555
FXUS02 KWBC 070709
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
309 AM EDT WED OCT 7 2026
VALID 12Z SAT OCT 10 2026 - 12Z WED OCT 14 2026
...TROPICAL SYSTEM WILL BRING HEAVY RAINFALL AND FLASH FLOODING
ACROSS PARTS OF THE SOUTHEAST INTO THE MID-ATLANTIC THROUGH THE
WEEKEND...
..PATTERN OVERVIEW
THE GULF TROPICAL CYCLONE WILL LIFT NORTHEASTWARD BRINGING CHANCES
FOR EXCESSIVE RAINFALL ACROSS PORTIONS OF THE SOUTHEAST INTO THE
OHIO VALLEY/MID-ATLANTIC THROUGH THE WEEKEND. A AMPLIFIED WESTERN
TROUGH WILL INTERACT WITH HURRICANE RACHEL, BRINGING WIDESPREAD
RAIN ACROSS THE SOUTHWEST INTO THE GREAT BASIN AND INTERMOUNTAIN
WEST/ROCKIES. CHANCES FOR SNOW INCREASES FOR HIGH ELEVATIONS OVER
THE NORTHERN ROCKIES THROUGH THE WEEKEND.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE MODELS CONTINUE TO HAVE DECENT AGREEMENT ON THE WESTERN TROUGH
AS IT CONTINUES TO DEEPEN THROUGH THE WEEKEND, WHILE INTERACTING
WITH MOISTURE FROM HURRICANE RACHEL. UNCERTAINTY INCREASES IN
REGARD TO THE EXACT AMPLITUDE AND PROGRESSION OF EMBEDDED
SHORTWAVES, ESPECIALLY TOWARDS MONDAY INTO TUESDAY. ANOTHER AREA OF
UNCERTAINTY REMAINS WITH THE TROPICAL SYSTEM OVER THE GULF AS IT
BEGINS TO MOVE INLAND. THE GREATEST UNCERTAINTIES AMONG THE MODELS
IS THE EXACT TRACK AND THE MAGNITUDE AND EXTENT OF THE TROPICAL
MOISTURE AND ASSOCIATED HEAVY RAINFALL. THE AI GUIDANCE SEEMED TO
HAVE A BETTER HANDLE ON THE STORMS TRACK AS IT MOVES INLAND AND THE
ENSEMBLE MEANS HELPED SMOOTH OUT EXTREME RAINFALL AMOUNTS.
THEREFORE, THE FORECAST INCORPORATED A MULTI-MODEL BLEND THROUGH
THE FIRST PORTION OF THE PERIOD, WITH HEAVIER WEIGHT ON THE
ENSEMBLE MEANS AND AI GUIDANCE TOWARDS EARLY NEXT WEEK.
..WEATHER/HAZARDS HIGHLIGHTS
THE PRIMARY CONCERN FOR THE UPCOMING WEEKEND WILL BE THE ONGOING
HYDROLOGICAL EFFECTS OF THE TROPICAL SYSTEM THAT CROSSES THE
NORTHERN GULF COAST LATE THIS WEEK. EVEN AS THE CYCLONE WEAKENS
INLAND, A DEEP PLUME OF GULF MOISTURE AND A BROAD CIRCULATION WILL
SUPPORT PERIODS OF MODERATE TO HEAVY RAINFALL ACROSS PORTIONS OF
SOUTHEAST NORTHWARD INTO THE MID-ATLANTIC AND OHIO/TENNESSEE
VALLEY. LOCALLY EXCESSIVE RAINFALL REMAINS POSSIBLE WHERE TRAINING
OCCURS AND/OR WHERE THE REMNANT CIRCULATION INTERACTS WITH FRONTAL
BOUNDARIES. ANTECEDENT WET SOILS FROM PREVIOUS RAINFALL WILL
INCREASE THE POTENTIAL FOR RENEWED FLOODING, ESPECIALLY OVER
PORTIONS OF THE SOUTHEAST INTO THE CAROLINAS AND MID-ATLANTIC,
WHICH IS REFLECTED IN WPC EXCESSIVE RAINFALL OUTLOOK FOR
DAY4/SATURDAY.
THE SYSTEM WILL TRACK NORTHEASTWARD SUNDAY INTO MONDAY, BRINGING
CHANCES FOR HEAVY RAINFALL ACROSS PORTIONS THE OHIO VALLEY/GREAT
LAKES INTO THE MID- ATLANTIC AND NORTHEAST. A COMBINATION OF
ANOMALOUS MOISTURE, LOW- LEVEL INFLOW, AND FORCING SHOULD SUPPORT A
PERIOD OF HEAVY RAINFALL, LEADING TO FLOODING CONCERNS, ESPECIALLY
OVER PORTIONS OF THE MID-ATLANTIC AND NORTHEAST COASTAL AREAS.
REFER TO NHC.GOV FOR MORE INFORMATION AND UPDATES ON THE TROPICAL
SYSTEM. THE TROPICAL MOISTURE PLUME AND ASSOCIATED FRONTAL SYSTEM
SHOULD CONTINUE NORTHEASTWARD INTO MONDAY, BRINGING ADDITIONAL
RAINFALL OVER THE NORTHEAST.
OVER WESTERN U.S., THE UPPER TROUGH WILL BRING PERIODS OF RAIN
THAT WILL IMPACT THE PACIFIC NORTHWEST AND INTERMOUNTAIN WEST,
WITH RAIN SPREADING INTO THE NORTHERN/CENTRAL ROCKIES AS THE TROUGH
DIGS SOUTHEASTWARD. SNOW LEVELS SHOULD LOWER AS COLDER AIR
OVERSPREADS THE REGION, RESULTING IN ACCUMULATING SNOW ACROSS
HIGHER ELEVATIONS OVER THE NORTHERN ROCKIES/INTERMOUNTAIN WEST.
AS THE TROUGH DEEPENS AND INTERACTS WITH TROPICAL MOISTURE FROM
HURRICANE RACHEL, CHANCES FOR WIDESPREAD HEAVY RAINFALL AND
LOCALIZED FLOODING INCREASES OVER THE SOUTHWEST INTO THE GREAT
BASIN AND CENTRAL ROCKIES THROUGH THE WEEKEND. TEMPERATURES SHOULD
TREND DOWNWARD BEHIND THE ADVANCING WESTERN TROUGH OVER THE
NORTHWEST INTO THE NORTH/CENTRAL PLAINS THROUGH WEDNESDAY. PERIODS
OF RAIN WILL CONTINUE ALONG THE FRONTAL BOUNDARY FOR THE SOUTHWEST
INTO THE PLAINS AND UPPER MIDWEST FROM MONDAY THROUGH TUESDAY.
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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