283
FOCN45 CWWG 151900
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CDT MONDAY
SEPTEMBER 15 2025.
ALERTS IN EFFECT...AIR QUALITY ALERTS FOR PARTS OF THE NORTHWEST
TERRITORIES, NORTHERN ALBERTA, AND NORTHERN SASKATCHEWAN. SPECIAL
WEATHER STATEMENT FOR FUNNEL CLOUDS OVER SOUTHEAST SASKATCHEWAN AND
SOUTHWEST MANITOBA.
SYNOPTIC OVERVIEW...ALOFT, A HIGHLY AMPLIFIED PATTERN SITS OVER
CANADA WITH A LONG WAVE RIDGE CENTRED OVER ONTARIO AND TROUGHING
BOUNDING THE RIDGE OVER WESTERN AND EASTERN CANADA. ZONAL FLOW SITS
ACROSS THE EASTERN ARCTIC WITH A SHORTWAVE RIDGE OVER THE WESTERN
ARCTIC.
AT THE SURFACE, A 1005 MB LOW SITS OVER NORTH DAKOTA WITH A WARM
FRONT ARCING NORTH INTO SOUTHERN MANITOBA. A SECOND 1005 MB LOW SITS
OVER NORTHERN ALBERTA WITH A COLD FRONT EXTENDING SOUTH INTO IDAHO
AND A WARM FRONT ARCING ARCOSS NORTHERN ALBERTA THEN SITTING ALONG
THE 60TH PARALLEL. A 1005 MB LOW SPINS OVER FOXE BASIN WITH A WARM
FRONT CUTTING ACROSS BAFFIN ISLAND AND A COLD/STATIONARY FRONT
STRETCHING BACK WEST THROUGH GREAT BEAR LAKE AND THEN INTO SOUTHERN
ALASKA.
DISCUSSION...
AB/NORTHERN SK...THERE IS A CHANCE OF THUNDERSTORMS OVER SOUTHERN AND
EASTERN PARTS OF ALBERTA TODAY. THE MOST LIKELY REGIONS TO SEE
CONVECTIVE ACTIVITY WILL BE IN THE NORTHEAST AHEAD OF A COMPACT UPPER
LOW APPROACHING THE AREA, AND IN THE SOUTH WITH TERRAIN ACTING AS THE
TRIGGER. FOR LACK OF MUCH IN THE WAY OF ORGANIZING SHEAR, THESE
THUNDERSTORMS SHOULD REMAIN SUB-SEVERE.
SPECIAL AIR QUALITY STATEMENTS REMAIN IN EFFECT FOR A FEW REGIONS IN
THE NORTH, DOWNSTREAM OF ONGOING FIRES. A WIND SHIFT TO NORTHWESTERLY
TODAY WILL PUSH THE SMOKE AROUND AND ALERTS WILL BE ADJUSTED AS
NECESSARY.
TEMPERATURES ARE FORECAST TO REACH THE LOW SINGLE DIGITS TONIGHT IN
WESTERN ALBERTA, BRINGING A RISK OF FROST.
MB/SOUTHERN SK...ANOTHER ROUND OF CONVECTION WILL IMPACT SOUTHERN
MANITOBA AND PARTS OF EASTERN SASKATCHEWAN AGAIN TODAY AS AN
UNSEASONABLY WARM, AND UNSTABLE AIRMASS REMAINS IN PLACE OVER THE
EASTERN PRAIRIES. A NEGATIVELY TILED TROUGH SITS OVER THE DAKOTAS
THIS MORNING AND WILL SLIDE INTO SOUTHERN MANITOBA THIS AFTERNOON,
PROVIDING SUPPORT FOR THUNDERSTORM DEVELOPMENT OVER MUCH OF SOUTHERN
MANITOBA THIS AFTERNOON. SURFACE DEW POINT VALUES STILL REMAIN QUITE
HIGH FOR THIS TIME OF YEAR SITTING IN THE 16-20 DEGREE RANGE OVER
MUCH OF SOUTHERN MANITOBA. THE RICH BOUNDARY LAYER MOISTURE IS
CONTRIBUTING TO HIGH PWAT VALUES OVER SOUTHERN MANITOBA RANGING FROM
40-60 MM. HOWEVER, THE MID-LEVEL LAPSE RATES WILL REMAIN MODEST AT
BEST OVER THE REGION LEADING TO MLCAPE VALUES IN THE 800-1200 J/KG
RANGE OVER EASTERN MANITOBA THIS AFTERNOON. ROUNDING THE BASE OF THE
TROUGH IS A 60 KT UPPER LEVEL JET WITH THE LEFT EXIT OF THE JET
POKING INTO EAST/CENTRAL MANITOBA BY MID AFTERNOON CONTRIBUTING TO
30-40 KTS OF 0-6 KM BULK SHEAR. THUS, THE ENVIRONMENT IS AGAIN
SUPPORTIVE OF SEVERE THUNDERSTORMS OVER EAST-CENTRAL MANITOBA THIS
AFTERNOON WITH LARGE HAIL, STRONG WIND GUSTS AND HEAVY RAIN BEING THE
PRIMARY THREATS.
