Spring is in Sight

Brad Leave a comment
The GFS depicts an upper-level ridge building into our region early next week.
The GFS depicts an upper-level ridge building into our region early next week.

Winter-weary Winnipeggers can take solace in the fact that an end to the never-ending winter is in sight. There is increasing confidence that a large upper-level ridge will build into the Central U.S. and Southern Prairies early next week and finally bring some seasonal to slightly above seasonal temperatures to the region. First, though, we’ll have to make it through the rest of the week.

A Cold End to the Week

Cold temperatures will continue to persist through the remainder of the week with well below seasonal highs and lows expected. These cold temperatures are being caused by a large stationary trough of cold air over Hudson Bay that has locked the eastern Prairies into a northwesterly flow that has allowed cold Arctic air to spill southwards, dashing the warm-weather hopes of battered and beleaguered Manitobans.

Wednesday
-2°C / -17°C
A few clouds.

Thursday
0°C / -10°C
Partly cloudy. Slight chance of flurries.

Friday
5°C / 1°C
Late day cloudiness; warming up.

Tonight will be the coldest night for the remainder of the week in the Red River Valley thanks to another push of cold air on the back side of a low pressure system passing to our south. There will be a strong chance of another swath of record low temperatures broken – similar to Monday night – as overnight lows dip some 15-20°C below normal.

Thursday brings a similar high to today, around -2°C, however temperatures just off the ground will be a little bit cooler. This combination will result in stronger low-level instability and we could potentially see a few light flurries develop through the Red River Vally similar to what was seen on Monday afternoon. Overall the risk is very slight, though. Temperatures will drop to a more mild -10°C Thursday night as warmer air begins pushing eastwards.

Friday will be the warmest day so far this week. Temperatures look to climb above the freezing mark towards +4 or +5°C with only a bit of cloudiness to contend with. Winds will be a little breezy out of the southeast to around 20-30km/h, but overall it will be quite a pleasant day with plenty of sunshine. Some cloud will begin streaming in late in the day ahead of the next system pushing towards the region. The cloudier skies will help keep our overnight low fairly warm, with a chance we won’t even drop below 0°C. We may have to contend with some unpleasant weather through the overnight hours, though…

Big Shift on the Weekend

Precipitation amounts forecast on Friday night by the GDPS.
Precipitation amounts forecast on Friday night by the GDPS.

Models are all hinting towards some precipitation on Friday night into Saturday morning as a low pressure system lifts northeastwards through the Prairies. It’s still far too early to speak towards the system in much detail at all, other than saying the bulk of it looks to happen during the overnight period. Some models, such as the pictured output from the GDPS[1] really wind the system up and produce significant quantities of rain or snow while others lift the system much further north with little precipitation development. We’ll have more details on precipitation type and how much of what to expect later on in the week.

The bigger news is that this system marks a significant pattern shift as the upper level ridge we mentioned at the beginning of the article begins developing and pushing eastwards. As it does so, warmer air looks set to flood the Prairies, quickly launching our temperatures back towards seasonal to above-seasonal. Sunday will have temperatures close to normal[2] and we might see it get as warm as the low-to-mid teens on Monday, if we can manage to work past our snow cover.

Multiple days of near-to-just-above freezing temperatures coupled with the strong April sun should do quick work to melt the remaining snowpack across much of the Red River Valley. Melt will be minimal until the weekend, but even one or two days with temperatures in the 5-10°C range will do quick work with much of the remaining snow. Once we can eliminate the snow pack, extremely abnormal cold will be much harder to come by and it will be much easier to see seasonal temperatures.

  1. Global Deterministic Prediction System – Canada’s long-term forecast model.  ↩
  2. Seasonal temperatures for Winnipeg currently are around 11°C for a daytime high and 0°C for an overnight low.  ↩

Winter’s Last Gasp

Brad Leave a comment

This week will see one last wintry blast in southern Manitoba before spring finally arrives for good.

A surface ridge of high pressure will bring cold weather to southern Manitoba to start the week
A surface ridge of high pressure will bring cold weather to southern Manitoba to start the week

Monday

Monday
-7°C / -18°C
Mainly sunny. Chance of flurries.

