929
FXUS02 KWBC 051954
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
354 PM EDT MON OCT 5 2026
VALID 12Z THU OCT 08 2026 - 12Z MON OCT 12 2026
...EXCESSIVE RAINFALL/FLASH FLOOD THREAT CONTINUES FOR CENTRAL
GULF COAST AND SOUTHEAST THROUGH THIS WEEKEND...
..HEAT WAVE IN CALIFORNIA BEGINS TO WEAKEN ON THURSDAY
..GUIDANCE/PREDICTABILITY ASSESSMENT
CONTINUING WITH RECENT TRENDS, MODELS ARE IN GOOD AGREEMENT
REGARDING MEAN TROUGHING IN THE NORTHEAST. MODELS ARE BEGINNING TO
CONSOLIDATE AROUND A SPLIT FLOW PATTERN WITH A CUT-OFF LOW
DEVELOPING OVER THE NORTHWEST THIS WEEKEND. CLUSTER ANALYSIS EOF
SIGNALS SUGGEST THAT THIS TROUGH PATTERN IN THE WEST IS THE MOST
UNCERTAIN ASPECT OF THE CONUS FORECAST IN THE MEDIUM RANGE.
A GENERAL MODEL BLEND (NOT INCLUDING THE GFS) IS USED ON DAY 3 DUE
TO DIFFERENCES AROUND THE STRENGTH OF A SOUTHWESTERN U.S./BAJA/EAST
PAC RIDGE. THE GFS IS INCORPORATED BACK INTO THE BLEND ON DAY 4 AND
CONTINUES TO BE USED THROUGH DAY 7. ENSEMBLE MEANS ARE GRADUALLY
INCREASED IN WEIGHTING BEGINNING ON DAY 5 AND MAKE UP A MAJORITY OF
THE BLENDS BY DAY 6.
..PATTERN OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
THE BROAD MEAN TROUGH OVER EASTERN U.S. WILL REMAIN WELL
ESTABLISHED THROUGH THE PERIOD, WHILE A REINFORCING SHORTWAVE
ROTATING THROUGH THE BASE WILL SUPPORT ANOTHER SURFACE FRONTAL
PROGRESSION ACROSS THE MIDWEST, GREAT LAKES, AND NORTHEAST BRINGING
COOLER CONDITIONS BEHIND THE FRONT. FARTHER SOUTH, THE GULF
COAST/SOUTHEAST WILL REMAIN COMPARATIVELY WARM BENEATH PERSISTENT
SOUTHERLY FLOW AHEAD OF THE SLOW-MOVING FRONTAL BOUNDARY. DEEP
TROPICAL MOISTURE WILL CONTINUE TO INTERACT WITH THE BOUNDARY,
LEADING TO SHOWERS AND THUNDERSTORM DEVELOPMENT ACROSS THE
SOUTHEAST, GULF COAST, AND FLORIDA THROUGH THIS WEEKEND. THE
COMBINATION OF INCREASING LOW- LEVEL MOISTURE, WEAK FRONTAL
PROGRESSION, AND LOCALLY FAVORABLE LOW- TO MID-LEVEL FLOW MAY LEAD
TO EXCESSIVE RAINFALL AND LOCALIZED FLOODING ALONG THE GULF COAST.
WITH THE POTENTIAL FOR REPEATED CONVECTION AND HIGH RAINFALL RATES,
WPC HAS A MARGINAL RISK ACROSS THE GULF COAST INTO THE EASTERN
TEXAS COAST AND PORTIONS OF WESTERN TEXAS IN THE EXCESSIVE RAINFALL
OUTLOOK FOR DAY4/THURSDAY. THE MARGINAL RISK CONTINUES FOR THE
GULF COAST INTO AND WESTERN TEXAS FOR DAY5/FRIDAY. BY SATURDAY, THE
HEAVIEST RAINFALL AXIS STARTS TO EXPAND INLAND ACROSS THE
SOUTHEAST. ON SUNDAY, A SURFACE WAVE WILL DEVELOP ALONG A PORTION
OF THE FRONTAL BOUNDARY AND GRADUALLY LIFT NORTHWARD ALONG THE
EAST COAST, SPREADING SHOWERS AND THUNDERSTORMS FROM THE SOUTHEAST
INTO THE NORTHEAST.
ACROSS THE WEST, UPPER RIDGING WILL CONTINUE TO SUPPORT DRY AND
ANOMALOUSLY WARM TEMPERATURES THROUGH THURSDAY. THE STRONGEST HEAT
WILL PERSIST FOR PORTIONS OF CALIFORNIA AND THE SOUTHWEST, WHERE
HIGHS ARE EXPECTED TO REACH 90S TO LOW 100S. WARM OVERNIGHT
TEMPERATURES WILL ALSO LIMIT RELIEF FROM THE HEAT, LEADING TO HEAT-
RELATED ILLNESS CONCERNS, ESPECIALLY FOR THOSE WITHOUT ADEQUATE
COOLING AND HYDRATION. THE RIDGE WILL GRADUALLY WEAKEN AS AN
UPPER-LOW DIVES DOWN FROM BRITISH COLUMBIA AND DIGS INTO THE WEST
ON SATURDAY. THIS WILL BRING PRECIPITATION CHANCES ACROSS THE
PACIFIC NORTHWEST AND NORTHERN ROCKIES, ESPECIALLY ON SATURDAY
INTO SUNDAY AS THE TROUGH BECOMES MORE AMPLIFIED. SHOWERS WILL
CONTINUE TO EXPAND EASTWARD FROM THE PACIFIC NORTHWEST/NORTHERN
ROCKIES INTO PORTIONS OF THE MIDWEST BY SUNDAY, WITH LOCALLY
MODERATE TO HEAVY SNOWFALL POSSIBLE ALONG FAVORED TERRAIN AND
FRONTAL ZONES. ADDITIONALLY, AS THE WESTERN RIDGE WEAKENS, THE
TROUGH WILL BRING COOLER TEMPERATURES THAT WILL SPREAD ACROSS THE
PACIFIC NORTHWEST INTO NORTHERN PLAINS THROUGH THE REST OF THE
WEEKEND AND INTO EARLY NEXT WEEK.
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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