401
FXUS02 KWBC 100701
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT TUE OCT 10 2023
VALID 12Z FRI OCT 13 2023 - 12Z TUE OCT 17 2023
...EXCESSIVE RAIN THREAT TO SHIFT FROM THE MIDWEST/GREAT LAKES TO
THE NORTHERN MID-ATLANTIC/NORTHEAST FRIDAY INTO SATURDAY AS HEAVY
RAINS EXIT THE SOUTHEAST...
..OVERVIEW
A DYNAMIC UPPER TROUGH/CLOSED LOW AND DEEPENED SURFACE LOW/FRONTAL
SYSTEM WILL STEADILY TRACK FROM THE PLAINS TO THE NORTHEAST FRIDAY
THROUGH NEXT WEEKEND. THIS WILL FOSTER THE SPREAD OF HEAVY
PRECIPITATION FROM THE MIDWEST/GREAT LAKES THROUGH THE
MID-ATLANTIC/NORTHEAST AS INFLOW MOISTURE INCREASES AND IS
SUSTAINED WITH ADDITION INFLUX FROM THE ATLANTIC. TO THE SOUTH, A
FRONTAL BOUNDARY ENHANCED WITH TROPICAL MOISTURE WILL LIFT FROM
THE GULF OF MEXICO TO SPREAD HEAVY PRECIPITATION ACROSS THE
SOUTHEAST THROUGH FRIDAY BEFORE LIFTING OFFSHORE. WELL UPSTREAM, A
SLOW TRANSLATION OF AN AMPLIFIED AND COMPLEX EASTERN PACIFIC
UPPER/SURFACE SYSTEM SEEMS SET TO RENEW WET FLOW INTO THE PACIFIC
NORTHWEST INTO EARLY NEXT WEEK.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
MODEL AND ENSEMBLE FORECAST SPREAD REMAINS ON THE LOW SIDE THROUGH
MEDIUM RANGE TIME SCALES 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 WELL CLUSTERED GUIDANCE FRIDAY INTO THE WEEKEND FROM THE 18 UTC
GFS AND 12 UTC ECMWF/CANADIAN/UKMET ALONG WITH THE COMPATIBLE 01
UTC NATIONAL BLEND OF MODELS. SHIFTED WPC GUIDANCE BLEND EMPHASIS
TOWARD ENSEMBLES AT LONGER TIME FRAMES AMID SLOWLY GROWING
FORECAST SPREAD/UNCERTAINTY, BUT FAVORED THE MORE AMPLIFIED/LESS
PROGRESSIVE ECMWF ENSEMBLE MEAN VERSUS THE GEFS GIVEN UPSTREAM
AMPLITUDE AND OVERALL GUIDANCE TRENDS. WPC PRODUCT CONTINUITY IS
WELL MAINTAINED WITH THIS FORECAST PLAN AND 00 UTC GUIDANCE
OVERALL REMAINS IN LINE.
..WEATHER/HAZARDS HIGHLIGHTS
DYNAMIC UPPER TROUGH SUPPORT AND DEEP CYCLOGENESIS/WRAPPING
ANOMALOUS MOISTURE INTO WARM/OCCLUDED FRONTS ACROSS THE CENTRAL TO
EASTERN U.S. WILL SHIFT FOCUS FOR EMERGING HEAVY RAINS FROM THE
MIDWEST/GREAT LAKES TO THE NORTHERN MID-ATLANTIC/NORTHEAST FRIDAY
INTO THE WEEKEND. WHILE LONGER DURATION RAINS AND AMBIENT
RELATIVELY DRY SOILS MAY PARTIALLY LIMIT IMPACT, THE WPC DAY
4/FRIDAY EXCESSIVE RAINFALL OUTLOOKS (ERO) SHOWS COLLABORATED
MARGINAL AND SLIGHT RISK AREAS GIVEN POTENTIAL FOR TRAINING AND
MODEL AND ENSEMBLE SIGNALS FOR SOME HIGHER RAIN TOTALS. THE DAY
5/SATURDAY ERO SHOWS A MARGINAL RISK AREA CENTERED OVER THE
NORTHERN MID-ATLANTIC WITH SYSTEM APPROACH AND ENHANCING ATLANTIC
MOISTURE INFLOW AND POSSIBLE COASTAL DEVELOPMENT THAT WILL PRESENT
A PROTRACTED MARITIME RISK. THIS AREA IS BEING MONITORED FOR
POSSIBLE FUTURE SLIGHT RISK ISSUANCE GIVEN BETTER CONSISTENCY WITH
FUTURE MODEL CYCLE INLAND INSTABILITY FOCUS TO ENHANCE
DURATION/TRAINING ACTIVITY. WIDESPREAD ENHANCED WINDS ARE POSSIBLE
ON THE BACKSIDE OF THE LOW FIRST IN THE PLAINS AND TRACKING
EASTWARD INTO THE ATLANTIC. THE SYSTEM'S COLD FRONT WILL ALSO
SPREAD COOLER THAN AVERAGE TEMPERATURES FROM WEST TO EAST ACROSS
THE LOWER 48, WITH A FIRST FROST/FREEZE OF THE FALL SEASON
POSSIBLE IN THE CENTRAL PLAINS.
MEANWHILE, A SEPARATE FRONT MEANDERING THROUGH THE GULF OF MEXICO
AND THE FLORIDA PENINSULA LIFTING IN ADVANCE OF THE AFOREMENTIONED
MAIN STORM WILL BRING SPREAD A THREAT FOR HEAVY RAINFALL ACROSS
THE SOUTHEAST INTO FRIDAY. THIS MAY BE AIDED BY AN AREA OF LOW
PRESSURE IN THE GULF OF MEXICO THAT IS NOW BEING MONITORED BY NHC
AND POSSIBLE EASTERN PACIFIC REMNANT TROPICAL MOISTURE. THE DAY
4/FRIDAY ERO SHOWS A MARGINAL RISK AREA. THE WARM FRONT LIFTING
LATE WEEK MAY INCREASE CONVECTION AREAL COVERAGE THERE AS
INSTABILITY LIFTS INLAND.
WELL UPSTREAM, GUIDANCE SIGNALS ARE GROWING THAT THE SLOW
TRANSLATION OF AN AMPLIFIED AND COMPLEX EASTERN PACIFIC
UPPER/SURFACE SYSTEM SEEMS SET TO RENEW WET FLOW INTO THE PACIFIC
NORTHWEST/NORTHWEST INTO EARLY NEXT WEEK, WITH LIKELY MODERATE
TOTALS TO FOCUS OVER THE PACIFIC NORTHWEST TO INCLUDE SOME HIGHER
ELEVATION SNOW.
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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