137
FOCN45 CWWG 091900
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CDT WEDNESDAY
SEPTEMBER 9 2026.
ALERTS IN EFFECT...AIR QUALITY WARNING FOR FORT SIMPSON.
SYNOPTIC OVERVIEW...ALOFT, A LOW SPINS NEAR THE MACKENZIE MOUNTAINS
WITH TROUGHING TO THE SOUTHWEST. AN UPPER RIDGE ARCS OVER SOUTHERN
BC AND SPRAWLS NORTHEAST OVER THE PRAIRIES AND INTO NUNAVUT. AN
UPPER LOW IS OVER SOUTHERN HUDSON BAY WITH TROUGHING INTO ONTARIO.
UPPER RIDGE OVER EASTERN CANADA.
AT THE SURFACE, A HIGH PRESSURE OVER THE PACIFIC NORTHWEST SPREADS
A RIDGE OVER BC AND THE SOUTHERN PRAIRIES. A LOW NORTHEAST OF GREAT
SLAVE LAKE HAS A TROUGH HANGING SOUTHEAST INTO NORTHERN
ALBERTA/SASKATCHEWAN. ANOTHER HIGH PRESSURE CENTRE IS NEAR THE
BOOTHIA PENINSULA. A LOW SPINS OVER SOUTHERN HUDSON BAY.
DISCUSSION...
WESTERN PRAIRIES AND NT...A FEW ISOLATED SHOWERS ACROSS NORTHERN
ALBERTA AS A LOW PRESSURE SYSTEM ESTABLISHES ITSELF OVER THE
SOUTHERN MACKENZIE. WITH A TROUGH EXTENDING SOUTHWARD FROM THE LOW,
WESTERLY WINDS ARE EXPECTED ACROSS ALBERTA WITH THE STRONGEST GUSTS
FORECAST TO OCCUR NEAR THE PEACE RIVER-GRANDE PRAIRIE-SLAVE LAKE
REGIONS; GUSTS UP TO 70 KM/H HAVE BEEN INCLUDED IN THE FORECASTS.
FOCUS QUICKLY TURNS TO THE DEVELOPING LOW THAT WILL CONTINUE TO
DEVELOP TONIGHT OVER THE SOUTHERN NT, AND GENERATE PROLONGED,
WIDESPREAD SHOWER ACTIVITY NEAR GREAT SLAVE LAKE, DEHCHO AND
NORTHERN ALBERTA TONIGHT INTO THURSDAY. SOME MID-LEVEL INSTABILITY
EXISTS OVER THESE NORTHERN REGIONS AND THIS COULD LEAD TO ADDITIONAL
THUNDERSTORM DEVELOPMENT THIS AFTERNOON AND EVENING. TOTAL
PRECIPITATION AMOUNTS WITH THIS SYSTEM OVER THE AFOREMENTIONED
REGIONS WILL RANGE BETWEEN 5-20 MM DEPENDING ON LOCATION AND
ENHANCED CONVECTIVE ACTIVITY.
A COLD FRONT FROM THIS LOW WILL SWEEP SOUTHWARD THROUGH ALBERTA
BEGINNING LATE THIS AFTERNOON OVER NORTHERN ALBERTA, AND CLOSER TO
MIDNIGHT-OVERNIGHT OVER CENTRAL AND SOUTHERN REGIONS. AGAIN,
MID-LEVEL INSTABILITY (ALBEIT WEAKER AND MORE ISOLATED IN NATURE)
EXISTS AS IT TRANSITIONS SOUTHWARD AND COULD GENERATE A FEW LIGHTNING
STRIKES THROUGH THE NIGHT. STRONG, GUSTY WINDS ALONG AND BEHIND THE
COLD FRONT WILL DEVELOP AND PERSIST THROUGH THE REMAINDER OF THE
FORECAST PERIOD.
GUSTY WINDS ARE ALSO EXPECTED OVER SOUTHWESTERN ALBERTA TONIGHT AHEAD
OF THE COLD FRONT, PARTICULARLY NEAR THE CROWSNEST-CARDSTON-OKOTOKS
REGIONS WHERE AN INVERSION AND A STRONG CROSS-BARRIER FLOW OF 55-60
KTS COULD GENERATE WIND GUSTS UP TO 80-90 KM/H TONIGHT.
THE COLD FRONT IS ALSO EXPECTED TO LOWER SNOW LEVELS IN THE MOUNTAIN
PARKS, WITH LEVELS DROPPING TO ROUGHLY 2000M TONIGHT AND CLOSE TO
1500M ON THURSDAY. THIS COULD LEAD TO MIXED PRECIPITATION OVER THE
HIGHEST TERRAIN WEDNESDAY NIGHT INTO THURSDAY WITH A TRANSITION OVER
TO SOME SNOW AT THESE HIGHER ELEVATIONS.
IN FORT SIMPSON, VERY POOR AIR QUALITY THIS AFTERNOON AS THE WINDS
HAVE SHIFTED AND MOVED THE SMOKE FROM THE SOURROUNDING WILDFIRES
INTO THE COMMUNITY. CONDITIONS ARE ANTICIPATED TO IMPROVE THIS
EVENING AS STRONGER NORTHERLY WINDS MOVE THROUGH THE REGION.
ALONG THE ARCTIC COAST, LOTS OF FOG AND DRIZZLE IN ONSHORE FLOW.
EASTERN PRAIRIES...QUIET WEATHER FOR WEDNESDAY AND INTO THE
OVERNIGHT WITH THE SURFACE RIDGE OVER THE AREA. THE NEXT SYSTEM TO
AFFECT THE AREA WILL BE THE LOW NEAR GREAT SLAVE LAKE. SHOWERS AND
THUNDERSTORMS WILL ENTER NORTHERN MANITOBA THURSDAY MORNING. IT WILL
BE A PROLONGED RAIN EVENT LASTING INTO THE WEEKEND. TOTAL RAINFALL
AMOUNTS LOOKS TO BE 20 TO 50 MM BY SATURDAY. RAINFALL WARNINGS MAY
BE ISSUED FOR THE CHURCHILL AND ARVIAT REGIONS FOR 25 MM IN 24
HOURS. STRONG WIND GUSTS OF 70 TO 80 KM/H WILL ALSO BE PRESENT
STARTING THURSDAY EVENING IN ARVIAT AND CHURCHILL.
NUNAVUT..NIL SIG WX.
END/BILOUS/GREENHOUGH
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