130  
FXUS02 KWBC 120700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT WED JUN 12 2024  
 
VALID 12Z SAT JUN 15 2024 - 12Z WED JUN 19 2024  
 
 
...HEATWAVE TO SPREAD FROM THE SOUTHWEST TO PARTS OF THE CENTRAL  
AND EASTERN U.S. DURING THE PERIOD...  
 
...EXCESSIVE RAINFALL THREAT FOR FLORIDA WANES THIS WEEKEND WITH  
FOCUS SHIFT TO THE CENTRAL GULF COAST INTO NEXT WEEK...  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT  
 
GUIDANCE MOSTLY REMAINS IN GOOD OVERALL AGREEMENT INTO NEXT WEEK  
WITH RESPECT TO THE OVERALL PATTERN, FEATURING MEAN RIDGING OVER  
THE WEST PROGRESSING EASTWARD THROUGH THE PERIOD OVER THE CENTRAL  
AND THEN EASTERN U.S., AND WITH MEAN TROUGHING SETTLING IN OVER THE  
WEST IN THE WAKE. GUIDANCE INDICATES A SOUTHERN STREAM SHORTWAVE  
OVER THE SOUTHWEST WILL LIFT NORTHEAST ROUNDING THE BUILDING RIDGE  
WITH ADDITIONAL EMBEDDED WAVES TRANSLATING THE NORTHERN TIER AS THE  
MEAN TROUGHING BEGINS TO TAKE HOLD BACK OVER THE WEST.  
 
AN UPPER-LEVEL WEAKNESS OVER FLORIDA THIS WEEK WILL SLOWLY  
RETROGRADE OVER THE GULF OF MEXICO THIS WEEKEND INTO NEXT WEEK.  
THIS WILL SHIFT A STORMY PATTERN OUT FROM FLORIDA TO THE GULF AND  
CENTRAL TO WESTERN GULF COAST, WITH THE RIDGE TRANSITIONING OVER  
THE EAST ALSO HELPING TO FUNNEL TROPICAL MOISTURE NORTHWARD.  
 
ACCORDINGLY, THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY  
DERIVED FROM A COMPOSITE BLEND OF BEST CLUSTERED GUIDANCE OF THE 12  
UTC ECMWF/CANADIAN/UKMET, THE 01 UTC NATIONAL BLEND OF MODELS AND  
WPC CONTINUITY FOR SATURDAY INTO MONDAY IN A PATTERN WITH AVERAGE  
TO ABOVE AVERAGE PREDICTABILITY. SWITCHED TO A COMPOSITE OF THE  
GEFS/ECMWF ENSEMBLE MEANS AND BEST CLUSTERED ECMWF EARLY-MID NEXT  
WEEK AMID GROWING FORECAST SPREAD.  
   
..WEATHER/HAZARDS HIGHLIGHTS  
 
A COMPLEX EXCESSIVE RAINFALL EPISODE ONGOING OVER THE CENTRAL AND  
SOUTHERN FLORIDA PENINSULA SHOULD WANE THIS WEEKEND AS THE MAIN  
TROPICAL MOISTURE AND SYSTEM/FLOW FOCUS LIKELY SHIFTS TO BOTH OVER  
THE WESTERN ATLANTIC AND ALSO BACK ACROSS THE GULF OF MEXICO AND  
THE CENTRAL TO WESTERN GULF COAST REGION. A DAY4/SATURDAY ERO  
MARGINAL RISK REMAINS FOR LINGERING ACTIVITY OVER FLORIDA. HOWEVER,  
AS THE WEEKEND PROGRESSES AND INTO EARLY NEXT WEEK, THERE IS A  
GROWING GUIDANCE SIGNAL THAT MOISTURE INFLUX AND POSSIBLE HEAVY  
RAINFALL MAY REFOCUS AND INCREASE INTO THE CENTRAL GULF COAST AND  
VICINITY. A DAY 5/SUNDAY MARGINAL RISK ERO HAS BEEN INTRODUCED  
GIVEN THE MOIST PATTERN. UNCERTAINTY REMAINS, PARTICULARLY WITH THE  
POTENTIAL AMOUNT OF RAINFALL AND WITH WESTWARD EXTENT INTO THE  
WESTERN GULF THROUGH EARLY-MID NEXT WEEK.  
 
ELSEWHERE, A CONVECTIVE PRECIPITATION THREAT WILL SHIFT ACROSS THE  
CENTRAL AND NORTHERN PLAINS TO THE UPPER MIDWEST/GREAT LAKES THIS  
WEEKEND AS SOUTHERN STREAM TROUGHING EJECTS NORTHEASTWARD TOWARD  
THE REGION FROM THE SOUTHWEST TO FOCUS LIFT/INSTABILITY. WPC ERO  
MARGINAL RISK AREAS HAVE BEEN INTRODUCED FOR DAY4/SATURDAY AND DAY  
5/SUNDAY GIVEN SYSTEM PROGRESSION AND POOLING MOISTURE/INSTABILITY.  
 
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 MUCH  
WARMER THAN AVERAGE TEMPERATURES AND THE THREAT FOR SOME RECORD  
HEAT. 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 AND VICINITY INTO NEXT WEEK  
AS THE UPPER-LEVEL RIDGING BUILDS IN. HIGHS ARE FORECAST WELL INTO  
THE 90S, POTENTIALLY LOW 100S, AND WITH LOWS IN THE 70S PROVIDING  
LITTLE RELIEF FROM THE HEAT OVERNIGHT. THE CLIMATE PREDICTION  
CENTER CONTINUES A HEAT THREAT INTO WEEK 2.  
 
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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