PASPC Thunderstorm Outlook Day 1

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FOCN45 CWWG 191200

SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT THURSDAY OCTOBER 19 2017.

ALERTS IN EFFECT...WIND WARNING FOR SOUTHWESTERN ALBERTA. AIR QUALITY STATEMENT FOR SOUTHERN ALBERTA DUE TO SMOKE FROM GRASS FIRES.

SYNOPTIC OVERVIEW...ALOFT THIS MORNING, AN UPPER RIDGE HAS SETTLED OVER THE EASTERN PRAIRIES WHILE TROUGHS WITH CLOSED LOWS LIE OVER HUDSON BAY AND THE GULF OF ALASKA. A COLD LOW CONTINUES TO SIT OVER THE BEAUFORT SEA. AT THE SURFACE, A 984 MB OCCLUDED LOW IS FILLING IN SOUTHERN HUDSON BAY AND CONTINUES TO TRACK BRISKLY NORTHEASTWARD. A 972 MB LOW HAS STALLED NEAR HAIDA GWAII, WHILE THE ASSOCIATED FRONTAL WAVE HAS PUSHED INLAND TO THE BC/ALBERTA BORDER. A WEAK RIDGE LIES BETWEEN THE TWO LOWS FROM KIVALLIQ SOUTH ALONG THE SASKATCHEWAN/MANITOBA BORDER.

DISCUSSION...

WESTERN PRAIRIES...AT THIS TIME IT APPEARS THAT MOST OF THE GRASS FIRES HAVE BEEN EXTINGUISHED EXCEPT FOR THE FIRE WEST OF COLEMAN ALBERTA. WE WILL WAIT FOR CONFIRMATION FROM ALBERTA HEALTH PRIOR TO ENDING THE AIR QUALITY ADVISORIES IN THESE AREAS.

STRONG WINDS CONTINUE THIS MORNING IN SOUTHWESTERN ALBERTA WITH GUSTS APPROACHING OR EXCEEDING 90 KM/H FROM PRIDDIS TO CARWAY. THE WINDS ARE EXPECTED TO DIMINISH LATER THIS MORNING AS THE LEE TROUGH WEAKENS AND MOVES FURTHER TO THE EAST.

PRECIPITATION CONTINUES TO PILE UP AGAINST THE DIVIDE WITH SOME LEAKING ACROSS INTO THE MOUNTAIN PARKS. LIKELY HAD A RAIN/SNOW MIX IN THE VALLEYS WITH TEMPERATURES NEAR OR SLIGHTLY ABOVE ZERO.

EASTERN PRAIRIES...A MUCH QUIETER DAY ON TAP AS YESTERDAY'S SYSTEM HAS MOVED OFF INTO HUDSON BAY. WARM SOUTHERLIES ARE ALREADY RETURNING TO SASKATCHEWAN THIS MORNING COURTESY THE BC LOW AND DIGGING UPPER TROUGH ON THE COAST. THE TROUGH PUSHES INLAND ON FRIDAY AND ANOTHER LOW DEVELOPS OFF OF THE ROCKIES THROUGH THE DAY. ONCE AGAIN THERE IS QUITE A BIT OF DISAGREEMENT ON WHERE THIS NEXT LOW WILL DEVELOP, WITH MODEL SOLUTIONS ANYWHERE FROM CENTRAL ALBERTA TO SOUTHERN MONTANA.

AT ANY RATE THIS LOW IS RATHER WARM AND DRY - WITH TEMPERATURES BACK INTO THE TWENTIES ON FRIDAY ACROSS MOST OF THE SOUTH, THOUGH THIS COULD BE DAMPENED AT BIT BY HIGH CLOUD COVER AND BRISK SOUTHERLIES AHEAD OF THE LOW. MODEL OUTPUT HAS BEEN STRUGGLING TO CAPTURE THE ONGOING HEAT OF LATE, AND EVEN THE STATISTICAL NUDGING HAS NOT BEEN PUSHING UP THE DAYTIME HIGHS SUFFICIENTLY UNDER THE RATHER DRY AIR. MANY SITES WILL BE AT RECORD HIGHS FRIDAY AFTERNOON IF TEMPERATURES CAN REACH THE MID TWENTIES.

WIND WILL ALSO BE AN ISSUE YET AGAIN IN BEHIND THIS SYSTEM FRIDAY NIGHT INTO SATURDAY ACROSS SOUTHERN SASKATCHEWAN EARLY YET AND WITH PLENTY OF DISAGREEMENT, BUT EVEN THE ENSEMBLE MEAN WINDS ARE POINTING AT 70 TO 80 KM/H NORTHWESTERLY GUSTS, WITH A COUPLE SOLUTIONS WELL ABOVE THAT INTO SEVERE TERRITORY ALREADY. FURTHER NORTH, YET AGAIN THERE IS POTENTIAL FOR MIXED PHASE PRECIPITATION INCLUDING FREEZING RAIN OVER EXTREME NORTHERN MANITOBA AND/OR SOUTHERN KIVALLIQ LATER FRIDAY INTO SATURDAY.

ARCTIC...GALE FORCE WINDS ACROSS MOST OF HUDSON BAY WITH THE TRANSITING LOW. CLOUD AND SOME LIGHT SNOW FOR THE MACKENZIE. OTWZ NIL SIG WX.

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