680  
FXUS02 KWBC 160541  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
140 AM EDT SAT MAR 16 2019  
 
VALID 12Z TUE MAR 19 2019 - 12Z SAT MAR 23 2019  
   
..OVERVIEW
 
 
A BLOCKING MID/UPPER-LEVEL RIDGE INITIALLY CENTERED FROM THE  
PACIFIC NORTHWEST TO WESTERN CANADA EARLY NEXT WEEK IS FORECAST TO  
VERY SLOWLY SHIFT EASTWARD THROUGH THE FORECAST PERIOD WHILE A  
MEAN UPPER-LEVEL TROUGH VERY INITIALLY ACROSS THE GREAT  
LAKES/NORTHEAST SLOWLY LIFTS OUT. STRONG WESTERLY FLOW ACROSS THE  
NORTH CENTRAL PACIFIC WILL SPLIT AS IT ENCOUNTERS THE RIDGE, WITH  
SOME SHORTWAVE ENERGY DIRECTED NORTH INTO THE HIGHER LATITUDES OF  
CANADA AND THE REST SEPARATING INTO THE SOUTHERN STREAM. STRONGER  
HEIGHT FALLS MAY APPROACH THE PACIFIC NORTHWEST BY LATE NEXT WEEK  
AS THE UPPER RIDGE AXIS SHIFTS EAST TO TOWARD THE HIGH PLAINS.  
 
   
..GUIDANCE ASSESSMENT/PREFERENCES
 
 
MODELS/ENSEMBLES SHOW ABOVE AVERAGE AGREEMENT AT THE LARGER SCALES  
THROUGH THE PERIOD. SOME DIFFERENCES REMAIN WHEN IT COMES TO THE  
DETAILS OF SPECIFIC SYSTEMS, BUT GUIDANCE OVER THE PAST DAY HAS  
SHOWN SOME TRENDS WORTH NOTHING. MODELS HAVE TRENDED MORE  
AMPLIFIED WITH SHORTWAVE ENERGY DIGGING INTO THE MIDWEST TUE-WED.  
THE GFS HAS GENERALLY LAGGED THE MAJORITY OF OTHER GUIDANCE ON  
THIS TREND WHILE THE FV3 HAS GENERALLY BEEN CLOSE TO THE  
CONSENSUS. FARTHER WEST, THE TREND HAS ALSO BEEN TOWARD THE DEEPER  
SOLUTIONS WITH SOUTHERN STREAM ENERGY REACHING CALIFORNIA BY WED,  
WITH THE GFS ALSO LAGGING TO SOME EXTEND ON THIS TREND. FINALLY,  
MODELS SHOW BROAD AGREEMENT THAT AN AMPLIFIED TROUGH SHOULD  
APPROACH THE PACIFIC NORTHWEST BY NEXT WEEKEND, ALTHOUGH GIVEN THE  
TIME FRAME SOLUTIONS DIFFER ON THE PRECISE TIMING, AMPLITUDE, AND  
STRUCTURE OF THIS FEATURE. GIVEN THESE CONSIDERATIONS, A BLEND OF  
THE ECMWF/CMC/UKMET/FV3-GFS WAS USED AS A FORECAST STARTING POINT  
DURING DAYS 3-5 (TUE-THU), WITH MORE WEIGHT SHIFTED TOWARD THE  
ECENS AND NAEFS ENSEMBLE MEANS DURING DAYS 6-7 (FRI-SAT).  
 
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
WIDESPREAD AND POTENTIALLY HEAVY RAINS SHOULD BE ONGOING TUE-WED  
ACROSS THE SOUTHERN HALF OF THE FLORIDA PENINSULA AS A WAVE OF LOW  
PRESSURE MOVES ALONG A SURFACE FRONT STALLED SOUTH OF THE STATE.  
FARTHER WEST, THE THE PACIFIC SYSTEM TRACKING INTO CALIFORNIA  
SHOULD SPREAD RAIN AND HIGH ELEVATION SNOW INTO THE SIERRA NEVADA,  
GREAT BASIN, AND CENTRAL/SOUTHERN ROCKIES BY NEXT WED-FRI, WITH  
SOME LOCALIZED ENHANCEMENT OF PRECIPITATION OVER FAVORED TERRAIN  
POSSIBLE. MOISTURE INCREASING AHEAD OF THE SYSTEM BY FRI MAY ALSO  
BRING AN INCREASE IN SHOWERS AND THUNDERSTORMS TO PORTIONS OF THE  
SOUTHERN PLAINS, WITH LOCALLY HEAVY RAIN POSSIBLE. FINALLY, THE  
STRONGER HEIGHT FALLS AND A COLD FRONT APPROACHING THE PACIFIC  
NORTHWEST BY FRI-SAT MAY BRING A RETURN OF RAINS AND MOUNTAIN  
SNOWS TO THAT AREA.  
 
THE EASTERN U.S. WILL BEGIN THE FORECAST PERIOD WITH CHILLY  
TEMPERATURES BENEATH THE BROAD UPPER TROUGH (HIGHS 5 TO 10 DEG F  
BELOW AVERAGE), BUT THESE SHOULD GRADUALLY MODERATE TO NEAR  
SEASONAL AVERAGES BY THU. MEANWHILE, HIGH TEMPERATURES WILL BE 5  
TO 15 DEG ABOVE AVERAGE TUE-WED FROM THE PACIFIC NORTHWEST TO THE  
NORTHERN ROCKIES, AND THESE ANOMALIES WILL SPREAD EAST INTO THE  
MIDWEST BY NEXT WEEKEND.  
 
RYAN  
 
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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