912  
FXUS02 KWBC 150648  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
247 AM EDT SUN SEP 15 2019  
 
VALID 12Z WED SEP 18 2019 - 12Z SUN SEP 22 2019  
   
..OVERVIEW AND GUIDANCE EVALUATION/PREFERENCES
 
 
MODELS AND ENSEMBLES OFFER A REASONABLY SIMILAR AND AMPLIFIED  
LARGER SCALE PATTERN OVER THE LOWER 48 AND VICINITY FOR MUCH OF  
THE UPCOMING MEDIUM RANGE PERIOD. FORECAST SPREAD AND UNCERTAINTY  
FOR SMALL-MID SCALE EMBEDDED FEATURES HAS ALSO IMPROVED,  
BOLSTERING FORECAST CONFIDENCE. FLOW WILL BE HIGHLIGHTED BY AN  
AMPLIFIED AND UNSETTLING MEAN UPPER TROUGH OVER THE WEST AND  
SPRAWLING/HOT LATE SUMMER EAST-CENTRAL STATES UPPER RIDGING. THE  
WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A  
COMPOSITE BLEND OF THE 18 UTC GFS/GEFS, 12 UTC ECMWF/ECMWF  
ENSEMBLE MEANS AND THE NATIONAL BLEND OF MODELS.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
TROPICAL STORM HUMBERTO CONTINUES TO BE FORECAST BY NHC TO TURN  
EAST AND AWAY FROM THE SOUTHEAST COAST AS A HURRICANE OVER THE  
NEXT COUPLE OF DAYS.  
 
A SERIES OF AMPLIFIED UPPER TROUGHS AND LEAD SURFACE FRONTAL  
SYSTEMS WILL DIG INTO THE WEST THEN EJECT NORTHEASTWARD OVER THE  
NORTH-CENTRAL U.S. THIS WEEK. THIS WILL BRING WIDESPREAD RAINS  
(SOME VERY HIGH ELEVATION SNOW) TO THE NORTHWEST. ACTIVITY SPREADS  
SOUTH INTO NORTHERN CA AND OUT THROUGH THE NORTHERN/CENTRAL GREAT  
BASIN/ROCKIES. AN ORGANIZED CONVECTIVE FOCUS WITH LOCALLY HEAVY  
DOWNPOURS SHIFTS TO THE UPPER MIDWEST WITH LEADING SHORTWAVE  
ENERGY/HEIGHT FALL PASSAGE INTO MIDWEEK AND MODEST/LOCAL POTENTIAL  
WITH SOUTHWARD AND EASTWARD PROGRESSING SURFACE FRONTAL SYSTEMS.  
INCREASED MOISTURE INFLOW MAY LEAD TO SOME RECORD HIGH MINIMUM  
TEMPERATURES. THE UPSTREAM PATTERN MEANWHILE RELOADS AGAIN OVER  
THE WEST TO REACH THE NORTH-CENTRAL STATES AGAIN NEXT WEEKEND.  
 
IN THIS PATTERN EXPECT SUBTROPICAL MOISTURE OUT OF MEXICO ON  
SOUTHWEST FLOW ALOFT OVER THE SOUTHWEST/FOUR CORNERS STATES. THIS  
MOISTURE MAY FUEL SUPPORT FOR AFOREMENTIONED POTENTIAL CONVECTION  
DOWNWIND INTO THE NORTH-CENTRAL U.S. STRONG RIDGING DOWNSTREAM  
OVER THE EAST-CENTRAL U.S. WILL FAVOR WELL-ABOVE AVERAGE  
TEMPERATURES NEXT WEEK WITH SOME NEAR RECORD DEEP SOUTH HEAT.  
NEARBY IN THE WESTERN GULF OF MEXICO, A TROUGH/WAVE ASSOCIATED  
WITH AN UPPER LOW FAVORS A POTENTIALLY HEAVY OVER COASTAL TEXAS  
MIDWEEK AND WEAK STEERING ALOFT MAY ALLOW THIS AREA OF RAIN TO  
PERSIST THROUGH LATE WEEK.  
 
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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