521
FOCN45 CWWG 171930
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CST TUESDAY
DECEMBER 17 2024.
ALERTS IN EFFECT...BLIZZARD WARNING FOR CLYDE RIVER. SNOWFALL WARNING
FOR WESTERN ALBERTA. EXTREME COLD WARNING FROM NORTHWESTERN ALBERTA
TO WEST-CENTRAL SASKATCHEWAN.
SYNOPTIC OVERVIEW...THE 12Z UPPER ANALYSIS REVEALED A LOW OVER BAFFIN
ISLAND WITH A TROUGH SOUTHWEST TO THE EASTERN PRAIRIES. A HIGH SAT
OVER THE BEAUFORT SEA CONNECTED TO A RIDGE OVER BC. A LOW AND TROUGH
ARE OVER THE EASTERN PRAIRIES.
THE SURFACE ANALYSIS SHOWS A STRONG HIGH OVER THE WESTERN NWT WITH A
RIDGE EXTENDING BOTH NORTH TO THE BEAUFORT SEA AND SOUTH TO ALBERTA
AND MONTANA. LOW PRESSURE CENTRES SIT OVER THE EASTERN PACIFIC,
CENTRAL QUEBEC, AND OVER DAVIS STRAIT.
DISCUSSION...
AB...A PACIFIC LOW IS SET TO MOVE THROUGH SOUTHERN ALBERTA AND
NORTHERN MONTANA, BRINGING SNOWFALL TO SOUTHERN AND CENTRAL ALBERTA
TONIGHT AND WEDNESDAY. SNOWFALL WILL BEGIN TONIGHT OVER PARTS OF
WESTERN ALBERTA, AND SPREAD EASTWARD THROUGH WEDNESDAY MORNING.
SNOWFALL TOTALS WILL BE HIGHEST FROM HINTON/GRANDE PRAIRIE THROUGH
EDMONTON AND EAST/SOUTHEAST TOWARD LLOYDMINSTER AND MEDICINE HAT.
NWP GUIDANCE OVER THE PAST 24-36 HOURS HAD BEEN SHIFTING THE HIGHEST
SNOWFALL TOTALS SOUTHEASTWARD, WELL INTO SASKATCHEWAN, BUT THAT TREND
HAS REVERSED. AT THIS TIME, AMOUNTS OF ROUGHLY 8-15 CM ARE EXPECTED,
WITH MANY REGIONS APPROACHING WARNING CRITERIA FOR THE WEDNESDAY
DAYTIME PERIOD. A SNOWFALL WARNING HAS BEEN ISSUED FOR HINTON, WITH
THE EXPECTATION THAT IT COULD POSSIBLY BE EXPANDED EASTWARD AS NWP
GUIDANCE CONVERGES ON A STABLE SOLUTION FOR THIS SYSTEM.
AHEAD OF THIS SYSTEM, CLEAR SKIES HAVE ALLOWED TEMPERATURES TO DROP
WELL BELOW THE -30 MARK IN PARTS OF NORTHWESTERN ALBERTA THIS
MORNING. THE EXTREME COLD WARNING IN EFFECT FOR THESE REGIONS HAS
BEEN EXPANDED TO INCLUDE A SWATH OF NORTH-CENTRAL ALBERTA. WIND CHILL
VALUES IN THE AREA COULD REACH -40 AS EARLY AS THIS EVENING BEFORE
INCOMING CLOUD FROM THE PACIFIC SYSTEM OVERNIGHT ALLOWS TEMPERATURES
TO WARN UP SLIGHTLY.
SK/MB...AS THE ARCTIC RIDGE OF HIGH PRESSURE BUILDS SOUTHEASTWARD ON
TONIGHT TEMPERATURES WILL FALL TO THE MINUS THIRTY DEGREE MARK.
COMBINED WITH WINDS OF 15 TO 20 KM/H, EXTREME WIND CHILLS ARE LIKELY
ACROSS PORTIONS OF WEST-CENTRAL SASKATCHEWAN TONIGHT AND WEDNESDAY
MORNING. EXTREME COLD WARNINGS ARE IN EFFECT FOR AREAS NEAR THE
ALBERTA BORDER, AS THE EXTREME COLD WILL HAPPEN EARLIER THERE, AND
WILL LIKELY BE EXPANDED EASTWARD THIS AFTERNOON.
