FOCN45 CWWG 311900
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CDT FRIDAY MAY
31 2024.

ALERTS IN EFFECT...FREEZING RAIN WARNING FOR RANKIN AND CHESTERFIELD
INLETS.

SYNOPTIC OVERVIEW...ALOFT TODAY, A HIGH-AMPLITUDE MERIDIONAL PATTERN
SITS OVER CANADA. IN THE WEST, AN UPPER RIDGE EXTENDS FROM THE
PACIFIC NORTHWEST NORTHWARDS THROUGH BRITISH COLUMBIA AND INTO
SOUTHERN YUKON. EAST OF THAT, A LARGE UPPER LOW SITS OVER NORTHWEST
MANITOBA WITH ITS CYCLONIC FLOW IMPACTING THE ENTIRE PRAIRIES AND
PARTS OF SOUTHERN NORTHWEST TERRITORIES AND NUNAVUT. FURTHER EAST, AN
UPPER RIDGE EXTENDS FROM THE GREAT LAKES NORTHWARD TO JAMES BAY AND
THEN ARCS NORTHWEST ACROSS HUDSON BAY INTO THE KIVALLIQ REGION OF
NUNAVUT. LASTLY, AN UPPER LOW SITS OVER GREENLAND AND DAVIS STRAIT
HAS A LONG-WAVE TROUGH SOUTHWARDS THROUGH LABRADOR AND THE MARITIMES.

AT THE SURFACE, A RIDGE OF HIGH PRESSURE EXTENDS FROM THE EASTERN
PACFIC INTO BRITISH COLUMBIA. A 982 MB LOW SITS ALONG THE NORTHERN
SASKATCHEWAN/MANITOBA BORDER WITH AN OCCLUDING FRONTAL WAVE TO ITS
EAST; A COLD FRONT ARCS FROM THE SOUTHERN KIVALLIQ INTO NW ONTARIO
AND THEN INTO MINNESOTA, AND THE WARM FRONT ARCS EAST-SOUTHEAST
ACROSS HUDSON BAY AND FORMS A PINCHED WARM SECTOR OVER THE KIVALLIQ
COAST. A 1025 MB HIGH SITS OVER SOUTHERN ONTARIO WITH A RIDGE
NORTHEAST TO A 1018 MB HIGH OVER LABRADOR. LASTLY, A 1008 MB LOW SITS
OVER NEWFOUNDLAND WITH A COLD FRONT SOUTHWEST AND WARM FRONT EAST.

DISCUSSION...

WESTERN PRAIRIES...LOW PRESSURE OVER NE SK/NW MB CONTINUES TO BRING
RAIN TO NORTHERN SK TODAY, WITH SOME WET SNOW DEVELOPING OVERNIGHT.
THE LOW WILL REMAIN ESSENTIALLY STATIONARY OVER THE NEXT 36 HOURS,
WITH THE ASSOCIATED PRECIPITATION GRADUALLY WEAKENING OVER THAT TIME.
COLD AIR MOVING IN FROM THE NORTH WILL CAUSE RAIN TO CHANGE OVER OR
MIX WITH SNOW, WITH SOME LIGHT SLUSHY ACCUMULATIONS POSSIBLE.

OTHERWISE, ANOTHER GUSTY DAY OVER EASTERN AND CENTRAL ALBERTA AND A
FEW NON-SEVERE THUNDERSTORMS ARE POSSIBLE ALONG THE DEFORMATION ZONE
WEST AND SOUTH OF THE LOW THIS AFTERNOON.

EASTERN PRAIRIES...SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP
ACROSS PORTIONS OF THE SOUTHERN PRAIRIES THIS AFTERNOON AS A
SHORTWAVE TRACKING EASTWARDS FROM THE CYPRESS HILLS MOVES INTO AN
UNSTABLE ENVIRONMENT. STORM ENERGETICS WILL BE LIMITED AS MUCH OF THE
MOISTURE THAT WAS IN THE REGION IN DAYS PRIOR HAS BEEN FLUSHED OUT
WITH THE PASSAGE OF A COLD FRONT. MLCAPE VALUES WILL CLIMB TO AROUND
500 J/KG THIS AFTERNOON WITH 15 TO 25 KNOTS OF DEEP-LAYER SHEAR. THE
WIND SHEAR IS MAINLY UNIDIRECTIONAL WITH A PREDOMINANTLY WESTERLY
COMPONENT. A STRONG PRESSURE GRADIENT THROUGH THE REGION IS
SUPPORTING MODERATE WESTERLY WINDS OF 30 TO 50 KM/H TODAY WITH GUSTS
AS HIGH AS 60 TO 70 KM/H. THESE WESTERLY WINDS COUPLED WITH DEW
POINTS IN THE LOW TO MID-SINGLE DIGITS WILL MEAN THAT ANY
THUNDERSTORMS THAT ARE ABLE TO FORM WILL BE CAPABLE OF PRODUCING
STRONG TO SEVERE WIND GUSTS AS HIGH AS 90 TO 100 KM/H. ASIDE FROM THE
WIND, HOWEVER, NO ORGANIZED SEVERE WEATHER THREAT EXISTS WITH TODAYâS
CONVECTION AS ENERGY AND SHEAR IS TOO LIMITED.

THE ACTIVITY WILL BE FOCUSED ALONG THE EASTERN VORTICITY ARC OF THE
SHORTWAVE, AND GIVEN THAT THEY WILL BE SUPPORTED BY THE FALLING
HEIGHTS OF THE SHORTWAVE IN AN ENVIRONMENT CHARACTERIZED BY STEEP
LAPSE RATES, THE SHOWERS WILL LIKELY CONTINUE INTO THE OVERNIGHT
PERIOD, THOUGH DIMINISHED IN STRENGTH AND EXTENT, AS THE SYSTEM
TRACKS ACROSS SOUTHERN MANITOBA TONIGHT.

