around 18 or 19°C. Southerly winds of 20 to 30 km/h wills shift to the west-southwest behind a cold front pushing through in the morning. There will be a chance of showers along the cold front as well as a bit later in the afternoon, but at this point it looks like the odds are relatively low. Winds will persist at 20 to 30 km/h overnight as temperatures dip to a low near 6°C.

Several American models show the potential for a few isolated showers on Saturday across southern Manitoba.

Sunday will bring some sunshine back to Winnipeg with any remaining cloud from Saturday’s system clearing out in the morning. Temperatures remain warmer than seasonal with highs near 15 or 16°C as winds shift back to the south ahead of yet another low pressure system zipping across the southern Prairies. Cloud will begin to build back in through the afternoon with a slight chance of showers returning Sunday evening into the night. Lows will dip down to around 7°C.

Long Range

Next week will kick off with a return to seasonal temperatures with northwesterly winds predominant through the Monday and Tuesday. The remainder of the week looks like a bit of a temperature rollercoaster with unsettled conditions, however details remain fuzzy at this point. That said, it looks like much of the week will bring variable cloudiness and a few chances for rain (or snow!) as the storm track slumps southwards.

Winnipeg’s seasonal daytime high is currently 9°C while the seasonal overnight low is -2°C.

Potent Fall Storm Brings Strong to Severe Winds to Winnipeg

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Strong to severe westerly winds will be out in full force today behind a cold front now pushing into Ontario. These winds are being created by a very potent fall storm over Northern Manitoba which is also bringing up to 25 cm of snow and blizzard conditions to the most northern regions of the province. The remainder of the week looks beautiful, however, with temperatures rebounding quickly back to well above-seasonal values.

Early morning cloud will quickly push eastwards this morning as very strong westerly winds move into the Red River Valley behind a cold front racing eastwards into Ontario. While skies will be sunny, it won’t be a particularly pleasant day out there as winds quickly increase to 50-60 km/h with gusts of 85-95 km/h. Winds will be just a bit lighter to the south of Winnipeg and a bit stronger to the north of Winnipeg. There will be a few areas that may see wind gusts in excess of 100 km/h: areas just downwind of the Riding Mountains and the Turtle Mountains, the Manitoba Lakes (Manitoba, Winnipegosis, Winnipeg), and across portions of the southern Interlake. These strong to severe winds will diminish quickly in the evening hours as temperatures cool and the low pushes off to the northwest.

RDPS Forecast 10m Wind Speed valid 18Z Wednesday October 18, 2017
Strong to severe (darker purple, red) westerly winds will move across southern Manitoba today behind a cold front associated with a potent fall storm moving through northern Manitoba.

All in all, about 9-12 hours of strong to severe winds are expected, so it will not be surprising if damage to buildings occurs. While the sustained winds may be below the EC³ warning criteria, once winds reach the 60 km/h, the stress incurred on buildings across numerous hours can cause structural failures. Hopefully the worst will just be some missing shingles, but recalling the May 18, 2015 wind storm, significant damage can occur with gusts to 90+ km/h. In that storm, winds were over 50 km/h for 20 hours, which we won’t see this time, but the strongest winds occurred in a 6-hour stretch where winds were maintained in excess of 60 km/h. While this isn’t the same storm, and thus we can’t expect the same outcome, it’s entirely possible that we may see damage that looks familiar.

So, other than the wind, temperatures will fall to around 13°C today as cooler air surges in from the northwest. That said, I don’t think there’s any room for complaints when temperatures remain above-seasonal behind a cold front in October. Lows will dip down to around 3°C with light winds and just a few clouds.

Tuesday will be just a tad breezy by comparison, as another warm front pushes into the region and brings southerly winds of 20 gusting to 40 km/h. Temperatures will climb to a high near 18°C under partly cloudy skies. Winds will remain out of the south at 20-30 km/h on Thursday night as skies become mixed and temperatures dip to a low near 8°C.

GDPS Forecast 2m Temperature Anomaly valid 00Z Saturday October 21, 2017
Temperatures will climb around 15°C above seasonal values on Friday as another surge of very mild air pushes through the province.

