031
FXUS02 KWBC 060657
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
257 AM EDT FRI SEP 6 2024
VALID 12Z MON SEP 09 2024 - 12Z FRI SEP 13 2024
..OVERVIEW
THE BEGINNING 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 WILL LIKELY ABATE BY
THE END OF THE WEEK AS AN UPPER TROUGH BUILDS IN ACROSS THE WEST
COAST AND THEN THE INTERMOUNTAIN WEST. HEAVY RAIN AND THUNDERSTORMS
WILL CONTINUE TO MAKE WEATHER HEADLINES FOR THE WESTERN GULF COAST
AS ANOTHER RESURGENCE OF GULF MOISTURE MOVES INLAND ACROSS TEXAS BY
TUESDAY, BUT NOT MUCH IN TERMS OF HEAVY RAINFALL ELSEWHERE ACROSS
THE NATION GIVEN A PAUCITY OF DEEP MOISTURE OUTSIDE OF THE GULF
COAST STATES.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE FEATURES GOOD OVERALL SYNOPTIC SCALE
AGREEMENT ACROSS THE NATION AS THE WORK WEEK BEGINS MONDAY, EVEN
THOUGH THERE ARE SOME LINGERING TIMING DIFFERENCES WITH LEADING
SHORTWAVE PERTURBATIONS ACROSS SOUTHERN CANADA, AND THE CMC IS
SLOWER TO ERODE THE EASTERN U.S. TROUGH. THE MODELS HAVE TRENDED
STRONGER WITH THE LARGE SCALE TROUGH/UPPER LOW THAT DEVELOPS ACROSS
THE WEST COAST/INTERMOUNTAIN WEST COMPARED TO RECENT CYCLES.
TOWARDS THE END OF THE WEEK, THE GFS LIFTS THE UPPER LOW OUT
QUICKER ACROSS MONTANA AND IS STRONGER WITH THE DOWNSTREAM RIDGE
ACROSS THE GREAT LAKES REGION.
FOR THE WPC OVERNIGHT FORECAST, A BLEND OF THE DETERMINISTIC
GFS/CMC/UKMET/ECMWF WAS USED AS A BASELINE FOR THE FIRST HALF OF
THE PERIOD THROUGH EARLY WEDNESDAY, WITH A LITTLE MORE WEIGHTING TO
THE ECMWF AND CMC GUIDANCE. ENSEMBLE MEANS WERE ADDED GRADUALLY TO
MAKE UP ABOUT 50% OF THE BLEND BY FRIDAY, WHICH HELPED TO SMOOTH
OUT INCREASING MESOSCALE DIFFERENCES.
..WEATHER/HAZARDS HIGHLIGHTS
TROPICAL MOISTURE MOVING INTO THE SOUTHWESTERN GULF IS EXPECTED TO
BRING AN INCREASING THREAT FOR HEAVY RAIN TO THE COASTAL AREAS OF
THE TEXAS GULF COAST, WHICH IS COVERED BY A MARGINAL RISK ON THE
NEW DAY 4/MONDAY ERO. SOME OF THE LATEST MODEL GUIDANCE SHOWS THE
POTENTIAL FOR IMPACTFUL RAINFALL TOTALS THAT WILL NEED TO BE
MONITORED GOING INTO THE DAY 5/TUESDAY TIME PERIOD, AND A SLIGHT
RISK OF EXCESSIVE RAINFALL IS NOW PLANNED FROM NEAR CORPUS CHRISTI
TO LAKE CHARLES. THIS REGION WILL LIKELY HAVE NOTEWORTHY RAINFALL
LEADING UP TO THIS, 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. GENERALLY
LIGHT RAINFALL AHEAD OF THE NEXT WESTERN U.S. TROUGH SHOULD BEGIN
TO MOVE INTO THE REGION LATE TUESDAY AND BEYOND.
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
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page