193
FXUS02 KWBC 090701
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT MON OCT 09 2023
VALID 12Z THU OCT 12 2023 - 12Z MON OCT 16 2023
...MID-LATE WEEK EXCESSIVE RAIN THREAT FOR THE MIDWEST/GREAT LAKES
TO NORTHEAST AS WELL AS THE SOUTHEAST...
..OVERVIEW
GUIDANCE STILL OFFERS A STRONG SIGNAL THAT A LEADING CLOSED UPPER
LOW WILL SHIFT SLOWLY EASTWARD ACROSS EASTERN CANADA LATE WEEK AND
EASE UNSETTLED CONDITIONS UNDER/AROUND THIS AMPLIFIED FEATURE AWAY
FROM THE NORTHEAST. MEANWHILE, DYNAMIC UPPER TROUGH/CLOSED LOW
ENERGIES AND SURFACE FRONTAL SYSTEM WILL WORK OUT FROM THE WEST TO
FAVOR ENHANCED MOUNTAIN SNOWS FOR ESPECIALLY THE NORTHERN ROCKIES
INTO THURSDAY. THIS POTENT AND WELL ORGANIZED UPPER SYSTEM WILL
THEN STEADILY TRACK FROM THE PLAINS TO THE NORTHEAST FRIDAY
THROUGH NEXT WEEKEND. THIS WILL FOSTER ENHANCED PRECIPITATION
CHANCES TO SPREAD IN EARNEST FROM THE CENTRAL U.S./MIDWEST THROUGH
THE NORTHEAST AS INFLOW MOISTURE INCREASES AHEAD OF DEEP
CYCLOGENESIS. TO THE SOUTH, A FRONTAL BOUNDARY ENHANCED WITH
TROPICAL MOISTURE WILL LIFT THROUGH THE GULF OF MEXICO TO INCREASE
HEAVY PRECIPITATION CHANCES ACROSS THE CENTRAL GULF COAST AND
FLORIDA/SOUTHEAST INTO LATER THIS WEEK BEFORE LIFTING OFF THE EAST
COAST. NEXT UPSTREAM, THE SLOW TRANSLATION OF AN AMPLIFIED AND
COMPLEX EASTERN PACIFIC UPPER/SURFACE SYSTEM MAY 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 THURSDAY INTO SATURDAY FROM THE 18 UTC
GFS/GEFS, 00 UTC ECMWF/CANADIAN/UKMET/ECMWF ENSEMBLE MEAN ALONG
WITH THE COMPATIBLE 01 UTC NATIONAL BLEND OF MODELS. SHIFTED WPC
GUIDANCE BLEND EMPHASIS TOWARD THE SOMEWHAT MORE AMPLIFIED/LESS
PROGRESSIVE ECMWF/CANADIAN/ECMWF ENSEMBLE MEAN CLUSTER VERSUS THE
GFS/GEFS BY SUNDAY/NEXT MONDAY GIVEN UPSTREAM AMPLITUDE/GUIDANCE
TRENDS. WPC PRODUCT CONTINUITY IS WELL MAINTAINED WITH THIS
FORECAST PLAN AND THE LATEST 00 UTC GUIDANCE OVERALL REMAINS IN
LINE.
..WEATHER/HAZARDS HIGHLIGHTS
DYNAMIC UPPER TROUGH/HEIGHT FALLS AND SURFACE SYSTEM PASSAGE
ACROSS THE WEST INTO THURSDAY WILL FAVOR A SWATH OF AUTUMN
MOUNTAIN SNOWS OUT FROM THE INTERMOUNTAIN WEST TO ESPECIALLY THE
NORTHERN ROCKIES. MEANWHILE DOWNSTREAM, PRECIPITATION CHANCES WILL
EXPAND EAST AS THIS MAIN SYSTEM WORKS INCREASINGLY INTO THE
CENTRAL U.S. BY LATER WEEK. 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 NORTH-CENTRAL PLAINS THROUGH THE MIDWEST/GREAT LAKES. WHILE
LONGER DURATION RAINS AND AMBIENT SOILS MAY PARTIALLY LIMIT
IMPACT, THE WPC DAY 4/THURSDAY AND DAY 5/FRIDAY EXCESSIVE RAINFALL
OUTLOOKS (EROS) ARE NOW PLANNED TO SHOW MARGINAL AND SLIGHT RISK
AREAS FROM THE NORTH-CENTRAL PLAINS/MIDWEST/GREAT LAKES GIVEN
POTENTIAL FOR TRAINING AND MODEL AND ENSEMBLE SIGNALS FOR SOME
HIGHER RAIN TOTALS. MEANWHILE, A SEPARATE WARM FRONT LIFTING
THROUGH THE GULF OF MEXICO AND THE FLORIDA PENINSULA BRINGS A
THREAT FOR HEAVY RAINFALL TO THE SOUTHEAST THURSDAY INTO FRIDAY.
THIS MAY BE AIDED BY AN AREA OF LOW PRESSURE IN THE GULF OF MEXICO
AND POSSIBLE REMNANT TROPICAL MOISTURE THAT IS NOW BEING MONITORED
BY NHC. ERO DAY 4/5 MARGINAL RISK AREAS SHIFT OUT FROM THE CENTRAL
GULF COAST TO THE SOUTHEAST. THESE TWO MAIN SYSTEMS MAY
INCREASINGLY INTERACT TO SOME DEGREE TO SPREAD ENHANCED RAINFALL
AND RUNOFF ISSUES POSSIBLE ACROSS THE EAST/NORTHEAST THIS WEEKEND
WITH COASTAL LOW DEVELOPMENT AND DEEPENING AS A MARITIME RISK
ALONG WITH WIDESPREAD ENHANCED BACKSIDE LOW WINDS AND POST-FRONTAL
FALLING TEMPERATURES BACK INLAND WITH SYSTEM PASSAGE.
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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