035  
FXUS02 KWBC 031600  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1100 AM EST SUN FEB 03 2019  
 
VALID 12Z WED FEB 06 2019 - 12Z SUN FEB 10 2019  
   
..OVERVIEW
 
 
POSITIVE HEIGHT ANOMALY NEAR THE GULF OF ALASKA WILL FAVOR WESTERN  
CONUS TROUGHING WED-SUN AND BROAD SW UPPER FLOW IN THE EASTERN  
STATES. SUBTROPICAL UPPER HIGH WILL DRIFT OUT OF THE BAY OF  
CAMPECHE AND INTO THE FLORIDA STRAITS WHICH WILL LARGELY KEEP THE  
STORM TRACK THROUGH THE MIDEST/GREAT LAKES AND ST. LAWRENCE  
VALLEY.  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT AND PREFERENCES
 
 
ALASKAN AND PACIFIC UPSTREAM FLOW AND NORTHERN/SOUTHERN STREAM  
SEPARATION OVER THE WEST CONTINUES TO BE POORLY RESOLVED BY THE  
MODELS/ENSEMBLES WITH NOTICEABLE RUN-TO-RUN CHANGES. THE ECMWF AND  
ITS ENSEMBLES HAVE BEEN QUITE DIFFERENT THAN THE GFS AND TO A  
LESSER EXTENT GEFS ENSEMBLES, WHILE THE CANADIAN AND ITS ENSEMBLES  
MOSTLY CLUSTERED NEAR THE ECMWF ENSEMBLES. RECENT GFS RUNS IN  
PARTICULAR SEEM QUITE THE OUTLIER UPSTREAM OVER THE NORTHEAST  
PACIFIC AND ALASKA IN BREAKING ENERGY MORE READILY THROUGH THE  
AMBIENT LONGWAVE MID-UPPER LEVEL RIDGE POSITION. PREFER THE  
CLUSTER NEAR THE ECMWF ENSEMBLE MEAN WHICH SHOWED A BIT QUICKER  
EXIT OF A MAIN TROUGH OUT OF THE ROCKIES LATE WED/EARLY THU. THIS  
MAINTAINS GOOD WPC CONTINUITY.  
 
WEATHER HIGHLIGHTS/HAZARDS...  
 
ABOVE AVERAGE TEMPERATURES IN THE SOUTHEAST/EAST (WITH RECORD  
HIGHS POSSIBLE) WILL BE REPLACED BY NEARER TO AVERAGE TEMPERATURES  
AS THE COLD FRONT CLEARS THE EAST COAST, BUT NOT THROUGH FLORIDA  
THANKS TO THE STRONG UPPER RIDGE. IN THE NORTHERN TIER FROM MT TO  
THE UPPER MIDWEST, TEMPERATURES WILL REMAIN WELL BELOW AVERAGE  
BEHIND AN ARCTIC FRONT THAT WILL GET HUNG UP NEAR THE DIVIDE (BUT  
STILL BRING COLD AIR TO THE PACIFIC NORTHWEST VIA NORTHERN STREAM  
HEIGHT FALLS).  
 
STORM TRACK FAVORS SNOW AND LOW ELEVATION RAINS THAT EXIT THE  
ROCKIES MIDWEEK AND ADDITIONAL BUT UNCERTAIN INFLUX OF SHORTWAVE  
IMPULSES WILL KEEP UPSTREAM FLOW INTO THE WEST WINTRY AND  
UNSETTLED. DOWNSTREAM, A SWATH OF HEAVIER PRECIPITATION WILL  
SPREAD ACROSS THE PLAINS THROUGH THE OH VALLEY AND INTO THE  
NORTHERN MID-ATLANTIC/NORTHEAST. THIS WILL INCLUDE A SIGNIFICANT  
HEAVY SNOW/ICE THREAT AROUND THE NORTH/NORTHWEST SIDE OF  
DEVELOPING SURFACE LOWS IN THE ARCTIC AIRMASS. FRONTAL/WARM-SECTOR  
RAINS MAY BE LOCALLY HEAVY FROM THE MID-MS VALLEY THROUGH THE OH  
VALLEY STATES AND NORTHERN MID-ATLANTIC, BUT TREND LIGHTER TO THE  
SOUTH UNDER STRONGER UPPER RIDGING AND WEAKER DYNAMICS. AS THE  
MAIN LOW PULLS AWAY, LAKE-EFFECT SNOW WILL RESUME AT LEAST FRIDAY  
INTO SATURDAY.  
 
FRACASSO/SCHICHTEL  
 
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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