FOCN45 CWWG 211900
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CDT WEDNESDAY MAY
21 2025.

ALERTS IN EFFECT...SPECIAL AIR QUALITY STATEMENT FOR PARTS OF
NORTHERN SASKATCHEWAN.

SYNOPTIC OVERVIEW...ALOFT TODAY, AN UPPER LOW SITS OVER NORTHERN
BRITISH COLUMBIA WITH A LONG-WAVE TROUGH SOUTHEAST INTO MONTANA AND
THE AMERICAN PLAINS. EAST OF THIS, AN UPPER HIGH SITS OVER NORTHERN
MANITOBA WITH RIDGING NORTH-NORTHWEST INTO THE CENTRAL ARCTIC. ALOFT,
AN UPPER LOW IS CROSSING SOUTHERN BAFFIN ISLAND WITHIN A LONG WAVE
TROUGH THAT DROPS SOUTH TO A SECONDARY UPPER LOW OVER JAMES BAY.
A WEAK DOWNSTREAM RIDGE EXTENDS FROM THE EASTERN UNITED STATES NORTH
OVER QUEBEC AND LABRADOR INTO THE LABRADOR SEA.

AT THE SURFACE, AN OCCLUDING 1028 MB LOW SITS OVER EASTERN FOXE BASIN
WITH ITS FRONTAL WAVE TO THE WEST WITH A WARM FRONT SOUTH TO THE
MANITOBA/ONTARIO COAST AND A COLD FRONT THAT ARCS OVER VICTORIA
ISLAND BEFORE DIGGING SOUTH TO THE ALASKA COAST. ANOTHER FRONTAL
BOUNDARY DROPS FROM NORTHERN ALASKA SOUTHEAST THROUGH ALBERTA AND
SOUTHWEST SASKATCHEWAN INTO MONTANA. EAST OF THIS, A 1036 MB HIGH
SITS OVER HUDSON BAY WITH RIDGING SOUTHWEST INTO THE EASTERN PRAIRIES
AS WELL AS EAST OVER THE UNGAVA PENINSULA.

DISCUSSION...

AB/NT...ORGANIZED SHOWERS SW OF EDMONTON WILL BRING ANOTHER 10-20 MM
TO AREAS ALONG THE SURFACE TROUGH TODAY. THIS AFTERNOON,
THUNDERSTORMS WILL DEVELOP OVER SOUTHERN AB AND NORTHWARD ALONG THE
AFOREMENTIONED SURFACE TROUGH UP THROUGH NORTHERN AB. THESE SHOULD BE
GENERALLY NON-SEVERE WITH RELATIVELY WEAK INSTABILITY AND SHEAR
THROUGHOUT THE RISK AREA. HOWEVER, THERE IS A CHANCE OF FUNNEL CLOUDS
IN EAST-CENTRAL ALBERTA WHERE THE CONVERGENCE IS SHARPEST AND THERE
IS A CHANCE OF SOME CLEARING BY THIS AFTERNOON. THE THUNDERSTORM RISK
EXTENDS ALL THE WAY UP INTO THE SOUTHWESTERN NWT, WHERE SLIGHTLY
BETTER SHEAR (THOUGH STILL ONLY ABOUT 20KT AT MOST) MAY ALLOW FOR
SOME MORE ORGANIZED STORMS. A SIMILAR THUNDERSTORM STORY IS FORECAST
FOR THURSDAY.

TONIGHT, CLEARING IN THE WAKE OF THE AFTERNOON CONVECTION WILL SET UP
A COLD NIGHT FOR MUCH OF SOUTHERN AND WESTERN ALBERTA.
FROST ADVISORIES ARE LIKELY ALONG PARTS OF THE FOOTHILLS, WITH MUCH
OF SOUTHERN/CENTRAL ALBERTA AS WELL AS PARTS OF THE NORTHWEST
FORECAST TO APPROACH THE FREEZING MARK AS WELL. ADDITIONALLY,
MOISTURE FROM THE AFTERNOON CONVECTION MAY ALLOW FOR SOME FOG PATCHES
TO DEVELOP OVERNIGHT IN SOUTHERN ALBERTA.

FURTHER NORTH, STRATUS AND FOG ARE AFFECTING THE MACKENZIE DELTA AND
NWT COAST. THE FOG SHOULD LIFT LATER TODAY. SOME FREEZING DRIZZLE HAS
ALSO BEEN REPORTED AT INUVIK AS WELL.

