223  
FOCN45 CWWG 211200  
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM  
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT SATURDAY  
OCTOBER 21 2017.  
 
ALERTS IN EFFECT...SNOWFALL WARNING FOR BAKER LAKE AND NAUJAAT,  
SPECIAL WEATHER STATEMENT FOR CHESTERFIELD AND RANKIN INLETS, ARVIAT  
AND CORAL HARBOUR. WINTER STORM WATCH FOR HALL BEACH AND IGLOOLIK.  
WIND WARNINGS FOR THE SOUTHERN ALBERTA FOOTHILLS.  
 
SYNOPTIC OVERVIEW...ALOFT THIS MORNING, SIGNIFICANT TROF  
EXTENDING FROM ALASKA THROUGH YK, AND WESTERN PRAIRIES. RIDGING  
THROUGH ONTARIO AND HUDSON BAY, TROUGHING OVER BAFFIN BAY.  
AT THE SURFACE, A 989 MB SURFACE LOW OVER THE MB INTERLAKE  
WITH A WARM FRONT RUNNING EASTWARD AND A COLD FRONT DIVING DUE  
SOUTHWARD. BROAD TROUGHING EXTENDS NORTHWESTWARD FROM THE LOW  
THROUGH GREAT SLAVE LAKE AND ALONG THE MACKENZIE. HIGH PRESSURE OVER  
THE HUDSON BAY AND BAFFIN ISLAND AND TROUGHING ALONG THE GREENLAND  
COAST.  
 
DISCUSSION...  
 
WESTERN PRAIRIES...FOG THROUGH NORTHERN SECTIONS THIS MORNING AND  
LIKELY TO RETURN SUNDAY NIGHT. WEAK LOW DEVELOPS OVER WESTERN  
ALBERTA TONIGHT TRACKING TO THE SOUTHEAST AND BRINGING A SLIGHT  
CHANCE OF FREEZING RAIN TO THE ELBOW REGIONS SUNDAY MORNING. OVER  
SOUTHERN ALBERTA A STRONG WESTERLY FLOW SETS UP SUNDAY. WARNING  
CRITERIA WINDS ARE EXPECTED ALONG THE SOUTHERN FOOTHILLS WITH THE  
LATEST GUIDANCE SUGGESTING HIGH POTENTIAL FOR EXPANSION TOWARDS  
CYPRESS HILLS. DIFFICULT FORECAST FOR THE MOUNTAINS TONIGHT AS THE  
WESTERLY FLOW DEVELOPS AND MODELS BUILD SIGNIFICANT PRECIPITATION  
ALONG THE ROCKIES. SOME OF THAT LOOKS TO MAKE ITS WAY INTO THE  
ICEFIELDS PARKWAY AND POSSIBLY TO LAKE LOUISE BUT BANFF SHOULDN'T  
SEE SIGNIFICANT AMOUNTS. THE SNOWFALL WARNING IS FOR HIGHER  
ELEVATIONS ALONG THE ROADWAYS.  
 
EASTERN PRAIRIES...A MONSTROUS WARM CONVEYOR BELT STRAIGHT OUT OF  
THE CARRIBEAN CONTINUES TO FEED RECORD SETTING WARMTH AIR AHEAD OF  
THE COLD FRONT THAT IS PUSHING THROUGH SOUTHERN MANITOBA THIS  
MORNING. IT'S POSSIBLE FOR A FEW THUNDERSTORMS ALONG THE FRONT JUST  
BEFORE IT PUSHES INTO ONTARIO THIS AFTERNOON. ADDITIONALLY,  
NOCTURNAL CONVECTION IS PROBABLE IN THE WARM SECTOR OVER  
NORTHEASTERN MANITOBA TONIGHT. OTHERWISE PATCHY SHOWERS WILL WRAP  
AROUND THE LOW TODAY OVER THE EASTERN PRAIRIES. TONIGHT AS THE LOW  
GETS ITSELF ORGANIZED SHOWERS WILL CHANGE TO CONTINUOUS RAIN AND  
THEN SNOW OVER NORTHERN MANITOBA AS COLD AIR WRAPS BEHIND THE LOW.  
SNOWFALL ACCUMULATIONS SHOULD REMAIN UNDER 5 CM.  
 
