934
FXUS02 KWBC 031924
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
324 PM EDT SAT OCT 3 2026
VALID 12Z TUE OCT 06 2026 - 12Z SAT OCT 10 2026
...PERSISTENT HEAVY RAINFALL THREAT CONTINUES ACROSS THE GULF COAST
INTO SOUTHEAST/FLORIDA INTO TUESDAY...
..LONG DURATION LATE-SEASON HEAT WAVE EXPECTED FOR CALIFORNIA
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS ARE GOOD AGREEMENT ON THE AMPLITUDE AND LOCATION OF MEAN
TROUGHING IN THE NORTHEASTERN U.S. DURING THE MEDIUM RANGE PERIOD.
THERE'S SOME UNCERTAINTY ON THE STRENGTH AND ORIENTATION OF A MID-
LEVEL RIDGE IN THE SOUTHWEST BETWEEN DAYS 3-5. THE TIMING OF A
MID- WEEK EAST PACIFIC TROUGH IS IN QUESTION AS WELL AS A POTENTIAL
SPLIT FLOW PATTERN, BUT THINGS APPEAR TO CONSOLIDATE AND AMPLIFY
OVER THE WEST COAST BY LATE NEXT WEEK.
A GENERAL MODEL BLEND CONSISTING OF THE AVAILABLE DETERMINISTIC AND
AI GUIDANCE WAS USED ON DAYS 3 AND 4. EURO AND CANADIAN ENSEMBLE
MEANS ARE INTRODUCED TO THE BLEND ON DAY 5 TO FAVOR A LESS
AMPLIFIED TROUGH IN THE EAST PACIFIC, WHICH IS APPARENT IN THE GFS
SUITE. THE AI AND ENSEMBLE MEAN GUIDANCE ARE FAVORED IN THE DAYS 6
AND 7 BLENDS DUE TO AGREEMENT ON THE WESTERN U.S. TROUGH PATTERN.
..PATTERN OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
A BROAD UPPER TROUGH OVER EASTERN U.S. WILL PERSIST THROUGH THE
WEEK, REINFORCING UNSETTLED WEATHER ACROSS THE SOUTHEAST. THE
PRIMARY FOCUS FOR RAINFALL WILL REMAIN ALONG THE GULF COAST AND
INTO FLORIDA, WHERE A SLOW-MOVING FRONTAL BOUNDARY WILL INTERACT
WITH DEEP TROPICAL MOISTURE. THIS SETUP IS FAVORABLE FOR A
PROLONGED PERIOD OF SHOWERS AND THUNDERSTORMS ALONG THE BOUNDARY.
REPEATED ROUNDS OF CONVECTION MAY LEAD TO LOCALIZED FLASH FLOODING
RISK ACROSS PORTIONS OF NORTHERN FLORIDA THROUGH THURSDAY, WHICH
IS REFLECTED IN THE WPC EXCESSIVE RAINFALL OUTLOOK FOR
DAY4/WEDNESDAY AND 5. HEAVY RAINFALL CONCERNS CONTINUE INTO NEXT
WEEKEND AS THE STATIONARY FRONT LINGERS.
FARTHER NORTH, A SERIES OF NORTHERN STREAM SHORTWAVES WILL
PROGRESS EASTWARD FROM THE NORTHERN ROCKIES/PLAINS TOWARDS THE
MIDWEST AND NORTHEAST. THESE DISTURBANCES WILL REINFORCE THE
BROADER EASTERN TROUGH, WHICH WILL SUPPORT PERIODIC LIGHT SHOWERS
ALONG ASSOCIATED FRONTAL BOUNDARIES ACROSS THE UPPER MIDWEST/GREAT
LAKES INTO THE NORTHEAST. BEHIND THE FRONT, COOLER AIR WILL BRING
BELOW NORMAL TEMPERATURES FROM THE NORTHEAST INTO PORTIONS OF THE
MID-ATLANTIC/SOUTHEAST THROUGH WEDNESDAY. THERE'S SOME FROST
POTENTIAL FOR PORTIONS OF THE LOWER GREAT LAKES/INTERIOR NORTHEAST
EARLY TUESDAY AND WEDNESDAY MORNINGS.
ACROSS THE WEST, UPPER RIDGING WILL CONTINUE TO SUPPORT ABOVE
AVERAGE TEMPERATURES, ESPECIALLY ACROSS CALIFORNIA AND DESERT
SOUTHWEST. DAYTIME HIGHS ARE EXPECTED TO REACH UPPER 90S TO LOW
100S, WITH MUCH OF SOUTHERN CALIFORNIA UNDER A MODERATE TO EXTREME
HEATRISK. THE RIDGE SHOULD GRADUALLY WEAKEN AND SHIFT EASTWARD BY
LATE NEXT WEEK, BUT THE PERSISTENT HEAT WILL BRING CONCERNS FOR
HEAT-RELATED ILLNESS, ESPECIALLY FOR THOSE WITHOUT ADEQUATE
COOLING AND HYDRATION. SEE WPC'S KEY MESSAGES FOR THE CALIFORNIA
OCTOBER HEAT WAVE FOR ADDITIONAL INFORMATION. BY LATE WEEK,
SCATTERED SHOWERS MAY DEVELOP FOR THE PACIFIC NORTHWEST AS THE NEXT
SHORTWAVE APPROACHES.
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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