Tag: heavy rainfall

Alberta

Much NEEDED RAINFALL & SNOW to Kick off the…

A potent upper-level system will stall all week across Alberta and Saskatchewan. The unsettled pattern will bring much-needed rainfall, thunderstorms, much below seasonal temperatures, and even accumulating S*** for Banff & Jasper.

Beneficial rainfall will persist all week in Alberta & Saskatchewan as an upper-level system stalls across the region. The heaviest rainfall is anticipated across Central Alberta where 50-75mm+ is expected by Friday. With much of that rain falling between Wednesday and Thursday. Some rainfall is in the forecast for drought-stricken High Level (Northern Alberta) & Moose Jaw (Southwestern Saskatchewan).

The much below seasonal temperatures and a soaking rainfall will make it feel more like the middle of October across the foothills. By Wednesday, temperatures will plummet nearly 10c below seasonal. Continuing through the day Thursday.

DAYS OF THUNDERSTORMS CONTINUE WITH THE THREAT OF SEVERE TUESDAY

Thunderstorms have been an almost daily occurrence over the last several days in the Prairies. The thunderstorm risk is expected to continue this week.

Monday: thunderstorms producing heavy downpours and small hail across Interior British Columbia and Northern Alberta.

Locally strong to severe thunderstorms expected across the yellow shaded area today.

Tuesday: better dynamics for potent thunderstorms across Southern Alberta (Calgary to Medicine Hat). Discrete cells or supercells could be capable of producing damaging winds and large hail.

Wednesday: daytime heating thunderstorm risk moves further East into Saskatchewan.

ACCUMULATING SNOW KICKS OFF SUMMER IN BANFF & JASPER

Between Wednesday night through Friday, accumulating up-sloping snow is expected over the high-elevation topography of Banff and Jasper National Parks. Believe or not, Friday is officially the first day of summer.

Alberta

Convective Outlook: Thunderstorms & Flood Risk

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.

-troy

New Brunswick

Texas Low: Severe Outbreak Precedes Potent Storm for Eastern…

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.

Moisture laden low developing in Texas bringing severe thunderstorms. With impacts across Eastern Canada to end the week. Persisting into early next week.

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.

A lousy system for the Great Lakes. Below seasonal temperatures, a soaking rainfall and more snow expected.

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.

Click to navigate a larger image of the map.

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.

British Columbia

How Two Storms Dancing in the Pacific Will Impact…

What is a dancing storm? Good question. The Fujiwara effect “dancing storms” refers to the interaction between two cyclonic vortices. When two low-pressure systems near each other, they begin to orbit one another around a mid-point separating the two systems. The effect gets its nickname from the interaction of two systems appearing to “dance” around one another. Read more here.

A pair of systems interacting in the Gulf of Alaska through the weekend. By Saturday afternoon, the systems merge into one stronger storm and stall in the Gulf. Heralding waves of precipitation & unsettled conditions along the coast.

WINDY DAY SATURDAY ALONG THE HAIDA GWAII ARCHIPELAGO

Southeasterly winds will pick-up along the channel separating the islands and the Mainland, Saturday. The most powerful wind & waves will remain off-shore. Still, gusty winds & rainfall along Vancouver Island and the Archipelago will lead to a lousy day. Wind gusts between 60-90km/h are likely.

WET ALONG THE COAST WITH SNOW IN THE MOUNTAINS

An unsettled couple of days across the Lower Mainland & Vancouver Island. 25-35mm of rainfall is expected across Vancouver & Victoria through Friday & Saturday. This will be a beneficial rainfall across the region, where its been an unusually-dry start to spring. Unfortunately, the rainfall isn’t expected to penetrate far enough into the interior to bring any relief to the dry conditions.

Projected Rainfall through the weekend.

A more prolonged and significant rainfall is expected along Western sections of Vancouver Island. 40-70mm of rainfall is expected by the end of the day Saturday. The mountain peaks along the coast will see heavy snow – mixing or light accumulation is possible along sections of Highway 19.

