Tag: Cold front

Cool Weather Returns

Brad Leave a comment

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.

March Madness

Brad Leave a comment

What a week it has been! Temperature records have fallen, our snow cover has disappeared, and thunderstorms are in the forecast – the question is what next?

Map showing the risk of thunderstorms on Monday, March 19, 2012

The light green region shows where there is a slight risk for severe thunderstorms on Monday

This week will start out on a warm and possibly stormy note. Monday’s temperatures are expected to be in the low to mid twenties across Southern Manitoba with a risk of thunderstorms. If Winnipeg records a high temperature on Monday that is greater than +23.3C the city will record a new all-time record high for the month of March. The previous all-time record high of +23.3C was set on March 27, 1946. On Sunday Winnipeg set a new record for the earliest ever occurence of a 20C high temperature, beating the old record of +22.8C set on March 23, 1910.

Day New
Record		 Old
Record		 Previous
Record Year
Sun Mar. 11 12.8°C 12.5°C 1981
Mon Mar. 12 9.7°C 7.2°C 1922
Thurs Mar. 15 14.4°C 11.1°C 1927
Fri Mar. 16 19.9°C 12.4°C 1981
Sat Mar. 17 19.2°C 12.8°C 1938
Sun Mar. 18 20.9°C 14.4°C 1910
Mon Mar. 19 23.7°C 18.9°C 1938
Table of daily record high temperatures over the past week.

As you may have noticed on Sunday, the humidity has risen significantly in the Red River Valley and South-Eastern Manitoba. When that extra moisture in the air is combined with warm temperatures, thunderstorms become possible. A strong jet stream is currently in place over Southern Manitoba, setting the stage for some potentially strong storms later on Monday afternoon into the evening. There will be a “lid*” over the atmosphere on Monday preventing storms from developing earlier in the day. This “lid” may or may not come off the atmosphere later on Monday. Whether or not the “lid” comes off will determine if storms can develop. Any storms that form shouldn’t be particularly strong, with the strongest storms only being marginally severe at best. However, with the way this March has gone it is best to assume that anything can happen – including stronger than expected thunderstorms.

The rest of the week looks a bit more “normal”. Actually temperatures will remain well above-normal but will seem more reasonable for this time of year. It looks like most days this week should feature high temperatures in the low double digits. As a result more temperature records will be threatened over the coming days, but they won’t be broken by the huge margins seen on the weekend. It doesn’t look like any more 20C days are imminent, but we certainly could hit 20 degrees again before the month is over.

In the long range models show continued warm weather through the end of March. With our snow cover gone it will be very difficult for conditions in Southern Manitoba to reach below-normal values. We’ll have to wait until our seasonal averages rise by several degrees before below-normal weather is even possible again. Bear in mind that above-normal temperatures don’t necessarily give way to beautiful weather conditions all the time. Models do hint at less settled weather over the next 7-10 days, which means we could get our first significant rain storm of the season (fingers crossed that it doesn’t turn into a snowstorm!)

Here is Environment Canada’s statement regarding broken temperature records on Sunday:

March 18, 2012 High Temperature Records

New high temperature records set on March 18, 2012

*A “lid” being on the atmosphere is simple way of referring to atmospheric capping. Capping is when there is warm air above the ground which prevents air near the surface from rising. We know that warm air rises and cold air sinks, but warm air only rises if it is warmer than the air around it. Therefore if the air at the surface is relatively warmer than the air aloft it will rise and if the air aloft is relatively warmer than the air at the surface the surface air won’t rise. On Monday the air aloft will be relatively warmer than the air at the surface for most of the day. Storms will only develop if colder air moves in aloft allowing the surface air to rise up high into the atmosphere. This may or may not happen, causing the thunderstorm forecast to remain uncertain.

Elsewhere in Weather News

Record Breaking Heat Wave Across the United States

The heat wave that currently has Southern Manitoba feeling more like May than March has also taken hold of much of the United States this past week. The unusual warmth is caused by a large surge in the jet stream over most of the US Plains, Midwest and East Coast. The jet stream, which acts as a fence between the cold air masses and warm air masses, is part of the reason why the US is experiencing its first major heat wave of the year. As the jet stream surges in the Plains and East, a trough (dip) in the jet stream over the west coast is bringing unseasonably cold air to the region and much precipitation with it.

250mb wind speeds, showing the jet stream, Sunday March 18th. (Source: Brad’s Model Viewer/COD)

250mb wind speeds, showing the jet stream, Sunday March 18th. (Source: Brad’s Model Viewer/COD)

Since the beginning of March the US has seen more than 1700 new records reached, including some records that weren’t even close to the previous records. Here are some notable ones from this past week across the US:

  • International Falls, MN: Previous record = 13°C, New record = 25°C, Average = 1°C
  • Marquette, MI: Previous record = 16°C, New record = 24°C, Average = 3°C
  • Minneapolis, MN: Previous record = 17°C, New record = 23°C, Average = 4°C

    Map showing record highs Wednesday, March 14th. 307 record highs were broken and 97 tied. (Source: National Climactic Data Center)

Map showing record highs Wednesday, March 14th. 307 record highs were broken and 97 tied. (Source: National Climactic Data Center)

As the jet stream shifts east early this week the spell of record-breaking temperatures will end for the plains, giving way to strong thunderstorms as the cool air from the west collides with the moist gulf air present over tornado alley. However, the Midwest and East Coast will remain near record breaking temperatures for a couple more days before cooler air arrives (but still above normal) and ushers showers in with it.

A Cooler Week Ahead

Brad Leave a comment

A cooler week is in store for us as we move into the last month of meteorological winter. Temperatures don’t, however, look like they’ll be too far from normal through most of the week.

