266  
FXUS02 KWBC 111951  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
351 PM 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...  
 
18Z UPDATE: THE 12Z MODEL GUIDANCE SUITE MAINTAINS ABOVE AVERAGE  
SYNOPTIC SCALE AGREEMENT ACROSS THE MAJORITY OF THE NATION THROUGH  
THE END OF THE WEEK, WITH THE MAIN EXCEPTION TO THIS BEING ACROSS  
THE GULF COAST REGION WHERE A COL IN THE RIDGE AXIS WILL EXIST. A  
WEAK MID-UPPER LEVEL TROUGH ALONG WITH AN ACCOMPANYING SURFACE  
TROUGH AND POTENTIAL LOW WILL MEANDER OVER THE NORTHERN GULF IN AN  
ENVIRONMENT OF EXTREMELY WEAK STEERING FLOW ALOFT. IT DOES APPEAR  
THE UKMET IS ON THE WESTERN EDGE OF THE CONSENSUS WITH THE MAIN  
TROUGH AXIS, SO MORE WEIGHTING TOWARDS THE GFS/ECMWF/CMC IN THE  
FORECAST PROCESS WAS APPLIED. REGARDLESS OF ANY POTENTIAL  
TROPICAL CYCLONE EVOLUTION, THE PROSPECTS FOR HEAVY RAIN FROM  
SOUTHERN LOUISIANA TO THE FLORIDA PANHANDLE REMAIN ELEVATED, AND  
THUS THE REASONING FOR THE SLIGHT RISK AREAS IN THE EXPERIMENTAL  
DAY 4 AND DAY 5 EXCESSIVE RAINFALL OUTLOOK. ELSEWHERE, THE GFS IS  
SLIGHTLY MORE AMPLIFIED WITH THE TROUGH/FRONT CROSSING THE UPPER  
MIDWEST AND GREAT LAKES REGION THIS WEEKEND, BUT STILL WITHIN THE  
ENSEMBLE SPREAD AND CONSIDERED A PLAUSIBLE SOLUTION. BY THE END  
OF THE FORECAST PERIOD NEXT MONDAY, THE CMC IS A BIT SLOWER AND  
MORE AMPLIFIED WITH THE TROUGH REACHING THE WEST COAST. ABOUT  
HALF OF THE GEFS/ECENS AND HALF OF THE CMC/ECMWF/GFS WAS USED FOR  
THE SUNDAY-MONDAY TIME PERIOD. THE PREVIOUS FORECAST DISCUSSION  
FOLLOWS BELOW FOR REFERENCE. /HAMRICK  
-----------------------------------  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
A SIGNIFICANT AREA OF UNCERTAINTY IN THE MEDIUM RANGE PERIOD  
REMAINS ALONG THE CENTRAL GULF COAST, WHERE THERE HAS BEEN  
INCREASING 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 NOTABLE 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  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, THU-FRI, JUL 14-JUL  
15.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST AND THE LOWER  
MISSISSIPPI VALLEY, THU-SAT, JUL 14-JUL 16.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE NORTHERN  
PLAINS.  
- EXCESSIVE HEAT ACROSS PORTIONS OF TEXAS, THU, JUL 14.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE NORTHERN HIGH PLAINS,  
SAT-SUN, JUL 16-JUL 17.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL AND NORTHERN  
PLAINS, THU-FRI, JUL 14-JUL 15 AND MON, JUL 18.  
 
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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