THE ENVIRONMENT IS DIFFERENT OVER WESTMAN/EASTERN SASKATCHEWAN THIS
AFTERNOON WHERE BOTH CAPE AND SHEAR VALUES ARE NOTABLY WEAKER UNDER
THE UPPER LOW. WITH THIS BEING SAID HOWEVER, SLOW STORM MOTIONS WILL
RESULT IN LONGER RESIDENCE TIMES LEADING TO A ISOLATED BUT HEAVY RAIN
THREAT OVER WESTMAN/EASTERN SASKATCHEWAN. THE UPPER LOW OVER
SOUTHWESTERN MANITOBA WILL ALSO BE SPORTING AN ENVIRONMENT RICH IN
VORTICITY. THEREFORE A FUNNEL CLOUD AREA HAS BEEN ADDED TO THE TSO.
CURRENT CAM/HREF GUIDANCE IS SUGGESTING STORMS FIRING BY EARLY
AFTERNOON AND CONTINUING INTO THE EVENING HOURS. THE SEVERE THREAT
SHOULD DIMINISH INTO THE LATE EVENING HOURS, BUT SHOWERS AND
THUNDERSTORMS WILL CONTINUE OVERNIGHT THROUGH CENTRAL MANITOBA.
WITH ALL THE LOW LEVEL MOISTURE HANGING AROUND, FOG PATCHES WILL
CONTINUE TO DEVELOP OVERNIGHT AND LAST INTO THE EARLY MORNING HOURS
OVER THE NEXT FEW DAYS.
NWT...WILDFIRES LOCATED NEAR WHATI, NEAR FORT PROVIDENCE AND
NORTHWEST OF FORT CHIPEWYAN ARE GIVING POOR TO VERY POOR ACROSS MUCH
OF THE SOUTHERN NORTHWEST TERRITORIES AT THE MOMENT. A LOW PASSING
THROUGH THE REGION WILL BRING A SHIFT TO NORTHWESTERLY WINDS ALONG
WITH SOME RAIN. THIS SHOULD HELP TO IMPROVE THE AIR QUALITY.
NUNAVUT...THE LOW MOVING THROUGH THE SOUTHERN NWT WILL ALSO AFFECT
THE WESTERN KITIKMEOT TODAY AND TONIGHT. 5-10 MM OF RAIN IS FORECAST
FOR KUGLUKTUK AND WET SNOW IS ON TAP FOR CAMBRIDGE BAY.
A DEVELOPING LOW OVER BAFFIN BAY WILL SET UP A NORTHERLY GRADIENT
OVER ELLESMERE ISLAND. PROG SOUNDINGS SUGGEST SOME POSSIBILITY OF
WARNING-LEVEL WINDS FOR THE COMMUNITY OF GRISE FIORD TONIGHT, BUT
CURRENT THINKING IS THAT THE LOW-LEVEL WINDS ARE A BIT TOO WEAK AND
THE INVERSION A BIT TOO LOW.
THE LOW MOVING THROUGH FOXE BASIN WILL CONTINUE TO SUPPORT SHOWERS/
FLURRIES OVER BAFFIN ISLAND TODAY.
END/ZIOLKOWSKI/KOKOLSKY/STAUNTON/GRIFFITH
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