242
FOCN45 CWWG 121200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT TUESDAY AUGUST
12 2025.
ALERTS IN EFFECT...AIR QUALITY WARNINGS FOR PORTIONS OF MANITOBA AND
SASKATCHEWAN.
SYNOPTIC OVERVIEW...
ALOFT, UPPER AIR ANALYSIS ALONG WITH GOES WATER VAPOUR IMAGERY SHOWS
BROAD TROUGHING CENTERED OVER MANITOBA THIS MORNING BOUNDED BY
RIDGING TO THE EAST AND WEST OF THE TROUGH. THIS RIDGE TROUGH PATTERN
LEADS TO NORTHWESTERLY FLOW OVER THE WESTERN PRAIRIES. FURTHER NORTH,
AN UPPER LOW IS ANCHORED OVER BAFFIN BAY WITH A TROUGH EXTENDING
SOUTH INTO THE KIVALLIQ. RIDGING EXISTS BACK TO THE WEST OF THE LOW
OVER THE SW NWT.
AT THE SURFACE, A 1009 MB LOW SITS OVER NW AB WITH WARM FRONT INTO
CENTRAL AB. A FRONTAL WAVE SITS OVER NORTHWESTERN ONTARIO WITH A
999 MB LOW ATTACHED ALONG THE HUDSON BAY COASTLINE EAST OF YORK
FACTORY. A BAROCLINIC ZONE SNAKES ALONG THE 60TH PARALLEL FROM HUDSON
STRAIT, INTO THE KIVALLIQ BEFORE TURNING SHARPLY NORTH INTO THE
ARCTIC OCEAN. A BROAD AREA OF HIGH PRESSURE DOMINATES THE PACIFIC
NORTHWEST.
DISCUSSION...
AB/NT...THE LOW WILL VERY SLOWLY MAKE IT'S WAY EAST THROUGH THE
WEEK. ALONG THE WARM FRONT AND TROWAL UP TO 25 MM OF RAIN IS
EXPECTED TODAY. PRECIPITATION WILL BECOME MORE SPOTTY TONIGHT
BEFORE REORGANIZING ITSELF TOMORROW AS THE COLD FRONT MOVES ACROSS
ALBERTA. DUE TO THE CONVECTION, CONFIDENCE IN AMOUNTS IS LOW FOR
WEDNESDAY BUT 10-20 MM IS POSSIBLE FOR AREAS FROM JASPER TO COLD
LAKE. STRONG WINDS ARE ALSO EXPECTED WITH THE COLD FRONT. MUCH OF
CENTRAL AB COULD SEE NORTHERLY GUSTS OF 60-70 KM/H WEDNESDAY
AFTERNOON/EVENING.
WARM TEMPERATURES AND MODERATE DEWPOINTS WILL ALLOW FOR MLCAPE
VALUES OF 500-1000 J/KG THIS AFTERNOON OVER CENTRAL AB. WITH THE
WESTERLY H500 JET AROUND 40 KT THERE WILL BE ENOUGH SHEAR TO
POTENTIALLY HAVE SEVERE THUNDERSTORMS DEVELOP. HOWEVER, WITH THE
UPPER RIDGE SITTING OVER SOUTHERN AB THINGS MAY REMAIN CAPPED UNTIL
EARLY EVENING. IT DOES LOOK LIKELY THAT THUNDERSTORMS WILL DEVELOP,
BUT THE TIMING WILL DETERMINE SEVERITY. SEVERE THUNDERSTORMS LOOK
MORE PLAUSIBLE ON WEDNESDAY ALONG AND AHEAD OF THE COLD FRONT WITH
HIGHER MLCAPE VALUES OF 1000-2000 J/KG AND 40 KT EBWD.