Heavy snow expected above 1500m.
New Brunswick

Bomb Cyclone Threatens Damaging Windstorm, Snow & Heavy Rain…

A weatherbomb is rapidly strengthening Tuesday off Cape Hatteras, North Carolina. Bringing hurricane-force winds, significant rain & lighting just off-shore. This system will undergo bombogenesis as it tracks up the Eastern Seaboard, through the Gulf of St. Lawrence into Labrador. 

Significant rainfall & snowfall accompanied by damaging winds gusting over 100km/h is anticipated. The most tempestuous conditions being felt across the Maritimes Wednesday afternoon & evening. For Newfoundland & Labrador conditions deteriorate rapidly overnight Wednesday. Persisting through most of the day Thursday.

DAMAGING WIND THREAT

Damaging winds will be the main story with this powerful storm. Atmospheric pressure is expected to drop 28mb within 24 hours. An expansive – strengthening wind field will result. Hurricane-force winds (gusts over 120km/h) expected along the Western coast of Newfoundland & Cape Breton Island.

Les Suetes winds gusting up 160 km/h are forecast to develop Wednesday afternoon, shifting southwesterly before dissipating. Wreckhouse winds could peak between 160-180km/h.

Click to navigate the wind impact map.

SIGNIFICANT WIND DRIVEN RAINFALL FOR COASTAL NOVA SCOTIA

Environment Canada has issued a Rainfall warning across Nova Scotia. The agency is warning up to 70mm of rain could fall, in the hardest hit regions along coastal Nova Scotia.

Rain at times heavy will develop early Wednesday morning over southwestern Nova Scotia and quickly spread to the remainder of the province by Wednesday afternoon. The rain will be mixed with snow to start over parts of mainland Nova Scotia Wednesday morning. Over Cape Breton, the rain will likely be preceded by a period of snow over some areas.

Rainfall amounts will be highest over Atlantic coastal regions of mainland Nova Scotia where 50 to 70 millimetres are forecast. Elsewhere, 25 to 40 millimetres of rain is expected.

Heavy downpours can cause flash floods and water pooling on roads. Localized flooding in low-lying areas is possible.

SNOWFALL ACROSS NEW BRUNSWICK & BLIZZARD CONDITIONS ACROSS LABRADOR

Environment Canada has issued several warning across New Brunswick. This is what they wrote in their statement. Snow will begin Wednesday morning over southwestern New Brunswick and then spread quickly across the province by noon. The snow will likely mix with rain in the afternoon. Snowfall amounts of up to 10 cm are possible. Over eastern regions of the province, snowfall amounts in excess of 15 cm are likely and snowfall warnings are in effect there. Along the Fundy coast, rainfall amounts near 25 mm are possible and rainfall warnings are in effect there. Northwestern New Brunswick will only receive light amounts of precipitation from this system.

Western Newfoundland will have to contend with sea-effect snow and blizzard-like conditions through the day Thursday. 5-15cm of accumulation is expected by Thursday evening. Heavy flurries and snowsqualls may continue Thursday overnight and Friday.

This will be a major winter storm for Labrador. Who has been no stranger to significant storms this season. Winter refuses to relinquish its icy grip. 25-40cm of fresh snow concurrent with 90km/h+ winds & blizzard conditions.

Manitoba

Tale of Two Seasons: Heavy Snow, Rain, & Summer…

An area of low pressure will strengthen as it tracks through the Upper Midwestern United States. Bringing accumulating snow and gusty winds across Northwestern Ontario. Summer-like heat & humdity returns to Southern Ontario.

TIMING & ACCUMULATIONS 

Snow flurries will begin mixing in along Highway 17 late Wednesday evening. With wet snow falling by Thursday morning. By Thursday afternoon, anywhere along and south of Highway 11 will likely be seeing rain. 

