341
FOCN45 CWWG 141200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT SUNDAY
SEPTEMBER 14 2025.
ALERTS IN EFFECT...AIR QUALITY ALERTS FOR PARTS OF THE NORTHWEST
TERRITORIES, NORTHERN ALBERTA, AND NORTHERN SASKATCHEWAN.
SYNOPTIC OVERVIEW...ALOFT, AN UPPER LOW SITS OVER SOUTHERN ALBERTA
WITH A TROUGH SOUTHWARD INTO THE WESTERN US LEAVING THE EASTERN
PRAIRIES IN AN ACTIVE SOUTHERLY UPPER FLOW WITH SEVERAL SHORTWAVES
EMBEDDED. AN UPPER RIDGE LIES OVER THE US MIDWEST AND EXTENDS
NORTHWARD INTO EASTERN MANITOBA AND THROUGH TO SOUTHERN BAFFIN
ISLAND. AN UPPER LOW IS OVER NORTHERN GREENLAND WITH A TROUGH
SOUTHWARD THROUGH THE ARCTIC ISLANDS. ANOTHER UPPER LOW IS OVER THE
LABRADOR SEA WITH A TROUGH SOUTHWARD THROUGH EASTERN CANADA.
AT THE SURFACE, A RIDGE OF HIGH PRESSURE EXTENDS FROM THE ARCTIC
OCEAN SOUTHWARD TO NWT. A 1000 MB LOW IS NEAR TALOYOAK WITH A WARM
FRONT SOUTHEASTWARD THROUGH FOXE BASIN. THE COLD FRONT EXTENDS
SOUTHWEST INTO NORTHERN ALBERTA AND CONNECTS TO A 1004 MB LOW OVER
CENTRAL BC. A 1023 MB HIGH PRESSURE CENTER IS OVER NORTHERN ONTARIO
AND A RIDGE AXIS WESTWARD EXTENDS INTO MANITOBA AND NORTHERN
SASKATCHEWAN. ANOTHER RIDGE AXIS EXTENDS NORTHWARD THROUGH SOUTHERN
BAFFIN ISLAND.
DISCUSSION...
AB...AN UPPER LOW MOVES NORTHWARDS TO APPROACH FORT MCMURRAY MUCH OF
THE PROVINCE COULD BECOME UNSTABLE WITH A CHANCE OF NON-SEVERE
THUNDERSTORMS FOCUSED NEAR THE LOW AND OVER THE FOOTHILLS. FOG OVER
EASTERN ALBERTA THIS MORNING AND ON THE BACKSIDE OF PRECIPITATION
ONCE AGAIN TOMORROW MORNING.
WILDFIRE SMOKE CONTINUES TO PLAGUE SEVERAL AREAS. A WILDFIRE IN
THE RED EARTH REGION CONTINUES TO REDUCE AIR QUALITY LOCALLY.
DENSE WILDFIRE SMOKE IS NOTED OVER FIRES NEAR BUFFALO NARROWS,
SK, WHICH HAS ADVECTED INTO PORTIONS OF NORTHEASTERN ALBERTA.
FINALLY, SMOKE FROM A FIRE NORTH NORTHWEST OF FORT CHIPEWYAN HAS LED
TO VERY POOR AIR QUALITY IN FORT SMITH, SO IT MAKES SENSE THAT
REGIONS DIRECTLY BORDERING THAT TOWN WOULD REQUIRE AN AIR QUALITY
WARNING.
