PASPC Thunderstorm Outlook Day 1

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FOCN45 CWWG 112000

SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM PREDICTION CENTRE OF ENVIRONMENT CANADA AT 2:00 PM CST MONDAY DECEMBER 11 2017.

ALERTS IN EFFECT...NONE.

SYNOPTIC OVERVIEW...STAGNANT UPPER PATTERN CONTINUES CONSISTING OF LARGE AMPLITUDE UPPER RIDGE OVER WESTERN NORTH AMERICA AND CUTOFF LOW OVER QUEBEC. SEVERAL MORE POWERFUL DISTURBANCES OVER THE EASTERN PACIFIC LOOK TO AMPLIFY THE RIDGE FURTHER THROUGH MID-WEEK AT LEAST. AT THE SURFACE, A SHARP FRONT STILL RUNS FROM THE MACKENZIE SOUTHEAST ACROSS SASKATCHEWAN AND INTO THE DAKOTAS, HAVING BEEN DEFLECTED LITTLE BY A 1006 MB LOW NOW OFF IN THE NORTHERN US. A WEAK RIDGE OF HIGH PRESSURE IS MOVING IN BEHIND THE LOW FROM THE NWT INTO THE EASTERN PRAIRIES FOR THE DAY.

DISCUSSION...

PRAIRIES...THE CLIPPER AFFECTING THE PRAIRIES HAS DEPARTED THE REGION AS QUICKLY AS IT ARRIVED, LEAVING ABOUT 5 CM OF SNOW OVER CENTRAL AND SE MANITOBA ALONG WITH PEAK WIND GUSTS OF AROUND 85 KM/H ACROSS SOUTHERN SASKATCHEWAN THROUGH THE NIGHT. DESPITE A COLD FRONT PASSAGE WITH THE LOW, THERE IS LITTLE TIME FOR COLD AIR TO GO MUCH OF ANYWHERE BEFORE THE FRONT REBOUNDS BACK EASTWARD LATER TODAY. BY TONIGHT, THE FRONT WILL ONCE AGAIN BE ROUGHLY ALONG THE SK/MB BORDER AS ANOTHER LOW FORMS OVER GREAT SLAVE LAKE. THE STILL AMPLIFYING UPPER RIDGE LOOKS TO PUSH THIS NEXT CLIPPER ON A TRACK SLIGHTLY NORTHEAST OF YESTERDAY'S FOR TUESDAY INTO TUESDAY NIGHT. THIS TIME, IT LOOKS TO LEAVE A NARROW SWATH OF ABOUT 5 CM OVER NORTHERN MANITOBA, AND EVEN MILDER TEMPERATURES FOR THE REST OF THE PRAIRIES ON THE DAY.

ARCTIC...VISIBILITIES HAVE BEEN BETWEEN 1/8 AND 2 SM IN THE SOUTHERN KIVALLIQ THIS MORNING WITH RIDGE OUTFLOW WINDS OF 40G60 KM/H CONTINUING OVER THE REGION. THROUGH THE NIGHT THE WINDS HAD LITTLE SUSTAINED IMPACT ON VISIBILITIES. A SHORTWAVE ROLLING THROUGH THE AREA EVEN NUDGED WINDS UP TO 50 KM/H BRIEFLY BUT HAS SINCE DROPPED SOUTHEAST INTO ONTARIO. TEMPERATURES ARE ALSO HOLDING UP IN THE MID -20 DEGREE RANGE, SO ELEMENTS ARE NOT AS WELL LINED UP FOR SUSTAINED BLIZZARD CONDITIONS OVER THE AREA TODAY. EXPECTING TO SEE CONTINUED VISIBILITY REDUCTIONS THROUGHOUT THE DAY BUT SIX HOURS OF SUSTAINED BLIZZARD CONDITIONS IS LOOKING UNLIKELY. HOWEVER, THERE IS ALWAYS THE POSSIBILITY OF A SHORT FUSE BLIZZARD WARNING BEING ISSUED. NAUJAAT ALSO BEARS SOME WATCHING AS SLIGHTLY FUNNELED OUTFLOW WINDS THERE WILL MAKE CONDITIONS A LITTLE MORE FAVOURABLE FOR BLOWING SNOW, BUT AGAIN HOVERING AROUND THE MARGINAL 40 KM/H MARK. AROUND BAFFIN, A STRONG LOW NEAR GREENLAND IS HELPING TO DEVELOP DECENT TROUGHING IN DAVIS STRAIT TODAY WHICH SHOULD BRING SOME WIND AND SUB-SEVERE BLOWING SNOW TO CLYDE RIVER.

SHORTWAVE TROUGH ROUNDING THE TOP OF THE UPPER RIDGE WILL BRING SNOW TO THE LOWER MACKENZIE TODAY AND THEN HELP DEVELOP AFOREMENTIONED GREAT SLAVE LAKE LOW. A FEW CM OF SNOW IS EXPECTED WITH A SMALL CHANCE OF PATCHY PELLETS OR FREEZING RAIN ALONG THE STRONG BAROCLINIC ZONE.

END/MOODIE/MACKAY