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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 MONDAY APRIL
6 2026.
ALERTS IN EFFECT...SNOWFALL WARNING FOR A SWATH OF NORTHERN ALBERTA.
BLIZZARD WARNINGS FOR, BAKER LAKE, ARVIAT, RANKIN INLET, AND NAUJAAT.
FREEZING DRIZZLE ADVISORY FOR THE FOOTHILLS WEST OF CALGARY AND SOME
AREAS NORTH OF CALGARY. SPECIAL WEATHER STATEMENTS FOR PORTIONS OF
CENTRAL SASKATCHEWAN AND THE ALBERTA ROCKIES.
SYNOPTIC OVERVIEW...ALOFT, DEEP UPPER TROF OVER WESTERN ALASKA AND
THE GULF OF ALASKA WITH A NORTHWESTERLY FLOW OVER WESTERN CANADA.
UPPER HIGH OVER THE BEAUFORT SEA AND UPPER LOW OVER BAFFIN ISLAND.
NORTHERLY FLOW OVER THE NORTHERN ARCTIC.
AT THE SURFACE, THERE ARE A SERIES OF WEAK LOWS FROM THE GULF OF
ALASKA TO NORTHERN ALBERTA. 1042 MB HIGH OVER NORTHERN SK. 988 MB LOW
OVER LABRADOR.
DISCUSSION...
WESTERN PRAIRIES...FREEZING DRIZZLE DEVELOPED LAST EVENING IN SOME
AREAS NORTH OF CALGARY, WITH BLACK ICE ON HIGHWAYS, ACCORDING TO
ALBERTA 511 REPORTS AND A WEATHER WATCHER. MORNING REPORTS SUGGEST
SIMILAR CONDITIONS DEVELOPED OVERNIGHT IN THE FOOTHILLS WEST OF
CALGARY. THERE'S BEEN EVIDENCE OF FREEZING DRIZZLE IN CALGARY ITSELF
AS WELL, BUT NOT IN A WIDESPREAD ENOUGH FASHION ON WEBCAMS AND NOT AT
THE INTERNATIONAL AIRPORT WHERE THE OBSERVER INSISTS IT'S SNOWING.
THE UPSLOPE FLOW IS PROBABLY A LITTLE STRONGER OVER THE FOOTHILLS
THAN CALGARY, SO HAVING AN ADVISORY IN THE FORMER AND NOT THE LATTER
MAKES SOME SENSE, THOUGH THE CUTOFF AS TO WHEN IMPACTS BECOME
SIGNIFICANT IS RATHER ARBITRARY. THE ADVISORY IS MAINTAINED AT
AIRDRIE FOR CONTINUITY SINCE THE RISK OF FREEZING DRIZZLE AT LEAST
ISN'T OVER.
A DIGGING UPPER TROUGH WILL DEVELOP AN ALBERTA CLIPPER TODAY.
SNOW WILL BE SRPEADING EASTWARDS ACROSS A WARM FRONT, REACHING PEACE
RIVER IN THE NEXT FEW HOURS AND THE SASKATCHEWAN BORDER BY THE
EVENING. THE SNOWFALL FORECAST IS SOMEWHAT COMPLICATED AND THERE'S
NOT GREAT AGREEMENT IN GUIDANCE, BUT A REPS AVERAGE DICTATES THAT THE
HEAVIEST SNOWFALL WILL FALL NORTH OF THE TRACK OF A FRONTAL WAVE THAT
WILL BE NORTH OF THE SURFACE LOW, IN A SWATH FROM PEACE RIVER TO COLD
LAKE, AND LIKELY SOUTH OF FORT MCMURRAY AND MORE LIKELY THAN NOT
NORTH OF THE SMOKY LAKE, THOUGH THIS IS ALOT LESS CERTAIN. SNOW WILL
LINGER IN A TROWAL HANGING BACK FROM THE LOW TOMORROW AS IT DEPARTS.
SNOWFALL AMOUNTS WILL GENERALLY BE IN THE 10 TO 15 CM RANGE IN THIS
SWATH, THOUGH COULD BE HIGHER NEAR THE BC BORDER. WE ANTICIPATE SLRS
TO BE NEARISH 10:1 AS THE SYSTEM ARRIVES AT NIGHT AND TEMPERATURS
WILL START BELOW ZERO.
