It’s been an active evening across extreme Southwestern Ontario. Severe storms produced torrential downpours, damaging winds, intense frequent lightning, and eerie skies. One storm chaser tracking the storms got more than he anticipated today.
Our forecasting team at TransCanada Weather is cautiously watching long range model guidance. Between Tuesday May 28th – Thursday, June 6th, the evolution of a pattern supportive of heavy rain, severe thunderstorms & unsettled conditions will envelop parts of Canada. Read below to find out where.
PRAIRIES: Unsettled Conditions, Risk of Cold Core Funnels, Threat of Thunderstorms
The Prairies will have to contend with unsettled conditions. Including a pattern that may support the risk of cold core funnel clouds & areas of severe thunderstorms between late May to early June. This is be welcomed news for Alberta; contending with out-of-control forest fires.
GREAT LAKES: Heavy Rain & Severe Thunderstorms
A second area we are watching closely: the Great Lakes/Ontario region. A supportive pattern for flooding and/or severe thunderstorms is possible between Tuesday May 28th to Thursday May 30th.
Abnormally, deep troughing, seasonably deep height-falls, strong waves of low-pressure, concurrent with a southeast ridge. Will bring surges of warm moist air along with supportive wind profiles for severe thunderstorms and/or flood risk. A significant severe day will be possible within this regime across Southern or Northeastern Ontario.
Saturday, May 25th: after Thursday, the next threat for severe across Southern Ontario will come Saturday. Risks across Southwestern Ontario include: isolated damaging wind gusts, large hail & torrential downpours.
Additional considerations: drought conditions in the Southeastern US allowing mid-level dry/warm air to migrate north within stronger circulations. Abnormally-wet southern plains, increasing low-level moisture transport/PWAT values in stronger 850mb flows.
A sudden surge of warm, summer-like air will herald in the risk of thunderstorms across the Lower Great Lakes. These thunderstorms may turn severe; capable of producing damaging winds & hail across portions of Southern Ontario.
SURGING TEMPERATURES, THUNDERSTORMS & RAIN
An area of low-pressure will transverse through the Midwestern United States towards Ontario, throughout the day Sunday. Ahead of the system, temperatures will surge into the mid-20s and humidity readings into the low-30s. Near the Lake-shore, cooler conditions are expected.
Showers are expected before midnight tonight, lasting into the pre-dawn hours. Persistent rain-showers and embedded thunderstorms are expected for Central Ontario – mainly East of Georgian Bay. Sunny breaks are anticipated through the morning hours, allowing for some instability to build before the arrival of a cold front.
At this point, it appears the setup will feature two potential waves of thunderstorms. The primary wave will consist of a complex of heavy rain showers with embedded thunderstorms impacting Southern Ontario between 4-10 pm. Initiating at approximately 4 pm in Windsor and exiting Eastern Ontario by 11 pm. Risks include: torrential downpours, lighting and isolated damaging winds. A potentially stronger second round of thunderstorms (along an advancing cold front) may happen on Sunday evening/overnight, across Extreme Southwestern Ontario. There is some uncertainty regarding the evolution of thunderstorm development. If thunderstorms do develop, risk factors include: hail and isolated damaging wind gusts.
Across Northern Ontario, a large swath of heavy rainfall is expected. Local rainfall totals nearing 50mm is anticipated.
A significant trough crossing the Guadelupe Mountains will drive the development of a potent area of low-pressure across Texas Saturday. Favorable conditions for the development of severe thunderstorms, will exist along the warm front axis; ahead of a vigorous cold front. This will be significant “severe weather event” for Northern Louisiana, Southern Arkansas, Western Mississippi, and Eastern Texas. Reloading for a second day of severe weather, across the Eastern United States.
During the day Sunday, the low is forecast to take a northeast hook towards the lower Great Lakes bringing a plume of rain and snow for Southern/Central Ontario & Southern Quebec.
Atlantic Canada is poised to see the most tempestuous conditions, with rapid deepening of the low-pressure center late Monday. This system will be a heavy-rain story for the Maritimes. On the contrary, Newfoundland could see heavy snow, significant freezing rain and strong winds.
COOL, WET & LOUSY COUPLE DAYS FOR SOUTHERN ONTARIO
Get out and enjoy the abundant sunshine and warm temperatures Saturday. A messy, moisture-laden system out of Texas will deliver below seasonal temperatures, a soaking rainfall, mixed precipitation and accumulating wet snow. The heaviest rainfall will be situated along the Lake Ontario shoreline into the Niagara Region. The heaviest of the snowfall will be seen across parts of Central Ontario – through cottage country.
