866
FOCN45 CWWG 291200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT MONDAY JUNE
29 2026.
ALERTS IN EFFECT...RAINFALL WARNING FOR MOST OF SOUTHERN ALBERTA.
HEAT WARNINGS FOR PARTS OF THE NORTHWEST TERRITORIES, NORTHERN
ALBERTA, NORTHERN SASKATCHEWAN AND CORAL HARBOUR. AIR QUALITY
WARNING FOR NORMAN WELLS, HAY RIVER AND PORTIONS OF NORTHERN
ALBERTA/SASKATCHEWAN.
OVERVIEW...ALOFT, AN UPPER LOW IS OVER ALASKA WITH TROUGHING
SOUTHWARD. AN UPPER RIDGE OF HIGH PRESSURE EXTENDS FROM THE EASTERN
PACIFIC THROUGH SOUTHERN BC AND INTO NORTHERN ALBERTA AND THE
CENTRAL ARCTIC. A COMPLEX OF UPPER LOWS WITH VARIOUS EMBEDDED
SHORTWAVES ARE OVER SASKATCHEWAN AND THE AMERICAN ROCKY MOUNTAIN
REGION. A STRONG SOUTHWESTERLY JET IS LOCATED OVER THE AMERICAN
GREAT PLAINS AND EXTENDS INTO SOUTHWESTERN MANITOBA. AN UPPER RIDGE
OF HIGH PRESSURE IS OVER ONTARIO AND QUEBEC. AN UPPER LOW IS OVER
THE HIGH ARCTIC WITH TROUGHING SOUTHWARD THROUGH DAVIS STRAIT.
ANOTHER UPPER LOW IS OVER THE SOUTHERN TIP OF GREENLAND.
AT THE SURFACE, RIDGING DOMINATES THE EASTERN PACIFIC. AN OCCLUDED
994 MB LOW IS OVER EXTREME SOUTHWESTERN SASKATCHEWAN. THE APEX OF
THE FRONTAL WAVE IS OVER EXTREME SOUTHWESTERN MANITOBA, THE WARM
FRONT EXTENDS EASTWARD THROUGH SOUTHERN MANITOBA AND THE COLD FRONT
STRETCHES SOUTHWARD THROUGH THE DAKOTS. A DEVELOPING LOW PRESSURE
CENTER IS OVER NEBRASKA WITH A WARM FRONT EXTENDING NORTHEASTWARD
THROUGH SOUTHERN SOUTH DAKOTA AND SOUTHERN MINNESOTA. LOW PRESSURE
IS OVER WESTERN NWT. HIGH PRESSURE IS OVER HUDSON BAY WITH A RIDGE
THAT EXTENDS INTO KIVALLIQ AND THE CENTRAL ARCTIC. LOW PRESSURE IS
OVER BAFFIN ISLAND.
DISCUSSION...
AB/NRN SK...THE RAINFALL OVER SOUTHERN ALBERTA WILL TAPER OFF OVER
THE NEXT 24 HOURS. MOST OF THE RAIN IS FALLING AS INTERMITTENT
SHOWERS WITH MORE ORGANIZATION ALONG THE EASTERN SLOPES OF THE
ROCKIES. THE FOOTHILLS ARE EXPECTED TO SEE ANOTHER 10 TO 40 MM AND
THE PLAINS AROUND 5 TO 10 MM BY TOMORROW MORNING. AMOUNTS WILL BE
HIGHER IN THUNDERSTORMS.
THUNDERSTORMS ARE EXPECTED TO DEVELOP ADVANCE OF A RETROGRADING
SHORT WAVE TROUGH AND ALONG A TROUGH RUNNING ALONG THE FOOTHILLS,
THROUGH THE MACKENZIE VALLEY TO VICTORIA ISLAND. THE ENVIRONMENT
WILL HAVE 500-1500 J/KG OF CAPE AND GENERALLY WEAK DYNAMICS. THE
PRIMARY THREAT WILL THEREFORE BE RAINFALL, HOWEVER, GIVEN THE SOGGY
ANTECEDENT CONDITIONS, THIS HAZARD COULD STILL BE IMPACTFUL. THERE
IS ALSO THE CHANCE OF FUNNEL CLOUDS OVER SOUTHEASTERN ALBERTA.
HEAT WARNINGS REMAIN IN EFFECT OVER NORTHERN REGIONS. THIS HEAT
EVENT IS EXPECTED TO END AROUND MID-WEEK.
EASTERLY FLOW NORTH OF THE DEPARTING LOW WILL SWEEP WILDFIRE SMOKE
FROM THE NORTHERN PRAIRIES INTO MUCH OF ALBERTA TODAY. AIR QUALITY
WARNINGS HAVE BEEN STEADILY EXPANDED THROUGH THE NIGHT.
SK/MB...SIGNIFICANT SEVERE WEATHER POTENTIAL CONTINUES MONDAY FOR
PARTS OF SOUTHERN MANITOBA.