SK/MB...CONVECTIVE FOCUS IS OVER FAR SOUTHWEST SASKATCHEWAN TODAY
WHERE DAYTIME HIGHS IN THE LOW TEENS AND DEW POINTS IN THE 2 TO 5 C
RANGE PRODUCE SBCAPE VALUES IN THE 400 TO 800 J/KG RANGE. BULK SHEAR
VALUES WILL SIT IN THE 20 TO 25 KNOT RANGE WHICH ISN'T THRILLING, BUT
A SHARP SURFACE TROUGH WILL PROVIDE FOCI FOR CONVECTION; WITH
INSOLATION AND NOTABLE VORTICITY GENERATION ALONG THE TROUGH,
LANDSPOUT/NON-SUPERCELL TORNADOES MAY BE POSSIBLE THIS AFTERNOON WITH
THE CONVECTION THAT DEVELOPS. THE SHOWERS AND THUNDERSTORMS WILL
TAPER OFF THIS EVENING.

OTHERWISE, BANDS OF SHOWERS WILL CONTINUE TO STREAM NORTHWEST ACROSS
SOUTHWEST MANITOBA INTO SOUTHERN SASKATCHEWAN TODAY. AS THE PARENT
LOW IN THE UNITED STATES TRACKS TO THE EAST, THE MOISTURE STREAM WILL
CUT OFF AND THE SHOWERS OVER THE PRAIRIES WILL TAPER OFF.

ONGOING FIRE ACTIVITY NORTHEAST OF PRINCE ALBERT IS BRINGING SMOKE
AND POOR AIR QUALITY TO PARTS OF NORTHERN SASKATCHEWAN. GUSTY WINDS
IN THE AFTERNOON HOURS HAVE BEEN ENHANCING SMOKE PRODUCTION FROM
THESE FIRES. THIS SMOKE THEN BECOMES TRAPPED NEAR THE SURFACE UNDER A
NOCTURNAL INVERSION, LEADING TO MORE WIDESPREAD POOR AIR QUALITY IN
THE OVERNIGHT HOURS. THERE IS SOME SHOWER ACTIVITY IN THE AREA TODAY
BUT IT REMAINS TO BE SEEN WHETHER THIS WILL BE ENOUGH TO TAMP DOWN
FIRE ACTIVITY GOING FORWARD.

FIRE ACTIVITY IN THE EASTERN PRAIRIES HAS BEEN DAMPENED BY THE RECENT
RAIN AND COOLER WEATHER, BUT THE SITUATION WILL HAVE TO BE MONITORED
THROUGH THE REMAINDER OF THE WEEK AS TEMPERATURES WARM BACK UP
TOWARDS SEASONAL VALUES WHILE RELATIVE HUMIDITIES REMAIN LOW DUE TO
THE DRY OUTFLOW FROM THE SLOW MOVING RIDGE OVER THE EASTERN PRAIRIES.

KITIKMEOT...STRATUS WILL CONTINUE TO IMPACT COMMUNITIES IN THE
KITIKMEOT TODAY. IT IS FORECAST TO CLEAR THIS AFTERNOON AS THE
ASSOCIATED LOW BUT CONFIDENCE IS RELATIVELY LOW ON THAT. THIS CLOUD
HAS A HISTORY OF PRODUCING FREEZING DRIZZLE SO THE CLEARING TREND
WILL NEED TO BE MONITORED CLOSELY.

QIKIQTAALUK...THE LOW PRESSURE SYSTEM TRACKING OVER SOUTHERN BAFFIN
ISLAND WILL SPREAD LIGHT SNOW ACROSS THE REGION. GENERAL
ACCUMULATIONS IN AFFECTED COMMUNITIES WILL LIKELY BE 2 CM OR LESS,
BUT AREAS WHERE ONSHORE FLOW RESULTS IN OROGRAPHIC LIFT COULD SEE AS
MUCH AS 4 TO 8 CM. THE SNOW WILL TAPER OFF EARLY THURSDAY.

THE NEXT CHANCE OF SNOW FOR BAFFIN ISLAND WILL MOVE INTO NORTHERN
PORTIONS OF THE ISLAND ON FRIDAY NIGHT AS A RENEWED PUSH OF WARM AIR
MOVES INTO THE REGION.

A WEAK IMPULSE WILL SKIRT THROUGH THE QUEEN ELIZABETH ISLANDS TODAY
AND TONIGHT. MODEL GUIDANCE HAS BEEN INCONSISTENT ON ITS TRACK, BUT
THE GENERAL IDEA IS THAT THE WORST OF THE SNOW WITH THIS SYSTEM WILL
PASS BETWEEN RESOLUTE AND GRISE FIORD. NEVERTHELESS THERE IS A CHANCE
OF SOME ACCUMULATING SNOW FOR RESOLUTE TONIGHT. SOME FREEZING PRECIP
IS ALSO POSSIBLE THOUGH IT LOOKS TO LARGELY AVOID THE COMMUNITIES.

END/VROLIJK/VAN LOCHEM