790
FOCN45 CWWG 041200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT THURSDAY JUNE
4 2026.
ALERTS IN EFFECT...AIR QUALITY WARNINGS FOR PARTS OF THE SOUTHERN
NWT. FOG ADVISORY FOR PARTS OF SOUTHERN ALBERTA.
OVERVIEW...ALOFT, AN UPPER LOW IS LOCATED OVER THE GULF OF ALASKA
WITH A LONG-WAVE TROUGH SOUTHEAST TO VANCOUVER ISLAND. AN UPPER RIDGE
IS OVER ALBERTA AND AN UPPER LOW SITS OVER SOUTHEASTERN SASKATCHEWAN.
A BROAD UPPER RIDGE IS OVER ONTARIO AND SOUTHERN QUEBEC. IN THE
NORTH, AN UPPER LOW IS OVER THE HIGH ARCTIC AND A SHORTWAVE TROUGH IS
TRACKING THROUGH KIVALLIQ.
AT THE SURFACE, WEAK LOW PRESSURE IS OVER YUKON AND NORTHERN BC.
A RIDGE OF HIGH PRESSURE IS OVER THE NORTHERN PRAIRIES AND EXTENDS
SOUTHWARD THROUGH ALBERTA. AN OCCLUDED LOW IS OVER SOUTHWESTERN
MANITOBA. A LOW IS OVER THE HIGH ARCTIC.
DISCUSSION...
AB/NORTHERN SK...DENSE FOG AFFECTING PARTS OF HIGHWAY 1 EAST OF
CALGARY WILL BURN OFF LATER THIS MORNING. PATCHES OF FOG HAVE BEEN
OBSERVED ELSEWHERE IN THE PROVINCE WITH BREAKS IN THE CLOUD COVER,
BUT THIS IS LESS WIDESPREAD. FOG ADVISORIES WILL BE EXPANDED IF
NEEDED THIS MORNING. FOG MAY RE-DEVELOP AGAIN TONIGHT IN MUCH OF THE
PROVINCE.
THE SHORTWAVE OVER BC WILL CROSS INTO ALBERTA THIS AFTERNOON,
TRIGGERING SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE PROVINCE.
WITH THE JET SUPPORT LARGELY FURTHER TO THE WEST, THUNDERSTORMS WILL
LIKELY BE LACKING IN SHEAR TO ORGANIZE THEM AND SHOULD REMAIN
SUB-SEVERE. SOME LIGHTNING IS LIKELY TO CONTINUE OVERNIGHT FOR PARTS
OF NORTHERN ALBERTA.
THUNDERSTORMS ARE EXPECTED AGAIN FRIDAY IN AN AREA EXTENDING FROM
CENTRAL ALBERTA UP INTO NORTHWESTERN SASKATCHEWAN, ASSOCIATED WITH A
DEVELOPING LOW AND COLD FRONT. MLCAPE VALUES UP TO 1000 J/KG AND UP
TO 40 KT OF EBWD COULD SUPPORT SEVERE STORMS IN THE AREA, THOUGH WITH
SHEAR VECTORS ALIGNED PARALLEL TO THE COLD FRONT, CONVECTION COULD
GROW UPSCALE RELATIVELY QUICKLY.
SOUTHERN SK/MB...THE UPPER LOW OVER SASKATCHEWAN AND SURFACE LOW
REFLECTION OVER SOUTHERN MANITOBA WILL SLOWLY DRIFT EASTWARD THROUGH
THE DAY AND CONTINUE TO WEAKEN. LINGERING INSTABILITY OVER MANITOBA
AND THE DYNAMIC SUPPORT FROM THE FEATURES WILL LEAD TO SCATTERED
SHOWERS AND THUNDERSTORMS OVER THE PROVINCE THIS AFTERNOON AND
EVENING, BUT NO SEVERE WEATHER IS ANTICIPATED. FURTHER WEST, SHOWERS
AND THUNDERSTORMS WILL BE POSSIBLE OVER PARTS OF SOUTHERN AND
SOUTHWESTERN SASKATCHEWAN AS WELL, SUPPORTED BY A SHORTWAVE LIFTING
NORTHEAST FROM MONTANA.
NWT...WILDFIRE SMOKE IS AFFECTING PARTS OF THE SOUTHERN NWT, WITH
SOUTHERLY FLOW PUSHING SMOKE AS FAR NORTH AS YELLOWKNIFE. CONDITIONS
IN YELLOWKNIFE SHOULD IMPROVE THIS MORNING WITH WINDS GRADUALLY
SHIFTING TO BLOW FROM THE NORTH, BUT SMOKE WILL LIKELY CONTINUE TO
DRIFT AROUND SOUTH OF GREAT SLAVE LAKE UNTIL FRIDAY, WHEN SHOWERS AND
THUNDERSTORMS MOVING THROUGH THE AREA SHOULD HELP DIMINISH THE SMOKE.
SOME PRECIP TYPING ISSUES ARE FORECAST FOR THE NORTHERN NWT WITH A
COLD FRONT SWEEPING DOWN FROM THE ARCTIC OCEAN. RAIN IS FORECAST TO
CHANGE OVER TO SNOW FOR MOST COMMUNITIES IN THE DELTA THIS MORNING AS
TEMPERATURES CONTINUE TO FALL. THERE IS A VERY SLIGHT CHANCE OF
FREEZING RAIN ASSOCIATED WITH THE CHANGEOVER, BUT MOST COMMUNITIES
ARE EXPECTED TO REMAIN JUST ABOVE THE ZERO DEGREE MARK.
NUNAVUT...THE SHORTWAVE CURRENTLY TRACKING THROUGH KIVALLIQ WILL MOVE
THROUGH MELVILLE PENINSULA AND SOUTHERN BAFFIN ISLAND OVERNIGHT AND
THROUGH FRIDAY BRINGING MIXED PRECIPITATION TO THE AREA.
END/MOODIE/STAUNTON
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