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FOCN45 CWWG 231900
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CDT MONDAY APRIL
23 2018.
ALERTS IN EFFECT...NONE.
SYNOPTIC OVERVIEW...ALOFT, THE PATTERN IS DEFINED BY A PERSISTENT
VORTEX OVER THE CANADIAN ARCTIC ARCHIPELAGO WITH A BROAD LONG-WAVE
TROUGH EXTENDING SOUTHWARDS INTO HUDSON BAY AND THEN SOUTHWESTWARDS
ACROSS MB/SK INTO MT/WY. WITHIN THIS LONG-WAVE TROUGH ARE TWO MAJOR
UPPER LOWS: THE FIRST IS OVER SOUTHWESTERN HUDSON BAY AND THE SECOND
IS OVER SOUTHERN MONTANA. WEST OF THE LONG-WAVE TROUGH A RATHER
SHARP UPPER-LEVEL RIDGE IS IN PLACE, EXTENDING FROM WASHINGTON STATE
NORTHWARDS ACROSS B.C./WESTERN AB INTO THE MACKENZIE REGION OF THE
NWT.
AT THE SURFACE, HUDSON BAY UPPER LOW HAS A 1003 MB LOW OVER THE
SOUTHERN HUDSON BAY. A STRONG BAROCLINIC ZONE RUNS THROUGH
NORTHERN QUEBEC INTO THIS LOW AND EXTENDS WESTWARD THROUGH THE
NORTHERN PRAIRIES AND CENTRAL YUKON. A BROAD AREA OF HIGH PRESSURE
COVERS MUCH OF THE WESTERN PRAIRIES WITH A 1033 MB HIGH
ON THE CANADIAN GREAT DIVIDE. FURTHER NORTH, A 1029 MB HIGH
SITS OVER WESTERN NUNAVUT WITH SURFACE RIDGE EXTENDING EASTWARDS TO
SOUTHAMPTON ISLAND. A 998 MB LOW SITS OVER BAFFIN BAY.
DISCUSSION...
WESTERN PRAIRIES...A RIDGE OF HIGH PRESSURE BUILDS IN FROM BC AT
BOTH THE SURFACE AND ALOFT. TEMPERATURES WILL GRADUALLY WARM TO NEAR
NORMALS TODAY IN ALBERTA AND THEN WE HIT THE 20 DEGREE MARK FOR
TUESDAY!!! IT'S FINALLY SPRING!
EASTERN PRAIRIES...FLURRIES AND PERIODS OF LIGHT SNOW CONTINUE IN
THE UPPER TROUGH OVER NORTHERN MANITOBA THIS AFTERNOON AND EVENING.
CLEARING FORECAST TONIGHT AS THE UPPER TROUGH SLIDES EASTWARD AND
THE SURFACE RIDGE BUILDS IN. IT CONTINUES TO BE QUIET OVER THE
SOUTHERN PRAIRIES WITH SURFACE HIGH BUILDING IN FROM BRITISH
COLUMBIA.
WESTERN ARCTIC...CLOUD IS SPREADING INTO THE MACKENZIE AHEAD OF A
PACIFIC LOW WHICH IS DEVELOPING OVER THE CENTRAL NWT TUESDAY. A
COUPLE CM OF SNOW WITH A RISK OF FREEZING RAIN WILL SPREAD
SOUTHEASTWARD FROM NORMAN WELLS TO NORTH OF GREAT SLAVE LAKE THEN TO
LUTSEL K'E. FREEZING RAIN IS MOST LIKELY NEAR GAMETI AND WEKWEETI
WHERE THERE IS MORE MOISTURE AND A MORE PROLONGED AFL.
EASTERN ARCTIC...SO FAR NO VISIBILITY REDUCTION WITH THE WINDS IN
IQALUIT. WINDS ARE FORECAST TO INCREASE TO 40 GUSTING TO 60 KM/H,
BUT GIVEN THAT THERE HASN'T BEEN MUCH BLOWING SNOW THUS FAR,
SIGNIFICANT VISIBILITY RESTRICTION APPEARS LESS LIKELY.
LIGHT TO MODERATE SNOW WILL CONTINUE NEAR POND INLET FOR THE NEXT
COUPLE DAYS WITH ACCUMULATIONS TOPPING OUT AT 2-4 CM PER 12 HOURS.
FURTHER WEST, LIGHT SNOW WILL SPREAD BACK INTO THE MELVILLE PENINSULA
OVER THE NEXT COUPLE DAYS, COMBINING WITH PERSISTENT NORTHWESTERLY
WINDS OF 30 TO 40 KM/H TO PRODUCE OCCASIONALLY REDUCED VISIBILITIES
IN BLOWING SNOW.
AS THE MACKENZIE LOW MOVES EASTWARD, THE NEXT CONCERN WILL BE THE
SPREAD OF SNOW INTO ARVIAT ON WEDNESDAY. WARNING AMOUNTS OF SNOWFALL
ARE POSSIBLE WITH NORTHERLY WIND GUSTS NEAR 70 KM/H. THE TRACK AND
INTENSITY OF THE LOW ARE STILL VERY UNCERTAIN, BUT A BRIEF BLIZZARD
IS A POSSIBILITY.
END/VAN WILGENBURG/ANISKA-ARO
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