323  
FOCN45 CWWG 241900  
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM  
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CDT WEDNESDAY MAY  
24 2017.  
 
ALERTS IN EFFECT... WIND WARNING FOR SOUTHERN AND EAST-CENTRAL  
ALBERTA, LEADER AND SHAUNAVON PLUS MUCH OF SOUTHEAST SASKATCHEWAN.  
SEVERE THUNDERSTORM WATCH OVER WEST-CENTRAL SASKATCHEWAN AND  
LLOYDMINSTER REGION. SPECIAL WEATHER STATEMENT FOR THE ALBERTA  
FOOTHILLS AND MOUNTAIN PARKS PLUS FORT MCMURRAY AND PORTIONS OF  
NORTHWESTERN SASKATCHEWAN.  
 
SYNOPTIC OVERVIEW... ALOFT, STRONG UPPER LOW NEAR CORONATION  
TRACKING EASTWARD. THERE ARE WEAKER QSTNRY UPPER LOWS, ONE NEAR  
GREAT BEAR LAKE AND ANOTHER NEAR RESOLUTION ISLAND. WEAK UPPER RIDGE  
POKING FROM THE DAKOTAS UP THROUGH MANITOBA, AND A STRONGER UPPER  
HIGH AND RIDGE OVER THE EASTERN PACIFIC AND GULF OF ALASKA.  
 
AT THE SURFACE, ANOMALOUSLY STRONG 979 OR 980 MB LOW JUST NORTHEAST  
OF LLOYDMINSTER AT 18Z WHICH SHOULD NOW BE CLOSE TO ITS LOWEST  
CENTRAL PRESSURE. FRONTAL WAVE OVER EASTERN MONTANA OCCLUDING OUT  
WITH TROWAL WRAPPING NORTHWARD INTO THE LOW THEN CURVING WEST INTO  
ALBERTA. 993 MB LOW JUST WEST OF ARVIAT. GENERAL HIGH PRESSURE OVER  
MOST OF QIKIQTAALUK. LARGE HIGH IN THE EASTERN PACIFIC.  
 
DISCUSSION...  
 
ALBERTA...A QUICKLY MOVING ALBERTA CLIPPER IS TRACKING THROUGH  
ALBERTA AND IS BRINGING 3 MAIN TYPES OF WEATHER TO ALBERTA  
FOR TODAY.  
 
1) SNOW IN THE HIGHER TERRAIN. RAIN HAS SWITCHED OVER TO WET  
SNOW THIS MORNING IN THE NORDEGG AND JASPER REGIONS. EXPECTING A MIX  
OF WET SNOW AND RAIN HERE FOR THE REMAINDER OF THE DAY AS SURFACE  
TEMPERATURES HOVER CLOSE TO 0. SOME OF THE HIGHER ELEVATIONS ALONG  
THE ICEFIELDS PARKWAY AND HIGHWAY 93 MAY SEE 5 TO 10 CM OF SNOW BY  
LATER THIS AFTERNOON.  
 
2) RAIN IN THE LOWER TERRAIN. CURRENT RAINFALL TOTALS IN THE  
HARDEST HIT REGION OF GRANDE PRAIRIE ARE STILL BELOW OUR WARNING  
CRITERIA OF 50 MM. SO FAR BEAVER LODGE HAS RECEIVED THE MOST RAIN  
WITH 44 MM OF RAINFALL. RAIN HAS SINCE MOVED OUT OF THIS REGION AND  
THE HEAVIEST PRECIP HAS MOVED SOUTH EXTENDING FROM THE CAPITAL  
REGION TOWARDS THE ROCKY MOUNTAIN AND NORDEGG REGIONS WHERE RAINFALL  
TOTALS ARE EXPECTED TO BE IN THE 20 TO 30 MM RANGE WITH LOCALLY  
HIGHER AMOUNTS POSSIBLE DUE TO EMBEDDED THUNDERSTORMS.  
 
3) WIND. THE BACKSIDE OF THIS SYSTEM WILL HAVE A TIGHT SURFACE  
PRESSURE GRADIENT WITH A 60 KT LOW LEVEL JET FORECAST TO DEVELOP  
EARLY THIS AFTERNOON. MOST OF CENTRAL AND SOUTHEASTERN ALBERTA  
CURRENTLY HAVE WIND WARNINGS IN PLACE WITH WINDS OF 60 GUSTING  
TO 90 KM/H EXPECTED TO DEVELOP ALONG A CORRIDOR FROM IN AND AROUND  
THE CAPITAL REGION EXTENDING SOUTH THROUGH CALGARY AND EASTWARD  
TOWARDS THE HANNA AND MEDICINE HAT REGIONS. A FEW ISOLATED WIND  
GUSTS OF UP TO 100 KM/H ARE NOT COMPLETELY OUT OF THE QUESTION  
EITHER. THIS WILL BE THE ELEMENT TO WATCH FOR SURE, AS THE WINDS  
WILL AFFECT MOST OF THE PROVINCE. FARTHER SOUTH STRONG WESTERLIES  
HAVE ALSO DEVELOPED WITH THIS SYSTEM GIVING GUSTS UPWARDS OF 100  
KM/H THIS MORNING AND AS SUCH WIND WARNINGS ARE OUT HERE AS WELL.  
 