THERE'S ALOT OF UNCERTAINTIES WITH THIS FORECAST. FIRST IS THE TRACK
OF THE FRONT AND SWATH OF SNOW ITSELF, SOMETIMES PLACED SOMEWHAT
FURTHER SOUTH SUCH AS IN THE CURRENT RDPS. 2ND IS THE POTENTIAL FOR
INSTABILITY TO INCREASE SNOWFALL AMOUNTS IN CONVECTIVE BANDS BOTH
NORTH OF THE LOW AND ALONG A COLD FRONT TRAILING IT. ALL THAT SAID,
CONFIDENCE IS NOT HIGH ENOUGH TO EXPAND THE SNOWFALL WARNING UNTIL
LATER...PERHAPS AS THE SNOWFALL DEVELOPS.
THE TRAILING COLD FRONT WILL ALSO BRING SOME PROBLEMATIC WEATHER.
SOME INSTABILITY COMBINED WITH A REASONABLE ISALLOBARIC PUSH WILL
PROBABLY BRING HIGH SNOWFALL RATES TO PORTIONS OF THE ROCKY MOUNTAINS
AND PERHAPS OTHER AREAS. EXACT SNOWFALL AMOUNTS ARE HARD TO PIN DOWN
DUE TO A WARM AFTERNOON POSSIBLY HEATING THE GROUND AND REDUCING SLRS
AND DUE TO THE CONVECTIVE NATURE OF THE SNOW. NONETHELESS, GIVEN
MULTIPLE GUIDANCE SUGGESTING SNOWFALL RATES NEAR 4 CM/HR, AND THE
PRESENCE OF A LITTLE CAPE AND PREVIOUS EXPERIENCE, WE FELT SOME
HEADSUP WAS WARRANTED AND A SPECIAL WEATHER STATEMENT HAS BEEN ISSUED
FOR THE MOUNTAIN PARKS AND NORDEGG. INSTABILITY MAY BE GREATER
TOMORROW, INCREASING THE POTENTIAL FOR HEAVY FLURRIES FURTHER SOUTH,
THOUGH, AGAIN, SIGNIFICANT UNCERTAINTIES HERE.
IN THE WAKE OF THE COLD FRONT, THERE WILL BE A DECENT ISALLOBARIC
PUSH ALLOWING FOR WIND GUSTS UP TO 70 KM/H OVER PORTIONS OF CENTRAL
ALBERTA. SIMILAR STRONG WINDS ARE POSSIBLE IN PINCHER CREEK TONIGHT ,
WEST OF TROUGHING IN DOWNSLOPE WINDS.
EASTERN PRAIRIES...FOR A CHANGE OF PACE FROM THIS WINTER, ANOTHER
ALBERTA CLIPPER! AS THE UPPER TROF OVER THE GULF OF ALASKA COMES
ONSHORE TODAY, IT WILL BOLSTER INTO A CLOSED LOW OVER NORTHERN BC,
WITH A 95KT H500 JET ROUNDING THE BASE. THE SURFACE LOW WILL DEVELOP
WITHIN THE LEE TROF NEAR THE AB FOOTHILLS OVERNIGHT MONDAY NIGHT INTO
TUESDAY MORNING. THE TRACK OF THE LOW WILL INITIALLY BE TO THE
SOUTHEAST INTO MONTANA, BUT THEN EASTWARD, AS THE RIDGING AHEAD OF
THE SYSTEM FLATTENS TO A MORE ZONAL FLOW OVER THE NORTHERN US PLAINS.
THERE IS A FAIR BIT OF AGREEMENT IN NUMERICAL GUIDANCE IN THE SPEED
AND TRACK OF THIS LOW. UNFORTUNATELY, ITS HAPPENING. WHAT THAT MEANS
IS A BIT MORE IN QUESTION.
