612
FXUS02 KWBC 041953
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
353 PM EDT SUN OCT 4 2026
VALID 12Z WED OCT 07 2026 - 12Z SUN OCT 11 2026
...EXCESSIVE RAINFALL THREAT RAMPS UP ONCE AGAIN ACROSS CENTRAL
GULF COAST AND SOUTHEAST ON FRIDAY...
..HEAT WAVE IN CALIFORNIA BEGINS TO WEAKEN ON THURSDAY
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS CONTINUE TO BE IN GOOD AGREEMENT ON THE EVOLUTION OF
TRANSIENT SHORTWAVE ENERGY PROPAGATING THROUGH THE BASE OF A MEAN
TROUGH IN SOUTHEAST CANADA/NORTHEASTERN U.S.. THERE CONTINUES TO BE
SOME UNCERTAINTY SURROUNDING THE STRENGTH OF THE EAST
PACIFIC/SOUTHWESTERN U.S. RIDGE MID-WEEK. THIS MIGHT BE INFLUENCED
BY THE APPROACHING UPSTREAM TROUGH AND THE MODEL DISPERSION
REGARDING ITS EVOLUTION, WITH SOME SUGGESTING IT'LL SPLIT INTO TWO
SEPARATE STREAMS AND ANOTHER CAMP KEEPING IT PHASED AS IT
APPROACHES THE WEST COAST. THE GFS SUITE IS IN THE SPLIT FLOW
PATTERN, WHILE THE EURO, CANADIAN AND UKMET SUITES ARE IN THE
PHASED TROUGH CAMP.
A COMPOSITE BLEND OF THE AVAILABLE NON-GFS DETERMINISTIC AND AI
GUIDANCE WAS SUFFICIENT ON DAY 3, FOLLOWED BY A DETERMINISTIC
EURO/CMC AND ECAIFS ON DAY 4. THE EURO SUITE AND ENSEMBLE MEANS
WERE USED ON DAY 5 AND MEANS WERE FAVORED THROUGH THE END OF THE
PERIOD.
..PATTERN OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
THE LARGE-SCALE PATTERN THROUGH THE PERIOD WILL FEATURE A
PRONOUNCED MEAN TROUGH OVER EASTERN U.S., RIDGING OVER WESTERN
U.S., AND TROUGHING OVER THE EASTERN PACIFIC. AT THE SURFACE, A
SLOW- MOVING FRONTAL BOUNDARY SHOULD REMAIN DRAPED ACROSS THE GULF
COAST AND SOUTHEAST/FLORIDA THROUGH THE WEEKEND. DEEP TROPICAL
MOISTURE WILL SPREAD NORTH FROM THE GULF AND INTERACT WITH THE
BOUNDARY LEADING TO REPEATED ROUNDS OF SHOWERS AND THUNDERSTORMS,
PARTICULARLY ACROSS FLORIDA AND ADJACENT PORTIONS OF THE SOUTHEAST.
TRAINING CONVECTION AND HIGH RAINFALL RATES COULD PRODUCE LOCALLY
EXCESSIVE RAINFALL, PARTICULARLY WHERE STORMS REPEATEDLY OCCUR.
THEREFORE, WPC EXCESSIVE RAINFALL OUTLOOK CONTINUES TO HIGHLIGHT A
MARGINAL RISK FOR PORTIONS OF FLORIDA ON DAY 4/THURSDAY. THE
GREATEST HEAVY- RAIN POTENTIAL SHOULD GRADUALLY SHIFT WITH THE
POSITION OF THE FRONT, BUT FLORIDA REMAINS THE FAVORED AREA FOR
PROLONGED CONVECTION THROUGH THURSDAY. BY FRIDAY, THE AXIS OF
HEAVY RAINFALL SHIFTS WESTWARD ALONG THE GULF COAST AND EVENTUALLY
INLAND INTO THE SOUTHEAST ON SATURDAY. GUIDANCE HAS TRENDED WETTER
FOR THE GULF COAST AND SOUTHEAST NEXT WEEKEND WITH A CORRESPONDING
INCREASED POTENTIAL FOR HEAVY TO EXCESSIVE RAINFALL.
ACROSS THE MIDWEST INTO THE NORTHEAST, THE PERSISTENT UPPER TROUGH
SHOULD MAINTAIN GENERALLY COOLER CONDITIONS. PERIODIC SHORTWAVES
ROTATING THROUGH THE TROUGH MAY PRODUCES AREAS OF LIGHT SHOWERS,
PARTICULARLY NEAR FRONTAL BOUNDARIES. FARTHER WEST, UPPER RIDGING
SHOULD CONTINUE TO SUPPORT ABOVE AVERAGE TEMPERATURES. HIGHS IN
THE UPPER 90S TO LOWER 100S WILL REMAIN POSSIBLE ACROSS PORTIONS OF
THE SOUTHWEST AND SOUTHERN CALIFORNIA. WARM OVERNIGHT TEMPERATURES
WILL ALSO LIMIT RELIEF FROM THE HEAT, LEADING TO HEAT-RELATED
ILLNESS CONCERNS ESPECIALLY FOR THOSE WITHOUT ADEQUATE COOLING AND
HYDRATION. EXTREME HEAT WARNINGS ARE IN EFFECT FOR PORTIONS OF
SOCAL, WHILE HEAT ADVISORIES ARE IN EFFECT FOR PARTS OF CENTRAL
AND NORTHERN CALIFORNIA. SEE WPC'S KEY MESSAGES FOR THE CALIFORNIA
OCTOBER HEAT WAVE FOR ADDITIONAL INFORMATION. THE RIDGE SHOULD
GRADUALLY WEAKEN, WHILE THE EASTERN PACIFIC TROUGH BECOMES MORE
AMPLIFIED LATER THIS WEEK. ADDITIONALLY, AS THE TROUGH CONTINUES
TO MOVE INLAND, PRECIPITATION CHANCES INCREASES INTO THE WEEKEND
OVER PACIFIC NORTHWEST INTO THE NORTHERN ROCKIES.
KEBEDE/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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