347
FOCN45 CWWG 161200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT SUNDAY AUGUST
16 2026.
ALERTS IN EFFECT...AIR QUALITY WARNING FOR THE FORT SIMPSON REGION.
SYNOPTIC OVERVIEW...ALOFT THIS MORNING, AN UPPER TROUGH EXTENDS FROM
SOUTHERN BRITISH COLUMBIA SOUTHWEST TO AN UPPER LOW OVER THE EASTERN
PACIFIC OFF THE COAST OF CALIFORNIA. THE FLOW REBOUNDS INTO A
MODERATE ZONAL FLOW ACROSS THE SOUTHERN PRAIRIES WITH A SHORTWAVE
EMBEDDED IN THE FLOW OVER NW ONTARIO/SOUTHERN HUDSON BAY, THEN DIPS
INTO ANOTHER UPPER TROUGH OVER THE ATLANTIC OFFSHORE FROM THE
MARITIMES & NEWFOUNDLAND. IN THE NORTH, A HIGH OVER LOW SITS OVER
ALASKA AND ITS NORTHERN COAST WITH THE FLOW DIVING INTO AN UPPER
TROUGH OVER THE NORTHWEST TERRITORIES EXTENDING FROM AN UPPER LOW
ALONG THE NWT/NU BORDER SOUTHWEST TO NORTHEASTERN BRITISH COLUMBIA.
THE FLOW TURNS EAST ACROSS THE NORTHERN PRAIRIES ALONG THE SOUTHERN
FLANK OF THE UPPER LOW, THEN REBOUNDS INTO A DOWNSTREAM RIDGE OVER
NORTHERN HUDSON BAY. IN THE EAST, A STACKED LOW SITS OVER DAVIS
STRAIT NEAR THE ENTRANCE TO CUMBERLAND SOUND WITH A LONG-WAVE TROUGH
WNW TO SOUTHERN FOXE BAISN.
AT THE SURFACE, A 1028 MB HIGH SITS OVER THE PACIFIC WITH RIDGING
THAT SPRAWLS INTO BRITISH COLUMBIA. TO THE NORTHEAST, A 1022 MB HIGH
SITS WEST OF KUGLUKTUK WITH RIDGING THAT SPRAWLS NORTHEAST ACROSS THE
CANADIAN ARCTIC ARCHIPELAGO. EAST OF THIS, A 1004 MB LOW SITS NEAR
CHESTERFIELD INLET, NU WITH A COLD FRONT SWEEPING SOUTHWEST INTO THE
NORTHERN PRAIRIES BEFORE CURLING BACK NORTHWEST NEAR THE YUKON BORDER
AND A WARM FRONT DRAPED SOUTHEAST ACROSS HUDSON BAY. FURTHER EAST, A
COUPLE OF LOWS SIT NEAR SOUTHERN BAFFIN ISLAND: ONE NEAR THE MOUTH OF
CUMBERLAND SOUND, AND ONE OVER THE SOUTHERN MAINLAND BETWEEN
CUMBERLAND SOUND AND FOXE BASIN. IN THE SOUTH, A TROUGH EXTENDS
NORTH-SOUTH ALONG THE ALBERTA/SASKATCHEWAN BORDER, A 1022 MB HIGH
SITS OVER NW NORTH DAKOTA WITH A RIDGE THAT ARCS NORTHEAST-NORTHEAST
THROUGH SOUTHERN SASKATCHEWAN AND CENTRAL MANITOBA. CONTINUING EAST,
A 1008 MB LOW SITS ALONG THE NW ONTARIO COASTLINE WITH A COLD FRONT
SOUTHWEST INTO THE AMERICAN PLAINS AND A WARM FRONT EAST-SOUTHEAST
ACROSS QUEBEC.
DISCUSSION...
AB...A COLD FRONT MAKING ITS WAY SOUTHWARDS ACROSS THE NORTHERN
PRAIRIES TODAY IS PRODUCING SHOWERS WITH ISOLATED THUNDERSTORMS.
THUNDERSTORMS ARE ALSO EXPECTED TO DEVELOP ALONG THE CENTRAL AND
SOUTHERN FOOTHILLS THIS AFTERNOON. THERE IS SOME RISK OF SUPERCELLS
WITH LARGE HAIL IF STORMS CAN GET GOING IN THE RIGHT SPOT.
THE CONCERN WILL BE SIMILAR ON MONDAY.
