Moderating Trend Gives Way to Rainy Holiday

Brad Leave a comment

Temperatures will moderate to seasonal values by the end of the weekend, but the Victoria Day holiday may end up being quite wet.

Relief is in store for Southern Manitobans weary of the prolonged cold weather as milder air is finally set to return to the region. The intense upper-level cold trough over Ontario that has been bringing a strong northerly flow and cool weather to the region will finally begin to collapse, allowing milder air to work its way eastwards again. Temperatures will remain fairly mild while the weather takes a turn for the worse on Victoria Day as a low pressure system brings the potential for substantial rains across much of Southern Manitoba.

Friday
14°C / 0°C
Mainly sunny.

Saturday
18°C / 6°C
A few clouds.

Sunday
18°C / 8°C
Mixed skies.

Today and tomorrow will see daytime highs climbing towards the high teens with minimal in the way of cloud cover. Both days will also see light winds thanks to a ridge of high pressure situated over the province. We’ll likely see temperatures dip to the freezing mark tonight[1], but milder air will be in place for Saturday night making the overnight low around 5°C warmer.

Sunday will be a more unsettled day. Most places in Southern Manitoba will see cloudy periods with a very marginal chance of a shower. Winds will shift out of the south to 20-30km/h as a warm front lifts northwards through the day. Temperatures should climb to around 18°C and the temperature will drop to around 8°C on Sunday night.

Potentially Stormy Victoria Day Holiday

Monday
15°C / 10°C
Mainly cloudy; rain likely.

A powerful low pressure complex will develop over Saskatchewan on Monday which will bring wet weather to Southern Manitoba as a conveyor belt of warm, moist air sets up all the way from the Gulf of Mexico. We won’t see that warm, humid air at the surface, but thanks to a strong southerly flow aloft, strong isentropic ascent over the warm front will produce a very saturated, potentially unstable atmosphere over Southern Manitoba.

Rainfall forecast (in inches) from NOAA's WPC for Sunday evening through Tuesday evening. The WPC is forecasting as much as 25-30mm of rainfall for Southern Manitoba.
Rainfall forecast (in inches) from NOAA’s WPC for Sunday evening through Tuesday evening. The WPC is forecasting as much as 25-30mm of rainfall for Southern Manitoba.

What does this mean? We could see fairly heavy rainfall on Monday. There is still enough time for things to change substantially between now and then, but amounts anywhere from 5-25mm seem quite possible. The rainfall does seem quite convectively driven, and with a moderately strong 850mb jet there’s always the possibility the rainfall becomes attached to the left-exit region and ends up remaining to our south/southeast. We’ll be tracking this system through the weekend and have updates below when things begin to take shape.

  1. Hopefully for the last time until the fall.  ↩

Mother Nature Mixes Up Months

Brad Leave a comment

Things will seem decidely early-April as extremely cool air settles in over the eastern Prairies bringing another stretch of days with temperatures some 10-15°C below normal. Seasonal weather doesn’t look to return until the end of the week when the cold air finally begins being shunted off to the east.

Wednesday
7°C / -4°C
Mainly cloudy. Clearing in the evening.

Thursday
10°C / -1°C
A few clouds.

Friday
12°C / 3°C
Mainly sunny. Cloudy periods overnight.

We’ll see a mainly cloudy sky today as we remain stuck under cloud wrapping around the backside of the low pressure system that impacted Winnipeg and the Red River Valley over the weekend and the first half of the week. Accompanying the cloud cover will be extremely cool temperatures for mid-May; the daytime high today will only reach 6 or 7°C, 10-15°C below the seasonal high of 19°C. The cloud cover looks to begin clearing out ovenright as we drop down to a low of -4°C, again nearly 10°C below our seasonal low temperature for this time of year. No precipitation is expected today or tonight.

Tomorrow will bring a few clouds as we sit on the fringe of the organized cloud pushing off to our east and then see some afternoon cumulus clouds develop. Temperatures will moderate a little to around 10°C, however that’s still nearly 10°C below normal for this time of year. We’ll drop to a low of around -1°C overnight under clear skies.

