570  
FXUS02 KWBC 250607  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
207 AM EDT MON MAR 25 2019  
 
VALID 12Z THU MAR 28 2019 - 12Z MON APR 01 2019  
   
..OVERVIEW
 
 
A POTENT/CLOSED EASTERN PACIFIC UPPER TROUGH WILL APPROACH THE  
WEST COAST MIDWEEK, WITH THESE SOUTHERN STREAM HEIGHT FALLS  
WORKING EASTWARD OVER THE NATION THU-SUN. SURFACE FRONTS IN THE  
WEST WILL SUPPORT SOME HEAVY PRECIPITATION INCLUDING HEAVY  
ELEVATION SNOWS. LOW DEVELOPMENTS IN THE PLAINS AND SUBSEQUENT  
MOVEMENT THROUGH THE MS VALLEY/MIDWEST WILL COMBINE WITH A SURGE  
OF DEEPENING MOISTURE/WARMTH FROM THE GULF OF MEXICO, WHICH MAY  
FUEL ENHANCED RAIN/THUNDERSTORMS IN THOSE AREAS LATE WEEK INTO THE  
WEEKEND. THE FRONTS/WAVES AND MODERATING PRECIPITATION WILL MAINLY  
EXIT THE EAST SUN. THIS PATTERN ALSO INCLUDES A RISK OF HEAVY  
SNOWS THU-SUN ON THE COOLED NORTHWEST TO NORTHERN PERIPHERY OF THE  
PRECIPITATION SHIELD FROM THE N-CENTRAL ROCKIES/PLAINS TO THE  
MIDWEST/GREAT LAKES AND NORTHERN NEW ENGLAND.  
   
..GUIDANCE ASSESSMENT/PREFERENCES
 
 
A MULTI-MODEL BLEND SEEMS QUITE REASONABLE THU INTO SAT FOR THE  
LARGER-SCALE FEATURES (UPPER TROUGH/LOW ENTERING THE WEST WITH  
SOME DOWNSTREAM RIDGING ALL UNDERNEATH A EAST-CENTRAL CANADIAN  
UPPER TROUGH) WHILE DE-EMPHASIZING THE SMALL-SCALE DIFFERENCES.  
THIS BLEND INCLUDES THE LATEST GFS, ECMWF, AND UKMET THAT CLUSTER  
WELL WITH THE LATEST GEFS/ECMWF ENSEMBLE MEAN DURING THIS TIME  
PERIOD. FORECAST SPREAD AND MODEL RUN TO RUN CONTINUITY ISSUES  
BECOME MORE PROBLEMATIC OVER THE WEEKEND AND NEXT MON. ACCORDINGLY  
PREFERRED A BLEND OF THE MORE COMPATABLE GEFS/ECMWF ENSEMBLE  
MEANS, WITH MORE WEIGHT ASSIGNED TO THE ECMWF ENSEMBLES THAT  
MAINTAIN SOMEWHAT BETTER WPC CONTINUITY.  
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
WITH THE UPPER TROUGH/LOW APPROACHING THE WEST, A COUPLE OF FRONTS  
WILL MAKE THEIR WAY THROUGH THE WEST AND SOME HEAVY PRECIPITATION  
EXPECTED INTO THU. SOME HEAVIER VALLEY RAIN/MOUNTAIN SNOWS WILL  
THREATEN NORTHERN CALIFORNIA/OREGON THROUGH THE NORTHERN ROCKIES,  
WITH HEAVY SNOW FORECAST FOR THE CENTRAL ROCKIES BY THU/FRI. AS  
THE TROUGH ENERGY EJECTS OUT THROUGH THE WEST, IT IS EXPECTED TO  
INDUCE CYCLO/FRONTOGENESIS IN THE PLAINS THEN MISSISSIPPI VALLEY,  
MIDWEST AND NORTHEAST. THIS PLUS A NORTHERN STREAM COLD FRONT  
DROPPING SOUTHWARD OUT OF CANADA WILL WORK IN TANDEM WITH  
DEEPENING LEAD RETURN FLOW FROM THE GULF OF MEXICO TO FUEL AN  
EXPANDING RISK OF ENHANCED RAINS/CONVECTION. IN THE COLD AIR  
BEHIND THE AFOREMENTIONED COLD FRONT COMING FROM CANADA,  
LATE-SEASON SNOW IS POSSIBLE IN THE NORTHERN/CENTRAL PLAINS TO  
MIDWEST/GREAT LAKES THEN NORTHERN NEW ENGLAND.  
 
SCHICHTEL  
 
ADDITIONAL 3-7 DAY HAZARDS INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDICES ARE 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  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 
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