MB/SK...TODAY’S THUNDERSTORM THREAT FOR THE PRAIRIES WILL LARGELY
COALESCE OVER SOUTHERN SASKATCHEWAN TODAY, ALONG THE ADVANCING COLD
FRONT ALONG A TROUGH OF LOW PRESSURE DRAPED FROM CENTRAL SASKATCHEWAN
TO THE SOUTHWESTERN CORNER OF THE PROVINCE. MLCAPE VALUES ALONG THIS
LINE WILL CLIMB TO AROUND 1,000 J/KG THIS AFTERNOON WITH BULK SHEAR
VALUES INCREASING INTO THE 25 TO 30 KNOT RANGE AS ZONAL UPPER-LEVEL
WINDS STRENGTHEN AS THE COLD FRONT PUSHES SOUTH. WITH THE COLD FRONT
AS ONE TRIGGER, TROUGH AS A SECOND, AND FALLING HEIGHTS AS A THIRD,
SCATTERED CONVECTION IS LIKELY TO DEVELOP THIS AFTERNOON. THERE WILL
BE A LOW RISK OF SEVERE WEATHER WITH PRIMARY THREATS OF DAMAGING HAIL
AND WIND GUSTS. THE CONVECTIVE ACTIVITY WILL PERSIST INTO THE NIGHT,
SUPPORTED BY THE ADVANCING COLD FRONT, FALLING HEIGHTS, AND
UPPER-LEVEL SUPPORT; THIS WILL BE LARGELY BASED ON DYNAMICS WITH
LIMITED ENERGETICS AVAILABLE THROUGH THE OVERNIGHT PERIOD.
THE OVERNIGHT CONVECTION WILL QUICKLY MOVE OUT OF SASKATCHEWAN AND
PUSH ACROSS MUCH OF SOUTHERN MANITOBA WITH THE MOST ORGANIZED
ACTIVITY CROSSING WESTERN MANITOBA AND THE INTERLAKE REGION,
SUPPORTED BY THE ADVANCING COLD FRONT, WHILE MORE SCATTERED ACTIVITY
TRACKS ACROSS THE SOUTHERN PORTIONS OF THE PROVINCE. NO ORGANIZED
SEVERE RISK IS EXPECTED TONIGHT.
WIDESPREAD SHOWERS AND THUNDERSHOWERS WILL SPREAD ACROSS NORTHERN AND
CENTRAL MANITOBA TODAY AS THE NWT COLD FRONT CONTINUES TO SURGE SOUTH
INTO THE PRAIRIES. MOST AREAS WILL SEE A HIGH CHANCE OF SOME RAIN
TODAY WITH GENERAL RAINFALL AMOUNTS OF 0 TO 15 MM AND LOCALIZED
ACCUMULATIONS OF 15 TO 30 MM.
LOOKING LONGER-RANGE, A LOW PRESSURE SYSTEM IN NUNAVUT WILL SLUMP
SOUTH WITH THE COLD FRONT, EVENTUALLY SITTING OVER NE MANITOBA AND
BRINGING AN AREA OF WRAP-AROUND RAINFALL TO PORTIONS OF NORTH-CENTRAL
AND NORTHEAST MANITOBA MONDAY INTO TUESDAY. THIS WILL BRING ANOTHER
10 TO 25 MM OF RAIN TO PARTS OF NORTHERN MANITOBA TO START THE WEEK.
AS THE NUNAVUT LOW-PRESSURE SYSTEM DROPS SOUTH, IT WILL DEEPEN AND
GENERATE MODERATE TO STRONG NORTHERLY WINDS ALONG ITS WESTERN FLANK.
WINDS UP TO 50 GUSTING 70 KM/H WILL DEVELOP OVER NORTH-CENTRAL
MANITOBA ON MONDAY AND SLOWLY SPREAD SOUTHEAST THROUGH THE DAY.
WINDS WILL BEGIN TO EASE ON TUESDAY.
NT...SMOKE CONTINUES TO AFFECT PARTS OF THE SOUTHERN NT. SOUTHERLY
FLOW IS EXPECTED TO PUSH SMOKE TO THE NORTH ON MONDAY.
NU...IN THE KIVALLIQ, RAIN SHOWERS WILL SLUMP INTO COASTAL REGION
TODAY AND THEN LINGER AS THE CHESTERFIELD INLET LOW DEEPENS AS IT
MOVES SOUTH AND STARTS TO GENERATE WRAP-AROUND RAINFALL OVER THE
SOUTHERN COASTAL REGIONS. THIS WILL BRING GENERALLY 10 TO 30 MM OF
RAIN TO THE SOUTHERN COASTAL REGIONS OVER THE COMING DAYS AND 5 TO
15 MM TO THE NORTHERN COAST. THE RAIN WILL TAPER OFF ON TUESDAY.
FURTHER EAST, WAVES OF RAIN SHOWERS WILL CONTINUE TO MOVE OVER
PORTIONS OF SOUTHERN BAFFIN ISLAND AS PLUMES OF MOISTURE WRAP AROUND
THE QUASI-STATIONARY UPPER LOW NEAR CUMBERLAND SOUND.
END/VROLIJK/ROMBOUGH
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