Light Snow Then A Return To Cold

Winnipeg seems to have found itself in the firm grip of winter as below-seasonal temperatures dominate the forecast. A low pressure system passing to our south today will bring snow and a slight moderation to our temperatures to near-normal values, but we’ll quickly drop back to well below-normal temperatures.

Storm-total liquid-equivalent precipitation accumulation

Liquid-equivalent (how much water there would be if you melted the snow) precipitation accumulation valid 18Z today.

A weak upper trough will swing through Southern Manitoba today, embedded within a strong northwesterly flow. While temperatures have warmed some 10-15°C aloft over the entirety of the Red River Valley, it looks like the surface warm front will halt part-way between Winnipeg and the U.S. border. Areas south of the warm front (probably areas south of Morris) will be able to tap into a southerly or even southwesterly flow, allowing temperatures to warm possibly as high as -5°C. Unfortunately for areas over the Northern Red River Valley, the warm front will likely remain well to our south, keeping our winds out of the southeast and slowly backing to northwesterly as the system passes by. These wind directions all favour the reinforcement of cold air as they tap into the colder air ahead and north of the low instead of the warmer air south of the low. That means that while there will be a slight increase in temperature from the advection (bringing in) of warm air aloft, a significant portion of the warming taking place over the Northern Red River Valley will be due to heat directed towards the surface from the clouds associated with this low. Highs north of the warm front will sit in the -12 to -15°C range.

Snow associated with this system pushed in overnight and will continue through the morning before tapering off around lunch time. Heaviest accumulations will lay north of the warm front with lighter accumulations south of the warm front. North of the warm front, including here in Winnipeg, we’ll see a total of 6-8cm of light, fluffy snow, while south of the warm front (the Southern Red River Valley) will probably only see a total of 2-4cm. There’s a slight chance that a few lingering flurries will hang on through the afternoon, but accumulations with those would be minimal should they happen.

Temperatures will drop down to around -25°C tonight as the clouds begin to break up and cold air filters southwards again in a northerly flow behind the low. Temperatures struggle to climb above -20°C tomorrow as we find ourselves deep in the cold air once again, some 8-10°C below normal for this time of year.

There are hints that temperatures may begin to moderate on Friday into the weekend, climbing as high as -9°C on Saturday, as a weak south/southwesterly flow develops. I’ll bite my tongue for now as models can sometimes be overly enthusiastic on moving the cold air out of the Red River Valley, but it does look like it’s at least a possibility. If that flow does develop, it’s likely we’ll see another batch of snow late this week as the warmer air pushes in. Until then, keep the long johns handy and be sure to check back in the comments below or follow along on Twitter for updates as the week progresses!

Cool Weather Returns

After enjoying a couple days of above-normal temperatures, a powerful low pressure system backing into Hudson Bay will drive a cold front southwards across Southern Manitoba today, bringing with it cooler weather.

850mb Temperature Analysis valid 15Z this morning

850mb GEM-Reg Temperature Analysis valid 15Z this morning.

The cold front will sweep through Southern Manitoba late this morning, with winds picking up from the north and increasing to 30-40km/h. Scattered showers will develop along the front as it pushes through the interlake, so most regions in the Red River Valley have a chance of seeing some rain later this morning. It won’t last long, though, and cooler air will stream in on the backside limiting our daytime high in Winnipeg to around 11°C. Skies will clear quickly tonight as an Arctic ridge builds in and helps our overnight low drop to -4°C.

The aforementioned low backing into Hudson Bay will become captured today and will block the eastwards advancement of the Arctic ridge which means, unfortunately, that we’ll be under the influence of the ridge and its outflow for the next few days. Thursday will see sunny skies with a daytime high of only around 9°C, and Friday will be much of the same with a high just a couple degrees warmer. By Saturday it looks like the ridge will start to move off and although the day will still be cool, a southerly flow will begin to bring warmer weather back to our region.

Chilly Start to the Week

We are about to get our first taste of below-normal weather in quite some time. Temperatures on Monday and Tuesday are expected to be several degrees colder than the seasonal average.