Surface Pressure Map

Surface Pressure Map – valid 12Z Tuesday, February 6, 2012

With the passage of a cold front this morning, gusty northerly winds will usher colder air into Southern Manitoba. As a result temperatures will fall throughout the day today, with midday conditions in the mid-minus single digits. There will be a few scattered flurries this morning through Southern Manitoba as the cold front works its way through the area, however there will be no significant accumulations with them. Tonight, a strong area of high pressure will build into Southern Manitoba, with the central pressure expected to be as high as 1045mb. This will bring significantly colder temperatures than we’ve enjoyed over the past week to our area overnight, with lows expected to be near -20°C in Winnipeg and as low as -25 or -26°C in some areas in the Red River Valley. Tuesday won’t be an extremely cold day as a weak warm front will push into our area from the north, but it will still be colder than we have been used to lately with highs unlikely to exceed -10C. Conditions through Wednesday will be slightly warmer, with highs expected to rise back up into the minus single digits.

Friday Morning GEMGLB Forecast Temperatures

Forecast surface temperatures from the GEM-GLB model valid 06Z Friday, February 10th with analysis. The thick black line represents the cold front.

There is some uncertainty as to how the weather will unfold later this week. Models are hinting at the potential for another push of cold air on Thursday into Friday as another cold front sweeps through the province. Models currently differ on the exact strength of the cold push, however, as shown in the image above, some models push temperatures as low as -30°C back into Southern Manitoba. Which if it comes true, we can at least take solace that we don’t live in Northern Saskatchewan, where temperatures are forecast to be as low as -45°C!

Elsewhere in Weather News

Europe Battles Cold and Snow

This past week Europe was battered with what Canadians would call a “light snowfall” where many parts of the United-Kingdom, including London, received 10cm of snow this past weekend. The European infrastructure isn’t equipped to handle a snow storm of such magnitude which was affirmed by the fact that there were widespread airport cancellations and traffic was crawling to a standstill – some drivers were even stuck in their cars on the freeways overnight. The storm also prompted the UK Met offices to issue freezing rain warnings and cold weather alerts. The snowfall was due to a warm front pushing inland off the Atlantic Ocean and clashing with colder air that was present in the region prior, thanks to another low pressure system off to the east. The snow storm that has been wreaking havoc is forecast to lift and leave the area by Tuesday morning, leaving warmer temperatures behind and clearer conditions to come.

Surface Map for the UK

System’s analysis with the warm front arriving inland, clashing with the colder air to the east (occluded front). (Source: Met Office: UK)

Cold weather also affected other parts of Europe including Ukraine and Italy, with Ukraine being one of the hardest-hit of the Eastern European countries and experiencing tragedy. Kiev, Ukraine’s capital city, normally has temperatures averaging minus five Celsius for the month of February. During this cold snap however, temperatures dipped lower than minus thirty Celsius and many people have died – over 300 as of this posting. Temperatures for the next week are forecast to remain well below average, with highs only reaching the minus teens.

Snow in Rome

City of Rome, largest snowfall in two and a half decades. (Source: Dailymail)

In Rome, Italy, the city has received its largest snowfall in two and a half decades. The city was buried in ten to twenty centimetres, leaving the city paralyzed and people freezing in their houses, since homeowners are only allowed twelve hours of heating per day (to reduce emissions). As the low pressure system plans to stick around for a couple more days, Rome will experience well below average high temperatures of about five Celsius (average of thirteen Celsius).

Surface Map of Europe

Europe’s system analysis, Feb 5th, showing both lows impacting Europe. (Source: Intellicast)

Elsewhere in Weather News has been provided by Matt

Pleasant Weekend Ahead…Enjoy It!

Brad Leave a comment

Winnipeg, along with the rest of Southern Manitoba, will enjoy a very pleasant weekend with temperatures climbing above 0°C over the next few days before a cold front sweeps through Southern Manitoba on Monday morning.

Foggy Winnipeg

A foggy morning in Winnipeg; submitted by JJ.

Winnipeg and the Red River Valley will enjoy a beautiful weekend with most cloud clearing out by this afternoon. Daytime highs will continue to climb over the next three days, with highs climbing to near 1 to 2°C today and Saturday, and getting up to nearly 4°C on Sunday.

Our warm temperatures, combined with light winds forecast for tonight means that fog will likely redevelop through many areas in the RRV; if it makes a return tonight, it will be the fourth night in a row with fog in Winnipeg and surrounding areas. Winds are forecast to increase through the night on Saturday night to 10-15km/h which should be enough to prevent fog from forming again.

Sunday Morning Prognosis

Analysis of the 72h prognosis from the GEM-Global, valid 12Z Sunday morning. Warm fronts and cold fronts are represented by red and blue lines, respectively.

The next change in the weather will be coming on Monday morning to Southern Manitoba. Through the weekend, a powerful low pressure system will track through the NWT into the Kivalliq region of Nunavut. This system will shift the large-scale pattern over the center of the continent and will allow arctic air that has been trapped unusually far north over the past couple weeks to spill southwards across the Eastern Prairies. The cold front will sweep across Manitoba on Sunday and push through Winnipeg by Monday morning.

This will bring brisk northerly winds to us for Monday and temperatures that gradually fall through the day. Currently it looks like we could see temperatures as low as -26°C on monday night into tuesday morning. Very little moisture is associated with this system, and current indications are that there will be very little or no snow with the passage of the cold front. Temperatures will be a little below normal on Tuesday and Wednesday, with daytime highs a little below -10°C.