Friday will bring plenty of sunshine with just a few clouds through the afternoon hours. We’ll see a high temperature of around 12°C as milder air continues to slowly push eastwards. There will be a few cloudy periods overnight as a weak disturbance moves thorugh and we’ll see an overnight low near 3°C. Precipitation is unlikely with this disturbance.

Returning to Near-Normal on the Weekend

Things will get back into form by the end of the weekend as the cold trough finally collapses and pushes well off to the east, allowing milder air to spill across the Prairies. Saturday looks like it will have a high somewhere in the mid-teens followed by temperatures near 20°C on Sunday. The weekend looks to be a bit of a mixed bag with sunny skies and relatively light winds on Saturday, but more cloud and stronger winds developing on Sunday as a warm front pushes into the region ahead of a low approaching from Wyoming. Areas all across Southern Manitoba may end up wtih the threat of some showers or rain activity by Sunday aftenroon. We’ll have more details on this system in Friday’s blog post.

Nasty Week Ahead

Brad Leave a comment

After a nice weekend, we’re in for a nasty work-week. More rain and chilly temperatures are on the way.

Rain is expected in south-eastern Manitoba on Monday
Rain is expected in south-eastern Manitoba on Monday

Monday

Monday
9°C / 5°C
Rain

Today will see rainy weather return, or continue, in southern Manitoba, depending on where you live. Western sections of the province should remain mostly dry, but south-eastern sections will be getting wet, as another strong weather system moves up from the south. Rainfall accumulations of 10-20mm are expected in Winnipeg with 15-25mm in areas south-east of the city, including Steinbach. Locally higher amounts are possible in the south-east corner of Manitoba where heavier rain bands will likely develop. The rain will be accompanied by a strong northerly wind, just adding to the misery!

Tuesday

Tuesday
9°C / -1°C
Mix of Sun and Cloud. Chance of Showers.

There may be some lingering rain showers on Tuesday morning in south-eastern Manitoba, and some more pop-up showers in the afternoon, but generally speaking Tuesday will be a dry day. It will also be a fairly crummy day, with a cool airmass of Arctic origins surging southward into the province. High temperatures aren’t likely to crack the double digits in most areas.

Wednesday

Wednesday
8°C / -2°C
Mix of Sun and Cloud. Chance of Showers.

Wednesday will see a continuation of Tuesday’s nasty, cool conditions, with even colder Arctic air surging southward. Once again, temperatures are not expected to reach double-digits, except for maybe far western sections of southern Manitoba. Pop-up showers may develop in the afternoon, just to cap things off!

Long Range

We should see temperatures return to near normal values by the end of the week into the weekend, however no above-normal weather is in store for the foreseeable future.

Elsewhere in Weather News: May 10th, 2014

Matthieu Leave a comment

Flooding Rains in New Orleans

A weak disturbance tracking across the southern Gulf States was the cause for some flash flooding in New Orleans last night. Precipitable water (PWAT) values exceeding 50mm were present in the area, meaning a very moist atmosphere was in place. Heavy rain fell in the wake of a squall line of storms Friday afternoon into early Saturday morning, causing significant flash flooding in New Orleans. Radar indicated that as much as 125mm fell across the New Orleans and reporting stations in the surrounding area showed widespread 80-100mm readings.

Storm totals according to radar (as of 1am today). Green boxes are flash flood warnings. (Source: GRLevel3)
Storm totals according to radar (as of 1am today). Green boxes are flash flood warnings. (Source: GRLevel3)

Flash flood warnings had also been issued by the National Weather Service for most of southeastern Louisiana, including New Orleans. In addition, several water rescues had to be executed in New Orleans due to cars being submerged up to their roof in water. This event comes just over a week after severe flooding affected the Florida Panhandle and dumped over 500mm over some areas.

Severe Weather Expected in the Plains

This weekend looks take an active turn weather-wise across much of the Central and Southern Plains of the United States. A strong low-level jet will aid in transporting significant moisture from the Gulf of Mexico northward ahead of the approaching system. CAPE values are expected to reach very unstable values, especially on Sunday across Tornado Alley; with limited capping (warm air aloft) storms are likely to become severe quickly and tornadoes are possible. Updates on this event will be available in the comments section as the event unfolds!

Following this event, a lull in the storm season is expected across the region for about a week before a return flow sets up and more Gulf moisture is able to start making its way poleward.