Tag: flood threat

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

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.