507
FOCN45 CWWG 081900
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CDT TUESDAY JULY
8 2025.
ALERTS IN EFFECT...HEAT WARNINGS FOR SOUTHEASTERN ALBERTA AND
SOUTHWESTERN SK. AIR QUALITY WARNINGS FOR KUGLUKTUK, NU, LA RONGE,
SK, THOMPSON, MB, AND PORTIONS OF SE MB. SPECIAL AIR QUALITY
STATEMENTS FOR MUCH OF MANITOBA AND NORTHERN SASKATCHEWAN AS WELL AS
PARTS OF THE SOUTHERN NT.
SYNOPTIC OVERVIEW...UPPER LOWS ARE NOTED OVER ELLESMERE ISLAND, OVER
LABRADOR SEA, AND OVER THE NORTHERN BC COAST. 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. IF ANYTHING DOES
DEVELOP EAST OF THE LOW, AS HINTED BY RECENT NWP RUNS, IT'S POSSIBLE
FOR AN ISOLATED SUPERCELL TO FORM LATE IN THE DAY, GIVEN THE 35 TO 40
KNOTS OF BWD. 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 OTHER CONCERN TOMORROW IN ALBERTA IS MORE SEVERE WEATHER, AS THE
ATTENDANT COLD FRONT FROM THE AFOREMENTIONED SYSTEM SLIDES SOUTHWARD
TOWARD THE HWY 1 CORRIDOR BETWEEN CALGARY AND MEDICINE HAT. THE ISSUE
HERE WILL BE THIS COLD FRONT POTENTIALLY STALLING OUT IN AN EAST-WEST
MANNER BY TOMORROW AFTERNOON; WITH AIR TO ITS SOUTH DRYING OUT WHILE
MOIST AIR REMAINS IN PLACE TO ITS NORTH. IF ENOUGH DAYTIME HEATING
OCCURS NORTH OF THIS FRONT AND LOW LEVEL WINDS REMAIN BACKED ENOUGH,
AS IN, EAST OR NORTHEAST...THE POSSIBILITY EXISTS FOR AN ISOLATED
SUPERCELL OR TWO TO DEVELOP ALONG THIS BOUNDARY AND TRACK EASTWARD.
COMBINED WITH 40-50 KTS OF BWD THERE EXISTS THE POSSIBILITY OF A
TORNADO AS ANY SUPERCELL WILL PROBABLY BE OF THE HP OR CLASSIC
VARIETY. THIS CONCERN MAY BE HEIGHTENED SHOULD A MESOLOW DEVELOP IN
THE VICINITY OF THIS BOUNDARY.
SRN SK/MB...A MOSTLY QUIET DAY OF WEATHER. SMOKE FORECASTING
CONTINUES TO BE PROBLEMATIC. A WEAK FLOW IS EXPECTED TO GIVE WAY TO A
SOUTHERLY ONE TODAY AND TONIGHT, ALLOWING SOME SMOKE TO MOVE TO THE
NORTH. THAT SAID, CONDITIONS ARE ALLOWING FOR THE RESURGENCE OF SOME
OF THE SOUTHERN MANITOBA FIRES, AND AN AQ WARNING HAS BEEN ISSUED FOR
PORTIONS OF SE MB.
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 PARTICULARLY
CHURCHILL WHERE A STRONG AND HOT SOUTHWESTERLY FLOW WILL PREVAIL
STARTING WEDNESDAY.
WEDNESDAY NOTABLY HAS POTENTIAL FOR SEVERE THUNDERSTORMS FROM
SOUTHERN SASKATCHEWAN 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 AN AQW FOR KUGLUKTUK.
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. THIS UNUSUALLY WARM AIR
MASS IS ALSO RESULTING IN 20+ DEGREE HIGHS AT KUGAARUK THIS AFTERNOON
WITH WARMER TEMPERATURES EXPECTED TOMORROW. A HEAT WARNING IS PENDING
WITH THE NEXT FORECAST ISSUE FOR THAT SITE.
END/CARLSEN/VAN LOCHEM
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