979  
FXUS02 KWBC 130700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT THU JUN 13 2024  
 
VALID 12Z SUN JUN 16 2024 - 12Z THU JUN 20 2024  
 
 
...EARLY SEASON HEATWAVE TO SPREAD FROM THE WEST/SOUTHWEST OUT THROUGH  
THE SOUTH-CENTRAL PLAINS TO THE MIDWEST/EAST COAST NEXT WEEK...  
 
...IMPROVED CONDITIONS FOR FLORIDA WHILE THE CENTRAL TO WESTERN  
GULF BECOMES MORE ACTIVE INTO NEXT WEEK...  
 
...MULTI-EPISODE HEAVY RAIN/CONVECTION PATTERN FOR THE NORTH-  
CENTRAL U.S. NEXT WEEK...  
 
   
..GENERAL OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT  
 
THE LATEST MODELS AND ENSEMBLES GENERALLY REMAIN IN GOOD OVERALL  
AGREEMENT INTO NEXT WEEK WITH RESPECT TO THE OVERALL PATTERN,  
FEATURING A STRONGLY BUILDING UPPER RIDGE ACROSS THE EASTERN HALF  
OF THE U.S., AND A DEVELOPING AMPLIFIED UPPER TROUGH OVER THE  
WEST. GUIDANCE INDICATES A SOUTHERN STREAM SHORTWAVE OVER THE  
SOUTHWEST WILL LIFT NORTHEAST, AND AROUND THE WESTERN PERIPHERY OF  
THE BUILDING RIDGE WITH ADDITIONAL EMBEDDED WAVES CROSSING THE  
NORTHERN TIER AS THE MAIN UPPER TROUGH BEGINS TO TAKE HOLD OVER THE  
WEST. AN UPPER-LEVEL DISTURBANCE NOW OVER FLORIDA SHOULD SLOWLY  
WORK WESTWARD OVER THE GULF OF MEXICO THIS WEEKEND INTO NEXT WEEK.  
THIS WILL BRING IMPROVING CONDITIONS FOR FLORIDA, WHILE INCREASING  
RAINFALL CHANCES FOR THE CENTRAL AND WESTERN GULF COAST AND  
VICINITY GOING INTO SUNDAY AND EARLY-MID NEXT WEEK.  
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A  
COMPOSITE BLEND OF BEST CLUSTERED GUIDANCE OF THE 18 UTC  
GFS/GEFS MEAN AND 18 UTC ECMWF/ECMWF ENSEMBLE MEAN, THE 01 UTC  
NATIONAL BLEND OF MODELS THROUGH MEDIUM RANGE TIME SCALES ALL NEXT  
WEEK IN A PATTERN WITH NEAR AVERAGE PREDICTABILITY OVERALL.  
   
..WEATHER/HAZARDS HIGHLIGHTS  
 
A MAIN AXIS OF TROPICAL MOISTURE IS FORECAST TO SHIFT WESTWARD  
ACROSS THE GULF OF MEXICO AND AFFECT THE CENTRAL TO WESTERN GULF  
COAST REGION NEXT WEEK. DAY 4/SUNDAY AND DAY 5/MONDAY ERO MARGINAL  
RISK AREAS HAVE BEEN INTRODUCED FOR THE WEST-CENTRAL GULF COAST  
GIVEN THE MOIST PATTERN. UNCERTAINTY REMAINS, PARTICULARLY WITH THE  
POTENTIAL AMOUNT OF RAINFALL AND WITH WESTWARD EXTENT INTO THE  
WESTERN GULF INTO LATER NEXT WEEK. THE 12 UTC CANADIAN OFFERED AN  
OUTLIER SOLUTION WITH TROPICAL DEVELOPMENT AND NORTHWARD INLAND  
TRACK NOT SUPPORTED BY NHC GUIDANCE. THE 00 UTC RUN BACKED OFF.  
 
ELSEWHERE, CONVECTIVE PRECIPITATION EVENT IS LIKELY ACROSS AN  
UNSTABLE NORTHERN PLAINS AND THE UPPER MIDWEST/WESTERN GREAT LAKES  
AS SOUTHERN STREAM TROUGHING EJECTS NORTHEASTWARD FROM THE  
SOUTHWEST AS WELL AS LAGGING NORTHERN STREAM UPPER TROUGH APPROACH.  
WPC ERO MARGINAL RISK AREAS HAVE BEEN INTRODUCED FOR DAY 4/5  
SUNDAY/MONDAY. THERE IS NOW A MORE CONSISTENT SIGNAL THAT THE SUBSEQUENT  
UPSTREAM MARCH OF AN AMPLIFIED UPPER TROUGH OUT FROM THE  
WEST/NORTHWEST WILL ACT TO ALSO SUPPORT THE MARGINAL RISK OF HEAVY  
RAINS OVER THE NORTHERN ROCKIES/HIGH PLAINS DAY5/MONDAY. THIS  
FOCUS IS EXPECTED TO SLOWLY WORK ACROSS THE NORTH-CENTRAL U.S.  
TUESDAY INTO NEXT THURSDAY AS AIDED BY RENEWED CYCLO/FRONTOGENESIS.  
 
AS FOR ANOMALOUS TEMPERATURES, AN AMPLIFIED UPPER RIDGE SLATED TO  
STEADILY/BROADLY SHIFT FROM THE SOUTHWEST THROUGH THE SOUTH-  
CENTRAL U.S. TO THE EAST OVER THE COMING WEEK WILL PRODUCE  
WIDESPREAD ANOMALOUS HEAT AND HUMIDITY, WITH THE POTENTIAL FOR SOME  
DAILY RECORD HIGHS TO BE ESTABLISHED. TEMPERATURES WILL ALREADY BE  
RATHER HOT OVER PORTIONS OF THE SOUTH BEFORE THE EVEN BROADER  
REGION OF HEAT EXPANDS INTO THE MIDWEST/OHIO VALLEY THEN MID-  
ATLANTIC/NORTHEAST NEXT WEEK AS THE UPPER-LEVEL RIDGING BUILDS IN.  
HIGHS ARE FORECAST WELL INTO THE 90S AND WITH LOWS IN THE MIDDLE  
60S TO MIDDLE 70S PROVIDING LITTLE OVERNIGHT HEAT RELIEF. LATEST  
GUIDANCE TRENDS ARE SLOWER TO ALIEVIATE THE HEATWAVE WITH MORE  
STEADFAST PERSISTENCE OF THE SUPPORTING UPPER HIGH/RIDGE.  
 
SCHICHTEL  
 
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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