Tag: Rain

Unsettled March Weather Continues

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Southern Manitoba played host to almost all the different kinds of weather out there, with many locations seeing almost any combination of thunderstorms, hail, rain, drizzle, snow and blowing snow. A system that brought heavy snowfall to Western Manitoba and the Interlake region as well as thunderstorms and rain to the Red River Valley and Southeast Manitoba has trundled off into Ontario; we’re not out of the woods yet, though, as another system is set to quickly make it’s way into the province by tomorrow morning.

Hail Accumulation

Photo of accumulated small hail at a downspout exit. Winnipeg was hit with hail from this size up to as large as dimes as a thunderstorm pushed through the city at around 2:30AM on Tuesday morning.

For today, we’ll see cloudy skies with a chance of a few remnant flurries this morning. We’ll see a daytime highs of only 2°C or 3°C through the RRV. Another low pressure system is already on it’s way to Manitoba, however, with the parent upper trough making landfall on the Oregon coast last night. This trough will advect eastwards and rotate northwards into the Central Prairies, bringing with it a warm front that will bisect the Prairies and slowly push eastwards.

This warm front is expected to push through the Winnipeg and the Red River Valley through the day on Thursday. Current indications are that we’ll be far enough south that we won’t have to worry about snow, that should be reserved for areas a bit further north in the Interlake region. We’ll see rain push in tomorrow morning around mid-morning and clear out by early evening. Rainfall totals currently look to be fairly uniform through the Red River Valley with totals around 10-15mm, however it does look like there’s a good chance for some enhanced convective areas which will result in fairly heavy showers interspersed through the general area of rain.We’ll enjoy warmer temperatures through the rest of the week, with the warm air pushing through bringing our daytime highs up to around 10°C.

We’re not out of the woods quite yet, though, as another low is forecast to track through the southern Interlake region bringing rain to areas along and north of the Trans-Canada Highway Friday night and Saturday morning. Current indications are that regions south of the Trans-Canada Highway will only see some scattered showers with this system.

8-14 Day Temperature Anomaly Outlook

NAEFS 8-14 Day Temperature Anomaly Outlook, valid for April 4 – April 11.

With a the passage of Tuesday’s weather system, North America has transitioned into a much different weather pattern that that which brought us our record-busting heat wave. With the blocking high collapsed over the SE United States, the summer-like heat will be contained further south in the Central and Southern Plains of the United States. Fortunately, the bitterly cold Arctic air that’s still omnipresent north of 60 will remain bottled up. So what does that mean for us? As the image above shows, ensemble forecasts are showing a moderate chance of above normal temperatures, however nothing nearly as certain as what was being predicted a couple weeks ago. The long-wave pattern has shifted to favor more frequent disturbances tracking through the Prairies, which should result in temperatures that may still be slightly above normal, but we’ll likely also see more precipitation than we had through much of March.

A Mixed Bag On The Way

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Today will bring warm temperatures along with a bit of light rain or snow as a Pacific system tracks through the Interlake towards Hudson Bay. Temperatures will climb above 0°C today before they gradually cool down by the end of the week to more seasonal values.

Probability of Snowfall >= 2cm

Probability of 12 hour snowfall accumulation exceeding 2cm, valid overnight Wednesday into Thursday morning.

A low pressure system tracking across the extreme Southern Prairies will arc northwards through Southern Manitoba today, lifting northwards through the Interlake region then exiting towards Hudson Bay. This system will intensify as it pushes into Manitoba and precipitation should blossom as it approaches the RRV. Two challenges exist with this system:

  1. When exactly will the precipitation develop/intensify?
  2. How far north with the system be?
  3. What will the phase of the precipitation be, snow or rain?

We’ll likely see some precipitation early this afternoon in the form of snow as the warm front pushes through the RRV. The Western RRV has a risk of some freezing rain if temperatures can stay below 0°C for long enough with this batch of precipitation. Any freezing rain that does develop will be short-lived, though. The snow will likely stop for the short period we’re in the warm sector of this system, but will return by late-afternoon/early evening with some rain or wet snow as the cold front passes through the area. The precipitation will end later in the evening. Snowfall accumulations today should be quite low in the RRV given the warm temperatures, however areas further east in the Whiteshell have a decent chance of getting around 2cm.

Temperatures should reach the 3-4°C range through most areas south of the Trans-Canada Highway today and drop only a little below 0°C overnight.

For Thursday, temperatures will reach close to 0°C as an elongated trough moves across the RRV, bringing with it a slight chance of flurries. It should pass by lunch, after which the NW winds will bring in cooler air and drop the temperature slowly through the afternoon.

The rest of the week will be relatively quiet, with temperatures gradually returning to more seasonal values (daytime highs moving from the low minus single digits to the high minus teens). The next chance for significant weather looks to be early next week.

