FOCN45 CWWG 161900
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CDT SATURDAY MAY
16 2026.

ALERTS IN EFFECT...SNOWFALL WARNING FOR PARTS OF THE ROCKIES. SPECIAL
WEATHER STATEMENTS FOR THE REMAINDER OF THE ROCKIES, THE FOOTHILLS
AND CALGARY. SPECIAL WEATHER STATEMENT FOR PARTS OF SOUTHERN SK AND
SOUTHERN MB.

DISCUSSION...ALOFT TODAY, A CONGLOMERATION OF WEAK UPPER LOWS SIT
OVER WESTERN CANADA WITH UPPER LOWS SITUATED OVER EAST-CENTRAL
ALBERTA NEAR THE SASKATCHEWAN BORDER, OVER NORTHERN BRITISH COLUMBIA,
SLUMPING SOUTH ALONG THE WEST COAST OF BRITISH COLUMBIA, OVER THE
BRITISH COLUMBIA INTERIOR. VIGOROUS SHORTWAVES ARE LIFTING NORTHEAST
OUT OF THIS BROAD VORTEX OF LOWS OVER SOUTHERN ALBERTA AND NORTHERN
IDAHO. EAST OF THIS, A WEAK UPPER RIDGE SITS ACROSS SOUTHEAST
SASKATCHEWAN AND SOUTHERN MANITOBA. MUCH OF EASTERN CANADA IS
ENCOMPASSED BY A BROAD VORTEX THAT IS ANCHORED BY AN UPPER LOW OVER
THE KIVALLIQ WITH A LONG-WAVE TROUGH EAST TO ANOTHER UPPER LOW OVER
SOUTHERN DAVIS STRAIT AND A SECONDARY LONG-WAVE TROUGH TO A VIGOROUS
SHORTWAVE EXITING JAMES BAY INTO CENTRAL QUEBEC.

AT THE SURFACE, A 1007 MB LOW SITS OVER SOUTHERN ALBERTA WITH A
TROUGH SOUTHEAST TO THE APEX OF A FRONTAL WAVE OVER MONTANA. EAST OF
THIS, A 1026 MB HIGH CENTRE SITS ALONG THE NWT/NU BORDER ALONG THE
MAINLAND COAST WITH RIDGING SOUTHEAST TO NORTHERN MANITOBA THEN
CONTINUING SOUTH THROUGH THE PROVINCE INTO THE DAKOTAS. FURTHER EAST,
A 985 MB LOW SITS ALONG THE WESTERN QUEBEC COAST WITH A WARM FRONT
EAST ACROSS THE UNGAVA PENINSULA AND UNGAVA BAY AND A WARM FRONT THAT
SWEEPS SOUTHWEST BACK INTO THE NORTHERN PLAINS OF THE UNITED STATES
STATES, THEN LIFTING NORTHWEST THROUGH SOUTHERN SASKATCHEWAN, CENTRAL
ALBERTA, AND BACK INTO THE WESTERN ARCTIC. AN OCCLUDED FRONTAL WAVE
SITS EAST OF THIS LOW CENTRE OVER NORTHERN QUEBEC WITH A COLD FRONT
THAT SWEEPS SOUTHWEST ACROSS CENTRAL ONTARIO INTO THE AMERICAN PLAINS
AND A WARM FRONT EAST OVER LABRADOR. A WEAK TROUGH-RIDGE PATTERN SITS
OVER BAFFIN ISLAND'S SPINE AND EASTERN COAST.

ALBERTA...SOME REMNANT WET SNOW REMAINS OVER EASTERN ALBERTA FROM THE
DEPARTING SYSTEM THAT AFFECTED ALBERTA OVER THE PAST COUPLE OF DAYS.
NO SIGNIFICANT AMOUNTS ARE EXPECTED WITH THIS PRECIPITATION BAND.