AS ALWAYS WITH THESE SHOULDER SEASON SYSTEMS, THE REALIZED WEATHER IS
A CHALLENGE TO FORECAST. THERE WILL BE A CONSIDERABLE AMOUNT OF
ISENTROPIC ASCENT OVER CENTRAL SASKATCHEWAN, WITH A FAIR BIT OF
INSTABILITY. HEAVY SNOW WILL FALL IN A CORRIDOR FROM MEADOWLAKE, SK
THROUGH PRINCE ALBERT, TOWARDS SWAN RIVER, MB. PROFILES SHOW A
FAVOURABLE ATMOSPHERIC COLUMN FOR SNOW PRODUCTION ALONG THE NORTHERN
FLANK OF THE SYSTEM TRACK, GENERALLY 5 TO 15 CM OF SNOWFALL EXPECTED.
RECENT WARMTH, REDUCED SNOWPACK, AND THE EFFECT OF HIGH SUN ANGLE DUE
TO THE TIME OF YEAR, THERE WILL MELTING AND COMPACTION AHEAD OF THE
ACCUMULATION, REDUCING THE EFFECTIVE SNOW TOTALS FOR THE EVENT.
WHEN THAT TRANSITION FROM MELTING TO ACCUMULATION OCCURS WILL
DETERMINE HOW MUCH EFFECTIVE SNOWFALL THERE WILL BE. THE ACTUAL
SNOWFALL ITSELF MAY END UP NOT HITTING 15 IN 24 HOUR CRITERIA.
IN THE WARM SECTOR, THERE WILL ALSO BE A RISK OF FREEZING RAIN ALONG
THE WARM FRONT WITH PERISTANT WARM AIR ADVECTION TO SUSTAIN THE
PROCESS. SURFACE TEMPS WILL GENERALLY BE ABOVE ZERO IN THE WARM
SECTOR HOWEVER AND THE RESULTANT BAND OF RISK WILL BE QUITE NARROW.
ADDITIONALLY, AS SPRINGTIME IS ON THE DOORSTEP THEORETICALLY, WITHIN
THE WARM SECTOR, THERE IS A NARROW FINGER 250 J/KG OF CAPE AND 40 TO
50 KT OF 0-6KM BULK SHEAR. ANY UPDRAFTS THAT ARE ABLE TO FORM ALONG
THE WARM SECTOR TROUGH WILL LIKELY GET SHEARED OFF, BUT SOME STRIKES
CERTAINLY ARE POSSIBLE.
A SPECIAL WEATHER STATEMENT HAS BEEN ISSUED FOR THE WINTER WEATHER.
THAT MAY BE ENOUGH TO COVER THE EVENT, BUT IT MAY REQUIRE UPGRADING
TO A SNOWFALL WARNING. IT WILL LIKELY BE EXTENDED EASTWARD THROUGH
MANITOBA AS WELL, BUT THAT IS IN THE OFFING.
WESTERN ARCTIC...FORT LIARD WILL BE CLIPPED BY OUR CLIPPER, WITH
GUIDANCE FAIRLY CONSISTANT SHOWING 5 TO 10 CM OF SNOW FOR THE TOWN
TONIGHT. OTHERWISE THERE'S NO SIGNIFICANT WEATHER UNDER A RIDGE.
EASTERN ARCTIC...A WEAK SHORTWAVE PASSING OVER THE KIVALLIQ EARLY
THIS MORNING IS INTRODUCING SOME FRESH SNOWFALL TO MANY OF THE
TOWNSITES. RANKIN INLET OVERPERFORMED IN BLOWING SNOW YESTERDAY WITH
NO FRESH SNOWFALL, AND THE REGION WILL BE IN THE SAME TODAY AS THEY
WERE YESTERDAY. ADDITIONALLY, ACCORDING TO CAPS GUIDANCE, THIS
MORNING, ALL SITES WILL BE EXHIBITING AN OVERSATURATION DUE TO ICE AT
THE TOP OF THE MIXING LAYER IN ADDITION TO THE RECENT FRESH SNOWFALL.
WITH THE SAME 40G60 WINDS, INCLUDING 50G70 AT BAKER LAKE, BLIZZARD
CONDTIONS ARE EXPECTED TO DEVELP AT ALL KIVALLIQ TOWNSITES, SAVE FOR
CHESTERFIELD INLET, WHICH IS A BIT MORE SHELTERED. BLIZZARD WARNINGS
WENT OUT WITH YESTERDAY AFTERNOONS FORECAST AND WILL BE CONTINUED BY
THE NIGHT SHIFT.
END/CARLSEN/BATE
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