753  
FXUS02 KWBC 060645  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
144 AM EST WED FEB 06 2019  
 
VALID 12Z SAT FEB 09 2019 - 12Z WED FEB 13 2019  
 
...OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT AND  
PREFERENCES...  
 
WESTERN TROUGHING WILL SLOWLY TRANSLATE EASTWARD BY THE MIDDLE OF  
NEXT WEEK AS RIDGING OVER FLORIDA SLIPS TOWARD THE GREATER  
ANTILLES. UPPER RIDGING JUST WEST OF THE GULF OF ALASKA WILL  
MAINTAIN THE GENERAL NORTHERLY FLOW ALOFT THROUGH THE PACIFIC  
NORTHWEST. THE MODELS/ENSEMBLES WERE IN REASONABLE AGREEMENT ON  
THE LONGWAVE PATTERN BUT CONTINUE TO HAVE TROUBLE RESOLVING THE  
SPLIT FLOW AROUND THE UPPER HIGH UPSTREAM (UNDERNEATH THE RIDGE  
AND TO ITS NORTHWEST THROUGH WESTERN CANADA). THAT PATTERN  
ORIENTATION YIELDS BELOW AVERAGE CONFIDENCE IN SYSTEM TRACK/TIMING  
REGARDLESS OF THE APPARENT MODEL AGREEMENT. THUS, A BLEND OF THE  
CLOSEST-CLUSTERING MEMBERS TO AN ACCEPTABLE EVOLUTION--MOSTLY NEAR  
THE WELL-PERFORMING ECMWF ENSEMBLE MEAN--DROVE THE FORECAST AGAIN  
TODAY. THIS INCLUDED THE 12Z ECMWF WITH SOME AGREEMENT BY THE 12Z  
GFS LATER IN THE PERIOD.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
MUCH BELOW AVERAGE TEMPERATURES WILL REMAIN ANCHORED OVER THE  
NORTHERN HIGH PLAINS THROUGHOUT THE MEDIUM RANGE PERIOD, NORTH 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 WITH SLIGHTLY BELOW AVERAGE TEMPERATURES IN  
THE UPPER MIDWEST. ANOTHER BRIEF SURGE OF ABOVE AVERAGE  
TEMPERATURES WILL PRECEDE A FRONTAL SYSTEM TUE/WED AS A SURFACE  
LOW LIFTS TOWARD THE GREAT LAKES/NORTHEAST.  
 
LATE THIS WEEKEND AND INTO EARLY NEXT WEEK, ANOTHER ROUND OF  
POTENTIALLY HEAVY PRECIPITATION WILL SPREAD INTO THE  
MID-MISSISSIPPI AND TENNESSEE VALLEYS VIA THE COMBINATION OF A  
LEAD WEAK IMPULSE OUT OF THE ROCKIES AND A SLOW SURGE OF MOISTURE  
ATOP A WARM FRONT ALONG THE GULF COAST. THROUGH THE WEST, LOW  
PRESSURE SYSTEMS WILL BRING SEVERAL ROUNDS OF LIGHT TO MODERATE  
VALLEY RAIN/MOUNTAIN SNOW TO THE REGION, ESPECIALLY FROM CENTRAL  
CA/SIERRA NORTHWARD TO OREGON. BACK TO THE EAST, ENSEMBLES  
CONTINUE TO FOCUS PRECIPITATION ON TN/KY NEXT WEEK.  
 
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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