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FOCN45 CWWG 061200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT SATURDAY JUNE
6 2026.
ALERTS IN EFFECT...YELLOW RAINFALL WARNING FOR FORT CHIPEWYAN. YELLOW
HEAT WARNING FOR PORTIONS OF SOUTHERN MANITOBA.
OVERVIEW...ALOFT TODAY, AN UPPER LOW SITS ALONG THE SOUTHERN BRITISH
COLUMBIA COAST WITH A WEAK UPPER TROUGH EXTENDING NORTHEAST TO A
SHORTWAVE OVER NW SASKATCHEWAN. A STRONG SOUTHWESTERLY FLOW LIFTS
THROUGH MUCH OF THE PRAIRIES AS IT CLIMBS INTO AN UPPER RIDGE THAT
EXTENDS FROM THE DAKOTAS NORTH THROUGH MANITOBA, WESTERN HUDSON BAY,
AND FOXE BASIN. EAST OF THIS, A COMPACT UPPER LOW SITS NEAR JAMES BAY
WITH A TROUGH SOUTH OVER THE GREAT LAKES. IN THE NORTH, THE POLAR
VORTEX IS ANCHORED OVER THE WESTERN ARCTIC ARCHIPELAGO; ITS CYCLONIC
FLOW ENCOMPASSES MUCH OF THE ARCTIC.
AT THE SURFACE, A 993 MB LOW SITS OVER NW SASKATCHEWAN WITH A TROUGH
SOUTHEAST TOWARDS THE MANITOBA BORDER. SOUTH OF THIS, A 1002 MB LOW
SITS OVER EASTERN MONTANA WITH A SHARPENING WARM FRONT DRAPED
NORTHEAST ACROSS SE SASKATCHEWAN INTO SOUTHERN MANITOBA, THEN SHARPLY
DROPS SOUTHEAST INTO MINNESOTA. FURTHER EAST, A 1003 MB LOW SITS OVER
SOUTHWEST QUEBEC WITH A COLD FRONT SOUTHWEST TO THE GREAT LAKES AND A
WARM FRONT EAST-SOUTHEAST. IN THE NORTH, A 999 MB LOW SITS OVER YUKON
AND A 1012 MB HIGH SITS OVER THE MAINLAND OF WESTERN NUNAVUT WITH
RIDGING ALONG THE COASTLINE BOTH EAST AND WEST. A 1002 MB LOW SITS
OVER THE MELVILLE PENINSULA WITH A COLD FRONT THAT SWEEPS SOUTHWEST
TO GREAT SLAVE LAKE, AND A WARM FRONT THAT DROPS SOUTHEAST.
DISCUSSION...
AB/NORTHERN SK...THE LOW PRESSURE SYSTEM IN NORTHWESTERN SASKATCHEWAN
WILL BRING RAIN TO NORTHERN ALBERTA AND NORTHERN SASKATCHEWAN THIS
WEEKEND. THE GREATEST RAINFALL AMOUNTS ARE EXPECTED TO FALL BETWEEN
RED EARTH, FORT MCMURRAY, AND FORT CHIPEWYAN, WITH TOTAL AMOUNTS OF
40 TO 60 MM LIKELY. EMBEDDED THUNDERSTORMS MAY CAUSE LOCALLY HIGHER
AMOUNTS, UP TO 100 MM IN TOTAL.
NON-SEVERE THUNDERSTORMS ARE POSSIBLE IN PARTS OF NORTHERN
SASKATCHEWAN AND ACROSS MUCH OF WESTERN AND CENTRAL ALBERTA TODAY.
THE BEST CAPE/SHEAR VALUES ARE EXPECTED ALONG THE FOOTHILLS, JUST
NORTH OF CALGARY. IF A SEVERE THUNDERSTORM DEVELOPS IN THIS AREA,
LARGE HAIL WILL BE THE PRIMARY THREAT.
