557  
FXUS02 KWBC 110656  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
256 AM EDT MON JUL 11 2022  
 
VALID 12Z THU JUL 14 2022 - 12Z MON JUL 18 2022  
 
...MULTI-DAY EXCESSIVE RAINFALL THREAT FOR THE CENTRAL GULF COAST  
STATES...  
 
...GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT...  
 
A SIGNIFICANT AREA OF UNCERTAINTY IN THE MEDIUM RANGE PERIOD  
REMAINS ALONG THE CENTRAL GULF COAST, WHERE THERE HAS BEEN  
INCREASINGING AGREEMENT THAT SOME SORT OF UPPER LEVEL ENERGY WILL  
GET LEFT BEHIND BY AN UPPER TROUGH SHIFTING EAST AT THE END OF THE  
SHORT RANGE, BUT THE EVOLUTION OF THAT IS IN QUESTION TOWARDS NEXT  
WEEKEND. SOME GUIDANCE (MOST NOTABLY RECENT RUNS OF THE ECMWF AND  
UKMET) REALLY WANT TO BLOSSOM THIS INTO A FAIRLY WELL DEFINED  
TROPICAL LOW, AND NHC HAS RECENTLY ADDED THIS AREA INTO THEIR  
OUTLOOK. THERE IS SIGNIFICANT UNCERTAINTY WHERE THIS MAY IMPACT  
FROM LOUISIANA TO THE WESTERN FL PANHANDLE. THE GFS AND CMC REMAIN  
LESS ENTHUSIASTIC, BUT STILL SUGGEST THE PRESENCE OF AT LEAST A  
TROUGH OR LINGERING FRONT FOR SOME TIME AND OVERALL GUIDANCE QPF  
IS TRENDING UPWARD. ACCORDINGLY, WPC QPF HAS INCREASED INLAND  
ACROSS THE CENTRAL GULF COAST. PLEASE REFER TO THE LATEST TROPICAL  
WEATHER OUTLOOKS FROM NHC FOR THE LATEST INFORMATION ON THIS  
FEATURE.  
 
OTHERWISE, THERE IS CONTINUED GOOD AGREEMENT FOR SOME SORT OF  
AMPLIFIED TROUGHING ACROSS THE EAST, AS A WEAK SHORTWAVE SLIDES  
INTO THE PACIFIC NORTHWEST ON WEDNESDAY AND RIDES OVERTOP A STRONG  
CENTRAL U.S. RIDGE THURSDAY-FRIDAY. EVENTUALLY, THIS ENERGY SHOULD  
DROP BACK TOWARDS THE GREAT LAKES SERVING TO REINFORCE TROUGHING  
OVER THE EAST BY LATE PERIOD. TYPICAL LATE PERIOD UNCERTAINTIES  
WITH TIMING AND DETAILS BEGINS TO ARISE BY DAYS 6-7 BOTH IN THE  
EASTERN U.S. TROUGH, BUT ALSO WITH A POSSIBLE CLOSED LOW TOWARDS  
THE PACIFIC NORTHWEST COAST IN ABOUT A WEEK.  
 
GIVEN NOTEABLE MODEL SMALLER SCALE DIFFERENCES AT MEDIUM RANGE  
TIME SCALES THAT AFFECT HEADLINE THREAT MESSAGING, THE WPC MEDIUM  
RANGE PRODUCT SUITE WAS MAINLY DERIVED FROM THE 18 UTC GEFS MEAN,  
12 UTC ECMWF ENSEMBLE MEAN, 01 UTC NATIONAL BLEND OF MODELS AND  
WPC CONTINUITY TO SMOOTH OUT THESE LESS PREDICTABLE FEATURES AND  
INTERACTIONS WHILE REASONABLY TRENDING CONTINUITY CONSISTENT WITH  
GRADUALLY GROWING GUIDANCE SIGNALS. THE LATEST 00 UTC GUIDANCE  
SUITE GENERALLY MAINTAINS THE LINE WITH PRIOR RESPECTIVE RUNS, BUT  
FALLS SHORT OF PROVIDING MUCH THREAT CLARITY.  
   
..OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
 
 
A MAIN UPPER HIGH/RIDGE WILL SETTLE WESTWARD INTO THE FOUR CORNERS  
THIS WEEK TO SUPPORT ABOVE NORMAL TEMPERATURES ACROSS MUCH OF THE  
WEST, BUT THE MOST ANOMALOUS HEAT IS FORECAST TO SPREAD DOWNSTREAM  
ACROSS THE NORTH-CENTRAL U.S. AS RIDGING/HEIGHTS BUILD OVER THE  
REGION. IN THIS PATTERN, MODEST MONSOONAL MOISTURE FLOW ACROSS THE  
SOUTHWEST INTO THE GREAT BASIN/ROCKIES UNDER THE UPPER RIDGE MAY  
OFFER DAILY CHANCES FOR SHOWERS WITH SOME LOCALLY HEAVIER  
DOWNPOURS WITH SLOWED CELL MOTIONS. MEANWHILE, A SERIES OF  
UNCERTAIN IMPULSES WILL ROUND THE TOP OF THE RIDGE TO PERIODICALLY  
FOCUS STRONG CONVECTION LOCALLY OVER THE NORTH-CENTRAL  
PLAINS/UPPER MIDWEST, BUT RAINS MAY PROVE MORE PROGRESSIVE IN  
NATURE.  
 
UPPER TROUGH POSITIONS WILL SANDWICH THE UPPER RIDGE BOTH OFF THE  
PACIFIC NORTHWEST WHERE RAINFALL CHANCES ARE LIMITED AND ALSO THE  
EAST WHERE FRONTS WILL FOCUS RAIN AND THUNDERSTORMS. MOISTURE WILL  
POOL FROM THE EASTERN MID-ATLANTIC TO THE SOUTHEAST AND GULF COAST  
STATES NEAR A WAVY STALLED LEAD FRONT. POSSIBLE  
SUB-TROPICAL/TROPICAL INTERACTION OVER THE NORTHERN THE GULF OF  
MEXICO MAY SUPPORT HEAVY RAIN POTENTIAL INTO THE CENTRAL GULF  
COAST AND VICINITY AS SLOW-MOVING AND REPEAT CELLS WITH VERY HEAVY  
DOWNPOURS LEAD TO LOCAL RUNOFF ISSUES. A "SLIGHT" RISK AREA WAS  
ISSUED ON THE EXPERIMENTAL WPC MEDIUM RANGE EXCESSIVE RAINFALL  
OUTLOOK THROUGH MID-LATE WEEK. MODELS OFFER POTENTIAL FOR A  
DISTURBANCE OR TROPICAL LOW, ALTHOUGH THERE IS SIGNIFICANT  
UNCERTAINTY IN THIS AS PER NHC. REGARDLESS, THERE IS A GROWING  
GUIDANCE SIGNAL THAT HEAVY RAINFALL LIKELY IMPACTS THE CENTRAL  
GULF COAST AS FUELED BY POOLING DEEP MOISTURE AND INSTABILITY NEAR  
THE LINGERING BOUNDARY.  
 
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, EXPERIMENTAL EXCESSIVE RAINFALL  
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES ARE  
AT:  
 
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  
 

 
 

 
 
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