397
FOCN45 CWWG 201200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT SUNDAY APRIL
20 2025.
ALERTS IN EFFECT...BLIZZARD WARNING FOR RESOLUTE. HEAVY SNOWFALL FOR
PORTIONS OF WESTERN ALBERTA.
ALOFT THIS MORNING, AN UPPER LOW SITS OVER WESTERN
VICTORIA ISLAND IN THE ARCTIC WITH A LONG-WAVE TROUGH SOUTH THROUGH
WESTERN CANADA INTO THE PACIFIC NORTHWEST. EAST OF THIS, AN UPPER LOW
SITS OVER SOUTH DAKOTA WITH A TROUGH SOUTH INTO THE TEXAS PANHANDLE,
THEN THE FLOW REBOUNDS INTO AN UPPER RIDGE THAT EXTENDS FROM THE
AMERICAN MIDWEST INTO NW ONTARIO AND THROUGH HUDSON BAY. IN THE EAST,
AN UPPER LOW SITS NEAR THE QUEBEC/LABRADOR BORDER WITH A TROUGH SOUTH
INTO THE AMERICAN NORTHEAST.
AT THE SURFACE, A 1002 MB LOW SITS NEAR RANKIN INLET (CYRT) WITH A
WARM FRONT SOUTHEAST INTO HUDSON BAY AND COLD FRONT THAT SWEEPS
SOUTHWEST INTO THE NORTHERN PRAIRIES THEN LIFTS NORTHWEST THROUGH
YUKON INTO NORTHERN ALASKA. NORTH OF THIS, A 999 MB LOW SITS OVER
NORTHERN VICTORIA ISLAND WITH A WARM FRONT NORTH AND A COLD FRONT
THAT ARCS SOUTH INTO THE KIVALLIQ THEN CURLS BACK NORTHWEST TO THE
ARCTIC COASTLINE. FURTHER SOUTH, A 1012 MB LOW SITS NEAR LAKE
WINNIPEGOSIS WITH A WARM FRONT THAT ARCS SOUTH AND A COLD FRONT THAT
SWEEPS SOUTHWEST INTO NORTHERN MONTANA BEFORE LIFTING INTO SOUTHERN
BRITISH COLUMBIA. LASTLY, A BROAD AREA OF HIGH PRESSURE SITS OVER
THE ARCTIC OCEAN WITH RIDGING DIGGING SOUTHEAST THROUGH WESTERN
NORTHWEST TERRITORIES TOWARDS NORTHERN ALBERTA, AND IN THE EAST A
1032 MB HIGH NEAR THE GREAT LAKES HAS A SURFACE RIDGE NORTH THROUGH
EASTERN HUDSON BAY TO SOUTHERN BAFFIN ISLAND.
DISCUSSION...
WESTERN PRAIRIES...CONVECTION IN THE FORM OF NON-SEVERE TS IS LIKELY
IN THE CARDS AGAIN TODAY AS A BAROCLINIC ZONE AND REMNANT TROUGH SITS
OVER NORTHERN ALBERTA AND AN UPPER TROUGH APPROACHES FROM THE WEST
OVER SOUTHERN ALBERTA. A DEVELOPING LOW AT THE BASE OF THIS SECOND
FEATURE IS ABOUT TO BRING THE NEXT BOUT OF HIW TO AB, PRIMARILY IN
THE FORM OF ACCUMULATING SNOW, BEGINNING TONIGHT. AT THIS TIME,
SNOWFALL AMOUNTS REMAIN HIGHLY UNCERTAIN. NWP GUIDANCE HAS BEEN
CONSISTENT WITH SHOWING WARNING LEVEL SNOWFALL POTENTIAL SOMEWHERE
ACROSS THE FOOTHILLS, HOWEVER THE EXACT LOCATIONS ARE NOT
WELL-DEFINED. BEST CHANCE FOR WARNING LEVEL SNOWFALL APPEARS TO BE
NORTHWEST OF CALGARY: TOWARD NORDEGG, SUNDRE, AND ROCKY MOUNTAIN
HOUSE. AS A RESULT HAVE ISSUED A SNOWFALL WARNING FOR THE EVENT
STARTING THIS EVENING. THE BULK OF THE SNOW IS LIKELY TO FALL ON
MONDAY. TO THE SOUTH OF THIS LOW, MORE CONVECTION IS LIKELY ON DAY 2
OVER EXTREME SOUTHEASTERN ALBERTA.
EASTERN PRAIRIES...THE NEXT ORGANIZED PRECIPITATION EVENT FOR THE
PRAIRIES WILL BEGIN ON MONDAY, DRIVEN BY A LOW PRESSURE COMPLEX THAT
WILL BE DRIVEN BY AN UPPER LOW THAT DROPS OUT OF CENTRAL BRITISH
COLUMBIA INTO SOUTHERN ALBERTA THEN SHIFTS EAST ACROSS THE SOUTHERN
PRAIRIES. THIS SYSTEM WILL SUPPORT A WEAK SURFACE LOW IN SOUTHERN
ALBERTA THAT WILL BE ABSORBED BY A STRONGER LOW CENTRE THAT THIS
SYSTEM DRAWS NORTH OUT OF THE UNITED STATES INTO SOUTHERN MANITOBA ON
MONDAY NIGHT. AS THIS SYSTEM DEVELOPS, IT WILL SUPPORT THE
DEVELOPMENT OF RAIN SHOWERS WITH A CHANCE OF THUNDERSTORMS OVER
SOUTHWEST SASKATCHEWAN; A GLANCING CHANCE ON SUNDAY AND A MORE
WIDESPREAD RISK ON MONDAY.
