A Glancing Blow

A Colorado low responsible for a tragic severe weather outbreak yesterday across the the Southern United States, and Arkansas in particular, has spread rain northwards into Southern Manitoba this morning. A decent soaking is in store today and then see a cooler, unsettled week ahead as the Colorado Low persists through much of central North America.

Monday
8°C / 0°C
Periods of rain ending by the evening. 10-15mm. Breezy.

Tuesday
10°C / 0°C
A few clouds.

Wednesday
7°C / 0°C
Showers likely.

Late last week it looked as if we were set to get as much as 25-30mm in a widespread swath through much of Southern Manitoba, however we pointed out the complexities of the setup and how minor changes in the positioning of features could cause big changes in how much precipitation is produced.

It turns out the models did fairly well with the overall picture. Thanks to a little more tilt to the upper trough and the upper low being captured a little sooner than originally forecast, the system as a whole won’t push as far northwards as it looked last week and as a result we’ll see a little less rain than it looked like then.

We’re still in for a decent soaking today, though. Periods of rain will persist through the late afternoon or early evening, and in general much of Southern Manitoba will see 10-20mm of rain. Areas further north, towards the Interlake and much of Parkland Manitoba will see in the 5-10mm range, but it does appear that, for the most part, anywhere along and south of the Trans-Canada corridor in SW Manitoba and the Red River Valley will see between 10 and 20mm with the higher amounts closer to the U.S. border. The temperature will sit around 8°C today with breezy winds out of the east at 30km/h with gusts to around 50km/h.

Total rainfall expected today across Southern Mantioba.
Total rainfall expected today across Southern Mantioba.

Near the border there’s a slight chance of accumulations creeping up towards 25mm (1”) or so, but that will depend on fairly heavy rain and some lingering rainfall a bit longer than it seems like it’s likely too. The rain will taper off by this evening and we’ll see gradual clearing through the evening. The temperature will drop to around 0°C.

Another Short-Lived Break

Tuesday looks to be a cool but pleasant day with a high temperature of around 10°C and mostly sunny skies. Temperatures will drop to around 0°C once again on Tuesday night with increasing cloudiness.

Wednesday brings back the showery weather as another shot of rainfall pushes into Southern Manitoba from east to west on the back-side of the Colorado Low. Accumulations don’t look significant at this point, perhaps 3-5mm on the high end, but it does seem like it will be a cool, dreary day with a high of only around 7°C. The showers should taper off by the evening as we drop to the freezing mark yet again, this time under cloudy skies.

Where’s Summer?

Unfortunately, not here. Below-normal temperatures are once again forecast for the 7-14 day outlook, meaning we’ll likely see high temperatures only in the high single digits or low teens for the next week or two.

But it’s gotta warm up eventually, right? Right? Here’s hoping for a big turnaround in May.

Elsewhere in Weather News: April 26th, 2014

Tornadoes Tear through North Carolina

It was an active day severe weather-wise for parts of East Coast yesterday, where tornadoes, large hail and strong winds were all experienced. These severe storms were triggered by a shortwave racing across the mid-section of the US and approaching the East Coast. Moisture was plentiful streaming up from the tropics which promoted low cloud bases and sufficient amounts of Convective Available Potential Energy (CAPE). In addition to this, wind shear was significant enough to support supercells as well as an approaching cold front from the west acting as a trigger mechanism. Considering all of these, conditions were primed for supercells in North Carolina and Virginia.

Trucked flipped in Chicod, NC. (Source: WITN)
Trucked flipped in Chicod, NC. (Source: WITN)

Supercells quickly formed Friday afternoon across eastern parts of North Carolina and Virginia as the atmosphere destabilized. Elizabeth City appeared to be the hardest hit, likely by straight line winds and not a tornado. As of Friday evening, several injuries were reported because of the strong winds downing trees and power lines in the city. According to the SPC there were 10 different tornado reports which appeared to account for three different tornadoes. Fortunately, no injuries or deaths were reported to be associated with any of the tornadoes.

This event comes at the same time a significant negatively-tilted trough arrives ashore on the west coast. The trough is expected to bring severe weather from the US plains this weekend, to the East coast for the beginning of next week. Sunday through Tuesday look to be the most dangerous days where numerous tornadoes could touch down across Dixie Alley and the Midwest. As of Friday evening, the SPC had already issued a Moderate Risk, mentioning strong tornadoes in their discussion and suggesting a high risk (highest tier) upgrade could be in order in future updates.

With only 89 tornadoes reported in the US as of April 13th, that number could easily double within the next few days.

A Brief Reprieve

This weekend will bring a brief reprieve from the wet weather before a Colorado Low begins impacting the region for the start of next week. Temperatures will remain below normal, but we should see plenty of sunshine with just relatively light south-easterly winds.

