679
FXUS02 KWBC 080700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT SUN OCT 08 2023
VALID 12Z WED OCT 11 2023 - 12Z SUN OCT 15 2023
...EXCESSIVE RAIN THREATS FOR THE MIDWEST TO NORTHEAST AND CENTRAL
GULF COAST/SOUTHEAST/NORTHERN FLORIDA MID TO LATE WEEK...
..OVERVIEW
A STORMY WEEK ON TAP FOR OUR FINE NATION. A CLOSED UPPER LOW WILL
SHIFT SLOWLY EASTWARD ACROSS EASTERN CANADA MID-LATER WEEK TO END
GREAT LAKE EFFECT RAINS AND SHIFT UNSETTLED CONDITIONS
UNDER/AROUND THIS AMPLIFIED FEATURE AWAY FROM THE NORTHEAST. FAR
UPSTREAM, DYNAMIC UPPER TROUGH ENERGIES WILL WORK ONSHORE AND DIVE
SOUTHEASTWARD THROUGH THE WEST. EARLY WEEK RAINS WILL EASE OVER
THE PACIFIC NORTHWEST WITH SYSTEM/FRONTAL PROGRESSIONS TO FAVOR
ENHANCED MOUNTAIN SNOWS FROM THE CASCADES TO ESPECIALLY THE
NORTHERN ROCKIES WITH CLOSED TROUGH/LOW DEVELOPMENT AND PASSAGE.
THIS POTENT UPPER SYSTEM WILL STEADILY TRACK FROM THE PLAINS TO
THE NORTHEAST FRIDAY INTO NEXT WEEKEND. THIS WILL FOSTER ENHANCED
PRECIPITATION CHANCES TO SPREAD IN EARNEST FROM THE CENTRAL
U.S./MIDWEST THROUGH THE NORTHEAST AS GULF THEN ATLANTIC MOISTURE
INFLOW DEEPENS WITH DEEP CYCLOGENESIS/FRONTOGENESIS. TO THE SOUTH,
A FRONTAL BOUNDARY WITH DEEPENED TROPICAL MOISTURE WILL LIFT
THROUGH THE GULF OF MEXICO TO INCREASE HEAVY PRECIPITATION CHANCES
ACROSS THE CENTRAL GULF COAST AND FLORIDA/SOUTHEAST BY MID TO
LATER THIS WEEK BEFORE LIFTING OFF THE EAST COAST.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
MODEL AND ENSEMBLE FORECAST SPREAD CONTINUES TO DECREASE THROUGH
MEDIUM RANGE TIME SCALES, NOW IN A PATTERN WITH SEEMINGLY BETTER
THAN AVERAGE PREDICTABILITY FOR FLOW EVOLUTION AND MAIN EMBEDDED
WEATHER FOCUSING STORMS/SYSTEMS OVER THE NEXT WEEK IN ACTIVE FLOW.
THE WPC PRODUCT SUITE WAS PRIMARILY DERIVED FROM A COMPOSITE BLEND
OF BEST CLUSTERED GUIDANCE FROM THE 18 UTC GFS AND 00 UTC
ECMWF/CANADIAN AND ECMWF ENSEMBLE MEAN ALONG WITH THE COMPATIBLE
01 UTC NATIONAL BLEND OF MODELS AND WPC CONTINUITY. LATEST 00 UTC
GUIDANCE OVERALL REMAINS IN CLOSE LINE.
..WEATHER/HAZARDS HIGHLIGHTS
DYNAMIC UPPER TROUGH/HEIGHT FALLS AND SURFACE SYSTEM PASSAGE
ACROSS THE WEST INTO MID-LATER WEEK WILL FAVOR A SWATH OF AUTUMN
MOUNTAIN SNOWS FROM THE CASCADES INTO THROUGH THE INTERMOUNTAIN
WEST AND ESPECIALLY THE NORTHERN ROCKIES. DOWNSTREAM,
PRECIPITATION CHANCES WILL EXPAND EAST THROUGHOUT THE WEEK AS A
FRONTAL SYSTEM MOVES ACROSS THE NATION, REACHING THE CENTRAL U.S.
BY MIDWEEK. DEEP CYCLOGENESIS AND WRAPPING ANOMALOUS MOISTURE INTO
A LEADING WARM FRONT LIFTING THROUGH THE EAST-CENTRAL U.S. WILL
SHIFT FOCUS FOR EMERGING HEAVY RAINS FROM THE CENTRAL PLAINS
THROUGH THE MIDWEST INTO WEDNESDAY. THE WPC DAY 4/WEDNESDAY
EXCESSIVE RAINFALL OUTLOOK (ERO) SHOWS A MARGINAL RISK OVER THE
MID-MS VALLEY GIVEN RISK FOR TRAINING AND GROWING MODEL AND
ENSEMBLE SIGNALS. GUIDANCE SUGGESTS THIS HEAVY RAINFALL AREA WILL
LIKELY EXPAND ACROSS THE MIDWEST WITH CONTINUED SYSTEM DEVELOPMENT
AND TRACK/INFLOW THAT IS COVERED AT THIS POINT BY A MARGINAL DAY
5/THURSDAY ERO RISK AREA. MEANWHILE WELL SOUTH, A SEPARATE WARM
FRONT LIFTING THROUGH THE GULF OF MEXICO AND THE FLORIDA PENINSULA
BRINGS A THREAT FOR HEAVY RAINFALL FROM THE CENTRAL GULF COAST TO
THE SOUTHEAST WEDNESDAY/THURSDAY. THIS MAY BE AIDED BY AN AREA OF
LOW PRESSURE IN THE GULF OF MEXICO AND POSSIBLE REMNANT TROPICAL
MOISTURE TO BE MONITORED. LATEST MODEL GUIDANCE PROMPTED AN ERO
MARGINAL RISK AREA FOR DAY 4/WEDNESDAY FROM THE CENTRAL GULF COAST
TO THE FLORIDA PENINSULA. A DAY 5/THURSDAY ERO MARGINAL RISK AREA
WAS ALSO INTRODUCED DOWNSTREAM TO SPAN PARTS OF THE SOUTHEAST.
THESE TWO MAIN SYSTEMS MAY INCREASINGLY INTERACT TO SOME DEGREE TO
SPREAD ENHANCED RAINFALL AND RUNOFF ISSUES POSSIBLE ACROSS THE
EAST/NORTHEAST FRIDAY INTO SATURDAY, WITH WIDESPREAD ENHANCED
BACKSIDE WINDS AND POST-FRONTAL FALLING AUTUMN TEMPERATURES.
SCHICHTEL
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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