824  
FXUS02 KWBC 211526  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1026 AM EST MON JAN 21 2019  
 
VALID 12Z THU JAN 24 2019 - 12Z MON JAN 28 2019  
   
..OVERVIEW
 
 
GUIDANCE SHOWS AN AMPLIFIED UPPER PATTERN FEATURING AN EASTERN  
PACIFIC/WEST COAST RIDGE AND AN EXPANSIVE EAST-CENTRAL NORTH  
AMERICAN TROUGH. THE OVERALL MEAN PATTERN APPEARS TO HAVE FAIRLY  
HIGH PREDICTABILITY, BUT EMBEDDED SHORTWAVES REMAIN MORE DIFFICULT  
TO RESOLVE. THE RIDGE MAY RETROGRADE A BIT NEXT WEEK AND  
TELECONNECTIONS FAVORS AN INCREASED POTENTIAL FOR POSITIVELY  
TILTED TROUGHING TO THEN DEVELOP OVER THE WEST.  
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS DERIVED FROM A BLEND OF  
REASONABLY WELL CLUSTERED GUIDANCE FROM THE 00 UTC GEFS/ECMWF  
ENSEMBLE MEANS. THE 06 UTC GEFS IS NOT AS WELL CLUSTERED.  
DETERMINISTIC MODELS OFFER EVEN MORE RUN TO RUN VARIANCE DAYS 4-7  
AND THEIR LESS CERTAIN DETAIL WAS DOWNPLAYED.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
FRONTAL WAVES WILL FOCUS AREAS OF SIGNIFICANT PRECIPITATION IN THE  
EAST THU WITH THE BEST SNOW POTENTIAL OVER INTERIOR NEW ENGLAND.  
THE GREAT LAKES WILL SEE EPISODES OF SNOW ALL WEEK FROM A  
COMBINATION OF PASSING SYSTEMS AND LAKE ENHANCEMENT, WITH OTHER  
AREAS EAST OF THE ROCKIES SEEING SOME PRECIPITATION WITH LOW  
PRESSURE/FRONTAL PASSAGES. ANOTHER ORGANIZED PRECIPITATION THREAT  
OVER THE EAST EXISTS THIS WEEKEND INTO NEXT MON. WHILE FORECAST  
CONFIDENCE IN COVERAGE/INTENSITY HAS BEEN LESS THAN AVERAGE, THE  
00 UTC GEFS/ECMWF ENSEMBLE MEANS ARE NOW IN BETTER AGREEMENT WITH  
THE DEVELOPMENT OF A MID-ATLANTIC COASTAL LOW. THE RAIN-SNOW LINE  
SHOULD EXTEND FAIRLY FAR SOUTHWARD GIVEN THE COLD PATTERN BECOMING  
ESTABLISHED OVER THE EASTERN HALF OF THE COUNTRY. MEANWHILE AT  
LEAST A COUPLE SHORTWAVES/FRONTS AND TRAILING HIGH PRESSURE SHOULD  
BRING PERIODS OF SNOW TO PARTS OF THE NORTHERN AND CENTRAL ROCKIES  
WITH MOST ACTIVITY LIKELY TO BE IN THE LIGHT-MODERATE RANGE.  
 
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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