851  
FXUS02 KWBC 080701  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
200 AM EST SAT DEC 08 2018  
 
VALID 12Z TUE DEC 11 2018 - 12Z SAT DEC 15 2018  
   
..PATTERN/WEATHER HIGHLIGHTS AND HAZARDS
 
 
A DEPARTING COASTAL LOW OFF THE CAROLINAS TUESDAY OFFERS A  
LINGERING MARITIME GALE HAZARD BEING FOLLOWED BY OPC. IN THE WAKE  
OF THE LOW, COOL TEMPERATURE REINFORCING/DRY HIGH PRESSURE SURGES  
DIG THROUGH THE CENTRAL AND EASTERN U.S. INTO NEXT MIDWEEK.  
 
OUT WEST, PRECIPITATION WILL PERIODICALLY INCREASE EARLY-MID NEXT  
WEEK AND INTO NEXT WEEKEND AS HEIGHTS FALL WITH A SUCCESSION OF  
APPROACHING SHORTWAVES/FRONTAL SYSTEMS. HIGHER TERRAIN OF WESTERN  
OREGON/WASHINGTON HAVE POTENTIAL FOR HEAVIEST PRECIPITATION  
AMOUNTS (RAIN AND MOUNTAIN SNOW) AS SHOTS OF DYNAMIC SNOWS DRIVE  
INLAND INTO FAVORED NORTH-CENTRAL GREAT BASIN/ROCKIES TERRAIN.  
SOME OF THIS ENERGY WILL PROGRESS EASTWARD OVER THE  
NORTH-CENTRAL THROUGH NORTHEASTERN US TO SUPPORT MODEST NORTHERN  
STREAM SNOWS. POTENTIAL FOR SUBSTANTIAL ENERGY INFUSION INTO AN  
EMERGING SOUTHERN STREAM LATER NEXT WEEK MEANWHILE OFFERS  
POTENTIAL FOR DEEPER SYSTEM GENESIS AND THE THREAT FOR MORE  
WIDESPREAD AND GULF OF MEXICO MOISTURE FUELED HEAVY PRECIPITATION  
OVER THE SOUTH-CENTRAL U.S. THEN NORTHEASTWARD ACROSS THE EASTERN  
SEABOARD INTO NEXT WEEKEND INCLUDING A THREAT OF SNOW/ICE ON THE  
COLDER NORTHERN PERIPHERY OF AN EXPANDING AND INTENSIFYING  
PRECIPITATION SHIELD.  
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A  
BLEND OF THE LATEST GEFS/ECMWF ENSEMBLE MEANS. RECENT  
DETERMINISTIC RUNS GFS/ECMWF HAVE BEEN OFFERED WELL LESS THAN  
STELLAR RUN TO RUN CONSISTENCY. THE ENSEMBLE MEANS HAVE VARIED A  
BIT MORE THAN NORMAL, BUT HAVE BEEN MUCH MORE CONSISTENT WITH THE  
ABOVE MENTIONED SYSTEMS, BUT AMPLE FORECAST SPREAD/UNCERTAINTY  
REMAINS. LATEST GFS/ECMWF RUNS OVERALL TREND BETTER IN LINE WITH  
THE ENSEMBLE MEANS, BUT STILL HAVE SOME SIGNIFICANT EMBEDDED  
SYSTEM TIMING DIFFERENCES.  
 
SCHICHTEL  
 
WPC MEDIUM RANGE 500 MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDEXES 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  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 
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