460
FOCN45 CWWG 271900
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CDT FRIDAY JUNE
27 2025.
ALERTS IN EFFECT...AIR QUALITY WARNING FOR FORT LAIRD. SPECIAL AIR
QUALITY STATEMENTS FOR FORT SIMPSON AND FAR NORTHWEST ALBERTA.
SYNOPTIC OVERVIEW...12Z UPPER AIR AND WATER VAPOUR ANALYSIS REVEALS
NEGATIVELY TILTED TROUGHING ACROSS WESTERN NORTH AMERICA WITH
MULTIPLE EMBEDDED SHORT WAVES; POTENT VORT CENTER THAT WILL IMPACT TS
DEVELOPMENT TODAY NOW LOCATED AT THE NOSE OF THE 250 MB JET IN
SOUTHERN BC TRACKING EAST.
AT THE SURFACE...BROAD TROUGHING ACROSS MUCH OF THE PRAIRIES. A FEW
WEAK LOWS, ALTHOUGH A PRETTY FLAT PATTERN. BROAD QS BAROCLINIC ZONE
EXTENDS WEST TO EAST FROM ALASKA TO CHURCHILL. SECOND BAROCLINIC ZONE
WEAVES ACROSS THE NORTHERN US PLAINS. WEAK SURFACE LOW IN N MB WITH
ASSOCIATED WEAK OCCLUDING FRONTAL WAVE; WARM FRONT TO THE SOUTHEAST
THROUGH MB AND COLD FRONT TO THE SOUTHWEST THROUGH SOUTHERN SK.
NORTH TO SOUTH SURFACE TROUGH IN SOUTHEASTERN SK.
DISCUSSION...
AB...UNSTABLE THROUGH MUCH OF THE PROVINCE TODAY. THUNDERSTORMS
SHOULD BE FOCUSED OVER THE FAR NORTH AND EAST. IN THE EAST A
VORTICITY CENTRE OVER SOUTHERN B.C. WILL MOVE TOWARD DRUMHELLER/
CORONATION AREA THIS AFTERNOON. WITH SOME CAPE VALUES NEAR 900 J/KG
AND VORTICITY, THERE IS A SLIGHT RISK OF FUNNEL CLOUDS AND POSSIBLY
LOCAL HEAVY RAIN. STORMS WILL BE SLOW MOVING HERE AND LIKELY TO
PERSIST THROUGH THE NIGHT.
POTENTIAL FOR SMOKE FROM HIGH LEVEL AND FORT NELSON TO PUSH EASTWARDS
TO FORT CHIPEWYAN AND SOUTH OF GREAT SLAVE LAKE SATURDAY. LIMITED
CONFIDENCE HERE AS AQ VALUES ARE GENERALLY MODERATE WITH ONLY A FEW
HIGH VALUES DOWNSTREAM OR NEAR THE LARGEST FIRES.
SK/MB...AS THE UPPER TROUGH CONTINUES ITS PROGRESSION EAST, WE HAVE
ANOTHER SEVERE THUNDERSTORM DAY ON TAP FOR THE SOUTHERN PRAIRIES.
A BROAD AREA OF INSTABILITY IS EXPECTED TO DEVELOP ACROSS SE SK AND
SW MB OF ABOUT 1200 TO 1700 J/KG ML CAPES WITH GENERALLY 30-35 KT 0-6
KM SHEAR. NAM SOUNDINGS AND HODOGRAPHS LOOK TO BE MORE FAVORABLE FOR
SEVERE POTENTIAL THAN THE RDPS SOUNDINGS. THUNDERSTORMS ARE EXPECTED
TO BE SUPERCELL IN STRUCTURE AND ARE EXPECTED TO DEVELOP ALONG THE
SURFACE TROUGH AND COLD FRONT. THE WEAK SURFACE LOW AND ASSOCIATED
FRONTAL WAVE MAY OCCLUDE SOUTH IN TO NORTH DAKOTA WHERE THERE IS
BETTER UPPER SUPPORT AND ENERGY. THE WESTERLY UPPER JET LIES JUST
SOUTH OF THE US BORDER. UPPER SHORT WAVES LIFT NORTHEAST INTO THE
SOUTHERN PRAIRIES THIS AFTERNOON WHICH MAY BE A MORE LIKELY TRIGGER
FOR THUNDERSTORMS DEVELOPMENT NORTH OF THE US BORDER. REGARDLESS,
SOUNDING ANALOGUES SHOW GOOD MATCHES FOR SUPERCELLS WITH POTENTIALLY
LARGE HAIL UP TO 6 CM WITH THE RISK OF A TORNADO. A FLY IN THE
OINTMENT MAY BE THE LINGERING SHOWERS AND CLOUD FROM LAST NIGHT'S
CONVECTION-THIS WILL ACT TO CAP INITIATION FROM OCCURRING TOO EARLY
IN THE DAY, BUT ALSO COULD KEEP TEMPERATURE AND ENERGY LOWER THAN
CURRENTLY FORECASTED.
THUNDERSTORMS ARE EXPECTED TO CONTINUE INTO THE OVERNIGHT HOURS IN
SOUTHERN MANITOBA WITH THE UPPER SHORT WAVE TRACKING INTO THE AREA.
ARCTIC...LOW TO THE EAST OF GRISE FIORD GIVES A CHANCE OF GUSTY
NORTHERLY WINDS TONIGHT. INVERSION IS A BIT HIGHER THAN PAST CASES
BUT A STRONG FLOW AND GOOD DIRECTION COULD BRING WINDS OVER 50 KMH.
END/DYCK/CARLSEN/PALMER
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