400
FXUS02 KWBC 021925
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
325 PM EDT FRI OCT 2 2026
VALID 12Z MON OCT 05 2026 - 12Z FRI OCT 09 2026
...LINGERING GULF COAST/SOUTHEAST U.S. EXCESSIVE RAINFALL/FLOODING
THREAT MONDAY INTO TUESDAY...
..LONG DURATION LATE-SEASON HEAT WAVE EXPECTED FOR CALIFORNIA
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS CONTINUES TO MAINTAIN GOOD AGREEMENT ON THE LARGE-SCALE
EVOLUTION OF AN AMPLIFIED NORTHERN-STREAM INTO THE EASTERN U.S.,
WITH A SERIES OF FRONTAL BOUNDARIES SETTLING SOUTHWARD ACROSS THE
NORTH-CENTRAL AND EASTERN STATES. THERE DOES REMAIN SOME FORECAST
UNCERTAINTY INCREASES WITH THE POSITIONING OF THE FRONTAL BOUNDARY
ACROSS THE GULF COAST/SOUTHEAST, ESPECIALLY TOWARDS MID-WEEK, WHICH
AFFECTS THE LOCATION FOR THE HEAVIEST PRECIPITATION. THE ECMWF
SEEMS SUPPORT A FASTER SOUTHEASTWARD PROGRESSION OF THE
PRECIPITATION AXIS, WHILE THE GFS MAINTAINS THE AXIS FURTHER NORTH.
USING A MODEL BLEND OF THE DETERMINISTIC, ENSEMBLE, AND AI
GUIDANCE, SEEMS TO SMOOTH SOME OF THE TIMING AND AMPLITUDE
DIFFERENCES ACROSS THE GULF COAST/FLORIDA. ELSEWHERE, THERE ARE
SOME TIMING DIFFERENCES OF SHORTWAVES ACTING TO REINFORCE THE
EASTERN U.S. TROUGH. GREATER UNCERTAINTY ARISES LATE WEEK AS
ANOTHER SHORTWAVE APPROACHES THE NORTHWEST. THE GFS HAS
CONSISTENTLY BEEN A BIT FASTER AND MORE AMPLIFIED WITH THIS FEATURE
WHICH SEEMS TO SHOW A FASTER BREAK DOWN OR SUPPRESSION OF A STRONG
RIDGE OVER THE WEST EARLIER IN THE WEEK. THE WPC FORECAST TRENDED
MORE TOWARDS THE ENSEMBLE MEANS WITH SOME INCLUSION OF THE ECMWF
AND EC-AIFS GUIDANCE, MAINTAINING GOOD CONTINUITY WITH THE PREVIOUS
WPC FORECAST AS WELL.
..PATTERN OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
A BROAD TROUGH EXTENDING ACROSS THE EASTERN U.S. WILL CONTINUE TO
SUPPORT A SLOW-MOVING FRONTAL BOUNDARY ALONG THE GULF COAST INTO
THE SOUTHEAST. DEEP MOISTURE FROM THE GULF WILL REMAIN POOLED ALONG
THE BOUNDARY, SUPPORTING LOCALLY HEAVY RAINFALL ACROSS THE CENTRAL
GULF COAST INTO FLORIDA. REPEATED ROUNDS OF HIGH RAINFALL RATES
WILL LEAD TO EXCESSIVE RAINFALL/FLASH FLOODING THREATS ACROSS SOUTH
TEXAS AND PORTIONS OF THE GULF COAST INTO THE SOUTHEAST AND
NORTHERN FLORIDA, WHICH IS REFLECTED ON THE DAY4/MONDAY EXCESSIVE
RAINFALL OUTLOOK WITH A MARGINAL RISK AREA. FLOOD RISK CONTINUES
FOR NORTHERN FLORIDA THROUGH DAY5/TUESDAY. TOWARDS MID- WEEK,
CHANCES FOR SHOWERS AND THUNDERSTORMS CONTINUES AS THE FRONTAL
BOUNDARY STALLS ACROSS THE GULF COAST INTO FLORIDA. THE AXIS OF
GREATEST RAINFALL WILL CONTINUE TO GRADUALLY SHIFT SOUTH AND EAST
AS THE HIGH PRESSURE STRENGTHENS OVER THE EASTERN STATES AND A DRY
AIRMASS BUILDS BEHIND THE FRONT.
FARTHER NORTH, A SERIES OF NORTHERN-STREAM SHORTWAVES WILL EJECT
FRONTAL PASSAGES ACROSS THE NORTHERN PLAINS, MIDWEST, OHIO VALLEY,
AND NORTHEAST. TOWARDS MID TO LATE WEEK, THE POTENTIAL FOR ISOLATED
LIGHT SHOWERS MAY DEVELOP ALONG THE BOUNDARY, WHILE COOLER AIR
BEHIND THE FRONT BEGINS TO SPREAD INTO THE NORTH- CENTRAL AND
NORTHEASTERN U.S.. ACROSS THE WEST, PERSISTENT UPPER RIDGING WILL
MAINTAIN ABOVE- NORMAL TEMPERATURES ACROSS MUCH OF WESTERN U.S.
INTO THE WORK WEEK. THE GREATEST HEAT WILL REMAIN CONCENTRATED
ACROSS CALIFORNIA AND THE DESERT SOUTHWEST WITH DAYTIME HIGHS
REACHING INTO THE 90S TO LOW 100S. THE PROLONGED HEAT WILL POSE A
RISK FOR HEAT RELATED ILLNESS, ESPECIALLY FOR THOSE WITHOUT
ADEQUATE COOLING AND HYDRATION, EQUATING TO EXTREME HEATRISK
ESPECIALLY FOR THE LOS ANGELES AND SAN DIEGO POPULATION AREAS. SEE
WPC'S KEY MESSAGES FOR THE CALIFORNIA OCTOBER HEAT WAVE FOR
ADDITIONAL INFORMATION.
SANTORELLI/OUDIT
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, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY MESSAGES
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
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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