291  
FXUS02 KWBC 301523  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1123 AM EDT SUN SEP 30 2018  
 
VALID 12Z WED OCT 03 2018 - 12Z SUN OCT 07 2018  
   
..NORTH-CENTRAL U.S. HEAVY RAINFALL THREAT
 
 
   
..OVERVIEW AND GUIDANCE EVALUATION/PREFERENCES
 
 
AN AMPLIFIED PATTERN WILL REMAIN IN PLACE OVER THE LOWER 48 (AS  
WELL AS UPSTREAM/DOWNSTREAM FROM THE CENTRAL PACIFIC THROUGH TO  
THE ATLANTIC) WITH A RELOADING UPPER TROUGH IN THE WEST AND A  
RESILIENT UPPER RIDGE IN THE EAST. THE LATEST MODELS/ENSEMBLES  
REMAIN IN GOOD AGREEMENT AND A GENERAL BLEND WAS USED AS A  
STARTING POINT FOR THE FORECAST, WHICH MAINTAINS GOOD CONTINUITY  
FROM OVERNIGHT.  
 
   
..WEATHER HIGHLIGHTS
 
 
PERSISTENT TROUGHING IN THE WEST WILL BE REINFORCED FROM TWO  
SOURCES (THE NORTHEAST PACIFIC AND WESTERN CANADA) WHICH WILL ACT  
TO KEEP COOLER THAN AVERAGE TEMPERATURES OVER MUCH OF THE WEST AND  
INTO THE PLAINS TO THE NORTH OF A WAVY SURFACE FRONT. WITH THE  
UPPER RIDGE IN THE EAST/SOUTHEAST ANCHORED IN PLACE, THE FRONT  
WILL BE PREVENTED FROM MOVING MUCH TO THE SOUTHEAST AS WAVES OF  
LOW PRESSURE (INCLUDING THE REMNANTS OF ROSA) LIFT NORTHEASTWARD  
ALONG A SIMILAR PATH FROM THE CENTRAL PLAINS TO THE GREAT LAKES.  
THIS WILL BRING ROUNDS OF RAIN (AND SOME NORTHERN FRINGE SNOW) TO  
THE SAME AREAS OVER SEVERAL DAYS GIVING WAY TO WETTER SOILS AND  
RISING RIVERS. TEMPERATURES TO THE SOUTH OF THE FRONT WILL BE  
RATHER SUMMER-LIKE INTO THE 80S AND SOME 90S ALONG THE GULF COAST  
(5-15 DEGREES ABOVE AVERAGE). BY THE COMING WEEKEND, ADDITIONAL  
TROUGHING INTO THE WEST WILL NUDGE THE TROUGH AXIS EASTWARD INTO  
THE GREAT BASIN WITH MORE RAIN AND HIGH MOUNTAIN SNOW FOR THE  
NORTHERN ROCKIES AND A NEW HEAVY RAINFALL THREAT FOR THE SOUTHERN  
PLAINS WITH MID-LEVEL SOUTHWEST FLOW ATOP THE LINGERING SURFACE  
FRONT.  
 
FRACASSO  
 
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