WIND WARNINGS ARE ONCE AGAIN A POSSIBILITY FOR SOUTHERN SK ON SUNDAY  
AS A WEAK LOW WILL RAPIDLY TRACK THROUGH THE PRAIRIES. RIGHT NOW  
ONLY THE GFS IS PUTTING IN GUSTS IN EXCESS OF 90 KM/H.  
 
EASTERN ARCTIC...KIVALLIQ TRACKING LOW CONTINUES TO PLAY HAVOK  
WITH THE MODELS AND THE FORECAST WITH THE RDPS SPITTING OUT A  
QUESTIONABLE WEAKER SOLUTION AND A MORE EASTWARD TRACK. RDPS NOW  
SHOWING COOLER TEMPERATURES TO THE WEST OF THE TRACK WHICH SEEMS AN  
IMPROVEMENT WITH RAIN NO LONGER EXPECTED IN BAKER LAKE. HOWEVER,  
THE RDPS NOW PUTS THE DEFORMATION ZONE TO THE EAST OF BAKER LAKE ON  
SUNDAY. GUIDANCE FROM CMC A&P RECOMMENDS A MORE WESTWARD SOLUTION  
WHICH BRINGS ADDITIONAL SNOWFALL INTO BAKER LAKE ON SUNDAY. HEDGED  
SOLUTION OF 15 TO 30 CM, HOWEVER UPWARDS OF 45 CM IS POSSIBLE IF THE  
LOW TRACK 50 KM FURTHER WEST. OTHERWISE THE FORECAST REMAINS MOSTLY  
UNCHANGED WITH SLIGHTLY MORE SNOW FORECAST IN THE SOUTHERN KIVALLIQ  
SITES BEFORE THE CHANGEOVER TO RAIN. SPECIAL WEATHER STATEMENTS  
REMAIN IN EFFECT FOR THE REMAINDER OF THE REGION. NORTHWARD, NAUJAAT  
HAS BEEN ROLLED OVER INTO A SNOWFALL WARNING WHERE 15-25 CM IS  
ANTICIPATED BEFORE CHANGING TO RAIN ON SUNDAY. AT THIS POINT,  
IGLOOLIK AND HALL BEACH COULD BE THE BIG WINNERS WITH THE GDPS  
COMING IN WITH 50 MM QPF THAT SHOULD BE NEARLY ALL SNOW THROUGH  
MONDAY. AS A RESULT A WINTER STORM WARNING HAS BEEN ISSUED FOR THOSE  
SITES.  
 
ON THE FRONT SIDE OF THIS LOW SOUTHEASTERLIES WILL GUST NEAR 80 KM/H  
AS THE LOW TRACKS NORTHWARD ALONG THE COAST. SNOW WILL BLOW AS IT  
FALLS, BUT WITH TEMPERATURES NEAR 0 IT SHOULD STICK ONCE IT HITS THE  
GROUND. ON THE BACK SIDE OF THE LOW IT LOOKS PROBABLE THAT NORTHWEST  
WINDS WILL EXCEED WARNING CRITERIA SUNDAY NIGHT OVER THE SOUTHERN  
KIVALLIQ.  
 
WESTERN ARCTIC...FOG REMAINS IN THE MACKENZIE AND IS LIKELY AGAIN  
TOMORROW MORNING. MAIN CHALLENGE WILL BE THE KIVALLIQ LOW TRACK.  
KUGAARUK IS NEAR THE SNOW EDGE AND COULD SEE 30 CM OR SO IF THE  
TRACK DEVIATES SLIGHTLY WESTWARDS. THEY WILL GET AN INITIAL IMPULSE  
TONIGHT WHICH HAS BEEN PRETTY CONSISTENTLY FORECAST BETWEEN 5 AND 10  
CM. LATE SUNDAY EASTERLY WINDS DEVELOP IN GRISE FIORD AND RESOLUTE  
WITH POTENTIAL FOR WARNING CRITERIA WINDS MONDAY.  
 
END/VAN WILGENBURG/WIELKI  
 
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