MB...SETTLED WEATHER WILL BEGIN TO SET IN TODAY AS THE LOW PRESSURE
SYSTEM THAT PASSED THROUGH YESTERDAY SLIDES INTO ONTARIO. HOWEVER,
ANOTHER PUSH OF SMOKE IS EXPECTED TO MAKE ITS WAY SOUTH AGAIN TODAY
AS NORTHWESTERLY FLOW SETS IN. A LARGE SMOKE OF PLUME WAS EVIDENT ON
SATELLITE IMAGERY MONDAY EVENING IN NORTHERN MANITOBA AND IS
FORECAST TO ADVECT SOUTH TODAY INTO SOUTHERN MANITOBA. AIR QUALITY
WARNINGS HAVE BEEN EXPANDED OVERNIGHT AND THE PLUME IS FORECAST TO
MAKE ITS WAY INTO SOUTHERN MANITOBA BY EARLY-MID MORNING. CONDTIONS
WILL BEGIN TO IMPROVE LATER IN THE AFTERNOON FROM NORTH TO SOUTH
WHICH SHOULD PROMPT AN END TO THE AIR QUALITY ALERTS. WINDS WILL
BEGIN TO SETTLE AS A RIDGE OF HIGH PRESSURE MOVES INTO NORTHERN
MANITOBA CAUSING THE WINDS TO TURN EASTLY AND CONFINING THE SMOKE IN
NORTHERN MANITOBA FOR THE NEXT FEW DAYS.
SK..QUIET WEATHER IS ONTAP FOR MOST OF THE PROVINCE TODAY WITH ONLY A
FEW THINGS TO NOTE. THE FIRST THING IS THE AFOREMENTIONED SMOKE PLUME
WILL CLIP PORTIONS OF SOUTH EASTERN SASKATCHEWAN THIS MORNING, MAINLY
THE HUDSON BAY AND KAMSACK REGIONS. SMOKE WILL BEGIN TO TAPER OFF IN
THE AFTERNOON HOWEVER AS THE RIDGE SLIDES IN AND WINDS TAPER OFF.
IN NORTHEASTERN SK SMOKE IS STILL CAUSING VERY POOR AIR QUALITY AT
TIMES AND WITH WINDS SHIFTING TO BLOW FROM THE EAST THROUGH THE DAY,
THE WARNINGS MAY NEED TO BE EXPANDED TO THE WEST. HOWEVER, INCOMING
SHOWERS FROM THE WEST MAY LIMIT HOW BAD THE SMOKE IS AWAY FROM THE
FIRES. RAINFALL AMOUNTS STARTING ON WEDNESDAY COULD BE LOCALLY
AROUND 25 MM FOR THE DAY BUT WITH THE CONVECTION AROUND THE LOW,
CONFIDENCE IS MINIMAL THIS FAR IN ADVANCE OF HOW MUCH WILL ACTUALLY
FALL. REGARDLESS, SHOWERY CONDITIONS THROUGH THE REST OF THE WEEK
LOOK LIKELY AND WILL SURELY BE A RELIEF. A WIDESPREAD AREA OF 25 MM
ACROSS NORTHERN SK BY FRIDAY MORNING LOOKS REASONABLE, WITH SOME
AREAS GETTING MORE THAN THAT.
SOME SHOWERS AND THUNDERSTORMS WILL BEGIN TO DRIFT IN FROM ALBERTA
OVER WEST-CENTRAL SASKATCHEWAN THIS EVENING, BUT THESE STORMS ARE
EXPECTED TO BE NON-SEVERE.
A MORE SIGNIFICANT SYSTEM WILL BEGIN TO MAKE ITS WAY INTO SOUTH
CENTRAL SASKATCHEWAN WEDNESDAY, USHERING IN A RETURN OF SEVERE
THUNDERSTORMS. BOTH CAPE AND SHEAR PROFILES SUPPORT THE FORMATION OF
SUPERCELLS OVER PARTS OF SOUTHERN SASKATCHEWAN, PARTICULARLY OVER THE
KINDERSLEY, BATTLEFORDS AND SASKATOON AREAS WEDNESDAY AFTERNOON.
CAPPING APPEARS TO BE A POTENTIAL INHIBITOR OF WIDESPREAD CONVECTION
AT THIS TIME AND MAY LIMIT OVER ALL STORM COVERAGE. TIMING AND
DETAILS WILL BECOME MORE CLEAR AS TIME APPROACHES AND CAMS GET WITHIN
RANGE TO CAPTURE MORE DETAILS ON THE EVOLUTION OF CONVECTION.
NU...NIL SIG WX.
END/ZIOLKOWSKI/ROMBOUGH
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