FOCN45 CWWG 231200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT SUNDAY AUGUST
23 2026.

ALERTS IN EFFECT...AQ WARNING FOR PARTS OF THE NWT. HEAT WARNING
FOR PARTS OF WESTERN SK. FOG ADVISORY FOR THE HIGH ARCTIC.

SYNOPTIC OVERVIEW...ALOFT, A LOW EXISTS NEAR GREAT BEAR LAKE WITH
ANOTHER LOW OVER SOUTHERN VANCOUVER ISLAND. AN UPPER RIDGE FROM THE
US ARCS OVER THE PRAIRIES AND SPRAWLS NORTH OVER EASTERN NWT.
THERE IS AN EMBEDDED SHORTWAVE IN THE FLOW NEAR LAKE ATHABASCA.
AN UPPER LOW SPINS OVER THE EASTERN KITIKMEOT WITH ITS LONGWAVE
TROUGH EXTENDING SOUTH TO ANOTHER LOW OVER ONTARIO. FINALLY, RIDGING
SPRAWLS ACROSS EASTERN CANADA AND EXTENDS INTO BAFFIN ISLAND.

AT THE SURFACE, 996 MB LOW NEAR GREAT BEAR LAKE WITH A TROUGH
SOUTHWARDS ACROSS AB. A WEAK TROUGH ALSO EXTENDS ALONG THE 60TH
PARALLEL. A HIGH PRESSURE CENTRE SITS OVER PRINCE OF WALES ISLAND
THEN, A WEAK LOW PRESSURE IS JUST WEST OF MELVILLE PENINSULA. A HIGH
PRESSURE CENTRE IS OVER NORTHWEST ONTARIO JUST EAST OF THE MB BORDER.

DISCUSSION...

AB/NRN SK...TROUGH OVER ALBERTA WILL DEVELOP A MESS OF THUNDERSTORM
ACTIVITY TODAY. MLCAPE VALUES IN EASTERN ALBERTA ARE FORECAST TO BE
OVER 3000 J/KG BUT THE EBWD IS ONLY AROUND 20 KT. LOOKS LIKE
SIGNIFICANT RAIN AND STRONG WINDS WILL BE THE MAIN HAZARD IN STORMS
THAT DEVELOP THROUGH THE DAY THERE. FOR CENTRAL AREAS MORE DISCRETE
THUNDERSTORMS ARE POSSIBLE WITH AROUND 1500 J/KG MLCAPE AND 30 KT
EBWD. LARGE HAIL WILL BE POSSIBLE. THIS TROUGH WILL DEVELOP INTO A
LOW FORECAST TO SIT OVER CENTRAL SK ON MONDAY. RAIN WILL WRAP AROUND
IT WITH SOME STRONGER NW WINDS ON THE BACKSIDE, IN EASTERN AB, WITH
GUSTS OF 70 KM/H. EAST CENTRAL ALBERTA WILL ALSO LIKELY SEE AT LEAST
25-50 MM OF RAIN, WITH MUCH HIGHER AMOUNTS POSSIBLE IN THUNDERSTORMS,
BUT TO THE NORTH OF WHERE THE STRONGEST WINDS ARE EXPECTED. PARTS OF
CENTRAL SK WILL ALSO GET AROUND 25 MM OF RAIN.

THE SMOKE THAT IS STICKING AROUND A FEW REGIONS ACROSS AB SHOULD
CLEAR OUT THROUGH THE DAY.

MB/SRN SK...THE UPPER RIDGE OVER THE PRAIRIES HAS BROUGHT WARM AIR TO
SOUTHWEST SK. A QUICK, MARGINAL HEAT EVENT CONTINUES FOR TODAY.
HEAT WARNINGS CONTINUE FOR PORTIONS OF THE WEST-CENTRAL AREA OF THE
PROVINCE. THE HEAT WILL END TONIGHT WHEN THE UPPER LOW FROM SOUTHERN
BC ENTERS THE AREA.