TONIGHT, AS THE B.C. UPPER LOW TRACKS EASTWARDS, RAIN WILL TURN TO
SNOW IN SOME AREAS OF THE MOUNTAIN PARKS. UPWARDS OF 15 CM OF SNOW IS
POSSIBLE ALONG SECTIONS OF THE ICEFIELDS PARKWAY. HOWEVER,
SIGNIFICANT UNCERTAINTY IN TOTAL SNOWFALL ACCUMULATION
REMAINS.
SOUTHERN SK/MB...A POTENT SEVERE WEATHER SETUP WILL DEVELOP TODAY
ALONG THE SURGING WARM FRONT OVER THE EASTERN PRAIRIES TODAY. BY MID-
TO LATE-AFTERNOON, THE WARM FRONT WILL LIE DRAPED ACROSS SOUTHEAST
SASKATCHEWAN, ROUGHLY FROM NEAR WEYBURN NORTHEAST TO TO WOLSELEY AND
ONWARDS TO ESTERHAZY, THEN ARCING ACROSS SOUTHERN MANITOBA FROM
RUSSEL EAST-NORTHEAST INTO THE MANITOBA INTERLAKE,THEN DROPPING
SOUTHEAST TOWARDS LAKE OF THE WOODS AND INTO MINNESOTA.
THE WARM SECTOR OF THIS FRONTAL WAVE WILL BE MARKED BY AMPLE HEAT AND
HUMIDITY; TEMPERATURES WILL RISE INTO THE UPPER 20S OR LOW 30S TODAY
WITH DEW POINT VALUES IN CLIMBING INTO THE 15-18 DEGREES C RANGE.
ALOFT, A 60 KNOT H500 JET WILL SET UP FROM SOUTHERN ALBERTA ACROSS
SOUTHERN AND CENTRAL SASKATCHEWAN INTO CENTRAL MANITOBA; THIS WILL
EASE TO A 30 TO 40 KNOT H500 FLOW OVER THE FRONTAL BOUNDARY REGION.
ENERGETICS WILL BE SUBSTANTIAL IN THE VICINITY OF THE FRONTAL
BOUNDARY OVER SE SASKATCHEWAN THIS AFTERNOON WITH MLCAPE VALUES
CLIMBING INTO THE 2,000 TO 2,500 J/KG RANGE. SHEAR PROFILES SHOW
STRONG VEERING WITH SOUTH-SOUTHEAST SURFACE INFLOW OF 10 TO 20 KNOTS
TURNING SOUTHWESTERLY ALOFT, RESULTING IN 35 TO 45 KNOTS OF 0-6 KM
BULK SHEAR. MLCIN VALUES WILL SIT AROUND 10 TO 20 J/KG, WHICH WILL BE
EASY ENOUGH TO OVERCOME WITH THE LIFTING FORCES IN THE VICINITY OF
THE WARM FRONT.
TO STATE IT WITH CLARITY: THERE WILL BE A SEVERE WEATHER OUTBREAK
OVER SOUTHEAST SASKATCHEWAN THIS AFTERNOON THAT WILL LIKELY EXPAND
INTO WESTERN MANITOBA LATER IN THE AFTERNOON. THE PRIMARY THREATS
WITH THESE THUNDERSTORMS WILL BE DAMAGING HAIL AND WIND GUSTS WITH A
SECONDARY THREATS OF OVERLAND FLOODING DUE TO TORRENTIAL RAINFALL.
THERE IS AN ELEVATED TORNADO THREAT WITH TODAY'S ACTIVITY. THE
PRIMARY THREAT AREA WILL EXTEND ALONG THE WARM FRONT FROM AROUND
THE WEYBURN AREA NORTHEAST TO ROUGHLY YORKTON. THE TORNADO RISK DOES
EXTEND FURTHER NORTHEAST ALONG THE WARM FRONT, BUT THE LIKELIHOOD IS
LOWER FURTHER AWAY FROM THE SURFACE LOW. THE TWO FACTORS THAT LIMIT
THE TORNADO THREAT TODAY WILL BE THE MAGNITUDE OF BACKING OF SURFACE
WINDS ON THE EASTERN SIDE OF THE FRONT, AND THE LIMITED MOISTURE
RETURN TODAY LEADING TO HIGHER LCLS.