Since it will likely be quiet on the weekend, I plan on having a bit of a special post on Friday! We’ll look at how warm this winter has actually been, and I’ll be unveiling a great new tool (barring no more problems…) that I’m really excited to let everybody get their hands on!

Slight Chance of Showers Saturday Evening

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A system tracking across the Rockies into Alberta will slide quickly across the Prairies, brining increasing cloudiness to Winnipeg and the RRV Saturday afternoon with a slight chance of showers in the evening. For more info, read on!

GEM-REG 3HR. QPF
12Z 21 October GEM-REG 3 hour precipitation accumulation valid at 00Z Sunday (Saturday Evening)

Overnight a low pressure system will track across the Central Prairies towards Manitoba with a developing N-S trough intensifying as it moves eastwards. As it enters The Pas and Norway House areas on Saturday, Winnipeg and the RRV will see increasing clouds and a strengthening southerly wind to 30-40 km/h. As the trough swings through Winnipeg in the late afternoon and early evening, we’ll see a slight chance of a shower or two. The bulk of the precipitation should stay north of the city, closer to the low, where there is more significant lift. All models bring the edge of the rain close to Winnipeg, though, so it certainly isn’t out of the question for us to end up getting 2-4 mm out of an hour or two of rain. It seems most likely, though, that late afternoon and the evening will be overcast with a scattered shower or two.

After this system passes through, we’ll enter a stagnant pattern for a couple days with daytime highs just below 10°C and overnight lows slightly below 0°C.

Ensemble 500mb Theta-E
Ensemble Mean 500mb θe

The next chance for significant weather looks to be next Tuesday night / Wednesday morning as a rather sharp 500mb cold trough swings across the province. This will present us with a slight chance of flurries overnight, but shouldn’t amount to too much. More on that next week.

Have a great weekend and enjoy these crisp fall days!

Significant Rainfalls On The Way for Tuesday

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A low-pressure system approaching Manitoba will rapidly develop this evening as it enters the province, bringing one of the most substantial widespread rainfalls of the last several months. The largest amounts will lie along a narrow axis called the deformation zone which makes these events hard to predict: a slight change in the track of the low can cause shifts in the placement of the deformation zone. So where will Winnipeg lie? What can other areas of the Red River Valley expect? Click through to find out!

12hr. QPF GEM-REG
12hr. Rainfall from the GEM Regional Model, valid 00Z Wednesday Evening

This system is slowly built into Southern Alberta through the night last night, and is now beginning to quickly move eastwards across the Prairies. Currently, the system is fairly weak, giving only light showers to many areas across Southern SK/AB, however a shortwave ejecting onto the Prairies from the Canadian Rockies will slidealong the US/Canada border this evening and overnight and will be able to tap into warmer air aloft over the Eastern Prairies and a pool of extremely cool, Arctic air over the Northwestern Prairies.

The combination of a powerful shortwave with access to these two air masses will result in a rapidly deepening low pressure system. Currently, the low sits just east of Regina and has a central pressure of about 100.8kPa. By mid-morning Tuesday, the low will sit over the Southern Red River Valley with a central pressure of 99.5kPa, which is a significant drop in pressure over 12-18 hours.

Rain will push into SW Manitoba by this evening, with a few scattered showers across the Red River Valley before midnight. Rain will intensify and build across the RRV into SE Manitoba overnight as the system really starts tapping into some of the cooler air across the Northern Prairies. The deformation zone will become quite apparent by tomorrow morning, which will make the precipitation forecasts easier, but right now it’s looking like it will set up just over or the southeast of Winnipeg.

So! What does this all mean?

Rain will push into Winnipeg and areas south overnight and be quite intense at times. Widespread amounts through these areas will likely be 5-10mm overnight, with the chance of some higher amounts over the Western Escarpment. Tomorrow will be quite an active weather day, with continuous rain for much of the RRV and strong winds with gusts as high as 70-80km/h from the north. These strong winds will likely cause some localized erosion on the lee beaches of the lakes which are still dealing with high water levels.

Areas south of Winnipeg will see an additional 15-25mm of rain tomorrow with few areas getting as much as 30mm, as will the Whiteshell. Winnipeg itself, however, will be trickier. If the deformation zone sets up to the southeast of us, we’ll likely only get perhaps 5-10mm. If we end up under it, or it moves to our NW, we could see substantial amounts of rain. Right now, the likely scenario is 10-15mm, with the potential for amounts as high as 30mm.

The system will clear out by Wednesday and we’ll be left with daytime highs in the mid to high teens for Wed/Thursday as we sit in cooler air behind the cold front associated with the system. By the end of the week, another upper ridge begins to build into the Prairies which will push sunshine and warm temperatures back into Southern Manitoba. Currently, it looks like we’ll see highs in the mid-20’s by week’s end.

So enjoy that (most of) you’ll be at work tomorrow during our kind of miserable day, and we’ll all enjoy the sunshine and warm temperatures in another taste of summer this weekend!