055
FOCN45 CWWG 281200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT SATURDAY JUNE
28 2025.
ALERTS IN EFFECT...SPECIAL AIR QUALITY STATEMENTS FOR PARTS OF
SOUTHWESTERN NORTHWEST TERRITORIES, NORTHWEST ALBERTA AND CENTRAL
SASKATCHEWAN.
SYNOPTIC OVERVIEW...00Z UPPER AIR AND WATER VAPOUR ANALYSIS REVEALS
PATTERN BECOMING MORE ZONAL WITH WEAK UPPER FEATURES. UPPER LOW
REMAINS IN GULF OF ALASKA WITH A BROAD NEGATIVELY TILTED TROUGH
THROUGH THE CENTRAL PRAIRIES. EMBEDDED SHORT WAVE OF NOTE CURRENTLY
IN SOUTHERN BC TRACKING EAST.
AT THE SURFACE...1002 MB LOW NEAR CHURCHILL WITH COLD FRONT TO THE
WEST THROUGH THE NORTHERN PRAIRIES AND NORTHWEST INTO THE YUKON AND
SURFACE TROUGH TO THE SOUTH. WARM FRONT SOUTHEAST INTO HUDSON BAY.
SECONDARY FRONTAL WAVE FROM 1003 MB LOW PRESSURE SYSTEM IN NORTH
DAKOTA.
DISCUSSION...
AB...SHOWERS CONTINUE THIS MORNING THROUGH CENTRAL ALBERTA.
THUNDERSTORMS WILL DEVELOP LATE THIS MORNING OR EARLY THIS AFTERNOON
THROUGH MUCH OF THE PROVINCE, SIMILAR TO YESTERDAY. THE GREATEST
INSTABILITY WILL BE OVER NORTHERN ALBERTA, WHERE GREATER THAN 1000 J/
KG OF MIXED LAYER CAPE IS EXPECTED. EFFECTIVE SHEAR IS FAIRLY WEAK
THROUGH THIS REGION. WHILE MOST THUNDERSTORMS SHOULD REMAIN
SUB-SEVERE, SOME MARGINALLY SEVERE PULSE STORMS ARE POSSIBLE.
IN SOUTHERN ALBERTA, THERE IS LESS INSTABILITY EXPECTED, BUT WITH A
LITTLE MORE SHEAR. THUNDERSTORMS WILL DEVELOP ALONG THE FOOTHILLS AND
PUSH EASTWARD. WEAK ISOLATED SUPERCELLS ARE POSSIBLE BUT AGAIN,
THUNDERSTORMS SHOULD GENERALLY REMAIN SUB-SEVERE.
SK...GENERAL NORTHWEST, UNSTABLE SURFACE FLOW IN PLACE OVER THE
PROVINCE FOR TODAY. SUB-SEVERE THUNDERSTORM DEVELOPMENT WILL FOCUS
AROUND THE UPPER SHORT WAVES THAT TRACK INTO THE SOUTHERN HALF OF THE
PROVINCE IN A WEST TO EAST LINE ALONG THE UPPER TROUGH FROM ABOUT
MEADOW LAKE TO YORKTON. FUNNEL CLOUDS ARE POSSIBLE FROM THUNDERSTORMS
THAT INITIATE UNDER ANY UPPER SHORT WAVES. THUNDERSTORMS WILL BE
SUPPORTED BY THESE UPPER FEATURES INTO THE OVERNIGHT HOURS.
MB...THE SURFACE TROUGH LINGERS OVER THE PROVINCE TODAY WITH A
SIMILAR SET UP AS YESTERDAY. ML CAPES IN SOUTHEASTERN PORTION OF THE
PROVINCE MAY REACH 1700-2000 J/KG WITH 40 KT OF 0-6 KM SHEAR.
THERE IS PRETTY GOOD AGREEMENT BETWEEN CAMS THAT THE SURFACE TROUGH
WILL SERVE AS A FOCUS FOR INITIATION EARLY THIS AFTERNOON NEAR THE
RED RIVER VALLEY. SUPERCELLS ARE EXPECTED TO QUICKLY GROW UPSCALE
INTO A LINE OF THUNDERSTORMS AND WILL TRACK INTO ONTARIO LATER THIS
AFTERNOON. ALL HAZADS ARE POSSIBLE. DCAPES ARE HIGHER THAN THE LAST
FEW DAYS SO WIND IS A MAIN HAZARD. LARGE HAIL OF 3 TO 5 CM IS LIKELY
DUE TO THE HIGH ENERGY. HIGH PWATS OF 40 MM, ABOUT 150% OF NORMAL
SUPPORTS HEAVY RAINFALL WITH ANY STORMS THAT ARE SLOW MOVING OR
TRAINING WHICH IS A POSSIBILITY WITH THE 700 MB STEERING FLOW ALIGNED
WITH THE SURFACE TROUGH. THERE IS A NON 0 CHANCE OF A TORNADO; LOW
LEVEL EHI IS MORE FAVORABLE SOUTH OF THE BORDER WITH HODOGRAPHS NORTH
OF THE BORDER MORE UNIDIRECTIONAL. LCLS ARE ALSO QUITE HIGH.
FOG HAS DEVELOPED IN THE ONSHORE FLOW ALONG THE HUDSON BAY COAST.
NORTHERLY FLOW IS EXPECTED TO PERSIST AT CHURCHILL FOR THE NEXT 24-36
HOURS WITH VISIBILITIES NEAR ZERO AT TIMES IN FOG.
WESTERN ARCTIC...SLOW MOVING THUNDERSTORMS ARE EXPECTED OVER THE
SOUTHERN HALF OF THE MACKENZIE VALLEY TODAY, WHICH COULD BRING 20-30
MM OF PRECIPITATION TO AFFECTED REGIONS.
EASTERN ARCTIC...NIL SIG WX.
END/DYCK/GRIFFITH
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