105
FOCN45 CWWG 081200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT TUESDAY JULY
8 2025.
ALERTS IN EFFECT...HEAT WARNINGS FOR SOUTHEASTERN ALBERTA AND
SOTHWESTERN SK. AIR QUALITY WARNINGS FOR LA RONGE, SK AND THOMPSON,
MB. SPECIAL AIR QUALITY STATEMENTS FOR MUCH OF MANITOBA AND NORTHERN
SASKATCHEWAN AS WELL AS PARTS OF SOUTHERN NT AND KUGLUKTUK, NU.
SYNOPTIC OVERVIEW...UPPER LOWS ARE NOTED OVER ELLESMERE ISLAND, OVER
DAVIS STRAIT, AND OVER THE ALASKAN PANHANDLE. A SHORTWAVE THROUGH IS
SITUATED NORTH OF GREAT SLAVE LAKE. A WEAK WESTERLY UPPER LEVEL FLOW
PREVAILS OVER THE PRAIRIES, WHILE A STRONGER WESTERLY FLOW PREVAILS
OVER MOST OF THE HIGH ARCTIC.
THE SURFACE ANALYSIS SHOWS A LOW DEVELOPING OVER THE LOWER MACKENZIE
RIVER WITH A FRONTAL BOUNDARY EXTENDING EAST ACROSS KITIKMEOT. A WEAK
HIGH IS OVER THE SOUTHEASTERN PRAIRIES. A SURFACE LOW IS OVER
NORTHERN ELLESMERE ISLAND.
DISCUSSION...
AB/NRN SK...A SHORTWAVE IS EXPECTED TO PASS ACROSS WEST-CENTRAL
ALBERTA TONIGHT AND SPAWN A FRONTAL SYSTEM OVER THE CENTRE OF
ALBERTA. CONVECTION MAY OCCUR LATE THIS AFTERNOON AHEAD OF THE
VORTICITY CENTRE, NEAR THE DEVELOPING SURFACE LOW, AND PERHAPS EAST
OF THE LOW WHERE A WARM FRONT MAY BEGIN TO FORM. THUNDERSTORMS WOULD
PROBABLY BE WEAK AND PERHAPS OVERSHEARED, AND IT MAY BE DIFFICULT TO
HAVE A STORM SET OFF UNDERNEATH THE THERMAL RIDGE OVER THE CENTRE TO
EAST OF THE PROVINCE. THAT SAID, IF ANYTHING DOES DEVELOP EAST OF THE
LOW, AS HINTED BY THE 12Z HRDPS RUN, IT'S NOT COMPLETELY IMPOSSIBLE
FOR AN ISOLATED SUPERCELL TO FORM LATE IN THE DAY, GIVEN THE 35 TO 40
KNOTS OF CURVED SHEAR.
THE SHORTWAVE, LOW AND FRONTAL BOUNDARY SHOULD PROGRESS TO THE EAST
TONIGHT, WHERE 1000 J/KG OF MUCAPE SHOULD ALLOW FOR THUNDERSTORMS
THROUGH THE NIGHT OVER NORTHERN SASKATCHEWAN, SOME OF WHICH COULD BE
STRONG OR EVEN SEVERE.
MEANWHILE, HOT WEATHER IS EXPECTED UNDER THE THERMAL RIDGE, WITH
HIGHS RANGING UP TO 35 DEGREES. FOR MUCH OF ALBERTA THIS WILL BE A
ONE DAY EVENT AS A COLD FRONT PRESSES SOUTHWARDS, BUT FOR THE
SOUTHEASTERN CORNER OF THE PROVINCE THE EVENT SHOULD LAST INTO
TOMORROW WARRANTING A HEAT WARNING. THE HEAT WARNING HAS BEEN EXTENED
INTO THE DRUMHELLER REGION GIVEN HOW IT'S PRONE TO HEAT.
SRN SK/MB...A MOSTLY QUIET DAY OF WEATHER. A FEW FOG/MIST PATCHES
DEVELOPED LAST NIGHT IN THE AREA WHERE THE DEWPOINTS WERE HIGHEST AND
SKIES CLEARED. THESE SHOULD BURN OFF A COUPLE HOURS AFTER SUNRISE.