GEM model high temperature forecast for Monday

GEM model temperature prediction for 4pm on Monday

High temperatures on Monday are expected to hover around the zero mark in much of Southern Manitoba. Combined with a brisk north-west wind, conditions on Monday will be rather cool. If you consider the wind chill, it will feel closer to -6 on Monday afternoon (calculated using a temperature of 0C and wind speed of 25km/h). Tuesday won’t be much warmer, with highs only expected to creep up in the low single digits. The wind will be lighter on Tuesday, making it feel significantly warmer than Monday…although it will still be chilly. Both Monday and Tuesday are expected to be mainly cloudy, which will also hold our temperature back. If the sun does come out in some areas on a localized basis it will be slightly warmer. In early April the normal high is about 8 degrees in Southern Manitoba, meaning most areas will be between 4 and 8 degrees colder than normal through the first two days of the week. Models show a gradual improvement in temperatures as we move later into the week. By Wednesday we should get up into the high single digits and by Thursday the double digits will become likely.

In the longer range it appears that next weekend could be a bit unsettled. At this time models show a low pressure system moving up into the Northern Plains, spreading rain across a large area, which may include Southern Manitoba. It is too early to say if this system will affect us at all, but it is something to watch.

Looking even further ahead it appears we are in for a period of more normal weather. Longer range guidance is hinting at normal to slightly above normal weather for the next couple weeks. There is also some indication that our weather may remain somewhat unsettled, which is fairly typical for this time of year. Wouldn’t it be something if the first half of April was cooler than the second half of March!

Elsewhere in Weather News

Intense Low Affects Japan

A very powerful low pressure system made landfall in Japan on Tuesday, April 3rd and brought with it incredibly strong winds and much rain. This storm, believed to be the strongest storm to hit Tokyo since 1959, generated 90km/h sustained winds and 150km/h wind gusts at times (highest gust reported in Niigata prefecture, 156.6km/h), in the western part of Japan. Rain rates of over 60mm/h also fell associated with the squall line as it moved across most of Japan’s main island. This caused more than 20,000 homes to lose power, various buildings to collapse and trees to fall – causing 97 injuries and 4 deaths. Flight cancellations and railway closures also had to be taken into mind when traveling, as more than 600 flights were cancelled departing from Japan. The very strong winds resulted in trucks being flipped over on the highways and bridge closures, bringing the traffic to a crawl. Waves of 10m were experienced off the coast, however it was strongly advised to stay inside.

Image of the powerful low centered over the Sea of Japan (East Sea), as and after the squall line passed it produced very high winds. (Source: The Watchers/Japan Meteorological Agency)

Image of the powerful low centered over the Sea of Japan (East Sea), as and after the squall line passed it produced very high winds. (Source: The Watchers/Japan Meteorological Agency)

A high-pressure has since moved into place giving way to sunnier skies with some stronger winds associated with it.

Texas Tornadoes

This past week brought very active weather not only in Japan, but also the US, where violent tornadoes hit populated areas of Texas and caused significant damage. Two supercells dropped tornadoes simultaneously on the afternoon of April 3rd in the Fort Worth and Lancaster areas, causing the most significant damage. Preliminary estimates rate these tornadoes between EF-2 and EF-3, where winds are measured at 177km/h to 266km/h. Tornado warnings had been posted by the National Weather Service well before the storm hit allowing residents to take the necessary precautions; although significant damage was caused to neighbourhoods and industrial parks it could have been much worse. Ten injuries and no deaths were reported, the Dallas mayor called it “miraculous” to see that the numbers weren’t more significant after a big damage path could be seen from aerial view.

Tractor-trailer picked up by the tornado in the Dallas/Fort Worth area. (Source: Reuters/NBC)

Tractor-trailer picked up by the tornado in the Dallas/Fort Worth area. (Source: Reuters/NBC)

Tornadoes had not been the only culprit to cause significant damage that day, as very large hail was also reported with this storm. Hail damage to 100 airplanes at the Dallas airport was reported, with issues ranging from minor inspection needed, to planes being put out of service indefinitely.

Lancaster (just south of Dallas) tornado information, with RADAR captures. (Source: NWS storm reports)

Lancaster (just south of Dallas) tornado information, with RADAR captures. (Source: NWS storm reports)

This week, more storms are expected in Texas and most of the Plains, as the jet stream remains south of the border and systems push through Tornado Alley.

Elswhere in Weather News has been provided by Matt