981  
FXUS02 KWBC 110700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT TUE JUN 11 2024  
 
VALID 12Z FRI JUN 14 2024 - 12Z TUE JUN 18 2024  
 
 
...HEATWAVE TO SPREAD FROM THE SOUTHWEST TO PARTS OF THE CENTRAL  
AND EASTERN U.S. DURING THE PERIOD...  
 
...EXCESSIVE RAINFALL THREAT FOR FLORIDA THROUGH LATE WEEK AND  
PERHAPS THE CENTRAL GULF COAST EARLY NEXT WEEK...  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT  
 
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A  
COMPOSITE BLEND OF REASONABLY WELL CLUSTERED OVERALL GUIDANCE FROM  
THE 18 UTC GFS AND 12 UTC ECMWF/CANADIAN/UKMET, THE 01 UTC  
NATIONAL BLEND OF MODELS AND WPC CONTINUITY FOR FRIDAY INTO SUNDAY  
IN A PATTERN WITH AVERAGE TO ABOVE AVERAGE PREDICTABILITY. OPTED  
FOR SMALLER INPUT FROM THE MODELS IN LIEU OF MORE RUN TO RUN CONSISTENT  
GEFS/ECMWF ENSEMBLE MEAN BLENDING INTO EARLY NEXT WEEK AMID  
GROWING UNCERTAINTIES, INCLUDING IN PARTICULAR CONTINUED VARIANCES  
WITH LOCAL SENSIBLE WEATHER/THREAT FOCUS. THE BLENDING PROCESS  
TENDS TO MITIGATE VARIANCE BY LIMITING DETAIL CONSISTENT WITH  
INDIVIDUAL FEATURE PREDICTABILITY. THIS ALSO ACTS TO MAINTAIN GOOD  
WPC PRODUCT CONTINUITY THAT REMAINS GENERALLY IN LINE WITH A  
SIMILAR BLEND OF LATEST 12 UTC GUIDANCE.  
   
..WEATHER/HAZARDS HIGHLIGHTS  
 
A PROTRACTED PERIOD FAVORABLE FOR HEAVY RAINS SHOULD CONTINUE  
THROUGH LATER WEEK FOR THE FLORIDA PENINSULA AS WELL ABOVE NORMAL  
TROPICAL/CARIBBEAN MOISTURE POOLS ALONG AND SOUTH OF A WAVY  
STALLED FRONT WITH AID FROM UPPER LEVEL IMPULSES/ENERGY BACK  
THROUGH AN UNSETTLED GULF OF MEXICO. THERE REMAINS HIGH CONFIDENCE  
IN HEAVY RAINFALL IN FLORIDA WITH LOCALLY HEAVY RAINFALL RATES, BUT  
LOWER CONFIDENCE ON PLACEMENT OF ANY EXTREME CONVECTIVE AMOUNTS ON  
ANY PARTICULAR DAY. STORM TOTAL RAINFALL (INCLUDING WHAT FALLS  
BEFORE THE MEDIUM RANGE PERIOD EVEN STARTS) OF 7-10 INCHES, WITH  
LOCALLY HIGHER AMOUNTS TO 15 INCHES, IS FORECAST. WPC EXCESSIVE  
RAINFALL OUTLOOK SLIGHT RISK AREAS REMAIN IN PLACE FOR THE CENTRAL  
TO SOUTHERN FLORIDA PENINSULA INTO DAY 4/FRIDAY. HEAVY RAIN MAY  
LAST INTO SATURDAY ACROSS FLORIDA WHERE A DAY 5 MARGINAL RISK HAS  
BEEN INTRODUCED VIA COLLABORATION WITH LOCAL WFO OFFICES FOR  
LINGERING ACTIVITY. 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 TO MONITOR FOR RUNOFF ISSUES  
GIVEN THE FAVORABLE DEEPLY MOIST PATTERN.  
 
MEANWHILE, LEADING AND DYNAMIC NORTHERN STREAM UPPER TROUGH ENERGY  
APPROACH AND PASSAGE IS EXPECTED TO FIRE CONVECTION ALONG/AHEAD OF  
A WAVY/POOLING SURFACE FRONT OVER THE NORTHEAST INTO FRIDAY WHERE  
A MARGINAL RISK AREA REMAINS IN PLACE AS THE PARALLEL UPPER FLOW  
AND CONVECTIVE AXIS MAY LEAD TO REPEAT CELLS AND RUNOFF ISSUES.  
 
ELSEWHERE, AN INCREASING CONVECTIVE PRECIPITATION THREAT WILL  
EMERGE ACROSS THE CENTRAL AND NORTHERN PLAINS/UPPER MIDWEST LATE  
WEEK INTO THE WEEKEND AS WELL DEFINED SOUTHERN STREAM TROUGHING  
EJECTS NORTHEASTWARD TOWARD THE REGION FROM THE SOUTHWEST TO FOCUS  
LIFT/INSTABILITY. A WPC ERO MARGINAL RISK AREA REMAINS IN PLACE  
FOR DAY4/FRIDAY FROM THE SOUTHERN HIGH PLAINS TO THE CENTRAL  
PLAINS, EXCEPT FOR THE SANDHILLS OF NEBRASKA THAT ARE NOT AS SENSITIVE  
TO HEAVY RAIN. A DAY5/SATURDAY MARGINAL RISK AREA HAS BEEN  
INTRODUCED FROM THE CENTRAL PLAINS TO THE UPPER MIDWEST GIVEN  
SYSTEM PROGRESSION AND CONTINUED UNSTABLE FLOW.  
 
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 WILL PRODUCE MUCH WARMER THAN AVERAGE  
TEMPERATURES AND THE THREAT FOR SOME RECORD HEAT INTO NEXT WEEK.  
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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