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Very emotional discussion this morning heralding the arrival of warm weather to Alberta. Still lots of talk about winter-like weather elsewhere though.
Quote:
674
FOCN45 CWWG 231200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM 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. A WEAKER SHORTWAVE HAS SLUMPED
SOUTHEASTWARDS FROM GREAT SLAVE LAKE INTO NORTHWESTERN MANITOBA
OVERNIGHT AND IS NOW INTENSIFYING AS IT CONTINUES ACROSS NORTHERN
MANITOBA. 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 1001 MB LOW JUST OFFSHORE
THE MB/ON BORDER. THIS LOW HAS A COLD FRONT DRAPED ACROSS NORTHERN
MANITOBA BEFORE IT ARCS BACK NORTHWARDS INTO THE WESTERN NWT, AND A
WARM FRONT RUNNING EASTWARDS INTO NORTHERN QUBEC. A BROAD AREA OF
HIGH PRESSURE COVERS MUCH OF THE WESTERN PRAIRIES WITH A 1032 MB HIGH
ANCHORED NEAR THE ALBERTA ELBOW REGION. FURTHER NORTH, A 1029 MB HIGH
SITS OVER WESTERN NUNAVUT WITH SURFACE RIDGE EXTENDING EASTWARDS TO
SOUTHAMPTON ISLAND. A 998 MB LOW SITS JUST EAST OF THE CANADIAN
ARCTIC ARCHIPELAGO, PRODUCING A MODERATE GRADIENT BETWEEN IT AND THE
HIGH OVER THE KIVALLIQ WHICH COVERS FROM THE MELVILLE PENINSULA
SOUTHEASTWARDS INTO SOUTHERN BAFFIN ISLAND.
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...NORTHERN MANITOBA STORM WILL GRADUALLY SHIFT
EASTWARD TODAY, BUT A SECOND AREA OF LIGHT SNOW WILL MOVE THROUGH AS
A SHORTWAVE MOVES ACROSS NORTHERN SASKATCHEWAN INTO THE PROVINCE.
GENERALLY AROUND 2-5 CM, BUT A SWATH OF 5 TO 10 CM IS POSSIBLE ALONG
A LINE ROUGHLY FROM BROCHET TO THOMPSON.
AREAS OF BLOWING SNOW POSSIBLE THROUGH CHURCHILL/YORK REGIONS TODAY
AS THE MANITOBA LOW MOVES OUT OVER HUDSON BAY. MODERATE NORTHERLY
WINDS OF 40 TO 50 KM/H WILL REMAIN IN PLACE MUCH OF THE DAY,
COMBINING WITH LIGHT SNOW TO PRODUCE REDUCED VISIBILITIES AT TIMES IN
BLOWING SNOW.
QUIET OVER THE SOUTHERN PRAIRIES WITH SURFACE HIGH BUILDING IN FROM
BRITISH COLUMBIA.
WESTERN ARCTIC...A COUPLE OF SHORTWAVES COMBINED WITH THE INVERTED
SURFACE TROUGH FROM THE LOW IN SK THROUGH THE GREAT SLAVE LAKE AREA
OVER NIGHT BRINGING A COUPLE OF CENTIMETRES OF SNOW. THE BUILDING
RIDGE WILL CLEAR OUT MOST AREAS AROUND GREAT SLAVE LAKE TODAY. A
PACIFIC LOW WILL MOVE INTO THE SOUTHERN NWT TUESDAY BRINGING A RISK
OF FZRA AND A COUPLE CM OF SNOW TO AREAS NORTH OF GREAT SLAVE LAKE.
EASTERN ARCTIC...BLOWING SNOW AT TIMES IN IQALUIT TODAY WITH MODERATE
NORTHWESTERLY WINDS OF 40 GUSTING 60 KM/H. FULL-ON BLIZZARD
CONDITIONS LOOKING UNLIKELY GIVEN FAIRLY DRY COLUMN, BUT SIGNIFICANT
LOW-LEVEL INSTABILITY MAY SUPPORT VERY POOR VISIBILITIES AT TIMES.
LIGHT TO MODERATE SNOW WILL CONTINUE NEAR POND INLET FOR THE NEXT
COUPLE DAYS. WHILE RATES LOOK LIKE THEY SHOULD REMAIN BELOW WARNING
CRITERIA, ACCUMULATIONS IN THE REGION COULD BE SIGNIFICANT WITH IN
EXCESS OF 25 CM POSSIBLE OVER HIGHER TERRAIN IN THE AREA BY TUESDAY
EVENING. POND INLET ITSELF SHOULD SEE MORE MODEST 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. QUIET OVER THE KIVALLIQ.
OTHER THAN THAT, THE NEXT SYSTEM OF CONCERN WILL SPREAD SNOW INTO
ARVIAT ON WEDNESDAY WITH NEAR-WARNING AMOUNTS POSSIBLE.
Updated spring leaf index anomaly. Presumably areas in grey in the upper Midwest and northern great plains have leaves at all yet.
Source: https://www.usanpn.org/data/spring
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