THE FOCUS FOR CONVECTION TODAY IS WITH THE TROUGH OF THE NORTHERN AB
LOW PRESSURE SYSTEM. THE TROUGH WILL MOVE INTO WESTERN SK THIS
AFTERNOON, TRIGGERING SHOWERS AND THUNDERSTORMS. ADDITIONALLY, THE
UPPER LOW OVER SOUTHERN BC WILL PUSH EAST INTO SOUTHERN ALBERTA
TODAY. TWO JETS WILL SPLIT AROUND THE BASE OF THE TROUGH OVER
SOUTHWESTERN SK THIS AFTERNOON CREATING AN AREA OF STRONG DIFFLUENCE.
INSTABILITY AND MOISTURE HAS ADVECTED INTO SK, IN THE SOUTHERLY FLOW
AHEAD OF THE TROUGH, BRINGING FUEL FOR THE THUNDERSTORMS. AN AXIS OF
1000-2000 J/KG OF MLCAPE WILL RUN THROUGH WESTERN SK AND WILL COMBINE
WITH 35 KTS OF 0-6 KM BULK SHEAR, SUPPORTING AN ORGANIZED SEVERE
THREAT. STORMS ARE EXPECTED TO REMAIN ISOLATED WITH TRANSIENT
SUPERCELL STURCTURES TO START. AS STORMS PROGRESS INTO THE EVENING
HOURS, CONVECTIVE COVERAGE IS EXPECTED TO INCREASE AND ORGANIZE INTO
A CONVECTIVE COMPLEX THAT WILL MOVE ACROSS SOUTHERN SK. THE MAIN
THREAT WILL BE STRONG WIND GUSTS OF 90-100 KM/H AND 2-4 CM HAIL.

THUNDERSTORMS ARE EXPECTED TO CONTINUE INTO THE OVERNIGHT HOURS AS
THE SURFACE TROUGH MOVES INTO EASTERN SK, ALONG WITH THE UPPER
SUPPORT OF THE STRONG DIFFLUENCE. THUNDERSTORMS WILL THEN ENTER INTO
WESTERN MB BY THE MORNING HOURS. THESE THUNDERSTORMS WILL CONTINUE TO
POSE A SEVERE THREAT WITH WIND BEING THE MAIN THREAT OVERNIGHT AND
INTO THE MORNING.

SMOKE FROM THE WILDFIRES IN BC IS EXPECTED TO MOVE BEHIND THE SURFACE
TROUGH AND IS PROGGED TO ENTER WESTERN SK THIS EVENING. PM2.5 VALUES
WILL LIKELY SPIKE BUT WILL BE MONITORED AS THE SMOKE MAKES IT WAY
THROUGH AB TODAY. AIR QUALITY WARNINGS WILL BE ISSUED, IF NECESSARY.

NT...THE GREAT BEAR LAKE LOW WILL SLOWLY WEAKEN AND MOVE EAST THROUGH
MONDAY. 10-20 MM OF RAIN HAS FALLEN AROUND IT SO FAR WITH ANOTHER
15-25 MM EXPECTED TODAY. NON-SEVERE THUNDERSTORMS WILL MOVE ACROSS
THE EASTERN PART OF THE TERRITORY THROUGH TONIGHT.

SMOKE CONTINUES AFFECTING SOME LOCATIONS. AREAS IN THE NORTH SHOULD
CLEAR UP LATER TODAY, WHILE SOUTHERN AREAS WILL LIKELY SEE SMOKE GET
WORSE.

NU...THE LOW PRESSURE SYSTEM NEAR MELVILLE PENINSULA WILL PRODUCE
SHOWERS TODAY IN COMMUNITIES IN THE AREA WITH NO SIGNIFICANT
ACCUMULATIONS EXPECTED.

FOG WILL CONTINUE IN THE HIGH ARCTIC AND EASTERN BAFFIN ISLAND
COMMUNITIES. FOR THE HIGH ARCTIC THE PATTERN DOESN'T REALLY CHANGE
UNTIL MID-WEEK.

END/BILOUS/ROMBOUGH