Friday will be a late-season “scorcher” in Winnipeg. Despite mixed skies, temperatures will soar to a high near 21°C on Friday afternoon. While we probably won’t be challenging the record high of 23.9°C set in 1958, it may end up coming close if we get enough sunshine. Winds will once again be in place out of the south at 30-40 km/h with some gustiness on top. Expect a low near 13°C on Friday night with winds continuing out of the south to southwest and increasing cloudiness.

Long Range

A second low pressure system will move through Friday night into Saturday, bringing more cloud, cooler temperatures, and a slight chance of showers on Saturday afternoon. While there may be some clearing on Saturday evening/night, more cloud is expected to move in on Sunday ahead of the next low pressure system cross the Prairies. Temperatures will remain above-seasonal throughout the weekend, but after a cold front pushes through on Sunday evening, a west to northwesterly flow will set up for the next few days, bringing seasonal temperatures back to the region.

The extended forecast looks relatively dry, but one wildcard is Saturday and Sunday. Overall, it seems models have having a hard time resolving exactly what kind of low will move through the region, the timing of it, and how much precipitation it will produce. Some models produce little rain with the low coming through — the GFS has essentially no precipitation for much of the Red River Valley — others, such as the GDPS, produce as much as 10-15 mm of rain. The solutions seem to be flipping around quite a bit right now, so it’s hard to pin down exactly what to expect. We’ll certainly be keeping an eye on it and have more details in Friday’s forecast.

Otherwise, next week looks like it will bring variable cloudiness to Winnipeg and the Red River Valley with the occasional chance for some rain showers.

Winnipeg’s seasonal daytime high is currently 9°C while the seasonal overnight low is -1°C.

Dry and Mild Conditions Ahead

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A series of low pressure systems tracking along the 60th parallel will spread mild Pacific air eastwards over the Prairies throughout the week, bringing warm and dry weather to Winnipeg for much of the coming week.

Breezy south-southwest winds of 20 km/h strengthening to 30 gusting to 50 km/h westerlies will bring above-seasonal high temperatures near 16°C to Winnipeg today as another warm front pushes across the Red River Valley. The front will bring partly cloudy to mixed skies in the morning, giving way to more sunshine in the afternoon. The clouds will completely clear out tonight as the winds taper off. Temperatures will dip down to a low near 4°C.

Even warmer temperatures are on the way Tuesday as even milder air pushes eastwards across the Prairies. Winnipeg and the Red River Valley can expect daytime high temperatures in the 18-21°C range under mainly sunny skies, but a moderate south-southwesterly wind of 30 gusting to 50 km/h will develop for the afternoon hours. These winds will persist into Tuesday night in the 20 to 30 km/h range as temperatures drop to a low near 9°C under partly cloudy skies.

GDPS Forecast 850mb Temperature Anomalies valid 00Z Wednesday October 18, 2017
Seen easily in this 850mb temperature anomaly forecast for Tuesday evening, significantly warmer-than-normal temperatures will be moving through the southern Prairies.

Slightly cooler temperatures return for Wednesday as a cold front sweeps through the Red River Valley early in the day, ushering northwesterly winds of 40 gusting to 60 km/h that will draw cooler air back into the region. Temperatures will reach a high in the low teens under partly cloudy skies. The “cooler” weather will be short lived, though, as another warm front pushes into Manitoba Wednesday night. This will bring more cloud to the region and keep overnight lows slightly warmer than Tuesday night at around 5°C.

Long Range

The remainder of the week looks quite warm with temperatures climbing back towards 20°C by the end of the week as yet another surge of mild air spreads eastwards across the Prairies.

GDPS Forecast 850mb Temperature Anomalies valid 00Z Wednesday Friday 20, 2017
An even warmer surge of mild air will return to southern Manitoba on Thursday into Friday

Slightly cooler conditions will move in for the weekend, as a disturbance moves through and brings a chance of showers, but temperatures are expected to remain above-seasonal until early next week.

Winnipeg’s seasonal daytime high is currently 10°C while the seasonal overnight low is -1°C.