131  
FXUS02 KWBC 021918  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
317 PM EDT THU MAY 02 2019  
 
VALID 12Z SUN MAY 05 2019 - 12Z THU MAY 09 2019  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
AN AREA OF ENHANCED RAINFALL IS EXPECTED FROM THE NORTHERN  
MID-ATLANTIC TO SOUTHERN NEW ENGLAND AS THE LEADING LOW MOVES  
OFFSHORE. THE TRAILING COLD FRONT WILL PROVIDE A FOCUS FOR SHOWERS  
AND THUNDERSTORMS TO DEVELOP ACROSS THE SOUTHEAST, GULF STATES AND  
THE SOUTHERN PLAINS. RAINFALL INTENSITY WILL LIKELY BECOME HEAVY  
AT TIMES, ESPECIALLY OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI  
VALLEY.  
 
RIDGING ALOFT WILL REMAIN ANCHORED OVER THE NORTHEASTERN PACIFIC  
WHICH WILL KEEP DRIVE SPLIT FLOW OVER THE LOWER 48 NEXT WEEK. AN  
UNSETTLING AND INITIALLY CLOSED SOUTHERN STREAM LOW WILL WORK INTO  
CALIFORNIA AND THE SOUTHWEST AS A SERIES OF COOLING AND  
PRECIPITATION FOCUSING NORTHERN STREAM SYSTEMS SKIRT ALONG THE  
US/CANADIAN BORDER. SCATTERED SHOWERS AND SOME CONVECTION WILL  
SPREAD ACROSS THE GREAT BASIN/ROCKIES. THE PRECIPITATION IS  
ANTICIPATED TO BE MOSTLY NEAR THE MID-TO-HIGH TERRAIN LOCATIONS.  
SOME SNOW MAY BE POSSIBLE AT THE HIGHEST ELEVATIONS, BUT SOME  
VALLEY RAIN AS WELL.  
 
ADDITIONALLY, THIS SYNOPTIC SETUP WILL BE FAVORABLE FOR PERIODS OF  
ORGANIZED STRONG CONVECTION WITH A CELL TRAINING/EXCESSIVE  
RAINFALL/RUNOFF THREAT AS A SERIES OF HARD TO TIME NORTHERN AND  
SOUTHERN STREAM IMPULSES EJECT OVER THE EAST-CENTRAL U.S. OVER TOP  
A BUILDING UPPER RIDGE OVER THE DEEP SOUTH. SYSTEMS MAY BE PRIMED  
TO PERIODICALLY TAP DEEPENING MOISTURE AND INSTABILITY POOLED BY  
RETURN GULF OF MEXICO INFLOW INTO TWO SURFACE FRONTAL  
SYSTEMS/ENHANCED BAROCLINIC ZONES.  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
THE LATEST RUN OF GUIDANCE IS MAINTAINING THE OVERALL PATTERN OF A  
LONGWAVE TROUGH SETTING UP OVER THE WEST/SOUTHWEST AND RIDGING IN  
OVER THE SOUTHEAST; WITH AN IMPROVED CLUSTERING WITH THE  
SHORTWAVES/LOWS IN THE SOUTHERN PLAINS, MID-ATLANTIC AND CENTRAL  
CANADA. THE WPC MEDIUM RANGE PRODUCT SUITE WAS COMPOSED FROM A  
BLEND OF THE 06Z GFS/00Z ECMWF/00Z UKMET INITIALLY WITH MORE  
WEIGHTING OF THE 06Z GEFS MEAN INCORPORATED BY THE END OF THE  
EXTENDED PERIOD.  
 
CAMPBELL  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY AND  
THE SOUTHERN PLAINS, TUE-WED, MAY 7-MAY 8.  
- HEAVY RAIN ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY, THE  
LOWER MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, THE OHIO VALLEY,  
AND THE TENNESSEE VALLEY, THU, MAY 9.  
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE  
MISSISSIPPI VALLEY, THE UPPER MISSISSIPPI VALLEY, AND THE NORTHERN  
PLAINS, MON, MAY 6.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE CENTRAL PLAINS, THE  
LOWER MISSISSIPPI VALLEY, THE GREAT LAKES, THE MIDDLE MISSISSIPPI  
VALLEY, THE UPPER MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE  
OHIO VALLEY.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE LOWER MISSISSIPPI VALLEY, THE NORTHERN PLAINS, THE  
GREAT LAKES, THE MIDDLE MISSISSIPPI VALLEY, THE UPPER MISSISSIPPI  
VALLEY, THE SOUTHERN PLAINS, AND THE OHIO VALLEY.  
- FLOODING LIKELY ACROSS PORTIONS OF THE CENTRAL PLAINS, THE  
MIDDLE MISSISSIPPI VALLEY, THE GREAT LAKES, AND THE OHIO VALLEY.  
 
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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