587
FOCN45 CWWG 201900
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CDT MONDAY JULY
20 2026.
ALERTS IN EFFECT...AIR QUALITY WARNINGS FOR THE SOUTHERN NWT AND
PORTIONS OF THE NORTHERN PRAIRIES, AS FAR SOUTH AS EDMONTON. SEVERE
THUNDERSTORM WATCHES FOR PARTS OF CENTRAL AND NORTHERN MANITOBA.
OVERVIEW...ALOFT, AN UPPER LOW SITS OVER NORTHWESTERN ONTARIO WITH AN
ASSOCIATED TROUGH EXTENDING NORTHEAST THROUGH HUDSON BAY TO HUDSON
STRAIT. AN UPPER RIDGE EXTENDS FROM THE CENTRAL CONUS NORTHWARD
POKING INTO BC AND THEN INTO YUKON. UPPER LOW COMPLEX OVER LABRADOR
WITH AN ASSOCIATED TROUGH EXTENDING NORTHWESTWARD THROUGH BAFFIN
ISLAND. A SHARP UPPER TROUGH LIES OFF THE COAST OF ALASKA.
AT THE SURFACE, THERE IS A 994 MB LOW OVER NORTHEASTERN ONTARIO.
A FRONTAL WAVE SITS SOUTHEAST OF THE LOW CENTRE WITH A WARM FRONT
EXTENDING SOUTHEASTWARD ACROSS NORTHERN ONTARIO AND A COLD FRONT
EXTENDING SOUTHWARD THROUGH LAKE SUPERIOR AND WISCONSIN. A SURFACE
TROUGH EXTENDS WESTWARD FROM THE LOW CENTRE THROUGH SOUTHERN MANITOBA
AND SASKATCHEWAN. A SERIES OF WEAKENING LOWS LIE IN A TROUGH THAT
EXTENDS FROM SOUTHERN BAFFIN ISLAND INTO FOXE BASIN. AN INTENSE LOW
LIES OVER NEWFOUNDLAND. HIGH PRESSURE LIES OVER THE YUKON AND WESTERN
NWT WITH RIDGING EXTENDING SOUTHWARD THROUGH BC AND WESTERN ALBERTA.
DISCUSSION...
AB...SMOKE FROM WILDFIRES IN THE NT WILL CONTINUE TO DIVE SOUTHWARDS
ACROSS ALBERTA TODAY AND TONIGHT IN THE WAKE OF THE TAIL END OF A
COLD FRONT. HOW FAR SOUTH IT GETS IS STILL IN QUESTION, BUT IT COULD
REACH THE CALGARY AREA TONIGHT. AIR QUALITY WARNINGS WILL BE EXPANDED
AS NECESSARY. WITH RIDGING BUILDING IN, A STAGNENT SUBSIDENT FLOW
WILL KEEP AIR QUALITY POOR AT LEAST AT TIMES OVER THE MUCH OF THE
PROVINCE THROUHG TUESDAY.
SHOWERS AND THUNDERSTORMS WILL CONTINUE TODAY AS WELL AS A CHAIN OF
SHORTWAVES TRANSIT THE PROVINCE, BUT STORMS SHOULD REMAIN SUB-SEVERE.
SK/MB...A MORE SEASONAL AND LESS HUMID AIR MASS MOVED INTO THE
EASTERN PRAIRIES IN THE WAKE OF SUNDAY NIGHT'S COLD FRONTAL PASSAGE.
THIS HAS BROUGHT AN END TO THE HEAT WARNINGS FOR THE TIME BEING.
HEAT AND HUMIDITY WILL BUILD INTO THE REGION AGAIN LATE WEEK INTO
NEXT WEEKEND, HOWEVER.
UNSETTLED NORTHWESTERLY FLOW WILL LEAD TO SCATTERED SHOWERS AND
THUNDERSTORM DEVELOPMENT TODAY ACROSS MUCH OF SOUTHERN SASKATCHEWAN
AND MANITOBA. WITH THE BULK OF THE HUMIDITY FLUSHED OUT, GENERALLY
NON-SEVERE THUNDERSTORMS ARE EXPECTED. HOWEVER, A ROGUE SEVERE WIND
GUST/HAIL STONE CANNOT BE RULED OUT OVER SOUTHEASTERN SASKATCHEWAN
AND EXTREME SOUTHERN MANITOBA WHERE 500 TO 1000 MLCAPE AND 30 KNOTS
OF EFFECTIVE SHEAR WILL EXIST ALONG A HANG BACK TROUGH OF LOW
PRESSURE EXTENDING WESTWARD FROM THE NORTHWESTERN ONTARIO LOW.
CONFIDENCE REMAINS TOO LOW FOR ANYTHING HIGHER THAN A GREY THREAT
AREA.
WILDFIRES CONTINUE TO BURN IN NORTHERN MB AND SK, REDUCING AIR
QUALITY DOWNWIND OF THE FIRES. AIR QUALITY WARNINGS CONTINUE FOR THE
AREA. SMOKE IS EXPECTED TO SPREAD SOUTH BEHIND THE COLD FRONT INTO
SOUTHERN SASKATCHEWAN AND MANITOBA TODAY. HOW MUCH SURFACES TO REDUCE
AQHI VALUES IS TO BE SEEN. THIS SITUATION WILL BE MONITORED FOR
POSSIBLE AQ WARNING ISSUANCE.
NT/NU...AS THE LABRADOR LOW CONTINUES TO SPIN, SOUTHEASTERN BAFFIN
ISLAND WILL SEE SHOWERS CONTINUE OVER THE NEXT FEW DAYS WITH NO
SIGNIFICANT QPF IN ANY TOWN SITES.
WILDFIRES BURNING IN THE NT CONTINUE TO SPREAD SMOKE AND POOR AIR
QUALITY THROUGHOUT SOUTHERN PORTIONS OF THE TERRITORY. STAGNENT FLOW
NEAR GREAT SLAVE LAKE WILL KEEP AIR QUALITY POOR AT TIMES AND A
SOUTHEASTERLY FLOW WILL ADVECT SMOKE AS FAR NORTH AS FORT GOOD HOPE
TOMORROW.
END/COLANGELO/BATE
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