SIGNIFICANT RAINFALL & GUSTY WINDS FOR THE MARITIMES
Significant rainfall will encompass much of Nova Scotia, the Bay of Fundy region in New Brunswick & Prince Edward Island. There is still considerable uncertainty how this low will develop in the Maritimes. Current projections have most of the precipitation falling as rainfall. As much as, 40-75mm of rain is possible, between Sunday night through Tuesday morning.
POTENTIAL ‘WEATHERBOMB’ FOR NEWFOUNDLAND
The system is expected to undergo rapid deepening Monday night. Slowing as it transverses through Gulf of St. Lawrence. A strengthening wind field along the Northwestern coast, persists all-day Tuesday. Refinements to the forecast will come throughout the coming days. Nevertheless, this is looking like a potent system for Newfoundland.
We are becoming increasingly concerned regarding a freezing rain threat for the north coast of Newfoundland. Including Fogo Island, Bonavista North & Green Bay. 10-15mm+ of freezing rain, ending as snow and strong winds could bring localized power outages.
Heavy snowfall will be the story across Northwestern Newfoundland with as much as 20-40cm falling over the hardest hit areas. Concurrent, with strong winds leading to blowing and drifting snow.
An area of low-pressure sliding out of Colorado will undergo explosive intensification through the day Wednesday. This will be an blockbuster blizzard for portions of the Upper Midwest including South Dakota & Minnesota. 40-60cm+ of snow concurrent with 70-90km/h winds will cripple the region.
BLIZZARD WEAKENS AS IT MOVES INTO NORTHWESTERN ONTARIO
The explosive Colorado Low that will cripple South Dakota, will thankfully be weakening as it approaches Ontario. Snow will move into the Thunder Bay, Nipigon, Atikokan, Upsala area before midnight Thursday. Accumulating snow will combine with gusty winds between 40-55km/h, through Thursday night and Friday. It will be a good day to stay home and off the roads if you can.
Wawa to Timmins will see more ice pellets and wet snow, than rain. A transition to rain showers is expected throughout Friday Afternoon.
Kapuskasing to Hearst will remain as snow, where 15-20cm is expected to fall.
SOUTHERN ONTARIO IMPACTS
Strong wind, a surge of warmer air and rainfall will be the story across Southern Ontario Friday. A cool and partly-cloudy day Thursday, with patchy mixed precipitation. Largely confined to Southwestern Ontario.
Strong wind anticipated across Southwestern Ontario Friday morning. Strong Southeasterly gusts between 70-80km/h is expected north of Lake Erie and East of Lake Huron.
Temperatures in the afternoon will spike into the double digits across Southern Ontario. The Nations Capital Region will see the temperature climb near 9c. The trade-off will be a lousy day with occasional rain or showers Thursday. There is even a risk for localized thunderstorms early in the day Friday.
Friday will be act as the calm before the storm. A pleasant day with single digit highs, light winds, and some sunshine. Beginning after midnight rain will start in the Windsor area. With a mixed bag of precipitation spreading throughout Southern Ontario during the pre-dawn & morning hours.
A moisture laden system will slide towards the lower Great Lakes late this evening, following along a boundary separating cool air across Southern Ontario with warm air south of Lakes Erie & Ontario. Concurrently, an arctic cold front will be descending southwards heralding the arrival of deepening trough over Ontario & the Great Lakes region for Sunday. Temperatures will be running much below seasonal Sunday, daytime highs will struggle to reach the freezing mark. Additionally, Lake-effect flurries or snow is likely across the northwesterly snow-belts.
The challenging aspect of this system will be determining how the air-masses interact. In forecasting situations like this, thickness (a function of the average virtual temperature between 1000 and 500 millibars; read more: https://bit.ly/2WykrG4) can be useful in determining precipitation types. Anywhere, along and north of the blue line will likely see rain change to wet snow. With a brief period of freezing rain or ice pellets possible. South of the red lines will see mostly rain. These lines will move southwards as we progress through the day Saturday. Meaning areas who see mostly rain near Lake Ontario and Lake Erie, may end as wet snow as the system departs.
OKAY SO WHAT DOES THAT MEAN – SNOW, RAIN, OR FREEZING RAIN?
Simply put, all of the above. Depending where in Southern Ontario or Quebec you reside.
The greatest threat for freezing rain will exist across the Ottawa and Montreal region. There’s potential for several hours of freezing rain for this area. And even a threat for appreciable accretion on untreated surfaces. The winds will be light, with temperatures teetering around freezing – largely mitigating any power outage threat.
