114  
FXUS02 KWBC 270657  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
257 AM EDT MON MAY 27 2024  
 
VALID 12Z THU MAY 30 2024 - 12Z MON JUN 03 2024  
 
   
..GENERAL OVERVIEW  
 
THE UPPER LEVEL PATTERN ACROSS THE CONTINENTAL U.S. WILL BE  
FEATURED WITH A TROUGH OVER THE NORTHERN ROCKIES, A RIDGE OVER THE  
UPPER MIDWEST, AND A TROUGH OVER THE NORTHEAST U.S. FOR THE  
BEGINNING OF THE FORECAST PERIOD THURSDAY. BOTH OF THESE TROUGHS  
MOVE RATHER SLOWLY EASTWARD THROUGH SATURDAY, WHILE THE SOUTHERN  
TIER STATES HAVE MORE ZONAL FLOW ALOFT. THE TROUGH CROSSING THE  
ROCKIES WILL BE ACCOMPANIED WITH A SURGE OF MOISTURE FROM THE GULF  
OF MEXICO AHEAD OF AN APPROACHING FRONTAL BOUNDARY, AND THIS WILL  
FUEL MULTIPLE ROUNDS OF HEAVY RAIN AND THUNDERSTORMS FROM NORTHERN  
TEXAS TO THE CENTRAL PLAINS FOR THE SECOND HALF OF THE WORK WEEK.  
THE TROUGH THEN REACHES THE UPPER MIDWEST BY NEXT WEEKEND AND THEN  
LIFTS NORTHWARD INTO CANADA, WHILE THE UPPER RIDGE REBUILDS ACROSS  
TEXAS LATE IN THE FORECAST PERIOD.  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT  
 
THE 00Z MODEL GUIDANCE SUITE IS IN GOOD OVERALL SYNOPTIC SCALE  
AGREEMENT FOR THURSDAY AND FRIDAY, EVEN THOUGH THE UKMET IS STILL A  
LITTLE MORE PROGRESSIVE WITH THE TROUGH EXITING THE ROCKIES TO THE  
NORTHERN PLAINS. THE UKMET IS NOW CLOSER TO THE CONSENSUS COMPARED  
TO PREVIOUS RUNS WHEN IT WAS MUCH FASTER THAN THE OTHER GUIDANCE.  
THE GFS IS NOW SLOWER WITH THE PASSAGE OF THE OTHER TROUGH ACROSS  
THE EAST COAST COMPARED TO THE CONSENSUS, BUT MATCHES UP PRETTY  
WELL ELSEWHERE THROUGH FRIDAY. A MULTI-DETERMINISTIC MODEL BLEND,  
WITH SLIGHTLY LESS WEIGHTING TO THE UKMET, SUFFICED AS A STARTING  
POINT IN THE FORECAST PROCESS THROUGH THE END OF THE WEEK.  
 
LOOKING AHEAD TO NEXT WEEKEND, THE GFS BECOMES STRONGER WITH A  
SECOND TROUGH DEVELOPING ACROSS THE NORTH-CENTRAL U.S. THAT DOES  
NOT CURRENTLY HAVE MUCH SUPPORT FROM THE OTHER GUIDANCE, AND THIS  
REMAINS THE CASE GOING INTO NEXT MONDAY. THE CMC IS THE FASTER  
SOLUTION WITH THE NEXT TROUGH APPROACHING THE PACIFIC NORTHWEST BY  
MONDAY. THERE IS GOOD OVERALL AGREEMENT THAT THE UPPER RIDGE WILL  
BUILD BACK ACROSS TEXAS BY THIS TIME AS WELL. ENSEMBLE MEANS  
ACCOUNTED FOR 30-50% OF THE FORECAST BLEND BY SUNDAY-MONDAY.  
   
