Surprise! More Hot Weather

This week will be another hot one in Southern Manitoba and indeed all over Western Canada. The potential for thunderstorms during the week may temper the heat somewhat.

A large ridge of high pressure will reside over Western Canada this week

A large ridge of high pressure will reside over Western Canada this week

The weather forecast for this week will be rather tricky. What we do know for sure is that it will be hot all week, with high temperatures being near 30C every day. However, what is somewhat unclear is the risk of thunderstorms during the week. Let’s start with the easy part – the heat.

Temperatures will start out the week in the upper twenties or near thirty on Monday and Tuesday in Southern Manitoba. Humidity levels should remain low on these day making conditions hot, but not excessively so. By Wednesday high temperatures should be be in the low thirties with the humidity making it feel closer to 40. It currently appears that temperatures for late week will remain around the 30C mark, with humidity levels remaining elevated.

A shortwave will move toward the Eastern Prairies on Wednesday, potentially helping to trigger thunderstorms

A shortwave will move toward the Eastern Prairies on Wednesday, potentially helping to trigger thunderstorms

The presence of heat and humidity over the Prairies this week will cause the atmosphere to become unstable, creating the risk of thunderstorms on many days. Unfortunately, the thunderstorm forecast is not entirely certain. The issue is that a large region of high pressure, such as the one we’ll be under, does not typically promote widespread thunderstorm activity. In fact high pressure usually suppresses convective activity. It looks like this ridge will not be very good at suppressing thunderstorms, which complicates the forecast significantly.

At this point it looks most likely that Southern Manitoba will see thunderstorms mainly during the second half of this week, from Wednesday onward. During that time period the atmosphere will be most unstable and there will be some weather features moving through the region which may trigger storms. The jet stream has weakened significantly over the Prairies as of late, meaning that most storms will be non-severe in nature. Heavy rain will likely still be a concern though due to slow storm motion. Some severe storms will also be possible just simply due to the instability present in the atmosphere. Although stronger storms will certainly be less widespread than weaker ones. As the week progresses we’ll have to reassess the thunderstorm risk one day at a time.

While my forecast for this week might seem a bit equivocal, that will just be the nature of the weather in the short-term. Unfortunately thunderstorms are just simply unpredictable a frustrating but unavoidable aspect of mother nature.

The Heat Is On!

This week will feature warm to hot weather in Southern Manitoba, a trend which is expected to continue into the long weekend.

Temperatures will be hot over much of Central North America this week

Tuesday’s high temperatures. Reds indicate temperatures near 30C.

A ridge of high pressure will be in place over Manitoba on Monday and Tuesday of this week. This ridge will pump warm air into the province, allowing high temperatures to reach the high twenties and even low thirties. Monday will be quite nice, with temperatures in the high twenties over all of Southern Manitoba. Humidity levels on Monday will remain low, making the day rather comfortable. By Tuesday the humidity will increase somewhat, but will still remain reasonable even as temperatures climb to around thirty degrees (except in Western Manitoba where the air will be a bit more tropical). A cold front will slice through the province on Wednesday, knocking down humidity levels with a strong westerly wind. However, temperatures won’t drop off by much, with highs staying in the mid to upper twenties on Wednesday.

CAPE graphic. CAPE is a measure of how unstable the atmosphere is, in other words, how severe a storm could potentially become

CAPE values are expected to be moderate to extreme over the prairies early this week. CAPE is a measure of how unstable the atmosphere is, in other words, how severe a storm could potentially become

You may be wondering if this heat will generate thunderstorm activity as the cold front moves in on Wednesday. The short answer to that question is maybe, but I will elucidate. There will certainly be severe storms in Saskatchewan on Monday and Tuesday this week, but the threat in Manitoba is less clear. At this time it looks like our best chance for seeing storms will be on Tuesday night into Wednesday morning as storms that develop over Saskatchewan and North Dakota drift into Manitoba during the overnight period. Even though these storms will happen after dark they may still be severe as they will have warm and humid air to work with. There may also be the risk of thunderstorms during the day on Monday and Tuesday in portions of west-central Manitoba (i.e. Swan River, The Pas, etc). Since these regions aren’t our focus, I won’t go into much further detail than that. Nocturnal thunderstorms may drift into Western Manitoba on Monday night or Tuesday morning, but aren’t expected to impact the majority of Southern Manitoba.

After the cold front passes through on Wednesday there will be a couple of days where the heat “reloads” ahead of the long-weekend. In other words Thursday and Friday will be a bit cooler, although still warm, with temperatures more in the mid twenties. It is expected that hot weather will crank up again for the long-weekend, with present modelling suggesting that temperatures near thirty degrees will be possible on Saturday, Sunday, and Monday. It is too early to be certain in those predictions, but at this point the long-weekend is looking rather nice…if you like hot weather that is.

Improving Weather

Southern Manitoba will see improving conditions today and round out the work week with nice conditions and near-normal temperatures.

Ridge Dominating Southern Manitoba

Model 3hr. QPF & MSLP w/Surface analysis valid 00Z Thursday April 19th

There will be a slight chance of some light snow this morning over the western half of the Red River Valley as a weak short wave slumps into North Dakota. As it exits the province, clouds will clear and we’ll be left with a sunny afternoon with a high near 8°C.

Clear skies will be the weather story for the rest of the week as a ridge of high pressure builds in from Northern Saskatchewan. We’ll have an overnight low near -6°C tonight and warm back up to a repeat of today on Thursday, with a high near 7°C. Rinse and repeat for Thursday night. As a system pushes into the NW United States, slightly warmer air pushes into Southern Manitoba and we’ll likely see our daytime high bumped up a few degrees to around 10°C.

Saturday brings with it a chance of rain as an upper trough swings across the Prairies. We’ll keep an eye on that as the week progresses!

In short, it’ll be a sunny, albeit a little cool, rest of the week!