AS THE ACTIVITY MOVES INTO THE EVENING, IT WILL UNDERGO UPSCALE
GROWTH AS A STRONG LOW-LEVEL JET DEVELOPS IN NORTH DAKOTA. THE LLJ
SPEED WILL INCREASE TO ROUGHLY 50 KNOTS OVERNIGHT, DRIVING HEAT AND
MOISTURE NORTH INTO THE REGION. NOTABLY, THE MOISTURE RETURN WILL BE
SUBSTANTIALLY OVERNIGHT WITH PWAT VALUES IN THE REGION INCREASING
FROM 30 TO 35 MM ON SATURDAY EVENING INTO THE 40 TO 45 MM RANGE BY
SUNDAY MORNING.
MUCAPE VALUES STAY ABOVE 1,000 J/KG THROUGH THE NIGHT, WHICH WILL
SUPPORT A SEVERE RISK RIGHT INTO SUNDAY MORNING. PRIMARY HAZARDS
OVERNIGHT WILL BE DAMAGING HAIL AND OVERLAND FLOODING DUE TO
TORRENTIAL RAINFALL.
HEADING INTO SUNDAY, THERE'S LOT OF UNCERTAINTY AS TO HOW THE
DAY WILL UNFOLD. GIVEN THE STRENGTH OF THE FORCING AND SIGNIFICANT
INSTABILITY, IT'S UNCERTAIN WHETHER THE NOCTURNAL CONVECTION
WILL CONTINUE THROUGH THE DAY, OR IF THE CONVECTION WILL TAPER OFF
OVERNIGHT. BOTH OPTIONS WILL DRAMATICALLY IMPACT HOW THE DAY PLAYS
OUT. FOR THAT REASON, WE'LL BE BRIEF ON THE RISK FOR THE DAY. IF
THE CONVECTION SUBSIDES IN THE MORNING, SUNDAY HAS THE POTENTIAL TO
BE AN EVEN MORE POTENT SEVERE WEATHER THREAT THAN SATURDAY. THE
FRONTAL BOUNDARY WILL BE ALIGNED NORTH-SOUTH ALONG THE
SASKATCHEWAN/MANITOBA BORDER AND THEN ARC INTO CENTRAL MANITOBA
BEFORE SHARPLY TURNING SOUTH AND DROPPING INTO MINNESOTA. THE SURFACE
LOW WILL BE GRADUALLY BUILDING INTO NORTH DAKOTA AND THE HEAT AND
MOISTURE ADVECTION THAT OCCURRED OVERNIGHT WILL BE APPARENT AS THE
DAY PROGRESSES. TEMPERATURES WILL CLIMB INTO THE LOW 30S ACROSS
SOUTHERN MANITOBA WITH WIDESPREAD DEW POINTS NEAR THE 20 DEGREES C
MARK. THIS WILL PUSH MLCAPE VALUES INTO THE 2,500 TO 3,500 J/KG
RANGE. THE UPPER-LEVEL FLOW WILL BECOME MORE AMPLIFIED WITH STRONGER
HEIGHT FALLS BEGINNING ACROSS THE EASTERN PRAIRIES AND BULK SHEAR
VALUES WILL RANGE FROM 25 TO 30 KNOTS OVER SW MANITOBA WHERE THE
HIGHEST MLCAPE VALUES ARE TO 40 TO 60 KNOTS FURTHER WEST ALONG THE
MLCAPE GRADIENT OVER SE SASKATCHEWAN. WITH SURFACE WINDS OUT OF THE
SOUTHEAST AT 15 TO 20 KNOTS AND MUCH LOWER LCLS GIVEN THE HIGHER
MOISTURE IN THE REGION, SUNDAY COULD END UP BEING A POTENT
ALL-HAZARDS SEVERE WEATHER OUTBREAK WITH OVERLAND FLOODING, DAMAGING
HAIL AND WIND GUSTS, AND A WIDESPREAD TORNADO THREAT.