A SEPARATE LOW PRESSURE SYSTEM OVER THE SOUTHERN ALBERTA FOOTHILLS IS
CREATING A MIX OF PRECIPITATION TYPES FOR THE MOUNTAIN PARKS AND THE
ADJACENT FOOTHILLS REGIONS. WITH TEMPERATURES HOVERING NEAR THE ZERO
MARK, PRECIPITATION IS SLOWLY TRANSITIONING OVER TO VERY WET SNOW.
WITH THESE SOMEWHAT WARM TEMPERATURE PROFILES, SNOWFALL AMOUNTS ARE
EXTREMELY HARD TO NAIL DOWN. A SNOWFALL WARNING REMAINS IN EFFECT FOR
BANFF, KANANASKIS AND NORDEGG AS WELL AS HINTON.

HOWEVER, AS IS OFTEN THE CASE IN SPRING SNOWFALL EVENTS, THERE IS
ALWAYS CAUTION TO BE TAKEN AS JUST 1 DEGREE COLDER OR WARMER CAN
GREATLY AFFECT SNOWFALL TOTALS AND SLIGHTLY HIGHER ELEVATIONS CAN SEE
SNOWFALL ACCUMULATE QUICKLY IN THIS HIGHLY UNSTABLE ENVIRONMENT.
WE STILL ANTICIPATE THAT THE HIGHEST SNOWFALL AMOUNTS THAT WILL
LIKELY OCCUR, WILL BE OVER BANFF NATIONAL PARK AND AREAS JUST TO THE
EAST, INCLUDING POTENTIALLY HIGHWAY 1 NEAR EXSHAW, WITH 10-20 CM
FORECAST. AREAS FURTHER EAST COULD SEE LOCAL AMOUNTS NEAR 5 CM.

HOWEVER WITH SOME WARMER AIR ANTICIPATED OVER THE REGION, THESE
SNOWFALL AMOUNTS MAY BE LESS OR MAY POSSIBLY REMAIN AS RAIN FOR MUCH
OF THE DAY, ESPECIALLY FOR AREAS TO THE SOUTHEAST OF CALGARY.
THE BIGGEST FLY IN THE OINTMENT WILL BE THE AMOUNT OF INSTABILITY
OVER THE REGION WITH THE COLD UPPER TROUGH CENTERED OVER THE
FOOTHILLS THIS AFTERNOON. THIS COLD AIR WILL INCREASE THE INSTABILITY
ALOFT AND MAY BE JUST WHAT WE NEED TO SEE THE HIGHER SNOWFALL AMOUNTS
MATERIALIZE.

AS THE UPPER VORTICITY MAXIMA MOVES EASTWARD THROUGH THE DAY TODAY, A
COUPLE AREAS OF THUNDERSTORMS ARE EXPECTED. THE FIRST IS OVER WEST
CENTRAL ALBERTA, FROM THE HINTON AREA AND AREAS TO THE NORTH AND EAST
OF THEM, WHERE ADDED LIFT FROM UPSLOPE FLOW IN ADDITION TO BROADLY
UNSTABLE CONDITIONS ALOFT FROM THE UPPER TROUGH, WILL LEAD TO SOME
SLOW MOVING THUNDERSTORMS OVER THIS REGION. THE SECOND AREA OF
CONCERN WILL BE OVER SOUTHERN ALBERTA WERE CONVERGENCE ALONG THE
SURFACE TROUGH MAY LEAD TO A FEW WEAK THUNDERSTORMS DEVELOPING.
NEAR THE VORT CENTRE, THERE MAY BE ENOUGH SPIN TO GENERATE A FUNNEL
CLOUD OR TWO IN CONJUNCTION WITH ANY LOW TOPPED CONVECTION.
THE GREATEST RISK FOR THIS WOULD LIKELY BE BETWEEN HWYS 1 AND 9 TO
THE E AND SE OF CALGARY.

BEYOND THIS SYSTEM, TEMPERATURES WILL REMAIN BELOW SEASONAL FOR THE
HOLIDAY WEEKEND. WIDESPREAD FROST IS ANTICIPATED TO DEVELOP TONIGHT
WITH A REPEAT PERFORMANCE ON SUNDAY NIGHT.