Today will likely be the coldest day of the week. High temperatures will be in the upper minus single digits, with a chance of flurries. This chance of flurries will arise from low-level instability that will develop as the surface warms during the day. To top it all off, there will be a breezy north-west wind – great!

Tuesday

Tuesday
-5°C / -15°C
Increasing cloudiness. Slight chance of flurries.

A low pressure system will pass to our south on Tuesday, allowing a cool north-easterly flow to remain established over southern Manitoba. Luckily, that system should remain far enough south to prevent us from seeing any more snow, although a couple of flurries can’t be ruled out.

Wednesday

Wednesday
-4°C / -17°C
Mix of sun and cloud. Chance of flurries.

A brisk northerly flow will remain in southern Manitoba on Wednesday, making for another cold day. High temperatures will be in the mid minus single digits, and there will once again be a chance of flurries.

Record Cold?

With the cold weather that’s expected this week, we will be challenging some cold weather records. The table below shows the record values for the next several days:

Record Cold Minimum and Maximum Temperatures
Date Record Low Record Cold High
Monday April 14 -16.7°C (1893) -7.8°C (1880)
Tuesday April 15 -16.7°C (1893) -6.7°C (1875)
Wednesday April 16 -16.7°C (1875) -4.4°C (1910)
Thursday April 17 -13.3°C (1953) -3.3°C (1953)

It looks like we will come close to setting new records on each of the days listed in the table. Stay tuned to see if we manage to actually break any records!

Long Range

The long range forecast calls for increasing temperatures as we move into the weekend. We’ll likely see seasonal temperatures (i.e. low teens) return by the weekend into next week. There is currently no strong prospective of above-normal weather, but we’ll probably see at least a couple seasonably warm days before the month is out.

Record Low Temperatures Broken

A large swath of record low temperatures were set on the morning of April 15, 2014 across the province of Manitoba thanks to a strong Arctic ridge of high pressure sprawled over the region. Overnight lows were 10-20°C below normal throughout the province. Winnipeg did not set a new record low, however some other locations in the Red River Valley did.

Record Low Temperatures set on April 15, 2014
Site New Record Old Record (Year)
Berens River –23.8°C –19.6 (1997)
Carberry –14.2°C –12.9 C (2000)
Carman –15 C –11.4 C (2000)
Fisher Branch –20.4 C –11.8 C (2000)
Flin Flon –20.5 C –16 (1997)
George Island –19.5 C –16.8 C (1997)
Grand Rapids –24.4 C –13 (1997)
Island Lake –20.7 C –20.6 C (2000)
McCreary –13.7 C –12 (2000)
Oak Point Marine –19.7 C –11.9 (1997)
Pinawa –21 C –12 (2000)
Roblin –11.4 C –11.3 C (1997)
Shoal Lake –11.5 C –10.2 C (2000)
Sprague –16 C –10.8 C (2000)
The Pas –20.5 C –18 C (1986)
Thompson –27.3 C –23.4 C (1985)
Victoria Beach –20 C –11 C (2000)
Wasagaming –15.5 C –15 C (1978)

More record lows will be at the risk of being broken as the week progresses.

Elsewhere in Weather News: April 12, 2014

Matthieu Leave a comment

Cyclone Ita hit North Queensland last Friday, called one of the worst ever in the region.

Visible satellite image of Cyclone Ita as it hit Far North Queensland
Visible satellite image of Cyclone Ita as it hit Far North Queensland

Cyclone Ita hit North Queensland, Australia as a category 3 storm on Friday into Saturday (local time), bringing strong winds and flooding rain to the region. Wind speeds higher than 120 km/h were reported near the small town of Cookstown, Australia and speeds near 160 km/h were reported at Cape Flattery. In addition, more than 125 mm of rain fell in Cookstown. However, the highest reported rainfall total was 311 mm in Bairds. Cyclone Ita hit the Soloman Islands before impacting Australia, causing 21 deaths there. The number of deaths, were there any, from Ita in Australia is not presently known. Luckily, the part of North Queensland hit by Ita is sparsely populated, helping to minimize the impact of the storm.

