661  
FXUS02 KWBC 041601  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1100 AM EST MON FEB 04 2019  
 
VALID 12Z THU FEB 07 2019 - 12Z MON FEB 11 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 WITH A STORM TRACK  
NORTHEASTWARD THROUGH THE GREAT LAKES/ST. LAWRENCE VALLEY.  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT AND PREFERENCES
 
 
THERE IS CLOSE AGREEMENT BETWEEN THE 00Z ECMWF/06Z GFS AND THEIR  
ENSEMBLES THURSDAY-SATURDAY WITH DEEP TROUGHING EJECTING INTO THE  
PLAINS AND EVENTUALLY LIFTING INTO EASTERN CANADA THIS WEEKEND,  
WHILE AT THE SAME TIME A TROUGH/CLOSED LOW DROPS SOUTHWARD ALONG  
THE WEST COAST. FOR THIS PERIOD (DAY 3-5), A MAJORITY  
DETERMINISTIC BLEND BETWEEN THE LATEST RUNS OF THE ECMWF/GFS AND  
THE PARALLEL FV3-GFS WORKED WELL FOR A STARTING POINT. THIS  
WEEKEND, THERE IS ALSO GOOD AGREEMENT WITH CANADIAN HIGH PRESSURE  
SLIDING SOUTHEASTWARD INTO THE MID-ATLANTIC, WHILE A WEEK SYSTEM  
ATTEMPTS TO LIFT INTO THE GREAT LAKES BY MONDAY. THE BIGGEST  
DIFFERENCES IN THE MEDIUM RANGE ARISE BY DAYS 6 AND 7, MAINLY IN  
THE DETAILS OF AN INTERACTION BETWEEN THE WESTERN U.S. TROUGH, AND  
SHORTWAVE ENERGY DROPPING INTO THE EASTERN PACIFIC. THE ENSEMBLE  
MEAN SOLUTIONS (GEFS/ECENS) COMPRISED THE MAJORITY OF THE BLEND  
FOR THE WPC FRONTS/PRESSURES DAYS 6 AND 7, WITH SMALLER  
CONTRIBUTIONS FROM THE DETERMINISTIC ECMWF MAINLY DUE TO SLIGHTY  
BETTER AGREEMENT WITH THE MEANS, AND OVERALL BETTER RUN-TO-RUN  
CONTINUITY. ONLY MINOR ADJUSTMENTS WERE NEEDED TO THE PREVIOUS WPC  
CYCLE OF MEDIUM RANGE PROGS.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
WELL ABOVE AVERAGE TEMPERATURES IN THE SOUTHEAST/EAST (WITH RECORD  
HIGHS POSSIBLE) THURSDAY WILL BE REPLACED BY NEARER TO AVERAGE  
TEMPERATURES AS THE COLD FRONT CLEARS THE EAST COAST. FROM MT 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.  
 
A SWATH OF HEAVIER PRECIPITATION (MOSTLY RAIN BUT PERHAPS NORTHERN  
FRINGE SNOW) WILL SPREAD EAST OF THE PLAINS THROUGH THE OH/TN  
VALLEYS AND INTO THE NORTHERN MID-ATLANTIC/NORTHEAST ON THURSDAY.  
FRONTAL/WARM-SECTOR RAINS MAY BE LOCALLY HEAVY ON THURSDAY BUT  
TREND LIGHTER ON FRIDAY AS THE SYSTEM WEAKENS AND LOOSES SUPPORT.  
TO THE NORTH, SOME LIGHT ACCUMULATING SNOW IS POSSIBLE ACROSS THE  
UPPER GREAT LAKES, WITH LAKE-EFFECT SNOWS RESUMING FRIDAY INTO  
SATURDAY WITH COLD AIR ADVECTION BEHIND THE MAIN SURFACE LOW AND  
AHEAD OF THE HIGH PRESSURE. 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 ANOTHER WEAK  
IMPULSE OUT OF THE ROCKIES AND TO THE NORTH OF A WARM FRONT ALONG  
THE GULF COAST.  
 
SANTORELLI/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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