IN THE NORTH, LIGHT RAIN WILL CONTINUE TO PIVOT AROUND THE UPPER LOW
IN NORTHERN MANITOBA OVER THE NEXT SEVERAL DAYS. THE NORTHWEST
CORNER OF THE PROVINCE WILL SEE AS MUCH AS 5 TO 10 MM TONIGHT, THEN
AMOUNTS WILL EASE AS THE SYSTEM WEAKENS THIS WEEKEND. 12-HOUR
ACCUMULATIONS WILL DIMINISH INTO THE 2-4 MM RANGE FOR SATURDAY AND
INTO SUNDAY ACROSS THE NORTH AS THE LOW WEAKENS AND MOVES INTO
HUDSON BAY.

LOOKING AHEAD, A FEW SHOWERS AND THUNDERSHOWERS WILL BE POSSIBLE ON
SATURDAY OVER CENTRAL AND NORTHEASTERN MANITOBA ALONG THE SOUTHERN
AND EASTERN CLOUD EDGES OF THE UPPER LOW. ENERGY WILL BE SEVERELY
RESTRICTED; NO SEVERE THREAT IS EXPECTED.

ON SUNDAY, A LOW WILL TRACK ALONG THE INTERNATIONAL BORDER INTO
MANITOBA, LIFTING A WARM FRONT TO LIE DRAPED WEST-EAST ACROSS
SOUTHERN PORTIONS OF THE PROVINCE. ASSOCIATED WITH THIS WILL BE A
STRONG THETA-E PUSH AS MOISTURE SURGES NORTHWARDS IN THE FLOW. MLCAPE
VALUES OF 1000 TO 1500 J/KG WILL BUILD NORTHWARDS WHILE STORM MOTIONS
ALIGN PARALLEL TO THE FRONTAL BOUNDARY. WHILE CAPPING WILL BE AN
ISSUE, AN UPPER TROUGH IS FORECAST TO MOVE INTO THE REGION LATE IN
THE DAY; THE FALLING HEIGHTS ASSOCIATED WITH THAT WILL LIKELY BE
ENOUGH TO TRIGGER CONVECTION...THOUGH WHETHER IT IS SURFACE-BASED OR
ELEVATED IS AN UNCERTAINTY. THERE WILL LIKELY BE WIDESPREAD
CONVECTIVE ACTIVITY BY THE END OF THE DAY WITH A LOW RISK OF SEVERE
THUNDERSTORMS. AS DEEP MOISTURE BUILDS NORTHWARDS THROUGH THE DAKOTAS
AND PRECIPITABLE WATER VALUES CLIMB INTO THE 30 TO 35 MM RANGE, ANY
CONVECTIVE CELLS THAT DEVELOP WILL BE CAPABLE OF HEAVY RAINFALL.

WESTERN ARCTIC...LOW PRESSURE OVER NORTHERN MB WILL BRING RAIN AND A
MIX OF RAIN AND SNOW TO REGIONS SOUTHEAST OF GREAT SLAVE LAKE TODAY
AND TONIGHT. AS IN NORTHERN SK, ACCUMULATIONS SHOULD BE NEGLIGIBLE
AND/OR SLUSHY.

A FEW NON-SEVERE THUNDERSTORMS ARE EXPECTED THIS AFTERNOON ALONG A
TROUGH IN CENTRAL NWT. FURTHER NORTH, STRATUS AND FOG ALONG WITH
DRIZZLE AND A RISK OF FREEZING DRIZZLE PERSIST OVER THE MACKENZIE
DELTA THIS MORNING AND WILL RETURN AGAIN OVERNIGHT TONIGHT.

EASTERN ARCTIC...AN AREA OF PRECIPITATION ASSOCIATED WITH THE FRONTAL
WAVE OVER THE KIVALLIQ REGION HAS STALLED OVER THE AREA, BRINGING A
MIX OF PRECIPITATION TO THE REGION. ARVIAT, SOLIDLY IN THE WARM
SECTOR, WILL SEE PERIODS OF LIGHT RAIN THROUGH THE DAY. FURTHER
NORTH, WHALE COVE WILL LIKELY SEE MAINLY RAIN TODAY, BUT RANKIN INLET
WILL SEE A MIX OF FREEZING RAIN AND RAIN TODAY. IN CHESTERFIELD
INLET, THE COMMUNITY WILL BE STUCK SOLIDLY WITH FREEZING RAIN ALL
DAY.

THE PRECIPITATION WILL CHANGE TO SNOW IN CHESTERFIELD INLET TONIGHT
AS THE FRONT DIPS SOUTHWARDS,  BUT RANKIN INLET COULD SEE A RETURN OF
FREEZING RAIN AS THE PRECIPITATION GRADUALLY BREAKS UP OVERNIGHT. A
LIGHT PATCHY MIX OF PRECIPITATION COULD LINGER IN RANKIN INLET, WHALE
COVE, AND CHESTERFIELD INLET INTO SATURDAY EVENING BEFORE TAPERING
OFF.

IN ADDITION TO THE MIX OF PRECIPITATION OVER THE REGION, STRONG
EASTERLY WINDS WILL SIT IN PLACE OVER PARTS OF THE KIVALLIQ TODAY
WITH EASTERLY WINDS UP TO 60 GUSTING 80 KM/H. THE WINDS WILL EASE
LATER ON SATURDAY AS THE SYSTEM AS A WHOLE BEGINS TO WEAKEN.

END/VROLIJK/VAN LOCHEM