Friday
8°C / 0°C
Mainly cloudy. Chance of showers or drizzle.

Saturday
10°C / 3°C
Partly cloudy.

Sunday
11°C / 4°C
Increasing cloud.

Today will bring mostly cloudy skies with a chance for some lingering showers or drizzle as the system that’s been impacting us over the past few days slides off into Ontario. Clouds will begin to break up a bit in the afternoon as we head towards our high of around 8°C, however it won’t be until the evening or overnight period until we see the clouds actually begin to clear out.

Saturday look like the nicest day of the next few, with more sun than cloud and a high near 10 or 11°C. The wind will be out of the southeast at around 20-30km/h, but otherwise it’ll be a pleasant – albeit cooler than normal – spring day. We’ll drop to around 2 or 3°C on Saturday night under mainly clear skies.

Sunday will herald the arrival of the next storm to impact the Prairies: a massive Colorado Low that looks to stall out over the northern Plains of the United States and absolutely smother the Prairies in precipitation.

24hr. precipitation forecast from the GDPS showing anywhere as much as 30-40mm of rain from Sunday night through Monday.
24hr. precipitation forecast from the GDPS showing anywhere as much as 30-40mm of rain from Sunday night through Monday.

This system looks to be extremely complex with multiple features interacting with each other: the Colorado Low itself, a large inverted trough that looks to develop along a north/south line through Saskatchewan, and the occlusion of the upper-level low centre that will stall the system out over the Northern Plains. Subtle variations in any one of these features can dramatically alter the weather outcome, let alone how those variations will interact with each other across these features. In addition, there will be a fairly significant high pressure system through Northern Manitoba that will surely do it’s best to inject dry air into the system and really sharpen up the northern edge of it. Needless to say, we’ll be keeping a close eye on this one and have more details on where, and how much, precipitation might actually happen in the comments below as things begin to come together.

Spring Storm Incoming

A potent storm system is on the way.
A potent storm system is on the way.

A large spring storm will bring the most significant rainfall to the Red River Valley since last October. It will be mainly rain that falls over the next couple days, however higher-terrain areas of Parkland Manitoba will likely see snow feature more predominantly. This system will be fairly long-lasting, too, with precipitation pushing into SW Manitoba this morning and lingering through Friday.

Wednesday

Wednesday
11°C
Increasing cloud.
Wednesday Night
3°C
Rain beginning in the evening. 5-10mm.

The wet weather over the next couple days is being caused by a strong upper-level trough (depicted in the picture at the top of this post) that is pushing inland from the Pacific. This feature will spawn an elongated trough of low pressure with embedded low pressure centres within it that spans all the way from Alberta through Saskatchewan, Manitoba, and southwards to Texas. This large feature will be aided by an upper-level low tracking along the Canadian/US border which will amplify the precipitation through the Canadian Prairies.

So, what will we see? Rain will spread into southwestern Manitoba this morning and slowly – quite slowly, actually – spread eastwards through the day towards the Red River Valley. By the afternoon, rain should push into the western RRV, but likely won’t reach Winnipeg and into the eastern RRV until late this afternoon or into this evening. By the evening, most areas across Southwest and Parkland Manitoba will likely see around 10-20mm of rainfall, with the potential for some localized amounts of 20-25mm.

Rain will continue to push eastwards through the night, bringing fairly steady rain to most areas in Southern Manitoba. Areas in extreme southwestern Manitoba may see things taper off as the main axis of rain begins shifting to the northeast. Another 5-10mm of rain will fall in most places, however in higher elevations of Parkland Manitoba the rain will switch over to snow overnight with 5-10cm of accumulation possible.

Thursday

Thursday
5°C / 0°C
Rain. 10-20mm.

Thursday will see rain tampering off in Southwest Manitoba, but being reinvigorated over the Red River Valley and Interlake by another shot of moisture lifting northwards along the trough line. Here in the RRV around another 5-10mm will fall, however portions of the valley into the Whiteshell may end up seeing 10-15mm if the heavier rain arrives a little earlier.

Storm-total precipitation expected from Wednesday through Friday.
Storm-total precipitation expected from Wednesday through Friday.

Light rain will persist through much of Thursday night and perhaps become mixed with snow as we approach our low temperature of around 1°C. Another 2-5mm of precipitation is expected.

Friday

Friday
5°C / -6°C
A few showers or flurries.

The system will finally begin pushing out of the region on Friday, however an lingering trough will hang back into the province for much of the day, spreading some showers or, at times through the morning, light flurries through the region. Further amounts of precipitation will be minimal – likely less than 2mm.

Things look to clear out for a sunny weekend. Saturday’s high will be below normal, somewhere around 6°C or so, and Sunday will return to a near-normal high in the low teens. The nice weather may be short-lived, though, as weather models are hinting towards the development of a Colorado Low that would impact Southern Manitoba starting Sunday night.