Next, the snow. Any snow that falls will be wet, the greatest accumulations will be across the Dundalk and Haliburton highlands/highway 60. 10cm or more expected South of Georgian Bay. 10-20cm+ for the Haliburton Highlands. Across much of Southern Quebec – well north of Montreal. Mont-Tremblant National Park could see accumulations as high as 20-30cm. Highways 117, 309, and 105 will be snow covered and slick through Saturday afternoon and evening.
Finally, the rain. 20-40mm will fall along the lower Great Lakes. Including the GTA, Golden Horseshoe, Southwestern Ontario, & Eastern Ontario.
Don’t let the calendar fool you – a bitter sweet transition to spring is expected. The final two weeks of winter will feature drastic temperature swings and at least one notable storm system this weekend.
An area of low-pressure will form lee of the Rockies in Colorado Friday. Deepening as it tracks northeastwards through the United States towards the Great Lakes Region Saturday evening.
15-25mm of rain across deep Southwestern Ontario & North of Lake Erie. Rain combined with snow-melt may lead to localized flooding.
10-20cm of snow for Northern Ontario. Heaviest snow falling East of Lake Superior & across the Nickel Belt.
Strong to damaging wind gusts for Southwestern & Central Ontario.
A surge of warm air in Southern Ontario precedes wrap around strong winds & snow
SNOW FOR NORTHERN ONTARIO
Like many of the storms this season, this system will feature appreciable snow across Northern Ontario. A large swath of 10-15cm is forecast for Wawa, Timmins and Sudbury areas. Local amounts may approach 20cm.
MESSY WINDSTORM FOR SOUTHERN ONTARIO
First and foremost, this is a messy system for Southern Ontario. Precipitation will move into Windsor in deep Southwestern Ontario around 6pm Saturday. Progressing Northeastwards across Southern Ontario during the evening and overnight. Main concern for along the Lake Erie shoreline will be heavy downpours combined with warmer temperatures, snow melt, and runoff. Minor flooding is possible; stretching into the GTA. Be sure to monitor any statements from your local conservation authority, as we progress through the weekend.
Strong to damaging easterly winds will develop ahead of the storm Saturday evening & overnight. The strongest wind gusts are expected East of Lake Huron. Including Goderich, where peak winds could exceed 100km/h late Saturday evening & overnight. The rest of Southern Ontario will have to contend with strong easterly winds gusting 60-90km/h through the overnight into Sunday morning. Once again, winds will strengthen out of the West Sunday, with the passage of a cold front. Frequent gusts between 50-70km/h is expected.
Considering temperatures will be teetering around the freezing mark, precipitation may begin as snow, freezing rain or ice pellets. Especially, South of Georgian Bay where elevation and heavy precipitation rates will aide in keeping temperatures below freezing for a longer duration. For Eastern Ontario, this system will bring more wet snow than rain. Refer to our forecast map for further details.
Our forecasting team is vigilantly monitoring a powerful low-pressure system expected to form North of the Texas Panhandle late this evening. The upper-level disturbance originating out of California, will coincide with a favorable setup for an explosive storm development. Read more about Panhandle Hooks’ here.
Did you know? It was an infamous Panhandle Hook which sank the SS Edmund Fitzgerald on November 10th, 1975.
This storm will feature strong winds, blizzard conditions, heavy rainfall, thunderstorms, and shifting ice-conditions across the Great Lakes. Almost everyone in Eastern Canada will feel the effects of this powerful storm. Read more to gain insight on how this storm may impact you.
BLOCKBUSTER BLIZZARD EAST OF LAKE SUPERIOR
Our forecast team is closely monitoring a soon-to-be rapidly strengthening Panhandle Hook, sagging into the Texas Panhandle. Gathering abundant gulf moisture before trekking towards the Upper Great Lakes. The storm will experience the most intensification while tracking Northeastwards through the Upper Midwest (United States), towards Lake Superior & Northern Ontario. Coinciding with an expanding strong to damaging wind field.
Confidence is considerable for a high-impact Low for regions N and NE of Lake Superior with likely 30cm or more of blowing snow contingent with 60km/h+ wind gusts. The heaviest snowfall will likely be 30-40km inland from the immediate Lake Superior shoreline. This is bad news (or good new depending on your prerogative), when considering how much snow has already fallen across this region. Some are running out of places to even put the snow.
The fiercest winds will not correspond with the heaviest snowfall rates. Still, inland locales such as Timmins & Kapuskasing will still have to contend with extensive blowing & drifting snow. Especially, once the low tracks into Quebec, with colder air and stronger gusts arriving on the backside of the low.
There will be a line of mixing of wintry precipitation likely from Sault Ste. Marie to Sudbury to the QC border. Including a brief period of ice pellets and rain-showers.