THAT SAID, IF THE NOCTURNAL CONVECTION DOES NOT DIE OFF IN THE
MORNING, AND INSTEAD INSTABILITY IS VENTED THROUGH THE DAY AND COLD
POOLS ARE CONSTANTLY GENERATED AND/OR REINFORCED, THEN THE SEVERE
RISK WILL BE DRAMATICALLY REDUCED; THERE WOULD LIKELY BE SOME LEVEL
OF SEVERE RISK IN THE AFTERNOON HOURS, BUT AT A MUCH LESSER EXTENT
AND SEVERITY THAN IN THE OTHER SCENARIO.
EITHER WAY, THE COMMONALITY IS THAT SUNDAY'S SETUP DEPENDS
DRAMATICALLY ON SATURDAY'S EVOLUTION. FOR NOW, WE MAINTAIN THE
HIGH RISK ASSESSMENT FOR TODAY'S THUNDERSTORM OUTLOOK AND WILL
ISSUE A MODERATE RISK FOR THE OVERNIGHT PERIOD.
ELSEWHERE IN THE EASTERN PRAIRIES, EACH ROUND OF CONVECTIVE
DEVELOPMENT WILL TRACK NORTH-NORTHEAST INTO NORTHERN MANITOBA,
BRINGING WAVES OF SHOWERS AND THUNDERSTORMS OVER THE COMING DAYS. NO
SEVERE WEAHTER IS EXPECTED THAT FAR NORTH, BUT WEEKEND RAINFALL
ACCUMULATIONS OF 20 TO 50 MM ARE POSSIBLE LOCALLY ACROSS NORTHERN
MANITOBA OVER THE COURSE OF MULTIPLE WAVES OF SHOWERS.
A YELLOW HEAT WARNING CONTINUES FOR PORTIONS OF SOUTHERN MANITOBA.
DAYTIME HIGHS WILL CLIMB INTO THE LOW 30S TODAY AND STAY MILD TONIGHT
AS MORE HEAT AND MOISTURE PUSHES NORTH. ON SUNDAY, TEMPERATURES WILL
AGAIN CLIMB INTO THE LOW 30S BUT WITH DEW POINTS NEAR 20 Ā°C
HUMIDEX VALUES WILL REACH THE UPPER 30S. TEMPERATURES WILL DROP INTO
THE HIGH TEENS OR LOW 20S ON SUNDAY NIGHT. COOLER TEMPERATURES WILL
PUSH INTO THE REGION ON MONDAY.
NWT...TRACES OF WILDFIRE SMOKE REMAIN SOUTH OF GREAT SLAVE LAKE. NO
AIR QUALITY WARNINGS ARE REQUIRED AT THIS TIME. NON-SEVERE
THUNDERSTORMS ARE POSSIBLE IN THE WEST-CENTRAL NWT TODAY.
NUNAVUT...RAIN WILL SPREAD ACROSS THE NORTHERN KIVALLIQ OVER THE NEXT
24 HOURS ALONG AND AHEAD OF A COLD FRONT ADVANCING INTO THE REGION.
RAIN WILL BLOSSOM AS A PLUME OF MOISTURE FROM THE PRAIRIES LIFTS OVER
THE ADVANCING COLD FRONT, BRINGING A BAND OF SHOWERS FROM THE BAKER
LAKE REGION NORTHEAST TO THE MELVILLE PENINSULA THAT WILL SLOWLY
TRACK EAST. RAINFALL TOTALS WILL VARY OVER THE REGION, BUT THE
HIGHEST AMOUNTS WILL FALL ALONG A LINE FROM BAKER LAKE (CYBK) TO
NAUJAAT (CYUT) AND ONWARDS TO THE MELVILLE PENINSULA WHERE AS MUCH AS
10 TO 15 MM CAN BE EXPECTED.
END/VROLIJK/VALLEE
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