737  
FXUS02 KWBC 061601  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1100 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 BEGINNING JUST WEST OF THE GULF OF ALASKA  
AND TRANSITIONING SLOWLY EASTWARD WILL MAINTAIN THE GENERAL  
NORTHERLY FLOW ALOFT THROUGH THE PACIFIC NORTHWEST. THE GFS AND EC  
MODELS/ENSEMBLES WERE IN REASONABLE AGREEMENT ON THE GENERAL  
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.THE 00Z GEFS MEAN AND 00Z AND 06Z GFS WERE UTILIZED AS WELL.  
THE 00Z UKMET EVOLVED THE UPPER LOW IN THE EASTERN PACIFIC  
DIFFERENTLY THAN OTHER MODELS, SPLITTING THE LOW AND SENDING  
ENERGY EASTWARD MORE QUICKLY. THIS WAS MUCH LIKE YESTERDAY'S 00Z  
ECMWF, WHICH WAS NOT PREFERRED, AND MODELS HAVE TRENDED AWAY FROM  
THAT SOLUTION. THAT AND THE 00Z CMC WERE EXCLUDED FROM THE MODEL  
PREFERENCE FOR DAY 4 AND BEYOND.  
 
   
..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 IS FORECAST TO SEE BELOW AVERAGE TEMPERATURES DUE TO THE  
PERSISTENT TROUGHING WITH SLIGHTLY BELOW AVERAGE TEMPERATURES IN  
THE UPPER MIDWEST. ANOTHER SURGE OF ABOVE AVERAGE TEMPERATURES IN  
THE SOUTHEAST TO OHIO VALLEY 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 LOWER TO  
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. AS A LOW PRESSURE SYSTEM  
STRENGTHENS IN THE OHIO VALLEY DURING THE MIDDLE OF NEXT WEEK,  
PRECIPITATION IS EXPECTED TO CONTINUE FOR THE TENNESSEE AND OHIO  
VALLEYS. WINTRY PRECIPITATION WILL BE POSSIBLE FOR THE NORTH  
CENTRAL AND NORTHEASTERN U.S. WHERE TEMPERATURES WILL BE COLDER.  
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.  
 
TATE/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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