MANITOBA/SASKATCHEWAN...A STRONG SOUTHWESTERLY JET AND FALLING
HEIGHTS WILL HELP SUPPORT THE DEVELOPMENT OF CONVECTION OVER
SOUTHWEST SASKATCHEWAN THIS AFTERNOON, WITH DEEP SYNOPTIC LIFT AND 50
KNOTS OF BULK SHEAR TRIGGERING THE DEVELOPMENT OF SHOWERS. SBCAPE
VALUES CLIMBING INTO THE 200 TO 500 J/KG RANGE WILL COMBINE WITH WEAK
SURFACE CONVERGENCE ALONG THE FRONT DRAPED THROUGH THE REGION WILL
LIKELY SUPPORT THE DEVELOPMENT OF ISOLATED THUNDERSTORMS, BUT THE
LARGEST THREAT FROM ANY OF THESE THUNDERSTORMS WILL BE GUSTY WINDS
FROM THE DRIER LOW-LEVELS AND INVERTED V PROFILES BELOW THE LCLS.
WIND GUSTS NEAR 80 KM/H LOOK POSSIBLE WITH CONVECTION THIS AFTERNOON.

HEADING INTO THE EVENING, A BROADER AREA OF RAIN WITH EMBEDDED
CONVECTION WILL BLOSSOM OVER MONTANA AND SPREAD INTO SOUTHERN
SASKATCHEWAN. LIGHT TO MODERATE RAIN WILL SPREAD THROUGH MUCH OF THE
SOUTHERN PORTIONS OF THE PROVINCE OVERNIGHT WITH MUCH OF THE
PRECIPITATION FALLING ALONG AND SOUTH OF A LINE THAT ARCS ROUGHLY
FROM VAL MARIE TO SWIFT CURRENT TO OUTLOOK TO YORKTON. BROAD RAINFALL
ACCUMULATIONS WILL LIKELY SIT IN THE 15 TO 35 MM RANGE WITH THE
POTENTIAL OF HIGHER ACCUMULATIONS OF 30 TO 50 MM IN AREAS THAT MAY
SEE MORE CONVECTIVE ENHANCEMENT OR AREAS THAT SEE PROLONGED RAINFALL
DUE TO THE SYSTEM’S DEFORMATION ZONE OR PIVOT POINTS OF THE
MOISTURE FEED AS IT WRAPS INTO THE NORTHERN FLANK OF THE SHORTWAVE
DRIVING THE SYSTEM.

AS THE NIGHT PROGRESSES, IT LOOKS LIKELY THAT PRECIPITATION MAY
SWITCH OVER TO SNOW ALONG THE TRANS-CANADA HIGHWAY CORRIDOR AND IN
ITS VICINITY. THIS SNOW WILL BE UNLIKELY TO ACCUMULATE GIVEN THE
NEAR-FREEZING TEMPERATURES AND GENERAL "WETNESS" OF EVERYTHING.
PRECIPITATION WILL CHANGE BACK TO RAIN AS IT TAPERS OFF AND WARMS ON
MONDAY.

IN MANITOBA, RAIN WILL PUSH INTO THE REGION ON SUNDAY MORNING AND
TAPER OFF ON SUNDAY NIGHT. GENERAL PRECIPITATION AMOUNTS WILL SIT IN
THE 10 TO 25 MM RANGE WITH THIS SYSTEM -- SIGNIFICANT, BUT LESS THAN
IN SASKATCHEWAN -- AND THERE WILL BE LESS RISK OF SNOW, EXCEPT FOR
THE RIDING MOUNTAINS. HERE, PRECIPITATION COULD CHANGE OVER TO SNOW
EARLY AND SEE NOTABLE ACCUMULATIONS OVER THE HIGHER TERRAIN WITH 5 TO
15 CM POSSIBLE BY THE TIME IT TAPERS OFF.

FURTHER EAST, PRECIPITATION WILL FALL AS LIGHT RAIN ACROSS THE
REMAINDER OF SOUTHERN MANITOBA; ACCUMULATIONS OF 5 TO 10 MM ARE MOST
LIKELY. ANOTHER SYSTEM WILL GRAZE SOUTHEAST MANITOBA EARLY IN THE
WEEK AND BRING ANOTHER FEW MILLIMETRES OF RAIN TO THE REGION.

NWT/NU...NIL SIG WX.

END/VROLIJK/GREENHOUGH/VAN LOCHEM