WIDESPREAD DAMAGING WINDS ACROSS SOUTHERN ONTARIO
Temperatures will begin to surge above freezing across Southwestern Ontario, as early as, late Saturday evening. Double-digit temperatures & strong Southwesterly winds will advance throughout the Southern half of the Province throughout the morning & afternoon. Rain-showers and even a risk of elevated thunderstorms is expected. Proceeded by, a sharp cold front & plummeting temperatures.
We anticipate extensive blowing snow and poor-visibility East of Lake Huron late Sunday evening through Monday. Avoid all unnecessary travel in the red highlighted area on our wind impact map.
The supportive track and strength of the low will herald in a significant damaging wind threat across Southern Ontario. The strongest winds could peak as high as hurricane force (120km/h), along the Northeast shore of Lake Erie. We anticipate wind gusts over 100km/h across Prince Edward County, and East of Lake Huron. Peak wind gusts will likely reach or exceed 90km/h across the rest of Southern Ontario.
The sudden onset of warm air, rainfall, and extreme wind gusts will bring treacherous ice conditions across the Great Lakes. Ice shoves may be damaging to infrastructure along exposed shorelines. If you participate in winter activities such as, ice fishing or snowmobiling, it would be a good idea to remove your ice hut from the Great Lakes. Avoid snowmobiling until ice conditions improve.
A NEW COASTAL LOW BOMBS OUT AS IT TRACKS THROUGH THE MARITIMES
The powerful storm sweeps through Quebec on Sunday, and will subsequently phase into a strong ‘weather bomb’ south of Yarmouth. Potentially, deepening below 970mb (967-969mb).
While the exact phasing & extend of warm air advection is not entirely set-in-stone, it appears the heaviest swaths of snowfall will likely be off the Gaspe Peninsula shoreline and into the North Atlantic, thereby mitigating what could have been 2 or more feet of snow.
Southern New Brunswick will likely experience a rain/snow/wintry mix. With amounts totaling near 10cm. Amounts increasing to 20-30cm across the Northern extent of the Province. Pockets of heavier enhancement, accompanied by similar conditions is expected across Extreme Southern Newfoundland
Western New Brunswick – Late Afternoon Sunday
Most of New Brunswick – Sunday Evening
Nova Scotia – Sunday Mid Evening
PEI – Sunday Overnight
Newfoundland – Monday
Extreme Southern Shoreline of Newfoundland (25-40cm)
DANGEROUS BLIZZARD CONDITIONS STRETCH FROM JAMES BAY THROUGH NORTHERN QUEBEC
A major blizzard is on-tap for much of Northern Quebec. The worst of the treacherous conditions will be felt across the mouth of the Rupert River, Southeast of James Bay. Where rural communities can expect winds over 90km/h combined with 15-25cm of freshly fallen snow. Extensive blowing/drifting snow & near-zero visibility is expected. Isolated communities across Central & Northern Quebec may become cut-off, briefly.
A risk of freezing rain supersedes an early February warm-up. A temperature roller coaster with a risk of freezing rain will be the story this week across Southwestern Ontario.
Rainfall and above seasonal temperatures are the story this evening into the overnight. Rainfall ends before morning, with temperatures falling throughout the day.
Be mindful around streams and creeks Tuesday morning. As well as, on roadways, where standing water could lead to hydroplaning. Rainfall and snow-melt will lead to higher water levels. Stay tuned to your local Conservation Authority for the latest information.
A freezing rain risk develops by Wednesday morning. This may be an extended period of freezing drizzle & freezing rain for locales north of Lake Erie, including the 401/402 corridor. Local freezing rain accretion may approach or exceed 15mm. Ice pellets and patchy freezing drizzle will be the story for the rest of Southwestern and Central Ontario.
There will be two waves of precipitation. The second translates across the region Thursday along a developing low-pressure system. There is some uncertainty in regards to the evolution of this system. Current model guidance suggests a northerly track, leading to a surge in temperatures (above freezing) across Southern Ontario, Thursday. This would be a big snow maker across Northern Ontario & Quebec.
Sporadic power outages are anticipated across portions of Southwestern Ontario. A stiff northeasterly wind (aiding in low-level cold delivery), will be enhanced over Lake Ontario. Bringing wind gusts to 40km/h downwind of the lake. Sporadic power outages will begin throughout the evening. Peaking between 8pm-12am Wednesday. An extended period of freezing drizzle will succeed the initial wave of convective-driven freezing rain. For regions East of the Escarpment, through South Central Ontario & the Northern GTA this will be a primarily ice pellet event. Briefly beginning as snow, especially stretching from the Bruce Peninsula through Northern sections of Central Ontario.
Charge those devices! And stay tuned.