North of Lake Superior, precipitation will fall as a cold rain with gusty winds. Including the Thunder Bay area, where cold rain and gusty winds will lead to a miserable day. 

Projected snowfall divisible by Postal Code. 
PostalCast©: NW. ON SNOWSTORM – Wednesday through Thursday
— MOST Impacted Locales (Based on First 3 Digits of a Postal Code) —
P0L (10-15cm for Southern Regions; 15-25cm for Northern)
P0T (<5cm near Superior; 25-30cm+ for Northern Regions)
P0V (<5cm for Northern Regions; 15-25cm for Southern)
P0W (10-15cm)
P0X (15-20cm)
P0Y (15-20cm)
P8N (20-25cm+)
P8T (20-25cm+)
P9A (8-15cm)
P9N (10-20cm)

By Wednesday afternoon or late evening, cold air will wrap around the deepening system. Heavy snowfall will begin accumulating in a line from Kenora to Dryden to Sioux Lookout to Pickle Lake. Continuing into extreme Southeastern Manitoba. Moderate to heavy snowfall and gusty winds will persist, increasing in coverage across Northwestern Ontario through the day Thursday. 

Projected amounts are subject to change based on the track & timing of the low + Hurricane Michael. Current guidance suggests a large swath of 20-30cm. 30-40cm could fall locally.

Preliminary snowfall projections will be updated throughout the week.

Actual accumulations will be largely dependant upon key factors: track of the low, temperature, and snowfall ratios. Moisture won’t be an issue with tropical moisture from Hurricane Michael. 

HEAVY RAINFALL 

While Northwestern Ontario deals with heavy snow, Northeastern Ontario will be dealing with heavy rainfall. A large swath of 50-75mm is expected East of Lake Superior. 

THE TALE OF TWO SEASONS 

As Northern Ontario deals with heavy rain and snow, Southern Ontario will get one last blast of summer. Temperatures Wednesday will likely be soaring into the mid or high-20s. With abundant humidity making it feel into the 30s. Forecast temperature & humidity readings will challenge all-time October records Tuesday and Wednesday.

Ontario

Stormy Evening & Overnight for Northeastern Ontario

Heavy showers & thunderstorms beginning this afternoon in Sudbury and Algoma District. Continuing through the overnight.

An area of low pressure will rapidly intensify as it tracks through Northern Ontario towards James Bay. A sharp cold front will trigger heavy rainfall and thunderstorms today and tonight across Northeastern Ontario.

THREATS

The primary threat will be torrential rainfall leading to minor flooding. Additionally, small hail and locally strong winds are possible in stronger thunderstorms.

NAM model rainfall projection for Wednesday into Thursday.

Rainfall totals in the range of 30-60mm is expected north of Manitoulin Island & East of Lake Superior.

Thunderstorm Outlook from Environment Canada

Ontario

Wet & Stormy Tuesday Across the Lower Great Lakes

Heavy thunderstorms expected Tuesday (August 21st, 2018) across Southern Ontario.

Rain-showers or thunderstorms are expected to begin moving into deep Southwestern Ontario overnight Monday into Tuesday. Convection will spread throughout Southern Ontario throughout the morning and afternoon as a maturing-low approaches from the US. Another round is possible by the mid-evening along the shores of Lake Huron.

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BRIEF CLEARING? & HEAVY RAINFALL

There may be some brief clearing stretching from the Golden Horseshoe into Southwestern Ontario. This would add more energy and instability, allowing for some isolated severe thunderstorms capable of very-strong winds and short-lived rotation.

Much of the day however, is expected to be dominated by cloud, showers and passing heavy thunderstorms – perhaps several rounds. This could lead to locally significant rainfall-totals. With the threat of localized flooding. Widespread amounts between 30-50mm is expected.

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BENEFICIAL RAIN:

East of Georgian Bay stretching into East of Superior will see a beneficial, soaking rainfall from this system. Which will help alleviate forest fire concerns, plaguing the region this summer.

