214   
FOCN45 CWWG 291300  
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM  
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CST THURSDAY  
DECEMBER 29 2011.  
  
DISCUSSION...FREEZING RAIN WARNINGS CENTRAL ALBERTA.  
  
FAIRLY ZONAL FLOW ACROSS THE PRAIRIES TODAY. SURFACE LOW CENTRAL AB  
WITH WRM FNT EXTENDING SEWD. LOW WILL TRACK SEWD ALONG THIS  
BARCOCLINIC ZONE, SK..PCPN TYPING AND RISK OF FZRA IN SWRN SK THIS AM  
AND THEN CNTRL PORTIONS THIS AFTN. PCPN MOSTLY RAIN NOW. THERE IS A  
RISK OF FZRA ALONG THE FNT HOWEVER SFC TEMPS RAPIDLY RISE TO ABV  
FREEZING. PERHAPS AS THE FRONT MOVES EWD INTO COLDER AIR, THERE IS A  
GREATER RISK. LATE AFTN HOWEVER MOST OF THE WARM AIR ALOFT PULLS OUT  
AND PCPN BECOMES MOSTLY SNOW. FCST DIFFICULTY IS THEN CLEARLY TIMING  
OF PHASE CHANGE AND RISK OF FZRA AND WHETHER IT NEEDS TO BE WARNED.  
  
MB...BOUNDRY LAYER MOISTURE IS MAIN PROB TODAY..ST/FOG AND TIMING OF  
CLEARING AND THUS DAYTIME HIGHS.  
  
AB..SNOW ALONG THE MOUNTAINS FROM THE ELBOW TO THE US BORDER - MODELS  
INDICATE AN AREA OF SNOW ON THE BC SIDE OF THE MOUNTAINS WITH SOME OF  
THIS SNOW MAKING ITS WAY INTO ALBERTA WITH POTENTIAL FOR 5 TO 10 CM.  
FZRA EVIDENT ON RADAR THIS MORNING ALONG THE TROWAL ASSOCIATED WITH  
THE LOW IN SOUTHERN ALBERTA. AS THE LOW PUSHES EAST THE PRECIP WILL  
TURN TO SNOW NEAR THE SK BORDER. COOL AIR WITH A SLIGHT BIT OF  
SURFACE HEATING WILL CREATE A WELL MIXED BOUNDARY LAYER UP TO 750MB  
FOR MUCH OF SRN AB THIS AFTERNOON. THIS DEEP PBL COULD RESULT IN  
WINDS UP TO 50KT MIXING TO THE SURFACE FROM CALGARY SOUTH. NERN AB  
IS EXPECTED TO RECEIVE 5-10CM OF SNOW AS THE SYSTEM PUSHES EAST.  
WITH SNOW RATIOS UP TO 20:1 WARNING CRITERIA COULD POTENTIALLY BE  
REACHED.  
  
WRN ARCTIC... SNOW WILL SPREAD ALONG THE MACKENZIE AND GREAT SLAVE  
LAKE AREAS TODAY. GENERALLY 2-4CM ARE EXPECTED. WITH HIGH SNOW  
TO WATER RATIOS AND A FAIRLY DEEP DENDRITIC GROWTH LAYER IN THE  
SOUTHERN NWT SNOWFALL AMOUNTS COULD CREEP INTO THE 5-10CM RANGE.  
THE DURATION IS NOT EXPECTED TO BE VERY LONG SO AMOUNTS ARE NOT  
EXPECTED TO REACH WARNING CRITERIA.  
  
ERN ARCTIC...SOME LIGHT SNOW AND BLSN ALONG THE COAST. BAFFIN ISLAND  
PRETTY QUIET WITH NIL SIG WX.  
  
END/SLIPEC/FOUGERE  
 
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