Cyclones are a common phenomenon in the waters surrounding Australia. Also called willy-willies by locals, cyclones are the same as hurricanes, except that they occur in the Pacific and Indian Oceans, rather than the Atlantic Ocean. The main requirements for cyclone formation are surface water temperatures of at least 27 degrees Celsius and weak vertical wind shear (the absence of a jet stream overhead). These conditions are most often met in the tropics, though cyclones and hurricanes have been known to impact areas at higher latitudes late in the summer and early in the fall.

Sources:

Remember Winter?

Brad Leave a comment
Expected precipitation types on Saturday.
Expected precipitation types on Saturday.

Supplications for summer will be silenced as the stage is set for a sloppy spring storm that will supply snow to Southern Manitoba. Two disturbances will impact the region – one this morning and the other tonight through Saturday – and bring decidedly messy spring-time weather to the region followed by a surprisingly cold air mass for mid-April. Get those snow shovels out and read on to find out what to expect in your area.

Disturbance #1

The leading disturbance moving through the province this morning is by far the weaker of the two and will move through quite quickly. Disorganized showers or flurries are possible across the region through the morning hours, then we’ll see the clouds begin to clear out giving some sun for the afternoon. We’ll reach a high of only around +4°C today with light northeasterly winds.

Friday
4°C / -3°C
Cloudy periods. Slight chance of morning flurries or showers.
Saturday
1°C / -8°C
Snow. 5-10cm.
Sunday
-2°C / -14°C
Mainly sunny.

Disturbance #2

Our reprieve from the snow threat will be short-lived, however, as another system pushes into Southern Manitoba tonight. Cloud will stream into the Red River Valley this evening ahead of the main precipitation associated with this low, which will not push into the RRV until the second half of the overnight period. Temperatures will drop to only around -3 or -4°C overnight.

As the precipitation shield undergoes rapid expansion early in the evening, snow, heavy at times, will fall along and south of the Trans-Canada Highway in southwestern Manitoba through a good portion of the night which will result in some of the highest accumulations for this storm. By the time all is said and done, 10-20cm of snow is possible over southwest Manitoba.

Further east in the Red River Valley, snow will push in much later in the overnight period, first spreading into the Morden/Winkler region and then pushing northeastwards. Snow will reach Winnipeg by early Saturday morning. The heaviest snow will fall in the southern portion of the RRV with enhanced amounts possible in the southwest corner near the escarpment where upslope winds will help enhance snowfall.

The main snowfall event for the Red River Valley will occur through the day on Saturday. Weak warm advection aloft will do little to help temperatures at the surface which will be stuck out of the north feeding cooler, dryer air into this system. Coupled with the snow, temperatures through the valley won’t climb much more than a degree or two above zero. It will likely be warm enough at the surface (and aloft) to melt some of the snow that falls. This will reduce snowfall amounts a bit, but given the intensity of the precipitation expected, snow accumulation should overpower the melting factor fairly quickly.

Total snowfall expected Friday night through Saturday. Amounts may be lower depending on how much melts.
Total snowfall expected Friday night through Saturday. Amounts may be lower depending on how much melts.

In general, most areas seem to be set to see around 5-10cm of snow, perhaps a little less if there’s more melting. With temperatures near zero, it will be a somewhat wet, heavy, sloppy snow that will likely make driving very unpleasant and slippery. The snow should taper off on Saturday evening as the system pushes off to the east. Skies will clear in advance of an Arctic ridge pushing into the Prairies and we’ll drop to an overnight low near -8 or -9°C.

Cooler Weather Ahead

Behind this system, very cool arctic air will push into the Prairies. Sunday will be mainly sunny with some afternoon cloud but the temperature will top out more than 10°C below normal at only around -2°C.

The start of next week continues the sunny trend, although Monday will be nearly 20°C below normal with a high of only -8°C. More seasonal air looks to build back in midweek.