SK/MB...AN ACTIVE CONVECTIVE PATTERN CONTINUES. SEVERAL SHORTWAVES
EMBEDDED IN THE SOUTHERLY UPPER FLOW WILL TRACK NORTHWARD OVER THE
COMING DAYS LEADING TO ROUNDS OF CONVECTIVE SHOWERS AND EMBEDDED
THUNDERSTORMS THROUGH SASKATCHEWAN AND MANITOBA. FOR TODAY'S
CONVECTIVE SET-UP, SOUTHERLY FLOW CONTINUES TO ADVECT SEASONABLY
WARM, MOIST AIR TO THE PRAIRIES, CREATING A BUOYANT AIRMASS OVER THE
AREA. A BLANKET OF STRATUS/FOG ENCOMPASSES MUCH OF SOUTHEASTERN
SASKATCHEWAN AND SOUTHWESTERN MANITOBA THIS MORNING, EVIDENCE OF THE
RICH BOUNDARY LAYER MOISTURE IN PLACE. THE FOG IS EXPECTED TO BURN
OFF THIS MORNING ALLOWING AN OPPORTUNITY FOR DAYTIME HEATING TO
DESTABILIZE THE AIRMASS. MODEL GUIDANCE IS INDICATING A THUNDERSTORM
ENVIRONMENT CHARACTERIZED BY 1000+ J/KG OF MLCAPE AND 30 KTS OF BWD
OVER SOUTHERN MANITOBA LATER TODAY. AN UPPER IMPULSE OVER THE
DAKOTAS WILL TRACK TOWARDS SOUTHWESTERN MANITOBA, REACHING THE AREA
BY EARLY EVENING, AND WILL PROVIDE AMPLE LIFT FOR THUNDERSTORM
DEVELOPMENT THIS EVENING OVER SOUTHWESTERN MANITOBA. GIVEN THE
MOISTURE RICH AIRMASS, HEAVY RAIN IS THE MAIN THREAT WITH
THUNDERSTORMS THAT DEVELOP AS WELL AS LARGE HAIL. ONE CAVEAT IS THE
TIMING OF THE CLOUD COVER ASSOCIATED WITH THE IMPULSE, AND HOW IT
IMPACTS DAYTIME HEATING. ITS CURRENTLY PROGGED TO ARRIVE IN
SOUTHWESTERN MANITOBA LATE THIS MORNING, WHICH WILL LIMIT DAYTIME
HEATING AND THEREBY REDUCED MLCAPE VALUES OVER THE AREA.
THE IMPULSE WILL CONTINUE TO TRACK NORTHWARD THROUGH MANITOBA
THROUGH THE OVERNIGHT WITH SHOWERS AND EMBEDDED THUNDERSTORMS
FORECAST TO LAST THROUGH THE OVERNIGHT, ALTHOUGH THE SEVERE WEATHER
THREAT WILL DIMINISH LATE IN THE EVENING. A SECOND WAVE OF NOCTURNAL
ACTIVITY WILL MOVE INTO SOUTHEASTERN SASKATCHEWAN/SOUTWESTERN
MANITOBA IN THE EARLY MORNING HOURS OF MONDAY AS A LOW WILL TRACK
NORTHWARD FROM THE US. A STRENGTHENING LOW LEVEL JET ASSOCIATED WITH
THE LOW WILL CONTINUE TO AID IN DEEP MOISTURE ADVECTION AND WILL
FUEL THUNDERSTORM DEVELOPMENT THROUGH THE MORNING HOURS. THIS LOW
WILL CONTINUE TO PROVIDE A FOCUS FOR THUNDERSTORM DEVELOPMENT
THROUGH MANITOBA ON MONDAY.
FOG WILL ALSO BE POSSIBLE THE NEXT FEW NIGHTS OVER THE SOUTHERN
PRAIRIES AS SEASONABLY HUMID AIR REMAINS IN PLACE OVER THE REGION.
ARCTIC...WILDFIRES LOCATED NORTHWEST OF GREAT SLAVE LAKE AND
NORTHWEST OF FORT CHIPEWYAN ARE GIVING POOR TO VERY POOR AIR
QUALITY TO FORT SMITH AND FORT PROVIDENCE.
THE LOW NEAR TALOYOAK WILL CONTINUE TO TRACK EASTWARD TODAY,
SPREADING A MIX OF PRECIPITATION THROUGH BAFFIN ISLAND.
PRECIPITATION WILL PRIMARILY FALL AS RAIN, BUT SOME SNOW MAY BE
MIXED IN AT TIMES IN NORTHERN REGIONS. NO NOTABLE AMOUNTS ARE
EXPECTED.
LOW TO DEVELOP EAST OF ELLESMERE ISLAND BRINGING GALES TO CLARENCE
AND WEST BAFFIN MARINE AREAS. THERE ARE STRONG WINDS ALOFT OVER
GRISE FIORD WITH THE SYSTEM BUT DIRECTION AND INVERSION HEIGHT
AREN'T TYPICAL OF A WIND WARNING SETUP.
STRONG SYSTEM MOVING FROM FORT LIARD TOWARDS KUGLUKTUK TOMORROW.
QUITE A FEW MODELS SHOW POTENTIAL FOR 25 MM NEAR KUGLUKTUK AND
LOCALLY 35 MM TODAY NEAR FORT SIMPSON.
END/MOODIE/WIELKI
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