..WEATHER/HAZARDS HIGHLIGHTS  
 
NUMEROUS SHOWERS AND THUNDERSTORMS ARE LIKELY ACROSS MUCH OF THE  
CENTRAL AND SOUTHERN PLAINS GOING INTO THE SECOND HALF OF THE WORK  
WEEK AS A WARM FRONT LIFTS UP FROM THE WESTERN GULF AND ADVECTS  
COPIOUS MOISTURE NORTHWARD. THIS WILL ALSO BE IN TANDEM WITH  
INCREASING LIFT AFFORDED BY AN INCOMING UPPER TROUGH FROM THE  
ROCKIES. A BROAD MARGINAL RISK AREA IS PLANNED FOR THE NEW DAY 4  
PERIOD THURSDAY FROM CENTRAL TEXAS TO THE EASTERN DAKOTA, WITH A  
SLIGHT RISK REMAINING IN PLACE OVER NORTH-CENTRAL TEXAS AND INTO  
SOUTHERN OKLAHOMA, WHERE MCS ACTIVITY IS MOST LIKELY TO DEVELOP.  
ADDITIONAL HEAVY RAIN IS EXPECTED ON FRIDAY ACROSS MANY OF THESE  
SAME AREAS WITH THE OVERALL WEATHER PATTERN NOT CHANGING ALL THAT  
MUCH, WITH A BROAD DAY 5 MARGINAL RISK AREA PLANNED FROM NORTHERN  
TEXAS TO THE UPPER MIDWEST. THERE WILL LIKELY BE THE NEED FOR A  
SLIGHT RISK AREA DURING THIS TIME IN FUTURE UPDATES, BUT THE  
DIFFERENCES IN QPF MAXIMA AMONG THE GUIDANCE PRECLUDE HAVING ANY  
SLIGHTS AT THIS TIME. SOME STRONG TO SEVERE THUNDERSTORMS ARE ALSO  
LIKELY. THE POTENTIAL EXISTS FOR 3-5 INCHES OF RAINFALL THROUGH  
LATE FRIDAY FOR SOME OF THESE AREAS THAT GET REPEATED ROUNDS OF  
CONVECTION.  
 
HOT AND HUMID CONDITIONS ARE EXPECTED TO CONTINUE ACROSS MUCH OF  
THE GULF COAST REGION, INCLUDING THE FLORIDA PENINSULA, GOING INTO  
THE END OF THE WEEK, BUT A FEW DEGREES COOLER COMPARED TO WHAT IS  
HAPPENING NOW. THIS WILL EQUATE TO HIGHS IN THE UPPER 80S TO MIDDLE  
90S FOR THESE AREAS, AND LOW-MID 100S FOR INTERIOR PORTIONS OF  
SOUTHERN TEXAS. THE OPPOSITE WILL HOLD TRUE FROM THE GREAT LAKES TO  
THE MID-ATLANTIC AND NORTHEAST AS A RELATIVELY STRONG COLD FRONT  
HERALDS THE ARRIVAL OF A HIGH QUALITY AIRMASS WITH PLEASANTLY COOL  
CONDITIONS AND LOWER HUMIDITY TO CLOSE OUT THE WEEK. THERE WILL  
LIKELY BE SOME SHOWERS ACROSS THE NORTHEASTERN QUADRANT OF THE  
NATION IN CONJUNCTION WITH THE TROUGH/UPPER LOW THAT PASSES  
THROUGH THE REGION. COOLER WEATHER IS ALSO EXPECTED FROM THE  
PACIFIC NORTHWEST TO THE NORTHERN ROCKIES COURTESY OF THE UPPER  
TROUGH MOVING OVERHEAD, AND THEN A RETURN TO WARMER CONDITIONS FOR  
MUCH OF THE WESTERN U.S. BY NEXT SUNDAY.  
 
HAMRICK  
 
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC MEDIUM  
RANGE HAZARDS OUTLOOK CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION FORECAST (QPF), EXCESSIVE RAINFALL  
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT  
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:  
 
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/#PAGE=ERO  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW  
 
 
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