877
FOCN45 CWWG 071200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT MONDAY JULY
7 2025.
ALERTS IN EFFECT...AIR QUALITY ALERTS FOR PARTS OF CENTRAL
SASKATCHEWAN, PARTS OF THE NORTHWEST TERRITORIES, AND MOST OF
MANITOBA. FOG ADVISORY FOR PORTIONS OF EASTERN ALBERTA AND
SOUTHWESTERN SASKATCHEWAN.
SYNOPTIC OVERVIEW...ALOFT THIS MORNING, GENERALLY WESTERLY FLOW OVER
THE PRAIRIES SAVE FOR A POTENT SHORTWAVE AND SOUTHWARD TROUGH NEAR
WYNYARD, SK, MAKING ITS WAY EASTWARD. TO THE NORTH, LARGE LOWS SIT
OVER EASTERN BAFFIN ISLAND AND THE GULF OF ALASKA WITH WEAK RIDGING
COVERING MOST OF THE MAINLAND ARCTIC.
AT THE SURFACE, VERY SLACK FLOW AND GENERALLY WEAK RIDGING IN ALL
DIRECTIONS OVER THE PRAIRIES SAVE FOR A NORTH TO SOUTH TROUGH OVER
SOUTHEASTERN SK INTO MONTANA. A 982 MB OCCLUDED LOW SITS AT THE
ENTRANCE TO DAVIS STRAIT AND IS SLOWLY DECAYING.
DISCUSSION...
AB...FOG PATCHES DEVELOPED ALONG THE ALBERTA/SASKATCHEWAN BORDER LAST
NIGHT, AND WERE DEEMED PERSISTANT ENOUGH TO WARRANT A FOG ADVISORY.
THIS FOG SHOULD LIFT SHORTLY AFTER SUNRISE.
OTHERWISE A GENERALLY QUIET DAY OF WEATHER IS IN STORE FOR MOST OF
ALBERTA, THE NOTABLE EXCEPTION BEING IN THE NORTH, WHERE AHEAD OF A
THERMAL RIDGE UP TO 750 J/KG OF MLCAPE, SURFACE HEATING, AND A WEAK
SHORTWAVE AS WELL AS A LOCATION IN THE LEFT EXIT OF A 250 MB JET
SHOULD ALLOW FOR THE DEVELOPMENT OF A FEW THUNDERSTORMS TODAY.
SK/MB...THE SURFACE AND SHORTWAVE TROUGH SHIFTING INTO SOUTHEASTERN
SK WILL AGAIN BE THE FOCUS FOR THUNDERSTORM ACTIVITY TODAY. THE BULK
OF THE INSTABILITY AND BETTER SHEAR ARE SLIPPING INTO NORTH DAKOTA,
WITH JUST THE SOUTHWESTERN CORNER OF MANITOBA - SOUTH OF THE THE
TRANS-CANADA HIGHWAY - LOOKING AT ANOTHER MARGINAL HAIL AND WIND RISK
FOR THE AFTERNOON. STORM MOTIONS MAY CARRY ACTIVITY EASTWARD FOR
AREAS NEAR THE INTERNATIONAL BORDER THROUGH THE EVENING.
THOUGH THERE'S NOT A WHOLE LOT OF INSTABILITY LEFT ALONG MOST OF THE
TROUGH, THERE'S EXCELLENT LOW LEVEL CONVERGENCE AND VORTICITY BOTH
BACK WESTWARD FROM THE MANITOBA BORDER THROUGH SOUTHEASTERN SK AND UP
THROUGH THE HIGHWAY 11 CORRIDOR. FUNNEL CLOUD ACTIVITY IS A DISTINCT
LIKELIHOOD LATE MORNING AND THROUGH THE AFTERNOON - THE SHORTWAVE HAS
REMAINED QUITE PROMINENT THROUGH LAST NIGHT, EASILY VISIBLE ON BOTH
RADAR AND SATELLITE WITH A CLEAR CENTRAL AREA FOR DAYTIME HEATING
LATER TODAY.
THE STAGNANT SURFACE FLOW, CLEAR SKIES, AND EXTRA MOISTURE LEFT IN
THE WAKE OF THE DISTURBANCE IS RESULTING IN A FAIR AMOUNT OF DENSE
FOG OVER SOUTHWESTERN SK THIS MORNING. CONDITIONS FOR WIDESPREAD FOG
LOOK EVEN BETTER TONIGHT FOR SOUTHEASTERN SK AND WESTMAN.
SMOKE FROM WILDFIRES WILL CONTINUE TO CAUSE POOR AIR QUALITY VALUES
THROUGH PARTS OF MANITOBA AND NORTH-CENTRAL SASKATCHEWAN. THE SLACK
FLOW IS MAKING CLEARING TIMES TRICKY FOR LONG-STALLED, NARROW BANDS
OF DENSER SMOKE NEAR THE SURFACE - NEARLY INVISIBLE ON SATELLITE.
SURFACE WINDS START TO TURN STRONGLY SOUTHWARD TUESDAY IN
SASKATCHEWAN AND WEDNESDAY IN MANITOBA.
NT...SMOKE FROM WILDFIRES NEAR WHATI AND SOUTHEAST OF YELLOWKNIFE IS
BEING ADVECTED NORTHWARDS AND NORTHWESTWARDS IN THE SOUTH TO
SOUTHEASTERLY FLOW, REDUCING AIR QUALITY IN THESE REGIONS.
AIR QUALITY WILL LIKELY BE AT LEAST MODERATELY POOR FOR PARTS OF THE
NORTH SLAVE REGION FOR THE NEXT 36 HOURS, THOUGH CONDITIONS MAY
IMPROVE LATER THIS MORNING IN YELLOWKNIFE AS THE FLOW IS EXPECTED TO
BECOME MORE SOUTHERLY OVER THE FIRE LOCATED TO THE SOUTHEAST OF THE
CITY. A FIRE IS ALSO NOTED VERY NEAR FORT MACPHERSON. THOUGH THERE'S
NO SURFACE OBSERVATIONS IN THE AREA, ENOUGH SMOKE WAS SWIRLING AROUND
ON VISIBLE SATELLITE TO ISSUE A SAQS FOR THE REGION LAST NIGHT.
OTHERWISE, SURFACE TROUGHING AND MODERATE INSTABILITY SHOULD ALLOW
FOR THUNDERSTORMS TO DEVELOP ONCE AGAIN THIS AFTERNOON FOR MANY AREAS
OVER THE MACKENZIE RIVER. A SHORTWAVE LOCATED WEST OF GREAT SLAVE
LAKE HAS PRODUCED LIGHTNING THROUGH MOST OF THE NIGHT AND IS ENOUGH
OF A TRIGGER TO INTRODUCE A RISK OF THUNDERSTORMS FOR THE YELLOWKNIFE
REGION THIS AFTERNOON.
NU...A SYSTEM SPINNING OVER ELLESMERE ISLAND SHOULD PROVIDE SCATTERED
FLURRIES AND A RISK OF FREEZING DRIZZLE FOR PARTS OF THE HIGH ARCTIC
TODAY, AS HAS BEEN OBSERVED AT TIMES LAST NIGHT.
END/KNIGHT/BATE
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