SMOKE FORECASTING CONTINUES TO BE PROBLEMATIC. A WEAK FLOW IS
EXPECTED TO GIVE WAY TO A SOUTHERLY ONE TODAY AND TONIGHT, ALLOWING
SMOKE TO MOVE TO THE NORTH.
HEAT WARNINGS ARE OUT FOR SOUTHEASTERN SASKATCHEWAN TODAY AHEAD OF
THE WHERE THE COLD FRONT SHOULD BE SITUATED WEDNESDAY AFTERNOON.
HEAT MAY BE A PROBLEM LATER OVER NORTHERN MANITOBA AND PARTICUALARLY
CHURCHILL WHERE A STRONG AND HOT SOUTHWESTERLY FLOW WILL PREVAIL
STARTING WEDNESDAY.
WEDNESDAY NOTABLY HAS POTENTIAL FOR SEVERE THUNDERSTORMS FROM
SOUTHERN SASKATCHWAN TROUGH NORTHERN MANITOBA. 35 TO 45 KNOTS OF
SHEAR AS WELL AS MLCAPE VALUES RAGING FROM OVER 1000 J/KG NEAR THE
NUNAVUT BORDER TO PERHAPS 2000 J/KG OVER SOUTHERN SASKATCHEWAN COULD
ALLOW FOR SUPERCELLULAR DEVELOPMENT. SOME CAPPING IS NOTED AT THE 850
MB LEVEL OVER SOUTHERN SASKATCHEWAN BUT IT'S PLAUSIBLE THIS CAP COULD
BE BROKEN TOWARDS THE END OF THE DAY WITH THE PASSAGE OF THE COLD
FRONT, PARTICULARLY TOWARDS THE ALBERTA BORDER.
NT...THE LOW OVER THE MACKENZIE RIVER IS EXPECTED TO MOVE
SOUTHEASTWARDS OVER THE NEXT 24 HOURS. THUNDERSTORMS ARE EXPECTED
OVER THE MACKENZIE RIVER TODAY AND NEAR GREAT SLAVE LAKE TONIGHT WITH
AN ASSOCIATED SHORTWAVE. RAIN LOCATED NORTHWEST OF THIS LOW WILL ALSO
SLIDE SOUTHEASTWARDS BRINGING ACCUMULATING RAINFALL, THROUGH RAINFALL
WARNING AMOUNTS ARE NOT EXPECTED. FURTHER NORTH NEAR THE FRONTAL
BOUNDARY, IT SHOULD BE COLD ENOUGH TONIGHT TO ALLOW FOR SOME SNOW TO
MIX WITH RAIN OVERNIGHT AND WEDNESDAY MORNING OVER THE MACKENZIE
DELTA. SMOKE IS EXPECTED TO DRIFT NORTH TODAY INTO JEAN MARIE RIVER,
SOME COMMUNITIES NORTH OF GREAT SLAVE LAKE AND NEAR, THOUGH PERHAPS
NOT IN, YELLOWKNIFE. A SWITCH IN FLOW AND RAINFALL SHOULD HELP
IMPROVE AIR QUALITY IN THESE REGIONS WEDNESDAY.
NU...SMOKE HAS MADE IT'S WAY FROM THE FIRES NEAR GREAT SLAVE LAKE TO
WESTERN KITIKMEOT COMMUNITIIES, REQUIRING A SAQS FOR KUGLUKTUK AND
PERHAPS SOON FOR CAMBRIDGE BAY. THIS SMOKE IS NOT EXPECTED TO BE TOO
LONG LIVED, WITH THE FLOW SWITCHING TO EAST THEN NORTHERLY STARTING
TONIGHT.
A SHORTWAVE AND AN UNUSUALLY WARM AIRMASS COULD AID IN TRIGGERING
THUNDERSTORMS OVERNIGHT IN EASTERN KITIKMEOT.
END/BATE
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