108
FXUS02 KWBC 061903
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
303 PM EDT FRI SEP 6 2024
VALID 12Z MON SEP 09 2024 - 12Z FRI SEP 13 2024
...MULTI-DAY WESTERN GULF COAST STATES HEAVY RAINFALL/FLOODING
THREAT THROUGH EARLY-MID NEXT WEEK ALSO BEING MONITORED BY NHC...
..OVERVIEW
HEAVY RAIN AND THUNDERSTORMS WILL CONTINUE TO MAKE WEATHER
HEADLINES FOR THE WESTERN GULF COAST STATES AS ANOTHER RESURGENCE
OF DEEP GULF OF MEXICO/TROPICAL MOISTURE FEEDS INLAND THROUGH EARLY-
MID NEXT WEEK AS A WARM FRONT LIFTS TOWARD THE REGION IN ADVANCE OF
A TROPICAL FEATURE BEING MONITORED BY NHC FOR POSSIBLE DEVELOPMENT.
ELSEWHERE, THE START OF NEXT WEEK WILL BE FEATURED WITH AN UPPER
LEVEL TROUGH ACROSS THE NORTHEAST U.S. AND A LARGE CANADIAN SURFACE
HIGH. THIS WILL RESULT IN A HIGH QUALITY AIRMASS ACROSS MUCH OF
THE EASTERN U.S. WITH A HINT OF FALL IN THE AIR, BUT A MODERATION
TREND ENSUES GOING INTO THE MIDDLE OF THE WEEK. OUT WEST, THE
PERSISTENT UPPER RIDGE AND WIDESPREAD ANOMALOUS WARMTH SHOULD ABATE
BY THE END OF THE WEEK AS AN UPPER TROUGH WITH PRECIPITATION WORKS
OVER THE WEST COAST AND NORTHERN INTERMOUNTAIN WEST/ROCKIES. THE
PATTERN SHOULD BE MAINLY BENIGN FOR THE REST OF THE NATION.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST MODEL GUIDANCE CONTINUES TO FEATURE GOOD OVERALL
SYNOPTIC SCALE AGREEMENT ACROSS THE NATION AS THE WORK WEEK BEGINS
MONDAY, EVEN THOUGH THERE ARE CHARACTERISTIC LINGERING TIMING
DIFFERENCES WITH SHORTWAVE PERTURBATIONS AND SURFACE FEATURES
DETAIL. THE MODELS HAVE TRENDED STRONGER WITH THE LARGE SCALE
TROUGH/UPPER LOW THAT WORKS ACROSS THE WEST COAST/INTERMOUNTAIN
WEST COMPARED TO PAST CYCLES.
ACCORDINGLY, THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY
DERIVED FROM A MODEL AND ENSEMBLE MEAN COMPOSITE AS HIGHLIGHTED BY
SOLUTIONS THAT AT THIS TIME ARE LESS ROBUST AND DETAILED WITH GULF
OF MEXICO TROPICAL DEVELOPMENT GIVEN CONTINUED NHC UNCERTAINTIES.
..WEATHER/HAZARDS HIGHLIGHTS
TROPICAL MOISTURE DEEPENING OVER THE SOUTHWESTERN GULF OF MEXICO
OVER THE NEXT FEW DAYS IS EXPECTED TO BRING AN INCREASING THREAT
FOR HEAVY RAIN TO THE COASTAL AREAS OF THE TEXAS GULF COAST BY
EARLY NEXT WEEK, WHICH IS COVERED BY A MARGINAL RISK ON THE WPC
DAY 4/MONDAY ERO. GUIDANCE SIGNALS ARE SOLIDIFYING IN SUPPORT FOR
POTENTIAL OF IMPACTFUL RAINFALL TOTALS THAT WILL NEED TO BE
MONITORED GOING INTO THE DAY 5/TUESDAY TIME PERIOD WHEN A SLIGHT
RISK OF EXCESSIVE RAINFALL IS INDICATED ALONG MUCH OF THE TEXAS
COAST TO LAKE CHARLES, LOUISANA. THERE IS A STILL UNCERTAIN THREAT
FOR TROPICAL SYSTEM DEVELOPMENT BEING MONITORED BY NHC THAT COULD
FURTHER ENHANCE THIS THREAT. THIS REGION WILL LIKELY HAVE
NOTEWORTHY RAINFALL LEADING UP TO THIS OVER THE NEXT FEW DAYS, AND
THIS WILL MAKE CONDITIONS MORE SUSCEPTIBLE TO POTENTIAL FLOODING
CONCERNS. OTHERWISE, MUCH OF THE COUNTRY SHOULD BE RELATIVELY
UNEVENTFUL AND DRY, ALTHOUGH SHORTWAVE ENERGY PIVOTING AROUND THE
WESTERN-CENTRAL U.S. UPPER RIDGING MAY PRODUCE ISOLATED TO
SCATTERED RAINFALL WITH MOSTLY LIGHT AMOUNTS. UPSTREAM, LIGHT TO
LOCALLY MODERATE PRECIPITATION AHEAD OF A WESTERN U.S. TROUGH
WILL BEGIN TO MOVE INTO/ACROSS THE REGION INTO MID-LATE NEXT WEEK.
TEMPERATURES ARE EXPECTED TO BE UNSEASONABLY WARM BY SEPTEMBER
STANDARDS ACROSS MUCH OF THE NORTH-CENTRAL U.S., WITH HIGHS
RUNNING ABOUT 5 TO 15 DEGREES ABOVE AVERAGE FROM THE FRONT RANGE OF
THE ROCKIES TO THE WESTERN GREAT LAKES FOR MUCH OF THE WEEK. THE
HOT WEATHER EXPECTED ACROSS MUCH OF THE WEST COAST AND
INTERMOUNTAIN WEST DURING THE SHORT RANGE PERIOD IS EXPECTED TO
IMPROVE GOING INTO THE MIDDLE OF NEXT WEEK AS THE UPPER TROUGH
BUILDS SOUTHWARD AND HERALDS THE ARRIVAL OF A COLD FRONT, BRINGING
TEMPERATURES OF 5-15 DEGREES BELOW NORMAL FOR PORTIONS OF THE WEST
COAST STATES AND INTO NEVADA. SLIGHTLY BELOW AVERAGE READINGS ARE
ALSO LIKELY FOR THE GULF COAST REGION (BUT STILL HUMID) OWING TO
INCREASED CLOUD COVER AND RAIN.
HAMRICK/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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