FOCN45 CWWG 221957
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CST FRIDAY
NOVEMBER 22 2024.

ALERTS IN EFFECT...SNOWFALL WARNINGS FOR MUCH OF CENTRAL AND SOUTHERN
ALBERTA AND SOUTHERN SASKATCHEWAN. BLIZZARD WARNINGS FOR RANKIN INLET
AND ARVIAT. FOG ADVISORY FOR IQALUIT.

SYNOPTIC OVERVIEW...UPPER TROUGH FROM THE HIGH ARCTIC ARCING
SOUTHWARDS ACROSS THE CENTRAL NWT. UPPER LOW SOUTHWEST OF VANCOUVER
ISLAND. UPPER RIDGE INTO SOUTHWESTERN ALBERTA. UPPER LOW OVER
NORTHERN MANITOBA. AN UPPER LOW IS OVER THE GREAT LAKES WITH A
DEFORMATION ZONE BACK NORTHWESTWARD ACROSS NORTHWESTERN ONTARIO.
A RIDGE OF HIGH PRESSURE IS OVER NORTHERN QUEBEC AND SOUTHEASTERN
BAFFIN ISLAND.

AT THE SURFACE, 984 MB LOW SITS SOUTHWEST OF VANCOUVER ISLAND. A 1045
MB HIGH PRESSURE CENTRE IS OVER YUKON WITH A RIDGE SOUTHEASTWARD
THROUGH ALBERTA AND SOUTHERN SASKATCHEWAN. A 1009 MB LOW IS OVER
WESTERN HUDSON BAY. A 1026 MB HIGH LIES OVER NORTHERN LABRADOR.
INTENSE LOW NEAR THE NORTH POLE.

DISCUSSION...

ALBERTA...SNOW OVER SOUTHERN ALBERTA WILL SPREAD NORTHWARDS TONIGHT.
GENERAL TOTALS OF 5-10 CM ARE EXPECTED BY SATURDAY MORNING WITH THIS
INITIAL IMPULSE. HOWEVER, THE FLUFFY FACTOR IS EXPECTED TO CREATE THE
HIGHEST ACCUMULATIONS IN THE SOUTHERN PORTION OF PEACE RIVER COUNTRY
WITH AMOUNTS CLOSER TO 15 CM LIKELY. AMOUNTS WILL BE RELATIVELY
VARIABLE TONIGHT WITH SOME CENTRAL AND SOUTHERN AREAS ONLY GETTING A
FEW CM.

ON SATURDAY MORNING, SNOWFALL WILL INTENSIFY AS A SURFACE LOW
DEVELOPS OVER MONTANA WITH A TROUGH TO THE NORTH (ACROSS EASTERN
ALBERTA). WITH COLD AIR IN PLACE OVER MUCH OF THE PROVINCE, AND AMPLE
PACIFIC MOISTURE MOVING IN, SNOW TO LIQUID RATIOS WILL BE NEAR 20 TO
1 THROUGH THIS EVENT. SNOWFALL AMOUNTS AS HIGH AS 15-25 CM ARE IN THE
FORECAST SATURDAY FOR EAST-CENTRAL ALBERTA, WHERE WEEKEND TOTALS OF
20-35 CM ARE EXPECTED. LESSER BUT STILL SIGNIFICANT AMOUNTS ARE
EXPECTED THROUGHOUT MUCH OF THE PROVINCE, AND SNOWFALL WARNINGS HAVE
BEEN ISSUED FROM GRANDE PRAIRIE TO THE CYPRESS HILLS. WARNINGS MAY
NEED TO BE EXPANDED NORTHWARDS AS THE SYSTEM DEVELOPS.

MANITOBA/SASKATCHEWAN...SNOW CONTINUES OVER NORTHERN REGIONS UNDER
THE UPPER LOW BUT WILL GRADUALLY TAPER OFF THROUGH THE DAY WITH A FEW
ADDITIONAL CM OF ACCUMULATION. STILL PLENTY OF ST/SC OVER MANITOBA
WITH SCATTERED FLURRIES, FOG AND FZDZ BUT THIS WILL GRADUALLY
DIMINISH THROUGH THE DAY.

A FAST MOVING IMPULSE THAT TRACKED ACROSS SOUTHERN SASKATCHEWAN
OVERNIGHT IS TRACKING ACROSS SOUTHERN MANITOBA THIS MORNING.
SOME ELEVATED INSTABILITY HAS REALLY HELPED FILL IN PRECIPITION AS IT
PUSHES EASTWARD, AND MORE INTENSE FLURRIES HAVE SEEN VISIBILITIES
DROP TO 3/8SM BRIEFLY. EVEN SO, ONLY A COUPLE CM OF LOCALIZED
ACCUMULATIONS ARE EXPECTED WITH THIS IMPULSE GIVEN THE SPEED.