FOR MONDAY'S SEVERE THUNDERSTORM SETUP, THE AREA OF CONCERN
ENCOMPASSES MUCH OF SOUTHERN MANITOBA, WITH ALL MODES OF SEVERE
WEATHER POSSIBLE. THE UPPER LOW COMPLEX WITH SEVERAL EMBEDDED
VORTICIES WILL REMAIN ANCHORED OVER SOUTHERN SASKATCHEWAN WITH THE
STRONG SOUTHWESTERLY JET MOVING OVER THE RED RIVER VALLEY AND
SOUTHEASTERN MANITOBA BY THIS AFTERNOON, WITH BULK SHEAR VALUES OF
40 TO 50 KTS OVER MUCH OF SOUTHERN MANITOBA. WITH THIS BEING THE
FOURTH DAY OF PERSISTANT SOUTHERLY FLOW CONTINUING TO PUMP HEAT AND
MOISTURE NORTHWARD, HEAT AND HUMIDITY CONTINUE TO INCREASE WITH
DAYTIME HIGHS ONCE AGAIN FORECAST TO BE IN THE MID TWENTIES, AND
DEWPOINTS PROGGED TO BE IN THE MID TO HIGH TEENS WITH MLCAPE VALUES
OF 1000 TO 1500 J/KG EXPECTED TO BE OVER THE AREA. ONCE AGAIN, WITH
THE EXPECTED CAPE VALUES TODAY, AND AMPLE SHEAR, STRONG WIND AND
LARGE HAIL ARE NOTABLE SEVERE WEATHER THREATS. AND, WITH THE
PERSISTENT TRANSPORT OF MOISTURE NORTHWARD, HIGH PWAT VALUES OF 40+
MM ARE LEADING TO HEAVY RAINFALL CONCERNS OVER ALREADY MOIST AREAS.
THE FOCUS FOR SEVERE CONVECTION, TODAY, WILL BE THE DEVELOPING LOW
OVER NEBRASKA AND SUPPORTING SHORTWAVE THAT IS EXPECTED TO TRACK
NORTHWARD THROUGH THE DAKOTAS THIS AFTERNOON AND INTO MANITOBA THIS
EVENING. SEVERE CONVECTION WILL INITIATE WITH THIS LOW THIS
AFTERNOON IN THE US AND THEN IS EXPECTED TO TRACK INTO SOUTHERN
MANITOBA LATE AFTERNOON/EVENING. THE WARM FRONT ASSOCIATED WITH THIS
LOW IS PROGGED TO BE ARCHING INTO SOUTHEASTERN MANITOBA THIS
AFTERNOON. ANY THUNDERSTORMS THAT LATCH ONTO THIS WARM FRONT WILL
HAVE THE CAPABILITY TO PRODUCE TORNADOES. RAPID UPSCALE GROWTH IS
ANTICIPATED THROUGH THE EVENING THROUGH SOUTHERN MANITOBA AS THE LOW
AND SHORTWAVE TRACK THROUGH THE AREA. THUNDERSTORMS ARE EXPECTED TO
PERSIST THROUGH THE NIGHT.
OVER SASKATCHEWAN, THUNDERSTORMS ARE ONCE AGAIN EXPECTED OVER MUCH
OF THE PROVINCE, BUT ARE NOT EXPECTED TO REACH SEVERE LIMITS. ONE
NOTE OF HEIGHTENED INTEREST IS OVER CENTRAL AND WEST-CENTRAL
SASKATCHEWAN WHERE THE ENVIRONMENT IS FAVOURABLE FOR FUNNEL CLOUD
DEVELOPMENT THIS AFTERNOON, AS THE UPPER LOW AND VARIOUS SHORTWAVES
REMAIN OVER THE REGION AND A SURFACE TROUGH IS LINGERING THROUGH
THE AREA, AS WELL.
IN NORTHERN MANITOBA, SCATTERED AIR-MASS THUNDERSTORMS ARE POSSIBLE
AGAIN THIS AFTERNOON AS A WEAK UPPER LOW/UPPER TROUGH CONTINUES TO
SIT OVER THE REGION.
IN NORTHERN MANITOBA, WILDFIRE SMOKE WILL CONTINUE TO PROPAGATE
THROUGH MUCH OF THE REGION, GRADUALLY SHIFTING TO BE A CONCERN FOR A
COUPLE AREAS ALONG THE SASKATCHEWAN BORDER AS AN EASTERLY FLOW
DEVELOPS -- MAINLY PARTS OF THE THOMPSON, LYNN LAKE, AND FLIN FLON
REGIONS.
NUNAVUT...ABOVE SEASONAL TEMPERATURES WILL CONTINUE WELL INTO NEXT
WEEK WITH CORAL HARBOUR SEEING HEAT WARNING LEVEL CRITERIA. DESPITE
SEEING TEMPERATURES WELL ABOVE SEASONAL, OTHER SITES ACROSS THE
KIVALLIQ AND SOUTHERN BAFFIN ISLAND LOOK TO REMAIN BELOW HEAT WARNING
LEVEL THRESHOLDS.
MORE SHOWERS AND THUNDERSHOWERS WILL DEVELOP ALONG THE WEST SIDE OF
THE UPPER HIGH OVER THE KIVALLIQ MAINLAND AND EASTERN NWT FOR THE
NEXT FEW DAYS. THERE WILL BE ONLY 10 TO 15 KNOTS OF 0-6 KM BULK
SHEAR, SO EXPECTING PULSE THUNDERSHOWERS WITH SOME HEAVIER RAIN.
NWT...HEAT WARNINGS REMAIN IN EFFECT AROUND GREAT SLAVE LAKE. COOLER
TEMPERATURES ARE EXPECTED LATER THIS WEEK. POOR AIR QUALITY IS
EXPECTED AT MANY SITES SOUTH OF THE TREELINE OVER THE COMING DAYS.
SCATTERED THUNDERSTORMS ARE EXPECTED AGAIN TODAY FROM FORT LIARD TO
VICTORIA ISLAND. GIVEN THE AMPLE MLCAPE VALUES, 30 TO 50 KT OF
EFFECTIVE SHEAR, AND A PROVEN TRIGGER, STORMS ARE LIKELY TO
BECOME SEVERE. GUSTY WINDS AND HAIL ARE THE PRIMARY CONCERN.
END/MOODIE/PATTEN
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