SEVERE THUNDERSTORMS WILL ALSO BE POSSIBLE THIS AFTERNOON OVER  
PORTIONS OF EAST CENTRAL ALBERTA AND WEST CENTRAL SASKATCHEWAN. 0-6  
KM SHEAR VALUES OF 25-35 KNOTS COMBINED WITH MLCAPE VALUES OF  
500-1000 J/KG WILL BE PRESENT AHEAD OF AN APPROACHING COLD FRONT.  
0-6 KM SHEAR VECTOR ORIENTATION RELATIVE TO THE FRONT MAY ALLOW FOR  
INITIALLY DISCRETE SUPERCELL DEVELOPMENT IN THE EARLY AFTERNOON WITH  
A QUICK TRANSITION INTO A LINEAR MCS BY EVENING. INITIAL THREATS  
WILL BE STRONG WINDS, NICKEL SIZE HAIL AND HEAVY DOWNPOURS. HIGHER  
VALUES OF 0-3 KM CAPE COMBINED WITH LOW-LEVEL VORTICITY MAY ALSO  
ALLOW FOR THE DEVELOPMENT OF NON-SUPERCELL TORNADOES/LANDSPOUTS AND  
FUNNEL CLOUDS AS THUNDERSTORMS DEVELOP.  
 
SASKATCHEWAN... SOUTHWESTERLY WIND WARNING THREAT SHOULD BE EASING  
SOON OVER THE SOUTHWEST CORNER, HOWEVER THE SOUTHERLY THREAT OVER  
THE SOUTHEAST WILL PERSIST INTO AT LEAST THE MID AFTERNOON HOURS.  
SEVERE THUNDERSTORMS POSSIBLE OVER WEST-CENTRAL SASKATCHEWAN THIS  
AFTERNOON AND INTO THE EVENING - MORE OF A WIND THREAT SOUTH OF  
SASKATOON WITH INVERTED V PROFILES, MORPHING INTO MORE OF A  
LANDSPOUT OR EVEN SUPERCELL THREAT NORTH OF SASKATOON. AS MENTIONED  
EARLIER, THE DYNAMICS OF VORTICITY THROUGHOUT THE COLUMN PLUS STRONG  
CONVERGENCE AND COOLING ALOFT MAY MAKE UP FOR MARGINAL  
THERMODYNAMICS, SBCAPES IN THE 500 TO 1000 J/KG RANGE. THE WIND  
WARNING MAY HAVE TO CONTINUE OVER LEADER AND SHAUNAVON DUE TO  
ALBERTA'S NORTHWESTERLIES ARRIVING DURING THE OVERNIGHT HOURS. IN  
ADDITION, 24 HOUR RAINFALLS AT MEADOW LAKE EXTENDING NORTHWARD  
INTO THE BUFFALO NARROWS AND KEY LAKE REGIONS COULD COME CLOSE TO  
THE 50 MM WARNING THRESHOLD. ON THURSDAY THE MAIN THREAT OVER  
SASKATCHEWAN WILL BE MORE OF THE FUNNEL CLOUD AND LANDSPOUT VARIETY  
AS THE LOW STARTS TO WEAKEN AND PUSH SLOWLY EASTWARD INTO WESTERN  
MANITOBA.  
 
THE WHOLE COLD LOW COMPLEX THEN WEAKENS AND SLOWLY MOVES EASTWARD.  
IT MAY NOT BE UNTIL THE END OF THE WEEKEND BEFORE IT COMPLETELY  
CLEARS OUT OF MANITOBA.  
 
KIVALLIQ... RAIN ASSOCIATED WITH THE LOW WEST OF ARVIAT WILL  
GRADUALLY WEAKEN OUT OVER THE NEXT 24 HOURS. FREEZING RAIN REPORTED  
AT CORAL HARBOUR SINCE LATE MORNING BUT EXPECT THIS TO CONTINUE TO  
BE QUITE LIGHT WITH INSIGNIFICANT AMOUNTS.  
 
WESTERN ARCTIC...A SMALL AXIS OF ISTABILITY MAY BRING THE ODD  
ISOLATED PULSE THUNDERSTORM TO THE FORT LIARD REGION TODAY OTHERWISE  
NOTHING MUCH OF INTEREST FOR THE SOUTHERN MACKENZIE. FURTHER TO THE  
NORTH, A FEW PRECIPITATION TYPING ISSUES OVER THE NORTHERN PARTS OF  
THE MACKENZIE AND PARTS OF THE ARCTIC COAST GIVING GENERALLY A  
RAIN/SNOW MIX FOR MUCH OF THE DAY AS COLD AIR CONTINUES TO WRAP  
AROUND THE LOW LOCATED NEAR KUGLUKTUK. PATCHY FOG ALSO CONTINUES  
ALONG THE ARCTIC COASTLINE FOR TODAY.  
 
END/MELSNESS/ALBRECHT  
 
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