327  
FXUS02 KWBC 191611  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1210 PM EDT WED SEP 19 2018  
 
VALID 12Z SAT SEP 22 2018 - 12Z WED SEP 26 2018  
 
...HEAVY RAINFALL POTENTIAL ACROSS THE ARKLATEX REGION INTO THE  
OZARKS FOR SATURDAY THROUGH MONDAY...  
 
...CONSIDERABLE COOL DOWN EXPECTED IN THE MIDDLE OF THE COUNTRY  
NEXT WEEK...  
   
..PATTERN OVERVIEW/MODEL GUIDANCE/PREFERENCES
 
 
THE LARGE SCALE PATTERN DURING THE EXTENDED PERIODS DEPICTS A  
TROUGH EXITING THE NORTHEAST, RIDGE EXTENDING FROM THE ATLANTIC TO  
PORTIONS OF THE SOUTHERN TIER STATES WITH AN EASTERLY WAVE  
DRIFTING WESTWARD ACROSS THE GULF OF MEXICO, AND A TROUGH DIGGING  
INTO THE CENTRAL U.S. MODEL GUIDANCE IS FAIRLY REASONABLE WITH  
TYPICAL NOISE OF SMALL TIMING AND PLACEMENT DIFFERENCES. ALTHOUGH  
CONFIDENCE ON THE EXACT AMOUNTS OF QPF EXPECTED ACROSS THE  
SOUTHERN/CENTRAL PLAINS AND OZARK REGION ARE STILL FAIR AT BEST,  
THE SIGNAL FOR HIGHER AMOUNTS HAVE CONTINUED OVER THE LAST FEW  
GUIDANCE CYCLES WHICH SUGGESTS THAT THIS REGION WILL HAVE AN  
INCREASE RISK FOR EXCESSIVE RAINFALL AND FLOODING. PWS HAVE  
CONSISTENTLY BEEN IN THE +2 TO +3 STD. DEV. OVER THIS AREA. WHILE  
THE GUIDANCE VARY WITH HOW QUICKLY THE EASTERLY WAVE WILL SHEAR  
ACROSS THE GULF OF MEXICO, ITS IMPACTS ARE PRIMARILY RESTRICTED TO  
THE OFFSHORE WATERS OF THE GULF. ONE KEY FEATURE WITH A GREAT DEAL  
OF PRECIPITATION UNCERTAINTY IS THE SLOW MOVING SHORTWAVE ACROSS  
THE SOUTHERN PLAINS. THIS AREA BEARS WATCHING DURING THE UPCOMING  
DAYS GIVEN THE POTENTIAL FOR FLOODING RAINS.  
 
THE MEDIUM RANGE FORECAST WAS LED BY THE 00Z/06Z GFS, 00Z  
ECWMF/UKMET/CMC WITH INCREASING WEIGHTING OF THE 00Z GEFS,EC MEANS  
AND NAEFS.  
   
..SENSIBLE WEATHER AND HAZARDS
 
 
A STRONG SIGNAL FOR WIDESPREAD, HIGHER PRECIPITATION PERSISTS FROM  
PORTIONS OF THE SOUTHERN/CENTRAL HIGH PLAINS TO THE OZARK REGION.  
THE CURRENT ANOMALOUS MOISTURE FEED INTO THE DESERT SOUTHWEST WILL  
MERGE OVER THE SOUTH PLAINS WITH POOLED MOISTURE FROM THE GULF OF  
MEXICO, TRIGGERING CONVECTION NEAR A STALLED BOUNDARY AND  
REINFORCED THIS WEEKEND AS A COLD FRONT CROSSES THE ROCKIES AND  
ANOTHER DROPS SOUTH THROUGH THE CENTRAL PLAINS. A MUCH COOLER  
AIRMASS WILL USHER INTO THE NORTHERN-TIER STATES, RESULTING IN  
TEMPERATURES WITHIN THIS REGION TO BE NEAR 15 TO 20 DEGREES BELOW  
SEASONAL NORMAL BY THE MIDDLE OF NEXT WEEK. IF THIS PANS OUT,  
AFTERNOON HIGHS WOULD ONLY BE IN THE LOW TO MID 50S THESE DAYS  
ALLOWING FOR A TRUE FEEL OF AUTUMN.  
 
CAMPBELL  
 
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  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page