WIND:

This will be an early fall-like system for the Great Lakes. As we move deeper into August we are beginning to enter a transitional period, where low-pressure systems produce synoptic rain and wind over a larger area. Widespread winds gusting between 50-70km/h are expected between Tuesday late-afternoon, and through the evening.

No need for “the end of sunmer blues” quite yet, temperatures by this weekend will be near 30c feeling closer to 40c with the humdity factored in.

Ontario

The Remnants of Tropical Storm Alberto Approach the Great…

Alberto has been blamed for flash flooding, mudslides and power outages in parts of the Southern United States. The remnants of Alberto will churn into Michigan this evening – increasing humidity readings and creating unsettled conditions for Southern Ontario, beginning late this evening.

High dew-point values will envelop much of Southern Ontario Wednesday through Thursday. Overnight lows near or above 20C Wednesday night, coupled with dew-points in the high teens, will lead to stifling conditions in doors for residences without air-conditioning or central-air.

High humidity with temperatures in the middle to high teens will act as fuel for Thunderstorms Wednesday night in Southwestern Ontario – with a widespread risk for Thursday morning through evening for the rest of Southern Ontario.

The remnant low of Tropical Storm Alberto will act as a trigger Wednesday night and Thursday. As the remnant low approaches Michigan, bands of showers and thunderstorms will wrap around the low.

What is left of Tropical Storm Alberto as it churns north – towards Michigan. Still displaying well defined circulation and heavy rainfall. 

On Thursday, the low will coalesce will a cold front and get absorbed by the Jet-stream. Upper-level energy and a cold front is expected to act as a trigger for widespread thunderstorms, some of which could turn severe. The primary risk with any thunderstorms that develop Thursday will be torrential rainfall and gusty winds. We will be watching Southwestern Ontario where rainfall could be an issue with minor flooding concerns.

A secondary cold front passage is expected Friday – which may act as a trigger for another round of thunderstorms. Again, rainfall will be the primary concern. Small hail is also a possibility.

It’s important to note, the next couple days aren’t expected to be a wash-out for everyone. Some locales may only see a few millimetres of rain. Whereas other locales, who receive several rounds of thunderstorms or training thunderstorms, could see locally 50mm or more.

Some solace from the humidity is expected by Saturday. Temperatures return to normal with brilliant sunshine and no humidity.

NORTHERN ONTARIO

A deep-layer of tropical moisture will move well north into Canada. Reaching as far North as James Bay and Northern Quebec. Heavy rainfall is expected along a boundary between Lake Superior and James Bay continuing into Northern Quebec. Totals rainfall amounts between 40-75mm are expected in the next 48 hours in the region.

Ontario

Thunderstorms, Locally Heavy Rainfall & Frequent Lightning for Southern…

Rain and thunderstorms expected early Tuesday (May 15, 2018) in Southern Ontario.

A complex of rain and thunderstorms is developing this hour in the Midwestern United States. This weather system is expected to push East late this evening, bringing widespread rain and thunderstorms after midnight.

Ahead of this system, humidity levels will increase – with temperatures into the high teens lingering late this evening and overnight.

TIMING:

Windsor to Goderich – approximately 1am Tuesday.

Port Rowan to K/W to Shelburne – approximately 3am Tuesday.

GTA to Barrie – approximately 4am Tuesday.

Peterborough to Eastern Ontario – after 5am Tuesday.

Kingston to Ottawa – approximately 9am Tuesday.

IMPACTS:

Heavy rainfall and frequent lightning for communities impacted by the complex of rainfall and thunderstorms tonight. A lessor threat for small hail and gusty winds also exists.

Due to already saturated soil, and rainfall intensity, a Special Weather Statement has been issued north of Lake Erie.

Rainfall totals between 20-40mm is expected north of Lake Erie. Locally, up to 50mm is possible. Elsewhere, expect 15+mm.

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– TCW