824  
FXUS02 KWBC 190751  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION...AMENDED  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
350 AM EDT SUN MAY 19 2019  
 
VALID 12Z WED MAY 22 2019 - 12Z SUN MAY 26 2019  
   
..OVERALL WEATHER PATTERN
 
 
THE UPPER LEVEL PATTERN ACROSS THE CONTINENTAL U.S. WILL REMAIN  
AMPLIFIED AND SLOW TO CHANGE NEXT WEEK. A HOT UPPER LEVEL RIDGE  
OVER THE SOUTHEAST U.S. BECOMES ANCHORED OVER THE REGION AND  
GRADUALLY BECOMES STRONGER FOR THE SECOND HALF OF THE UPCOMING  
WORK WEEK. ACROSS THE WESTERN U.S., A LARGE SCALE UPPER TROUGH  
WILL BE DOMINANT AS MULTIPLE SHORTWAVE PERTURBATIONS KEEP  
CONDITIONS COOL AND UNSETTLED. THIS WILL ALSO BE SLOW TO MOVE  
GIVEN THE EXPECTED DEVELOPMENT OF AN OMEGA BLOCK TYPE PATTERN  
UPSTREAM OVER THE EASTERN PACIFIC. LEAD MAIN WEATHER FEATURES  
INCLUDE A STRONG LOW PRESSURE SYSTEM FOR THE PLAINS AND UPPER  
MIDWEST MID-WEEK, FOLLOWED BY WEAKER LOWS AND SLOW MOVING FRONTS  
FROM THE SOUTHWEST TO THE NORTHEAST U.S. LATER IN THE WEEK ON THE  
WESTERN AND NORTHERN PERIPHERY OF THE SOUTHEAST RIDGE.  
 
   
..MODELS AND PREFERENCES
 
 
THE MODELS AND ENSEMBLE MEANS ARE IN RELATIVELY GOOD AGREEMENT ON  
WEDNESDAY, WITH THE GFS MORE PROGRESSIVE WITH THE TROUGH AXIS OVER  
THE DESERT SOUTHWEST AND THE CMC SLOWER THAN THE MODEL CONSENSUS.  
BY FRIDAY, THE GFS BECOMES AN OUTLIER SOLUTION REGARDING THE  
INTENSITY OF AN UPPER LOW OVER CALIFORNIA, WHEREAS THE OTHER  
OPERATIONAL GUIDANCE, INCLUDING THE FV3, IS MORE INDICATIVE OF AN  
OPEN TROUGH OVER THIS REGION. THERE HAS ALSO BEEN A WESTWARD AND  
SLOWER ADJUSTMENT TO THE SURFACE LOW OVER THE PLAINS THROUGH THE  
END OF THE WEEK, COMPARED TO EARLIER FORECASTS. BY THE END OF THE  
FORECAST PERIOD ON SUNDAY, THE GFS IS SUGGESTING LESS UPPER LEVEL  
RIDGING OVER THE EASTERN U.S. COMPARED TO THE MODEL CONSENSUS.  
THE FV3 WAS GIVEN GREATER WEIGHTING IN THE FORECAST PROCESS GIVEN  
ITS BETTER AGREEMENT WITH THE ENSEMBLE MEANS, AND THE ECMWF/EC  
MEAN/GEFS MEAN WERE ALSO INCORPORATED INTO THE FORECAST.  
 
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
THE MAIN THINGS THAT WILL MAKE WEATHER HEADLINES FOR THE SECOND  
HALF OF THE WEEK AND EXTENDING INTO NEXT WEEKEND WILL BE THE  
ANOMALOUS HEAT AND HUMIDITY BUILDING ACROSS THE SOUTHEASTERN  
QUADRANT OF THE NATION, THE UNSEASONABLY COOL WEATHER EXPECTED FOR  
THE INTERIOR WESTERN U.S. AND NORTHERN PLAINS, AND THE ONGOING  
THREAT OF HEAVY RAINFALL AND POTENTIAL SEVERE WEATHER ACROSS THE  
CENTRAL U.S. HIGH TEMPERATURES ARE FORECAST TO BE ON THE ORDER OF  
10 TO 15 DEGREES ABOVE LATE MAY AVERAGES FROM THE MIDWEST TO THE  
SOUTHEAST U.S., WITH THE HOTTEST READINGS EXPECTED FOR THE FRIDAY  
TO SUNDAY TIME PERIOD. THERE IS A GOOD CHANCE THAT THE FIRST 100  
DEGREE TEMPERATURES OF THE SEASON COULD BE REALIZED ACROSS INLAND  
PORTIONS OF SOUTHERN GEORGIA AND SOUTH CAROLINA. THE OPPOSITE  
WILL HOLD TRUE FOR THE WESTERN U.S. UNDER THE INFLUENCE OF THE  
UPPER LEVEL TROUGH, WITH DAYTIME HIGHS OF 15 TO 25 DEGREES BELOW  
NORMAL FOR MID-WEEK, AND THEN MODERATING TO 5 TO 15 DEGREES BELOW  
NORMAL BY THE END OF THE FORECAST PERIOD.  
 
HEAVY RAIN WILL LIKELY BE AN ISSUE AGAIN FOR PARTS OF THE CENTRAL  
PLAINS AND MIDWEST WITH THE STALLED FRONTAL BOUNDARY IN PLACE FOR  
THE END OF THE WEEK AND INTO THE WEEKEND. THERE ARE SOME  
DIFFERENCES IN THE MODEL PLACEMENTS OF THE HEAVIEST QPF AXIS, BUT  
THE CONSENSUS IS FOR THE HEAVIEST RAIN TO DEVELOP FROM NORTHERN  
TEXAS TO IOWA WITH THE POTENTIAL FOR FLASH FLOODING. STRONG TO  
SEVERE THUNDERSTORMS ARE ALSO LIKELY IN THIS SAME GENERAL AREA.  
 
D. HAMRICK  
 
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  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page