ON SUNDAY, SBCAPE VALUES OF 300 TO 500 J/KG WILL DEVELOP ON SUNDAY
AFTERNOON AND MONDAY AFTERNOON, EACH TIME COUPLED WITH 25 TO 35 KNOTS
OF BULK SHEAR. THIS CAPE COUPLED WITH A LOW BARRIER TO CONVECTIVE
INITIATION WILL SUPPORT SHOWERS AND ISOLATED THUNDERSTORMS.
SHEAR PROFILES WILL PREFER A FEW ISOLATED STORMS ARE POSSIBLE ON
SUNDAY WHILE MULTI-CELL CLUSTERS WILL BE MORE LIKELY ON MONDAY.
AS THIS SYSTEM TRACKS EAST, THE PRECIPITATION WILL BLOSSOM INTO A
BROADER AREA THAT PUSHES INTO SOUTHEAST SASKATCHEWAN ON MONDAY
EVENING, STRENGTHENING AS THE LOW CENTRE IN THE UNITED STATES LIFTS
INTO NORTH DAKOTA. COLD AIR INJECTION WILL GRADUALLY TRANSITION THE
RAIN SHOWERS TO SNOW ACROSS THE REGION, AND THE INSTABILITY
ASSOCIATED WITH THIS SYSTEM COULD RESULT IN AREAS OF HEAVIER SNOW
SHOWERS ON MONDAY NIGHT INTO TUESDAY MORNING.
THIS SYSTEM WILL BRING A WINTERY MIX OF PRECIPITATION TO THE
SOUTHEASTERN PRAIRIES ON TUESDAY, WITH MAINLY SNOW FALLING IN
SASKATCHEWAN TRANSITIONING TO RAIN AND SNOW IN SOUTHWESTERN MANITOBA.
SNOWFALL AMOUNTS WILL VARY IN SE SASKATCHEWAN, RANGING FROM LIGHT
AMOUNTS NEAR THE INTERNATIONAL BORDER TO AS MUCH AS 10 TO 20 CM
POSSIBLE NORTH OF YORKTON. AMOUNTS WILL DECREASE HEADING INTO
MANITOBA, SAVE FOR AREAS OF HIGHER TERRAIN SUCH AS THE DUCK MOUNTAINS
WHERE 10 TO 25 CM OF SNOW MAY BE POSSIBLE WITH THIS SYSTEM.
ANY PRECIPITATION THAT PUSHES FURTHER EAST TOWARDS THE RED RIVER
VALLEY LATER ON TUESDAY SHOULD FALL AS RAIN WITH RAINFALL TOTALS OF 5
TO 15 MM POSSIBLE.
KITIKMEOT/HIGH ARCTIC...NWT/NU LOW CONTINUES TO BRING UNSETTLED
WEATHER ACROSS THE REGION, GENERALLY IN THE FORM OF GUSTY WINDS AND
PROTRACTED SNOWFALL. AMOUNTS SHOULD GENERALLY BE LIGHT. BLIZZARD
CONDITIONS IN RESOLUTE BAY WILL CONTINUE TODAY AND TONIGHT BEFORE THE
GRADIENT WEAKENS ENOUGH TO IMPROVE VISIBILITIES.
KIVALLIQ...THE KIVALLIQ LOW WILL CONTINUE TO SPREAD SNOW EAST TOWARDS
BAFFIN ISLAND OVER THE NEXT 48 HOURS AS AN EXTENDED NORTH-SOUTH BAND
OF SNOW SHIFTS EAST WITH THE SYSTEM. THIS SYSTEM WILL BRING 2 TO 5 CM
TO THE SOUTH OF ITS LOW TRACK, WHILE A BROAD 5 TO 10 CM WILL FALL TO
ITS NORTH WHERE THE GREATER LIFT SUPPORTS MORE INTENSE RATES THAT
WRAP BACK TO THE VICTORIA ISLAND LOW. THIS SYSTEM WILL LIKELY BRING
OVER 10 CM OF SNOW IN 24 HOURS TO NAUJAAT (CYUT) BEGINNING SUNDAY
NIGHT. AS THE SYSTEM PUSHES EAST, THE ORGANIZED BANDING OF 10+ CM
ACCUMULATIONS BEGINS TO FRACTURE, AND A BROAD 5 TO 10 CM IS MORE
LIKELY FOR THE MELVILLE PENINSULA.
STRONG NORTHWEST WINDS WILL BUILD ACROSS THE KIVALLIQ TODAY,
INCREASING UP TO 50 GUSTING 70 AND SPREADING FROM THE INTERIOR NEAR
BAKER LAKE (CYBK) TOWARDS THE COAST. THESE WINDS WILL SUPPORT BLOWING
SNOW IN BAKER LAKE THIS MORNING BUT CONDITIONS WILL LIKELY IMPROVE
FOR THE AFTERNOON, BEFORE THE WINDS EASE THIS EVENING. AS A RESULT,
THE BLIZZARD WARNING HAS BEEN ENDED AS WE NO LONGER EXPECT THE
INTENSITY/DURATION CRITERIA TO BE ACHIEVED. FOR AREAS ALONG THE
KIVALLIQ COAST, BLOWING SNOW IS POSSIBLE BUT WILL LIKELY BE NOT AS
INTENSE AS INLAND NOR LASTING FOR AS LONG.
BAFFIN...NIL SIG WX.
NWT...A STRONG NORTHWESTERLY GRADIENT OVER PORTIONS OF THE ISR IS
GENERATING POOR VISIBILITIES IN BLOWING SNOW OVER SACHS HARBOUR AND
PAULATUK. SNOWFALL AMOUNTS OF 2-5 CM CAN BE EXPECTED AS WRAPAROUND
PRECIPITATION FROM THE STALLED NWT/NU LOW SPREADS WESTWARD.
END/VROLIJK/VAN LOCHEM
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