ATTENTION QUICKLY TURNS TO WEDNESDAY, WHEN ANOTHER SYSTEM WILL
DEVELOP IN THE LEE OF THE ALBERTA ROCKIES AND MAKE ITS WAY ACROSS THE
SOUTHERN PRAIRIES, BRINGING WARNING LEVEL SNOWFALL TO PARTS OF
SASKATCHEWAN WEDNESDAY AND WEDNESDAY NIGHT. THIS SYSTEM WILL CONTINUE
INTO SOUTHWESTERN MANITOBA EARLY THURSDAY MORNING BRINGING
POTENTIALLY WARNING LEVEL SNOWFALL TO THE REGION. THERE IS ALSO THE
RISK OF FREEZING RAIN/FREEZING DRIZZLE OVER SOUTHEASTERN AB AND
SOUTHWESTERN SASKATCHEWAN WITH THIS SYSTEM AS WELL AS SNOW/BLOWING
SNOW OVER SOUTHEASTERN SASKATCHEWAN WEDNESDAY. SNOWFALL WARNINGS WILL
BE ISSUED THIS AFTERNOON FOR PARTS OF SOUTHERN SASKATCHEWAN. BLOWING
SNOW AND FREEZING RAIN INTENSITY AND DURATION ARE UNCERTAIN ENOUGH
THAT WE HAVE MENTIONED THEM IN THE PUBLIC FORECASTS, BUT WE WILL STOP
SHORT OF ANY BULLETINS AT THIS TIME.
ARCTIC...A LOW, POSSIBLY POLAR, HAS DEVELOPED OVER CENTRAL DAVIS
STRAIT. GUIDANCE HAS BEEN CONSISTENT RUN-TO-RUN, WITH THE SYSTEM
STILL PROGGED TO RETROGRESS TOWARDS CLYDE RIVER DURING THE DAY TODAY,
SPREADING LIGHT SNOW TO THE COMMUNITY. OF GREATER CONCERN IS THE
TIGHT BACK SIDE GRADIENT. NORTHWESTERLY WIND GUSTS IN EXCESS OF
80 KM/H ARE LIKELY IN THIS GRADIENT WHICH, CONCURRENT WITH THE
FALLING SNOW, WILL LEAD TO BLIZZARD CONDITIONS BEGINNING IMMINENTLY.
WINDS WILL ABATE WEDNESDAY MORNING AS THE LOW DISSIPATES OVER THE
STRAIT BRINGING AN END TO THE BLIZZARD CONDITIONS TO THE COMMUNITY.
NWT...CLEAR SKIES UNDER A RIDGE OF HIGH PRESSURE HAVE BROUGHT SOME
EXTREMELY COLD WIND CHILLS TO PARTS OF THE TERRITORY OVERNIGHT.
A WARNING IS IN EFFECT FOR FORT LIARD AND NORMAN WELLS. TEMPERATURES
MAY MODERATE AT FORT LIARD AS SOME CLOUD MOVES IN OVERNIGHT, BUT
EXTREMELY COLD WIND CHILLS ARE LIKELY IN NORMAN WELLS, FORT GOOD
HOPE AND FORT MCPHERSON TONIGHT AND WEDNESDAY MORNING.
THE METEOROLOGICAL SERVICE OF CANADA IS INVESTIGATING THE
DISCONTINUATION OF THIS SIGNIFICANT WEATHER DISCUSSION. IF YOU USE
THIS BULLETIN AND HAVE ANY COMMENTS OR CONCERNS, PLEASE CONTACT US AT
FOCN45@EC.GC.CA WITH THE SUBJECT: "SIGNIFICANT WEATHER DISCUSSION
FEEDBACK". INCLUDE YOUR ORGANIZATION AND HOW YOU USE THIS PRODUCT.
END/CARLSEN/STAUNTON
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