111  
FXUS02 KWBC 241600  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1200 PM EDT SUN MAR 24 2019  
 
VALID 12Z WED MAR 27 2019 - 12Z SUN MAR 31 2019  
   
..OVERVIEW
 
 
A CLOSED EASTERN PACIFIC UPPER TROUGH WILL REACH THE WEST MIDWEEK,  
WITH HEIGHT FALLS WORKING EASTWARD OVER THE NATION THU-NEXT SUN.  
SURFACE FRONTS IN THE WEST WILL SUPPORT SOME HEAVY PRECIPITATION  
INCLUDING HEAVY ELEVATION SNOWS, AND 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 SOME ENHANCED RAIN/THUNDERSTORMS IN THOSE  
AREAS LATER IN THE WEEK. THE PATTERN ALSO INCLUDES A RISK OF  
WRAP-AROUND POST-FRONTAL SNOWS ON THE COOLED NORTHWEST PERIPHERY  
OF THE MAIN PRECIPITATION SHIELD.  
   
..GUIDANCE ASSESSMENT/PREFERENCES
 
 
FOR THE BEGINNING OF THE MEDIUM RANGE PERIOD, A MULTI-MODEL BLEND  
SERVED US WELL FOR THE LARGE-SCALE FEATURES (UPPER TROUGH/LOW  
ENTERING THE WEST WITH SOME DOWNSTREAM RIDGING) WHILE  
DE-EMPHASIZING THE SMALL-SCALE DIFFERENCES. THIS BLEND INCLUDED  
THE 00Z GFS, ECMWF, AND UKMET, AS WELL AS THE 00Z EC MEAN AND 06Z  
GEFS MEAN. BY DAY 5 (FRI), PREFERRED THE 00Z DETERMINISTIC GFS  
RATHER THAN THE 06Z RUN, AS MOST OTHER MODELS HAVE COME INTO  
BETTER AGREEMENT WITH THE THE LOCATION/ORIENTATION OF THE CLOSED  
UPPER HIGH IN WESTERN CANADA COMPARED TO YESTERDAY, AND THIS  
PLACEMENT IS UNLIKE THE 06Z GFS. DETERMINISTIC MODELS QUICKLY  
DIVERGE BY DAY 6-7, ESPECIALLY BY DAY 7 (SUN) AS THE 00Z EC  
COMBINES THE NORTHERN AND SOUTHERN STREAMS INTO ONE DEEP UPPER  
TROUGH ACROSS THE CENTRAL/EASTERN CONUS, WHEREAS THE GFS RUNS  
SEPARATE THE STREAMS BUT HAVE BEEN RATHER INCONSISTENT REGARDING  
PLACEMENT OF TROUGHS IN THE CENTRAL TO WESTERN U.S. THUS PREFERRED  
THE EC AND GEFS MEANS, WHICH WERE REASONABLY WELL-ALIGNED, FOR  
THIS MORE UNCERTAIN PORTION OF THE FORECAST.  
   
..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  
IS EXPECTED WED/THU. HEAVY 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. THIS PLUS ANOTHER COLD  
FRONT DROPPING SOUTHWARD OUT OF CANADA IN TANDEM WITH DEEPENING  
LEAD RETURN FLOW FROM THE GULF OF MEXICO WOULD FUEL AN EXPANDING  
RISK OF ENHANCED RAINS/CONVECTION. THE UPPER/MIDDLE MISSISSIPPI  
VALLEY (WHERE FLOODING IS ONGOING) IS CURRENTLY FORECAST TO  
RECEIVE RAINFALL BY THU-FRI, WITH RAIN EXPECTED IN THE LOWER  
MISSISSIPPI VALLEY BY SAT. UNCERTAINTY REMAINS REGARDING HEAVIEST  
RAINFALL AMOUNTS/PLACEMENT, BUT THE GUIDANCE SIGNAL FOR  
DEVELOPMENT CONTINUES TO GROW. IN THE COLD AIR BEHIND THE  
AFOREMENTIONED COLD FRONT COMING FROM CANADA, LATE-SEASON SNOW IS  
POSSIBLE IN THE NORTHERN/CENTRAL PLAINS TO MIDWEST.  
 
WARMER THAN AVERAGE TEMPERATURES ARE EXPECTED TO PREVAIL ACROSS  
THE PLAINS/MS VALLEY BEFORE THE SERIES OF COLD FRONTS DROPPING  
SOUTH THROUGH THOSE AREAS CHANGES THE REGIME TO COOLER THAN  
AVERAGE TEMPERATURES. THE EASTERN SEABOARD COULD HAVE ABOVE NORMAL  
TEMPERATURES NEXT WEEKEND AHEAD OF THESE COLD FRONTS.  
 
TATE/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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