979  
FXUS02 KWBC 091902  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
302 PM EDT SUN JUN 9 2024  
 
VALID 12Z WED JUN 12 2024 - 12Z SUN JUN 16 2024  
 
...HEAT FOCUS SHIFTS FROM THE SOUTHWEST TO SOUTH TEXAS THIS WEEK  
AS HEAVY RAINFALL THREAT LOOMS FOR FLORIDA...  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT  
 
LATEST SUITE OF GUIDANCE SHOWS FAIRLY GOOD AGREEMENT ON THE LARGE  
SCALE PATTERN FEATURING SHORTWAVES PROGRESSING THROUGH A MEAN GREAT  
LAKES TO NORTHEAST TROUGH WITH A BUILDING RIDGE BEHIND. THERE IS  
STILL SOME KEY DIFFERENCES IN THE SPEED AND AMPLITUDE OF THESE  
SHORTWAVES LATE WEEK, BUT A GENERAL MODEL COMPROMISE SEEMED TO WORK  
AS A GOOD STARTING POINT. MEANWHILE, OUT WEST, THERE IS INCREASING  
UNCERTAINTY ON HOW QUICKLY A NORTHEAST PACIFIC LOW OR ASSOCIATED  
ENERGY PROGRESSES INLAND. THE 00Z AND NEW 12Z ECMWF REMAIN ON THE  
FASTER SIDE OF GUIDANCE PULLING MUCH OF THE UPPER LOW INTO WESTERN  
CANADA NEXT WEEKEND, WHILE THERE SEEMS TO BE BETTER CONSENSUS FOR  
AT LEAST SOME ENERGY TO HANG BACK OFF THE BRITISH COLUMBIA COAST.  
 
MEANWHILE, THE EVOLUTION OF LOWERING HEIGHTS, AND HIGHLY ANOMALOUS  
MOISTURE AXIS, AND ENERGY OVER THE GULF OF MEXICO INTO FLORIDA  
CONTINUES TO OFFER A TON OF UNCERTAINTY. PER THE LATEST FORECAST  
OUT OF THE NATIONAL HURRICANE CENTER, TROPICAL DEVELOPMENT WITH  
THIS FEATURE IS NOT LIKELY, BUT REGARDLESS, CONFIDENCE IN A HEAVY  
TO EXCESSIVE RAINFALL THREAT FOR CENTRAL AND SOUTHERN FLORIDA IS  
INCREASING.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS  
 
A FRONT ACROSS THE SOUTH-CENTRAL PLAINS WILL COMBINE WITH SLOW  
MOVING UPPER SYSTEM ENERGY AND INSTABILITY TO OFFER A LINGERING  
THREAT FOR LOCAL HEAVY RAINFALL INTO WEDNESDAY. THE DAY 4 WPC ERO  
CONTINUES TO SHOW A SMALL MARGINAL RISK AREA FOR PORTIONS OF  
CENTRAL TO NORTHEAST TEXAS. A MULTI- DAY PERIOD FAVORABLE FOR HEAVY  
RAINS SHOULD DEVELOP EARLY THIS WEEK AND CONTINUE THROUGH MUCH OF  
THE MEDIUM RANGE PERIOD FOR THE FLORIDA PENINSULA AS WELL ABOVE  
MOISTURE POOLS ALONG AND SOUTH OF A WAVY/STALLING FRONT WITH AID  
FROM UPPER LEVEL IMPULSES/ENERGY BACK THROUGH AN UNSETTLED GULF OF  
MEXICO. THERE IS A LOT OF UNCERTAINTY IN THE DETAILS AND MUCH OF  
THE STATE IS IN AT LEAST A MODERATE DROUGHT. THERE IS INCREASING  
CONFIDENCE HOWEVER THAT SHORT RANGE HEAVY RAINFALL POTENTIAL MAY  
MITIGATE THAT ENOUGH TO SUPPORT A SLIGHT RISK INTRODUCTION FOR  
CENTRAL AND SOUTHERN FLORIDA ON THE DAYS 4 AND 5 EROS, WITH A  
LOOMING THREAT INTO LATER WEEK AS WELL THERE AND WITH ANY  
ACTIVITY/MOISTURE FEED EMANATING OVER THE GULF. STORM TOTAL  
RAINFALL (INCLUDING WHAT FALLS BEFORE THE MEDIUM RANGE PERIOD EVEN  
STARTS) OF 7-12 INCHES, WITH LOCALLY HIGHER AMOUNTS, IS POSSIBLE.  
MEANWHILE, AN INCREASING PRECIPITATION THREAT ACROSS MUCH OF THE  
CENTRAL AND NORTHERN PLAINS EMERGES LATE PERIOD WITH TROUGHING  
SHIFTING NORTHEASTWARD INTO THE REGION FROM THE SOUTHWEST.  
 
AN AMPLIFIED MEAN UPPER RIDGE SLATED TO SLOWLY SHIFT FROM THE  
WEST/SOUTHWEST TO THE SOUTH-CENTRAL U.S. AND PARTS OF THE EAST WILL  
CONTINUE TO PRODUCE MUCH WARMER THAN AVERAGE TEMPERATURES. THE  
HIGHEST TEMPERATURE ANOMALIES OF 10-20F ABOVE NORMAL ARE FORECAST  
FOR THE GREAT BASIN, SHIFTING EASTWARD AS THE WEEK PROGRESSES INTO  
THE ROCKIES AND PLAINS. IT WILL BE ESPECIALLY HOT ACROSS THE DESERT  
SOUTHWEST THEN SOUTH TEXAS GIVEN ELEVATED HEAT RISK AND HEAT INDEX  
THREAT VALUES.  
 
SANTORELLI/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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