ATTENTION QUICKLY TURNS TO A DEVELOPING LOW/INVERTED TROUGH OVER
SOUTHERN ALBERTA INTO NORTHERN MONTANA THAT WILL GIVE ANOTHER ROUND
OF HEAVY ACCUMULATING SNOW TO SOUTHERN SASKATCHEWAN AND MANITOBA INTO
THE WEEKEND. ALTHOUGH SNOW CONTINUES OVER SOUTHWESTERN SASKATCHEWAN
TODAY, THE HEAVIEST ACCUMULATIONS WON'T ARRIVE UNTIL SATURDAY.
CONFIDENCE HAS GENERALLY INCREASED FOR SOUTHEWESTERN REGIONS, ENOUGH
SO TO NAIL DOWN AN AXIS OF 10 TO 20 CM OF SNOW THAT WILL FALL ON
SATURDAY. SNOWFALL WARNINGS ARE ALREADY OUT FOR THOSE AREAS.

ELSEWHERE, LATEST MODEL RUNS CONTINUE TO INDICATE A MINOR NORTHWARD
SHIFT AS WELL AS SLIGHT CHANGES TO QPF NUMBERS, BUT NOT SO MUCH AS TO
MEANINGFULLY ALTER THE UPCOMING WARNING AREAS. IN FAVOUR OF HEAVY
SNOW IN ALL AREAS - EVEN WELL SUB 10 MM QPE EQUIVALENT - ARE STRONG
SYNOPTIC LIFT THROUGH A VERY LARGE DGZ, SATURATED ABOVE TO THE
TROPOPAUSE, AND THEN ROUGHLY -10C ISOTHERMAL FOR TO THE GROUND.
WITH RELATIVELY LIGHT WINDS AND THE CLASSIC SLOWER MOVING INVERTED
TROUGH ARRANGEMENT, SNOW WILL STAY FLUFFY AND SNOWFALL RATES WILL BE
HIGH. ALL OF SOUTHERN SK, EXCEPTING AREAS WITHIN ABOUT 100 KM OF THE
INTERNATIONAL BORDER EAST OF THE CYPRESS HILLS, WILL BE UNDER
SNOWFALL WARNINGS BY LATER THIS AFTERNOON. SHIFTING AND INTENSITY
CHANGES ARE MORE SIZABLE ON THE MANITOBA SIDE, BUT PORTIONS OF THE
PARKLANDS AND JUST NORTH WILL VERY LIKELY NEED WARNINGS BY SATURDAY
FOR SUNDAY AS WELL.

NWT...A COLD FRONT SWEEPING SOUTH THROUGH THE NWT WILL GIVE 2-4 CM OF
SNOW TO SOUTHWEST REGIONS OF THE TERRITORY. OTHERWISE STRATUS IS
MODERATING TEMPERATURES AND MAKING FORECASTS DIFFICULT, PARTICULARLY
OVER THE DELTA.

NU...MOST OF THE FOG AND FZDZ HAS TRANSITIONED OVER TO MODERATE SNOW
ACROSS THE KIVALLIQ. THE BAND OF SNOW EXTENDS NORTHEASTWARD ACROSS
THE MELVILLE PENINSULA AND INTO NORTHERN BAFFIN ISLAND WHERE
GENERALLY 2 TO 4 CM WILL FALL PER 12 HOURS OVER THE NEXT DAY OR SO.
AS THE LOW OVER WESTERN HUDSON BAY FINALLY MOVES OFF OVER HUDSON BAY,
A MODERATE TO STRONG PRESSURE GRADIENT WILL DEVELOP OVER THE KIVALLIQ
ON TONIGHT INTO SATURDAY GIVING STRONG WINDS UP TO 60 GUSTING TO
80 KM/H ALONG WITH REDUCED VISIBILITES IN BLOWING SNOW. WITH FORECAST
WINDS SLIGHTLY INCREASED AGAIN THIS MORNING, LIGHT SNOW PERSISTING,
THE RAPID COOLING RATE AND SATURATED BOUNDARY LAYER TONIGHT, SIGNS
INCREASINGLY POINT TO FULL BLIZZARD AND THE WARNINGS ARE OUT FOR
ARVIAT AND WHALE COVE.

END/KNIGHT/ROMBOUGH