235  
FXUS02 KWBC 020724  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
324 AM EDT TUE OCT 02 2018  
 
VALID 12Z FRI OCT 05 2018 - 12Z TUE OCT 09 2018  
 
...STORMY PATTERN FOR THE WEST/ROCKIES AND A CENTRAL U.S.  
EXCESSIVE RAINFALL THREAT...  
   
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
MODEL AND ENSEMBLE GUIDANCE REMAINS WELL CLUSTERED WITH  
DEVELOPMENT OF A HIGHLY AMPLIFIED WEATHER PATTERN FOR THE NATION  
THIS WEEKEND INTO NEXT WEEK, STRONGLY BOLSTERING FORECAST  
CONFIDENCE. THIS PATTERN OFFERS HEIGHT ANOMALIES OF 2-3 STANDARD  
DEVIATIONS ABOVE/BELOW NORMAL WITH A DIGGING WESTERN U.S. LONGWAVE  
TROUGH SANDWICHED BETWEEN RIDGES OVER THE EASTERN PACIFIC AND THE  
EAST COAST/ATLANTIC OCEAN. A DEEPENING/CLOSED LOW SETS UP OVER THE  
GREAT BASIN REGION AND MULTIPLE WAVES LIFT FROM THE GREAT  
BASIN/SOUTHERN AND CENTRAL ROCKIES INTO THE PLAINS WHERE A DEEP  
LAYERED SOUTHERLY FUNNEL OF GULF OF MEXICO MOISTURE POOLS TO 2+  
STANDARD DEVIATIONS FROM NORMAL INTO/OVER A SLOW MOVING BAROCLINIC  
ZONE. THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED  
FROM A BLEND OF THE GFS/ECMWF AND GEFS/ECMWF ENSEMBLE MEANS THAT  
OFFER A STRONG SIGNAL SUPPORTING THIS THREATENING PATTERN.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
COLDER THAN SEASONAL NORMAL TEMPERATURES AND HIGHLY UNSETTLED/WET  
WEATHER IS EXPECTED AS A PERSISTENT AND HIGHLY AMPLIFIED TROUGH  
MEAN ALOFT SETS UP OVER THE WEST, ESPECIALLY FROM THE EASTERN  
GREAT BASIN/SOUTHWEST TO THE ROCKIES. TERRAIN AND UPSLOPE ENHANCED  
SNOWS WILL SPREAD DOWN OVER THE NORTH-CENTRAL ROCKIES AND NORTHERN  
PLAINS, ENHANCED BY A COLD HIGH PRESSURE SURGE EARLY NEXT WEEK.  
WITH SUCH A STRONG WARMING/BLOCKING RIDGE OVER THE EAST, WAVES  
ALONG/OVER THE FRONT WILL SHOW LITTLE EASTWARD PROGRESSION. THIS  
WILL SET THE STAGE FOR A PROLONGER PERIOD FAVORING MULTIPLE ROUNDS  
OF HEAVY RAIN/CONVECTION WITH SOME FAR NORTHERN TIER FRINGE SNOW.  
TRAINING OFFERS A WIDESPREAD EXCESSIVE RAINFALL HAZARD.  
TEMPERATURES SOUTH OF THE FRONT WILL BE SUMMER-LIKE, SO THE  
FRONTAL ZONE WILL BE STARK.  
 
ELSEWHERE, A DEEP LAYERED EASTERLY FETCH OFF THE ATLANTIC SETS UP  
AND PERSISTS INTO NEXT WEEK OVER THE SOUTHEAST, SPREADING SHOWERS  
ACROSS FLORIDA AND THE GULF COAST/NORTHERN GULF OF MEXICO  
UNDERNEATH A NORTHWARD SHIFTING EASTERN U.S. CLOSED TROUGH ALOFT.  
THIS LEAVE ROOM FOR ATLANTIC ENERGIES AND A CARRIBEAN BASED  
TROPICAL DISTURBANCE TO WORK INTO FLORIDA AND THE GULF OF MEXICO  
NEXT WEEK THAT MAY ACT TO ENHANCE LIFT/MOISTURE POOLING.  
 
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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