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FOCN45 CWWG 181900
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CDT FRIDAY JULY
18 2025.
ALERTS IN EFFECT...AIR QUALITY ALERTS FOR PARTS OF ALBERTA,
SASKATCHEWAN, MANITOBA, AND THE NT. HEAT WARNING FOR PARTS OF THE
SOUTHERN NT. SEVERE THUNDERSTORM WATCHES IN PARTS OF SW ALBERTA.
SYNOPSIS...THE 12Z UPPER ANALYSES REVEALED A LOW OVER NORTHERN QUEBEC
WITH TROUGHS OVER THE EASTERN PRAIRIES AND OVER CENTRAL BC.
RIDGE OVER ALBERTA. LOW OVER BANKS ISLAND WITH TROUGH TOWARD GREAT
BEAR LAKE.
THE SURFACE ANALYSIS SHOWS A LOW OVER EASTERN HUDSON BAY. COLD FRONT
FROM THE LOW TO THE SOUTHWEST THROUGH NORTHERN MANITOBA, THEN
NORTHWEST TO A WAVE NEAR GREAT BEAR LAKE, THEN SOUTHWEST THROUGH THE
NWT AND NW INTO ALASKA. HIGH PRESSURE OVER SOUTHERN SASKATCHEWAN WITH
RIDGE TO THE NORTHEAST. LOW OVER SOUTHWESTERN NWT WITH
NORTHEAST-SOUTHWEST TROUGH. FRONTAL WAVE OVER SOUTHERN BC.
DISCUSSION...
AB...SEVERE THUNDERSTORMS WILL DEVELOP OVER WESTERN AB ALONG A
DEVELOPING TROUGH THIS AFTERNOON AND MOVE EASTWARD THROUGH TONIGHT.
PRIMARY RISKS WILL BE HAIL UP TO 5 CM IN DIAMETER AND DAMAGING
STRAIGHT-LINE WINDS. THERE IS A TORNADO RISK AS WELL, PRIMARILY SOUTH
OF CALGARY WHERE BWD VALUES ARE HIGHER, LARGELY OWING TO THE
POSSIBILITY OF STRONGER BACKED FLOW IN THE LOW LEVELS. WILL HAVE TO
MONITOR THIS AREA CLOSELY FOR EAST OR SOUTHEAST FLOW ON THE ORDER OF
10 TO 15 KTS. WITH ALL THE RECENT RAINFALL, SUFFICIENT MOISTURE IS
UNLIKELY TO BE AN ISSUE.
MOVING FORWARD, THE PARENT LOW WILL STALL AROUND THE EDMONTON AREA
THROUGH SATURDAY WITH TOTAL RAIN AMOUNTS POSSIBLY APPROACHING 50 MM
FOR AREAS WEST OF EDMONTON BY SATURDAY EVENING. WARM SECTOR
THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE A LANDSPOUT TORNADO
ON SATURDAY, ALTHOUGH THIS WILL BE CONTINGENT ON WHETHER AREAS SOUTH
OF THE RAIN SHIELD CAN CLEAR OUT, AND IF WINDS REMAIN BACKED ENOUGH
IN THIS VICINITY.
SMOKE FROM BOTH SK AND THE NWT WILL AFFECT PARTS OF NORTHERN AB
THROUGH SATURDAY. AIR QUALITY ALERTS ARE LIKELY TO BE EXPANDED
BETWEEN NOW AND THEN, PROBABLY TOWARD THE NORTH AND WEST.
SK/MB...THE SMOKE IS KEY THIS FORECAST PERIOD. THE MAIN FIRES OF NOTE
CONTINUE TO FUMIGATE DOWNSTREAM REGIONS AND THE AREAS AFFECTED WILL
DEPEND ON THE WINDS. OVER THE NEXT COUPLE OF DAYS, WITH A FAIRLY
SLACK FLOW PATTERN IN PLACE, SMOKE IS EXPECTED TO SLOWLY MOVE
SOUTHWARD, MOSTLY COVERING SOUTHERN MANITOBA AND AREAS IN
SASKATCHEWAN NORTH OF THE YELLOWHEAD BY SATURDAY EVENING.
ON SATURDAY AFTERNOON, INSTABILITY LOOKS TO RETURN TO SOUTHWESTERN
SASKATCHEWAN, WITH MLCAPE OF UP TO 1000 J/KG AND POCKETS OF UP TO 45
KNOTS OF BULK SHEAR. A FEW SUPERCELLS WITH LARGE HAIL AND DAMAGING
WINDS ARE POSSIBLE, AND A TORNADO CANNOT BE RULED OUT.
ARCTIC...THE SYSTEM OVER NORTHERN HUDSON BAY CONTINUES TO DECAY WITH
JUST A FEW SHOWERS LINGERING AROUND BAFFIN ISLAND AND KIVALLIQ.
WITH WEAK FLOW SETTLING OVER THE AREA, REMNANT CLOUD, DRIZZLE, AND
FOG WILL BE THE MAIN ISSUES FOR THE NEXT FEW DAYS.
UPPER TROUGH WILL HELP SPIN UP A NEW LOW ALONG THE SURFACE TROUGH AND
WILL WRAP AN AREA OF RAIN ACROSS EASTERN VICTORIA ISLAND TONIGHT AS
IT MOVES SLOWLY TO THE NE. THERE IS NOT A LOT OF CONSISTENCY BETWEEN
MODELS BUT RAIN AMOUNTS NEAR 25 MM ARE POSSIBLE TONIGHT AND SATURDAY
FOR PARTS OF THE ISLAND.
THE COLD FRONT FROM THIS LOW WILL MOVE ACROSS THE NWT ENDING THE
HEAT, BRINGING THUNDERSTORMS, AND PUSHING SMOKE TO THE SOUTHEAST.
HARD TO SAY IF FIRES WILL STILL CONTINUE PRODUCING MUCH SMOKE ONCE
COOLER CONDITIONS ARE IN PLACE ON SATURDAY.
END/CARLSEN/DYCK/ROMBOUGH/VAN LOCHEM
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