631  
FXUS02 KWBC 050648  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
147 AM EST TUE FEB 05 2019  
 
VALID 12Z FRI FEB 08 2019 - 12Z TUE FEB 12 2019  
   
..OVERVIEW
 
 
UPPER RIDGING WILL DOMINATE THE AREA JUST WEST OF THE GULF OF  
ALASKA AS WELL AS ACROSS THE FLORIDA STRAITS. THIS WILL FAVOR  
RENEWED TROUGHING ALONG THE WEST COAST AND BROAD WSW FLOW ALOFT  
THROUGH THE EAST.  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT AND PREFERENCES
 
 
18Z GFS AND 12Z ECMWF CLUSTERED NEAR THEIR ENSEMBLE MEANS THROUGH  
MOST OF THE PERIOD, AND A BLEND OFFERED A GOOD STARTING POINT.  
SPREAD INCREASED FIRST OVER BRITISH COLUMBIA ON SATURDAY WITH THE  
DEPTH/TRACK OF A FORMING UPPER LOW AND THEN AGAIN BY NEXT MON/TUE  
SOUTH OF THE GULF OF ALASKA AS THE UPPER RIDGING WOBBLES WESTWARD.  
THE ECMWF ENSEMBLE MEAN HAS GENERALLY BEEN THE LEADER IN THE  
PATTERN FOR SEVERAL DAYS AND OPTED TO GIVE THE MAJORITY WEIGHTING  
TO IT VS THE 18Z GEFS MEAN, WHICH HAS BEEN SUBJECT TO QUITE A BIT  
OF INCONSISTENT RUNS. AFTER A FAIRLY DEEP SYSTEM EXITS THROUGH  
ONTARIO FRIDAY THERE WILL BE A DEARTH OF DEEP SYSTEMS OVER THE  
CONUS, BUT THE PARADE OF UPPER HEIGHT FALLS INTO/THROUGH THE WEST  
WILL KEEP THAT AREA ACTIVE.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
COLD FRONT IN THE EAST WILL PUSH THE WELL ABOVE AVERAGE  
TEMPERATURES OUT TO SEA TO BE REPLACED BY NEAR AVERAGE TO COLDER  
THAN AVERAGE READINGS FOR THE WEEKEND. FROM MT/HIGH PLAINS TO THE  
UPPER MIDWEST TEMPERATURES WILL REMAIN WELL BELOW AVERAGE ON THE  
NORTH SIDE OF AN ARCTIC FRONT THAT WILL LINGER NEAR THE DIVIDE.  
THE REST OF THE WEST WILL MOSTLY SEE BELOW AVERAGE TEMPERATURES  
DUE TO THE PERSISTENT TROUGHING. SOME MODERATING IN TEMPERATURES  
IS LIKELY IN THE EAST NEXT WEEK AHEAD OF ANOTHER WEAK SYSTEM.  
 
LAKE-EFFECT SNOWS WILL RESUME FRIDAY INTO SATURDAY AS COLDER AIR  
WRAPS AROUND THE DEPARTING SURFACE LOW. LATE THIS WEEKEND AND INTO  
EARLY NEXT WEEK, ANOTHER ROUND OF POTENTIALLY HEAVY PRECIPITATION  
WILL SPREAD OUT OF THE PLAINS INTO THE MID-MS AND TN VALLEYS VIA  
THE COMBINATION OF ANOTHER WEAK IMPULSE OUT OF THE ROCKIES AND A  
SLOW SURGE OF MOISTURE ATOP A WARM FRONT ALONG THE GULF COAST.  
THROUGH THE WEST, SEVERAL SYSTEMS WILL BRING GENERALLY LIGHT TO  
MODEST AMOUNTS OF RAIN/SNOW TO THE REGION, ESPECIALLY FROM CENTRAL  
CA/SIERRA NORTHWARD TO OREGON.  
 
FRACASSO  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION AND WINTER WEATHER OUTLOOK  
PROBABILITIES ARE FOUND AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
 

 
 
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