781
FXUS02 KWBC 030716
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
216 AM EST TUE DEC 3 2024
VALID 12Z FRI DEC 06 2024 - 12Z TUE DEC 10 2024
..,RETURN FLOW MAY FUEL EMERGING RAINFALL FROM THE WEST-CENTRAL
GULF COAST TO THE APPALACHIANS THIS WEEKEND TO EARLY NEXT WEEK...
..GUIDANCE/PREDICTABILITY ASSESSMENT
LEANED ON RECENT ECMWF/UKMET AND TRENDS FROM GEFS/ECMWF ENSEMBLES
THAT HOLD MAIN RAINFALL DEVELOPMENT CLOSER TO THE WEST-CENTRAL
GULF COASTAL REGIONS LATE WEEK UNTIL LATER WEEKEND/EARLY NEXT WEEK
BREAKOUT UP THROUGH THE APPALACHIANS. INLAND QPF DEVELOPEMT IS
DELAYED COMPARED TO RECENT GFS/CANADIAN RUNS AND THE NBM. ACROSS
THE NATION, IT IS NOTEABLE THAT RECENT DETERMINISTIC MODEL
GUIDANCE FORECAST SPREAD AND CYCLE TO CYCLE CONTINUITY ISSUES ARISE
EARLIER THAN NORMAL INTO THE MEDIUM RANGE TIME SCALES, LOWERING
FORECAST CONFIDENCE FROM THE WEEKEND INTO NEXT WEEK DESPITE SOME
COMMON TRANSITION OF THE LARGER SCALE PATTERN. ACCORDINGLY, OPTED
TO PIVOT BROADLY TOWARD A MORE COMPATIBLE AND RUN STABLE
GEFS/ECMWF ENSEMBLE MEAN BLEND ALONG WITH THE NATIONAL BLEND OF
MODELS TO MAINTAIN FEASIBLE WPC CONTINUITY AMID UNCERTAINTY.
..WEATHER/HAZARDS HIGHLIGHTS
ARCTIC AIR THAT HAS PERSISTED OVER THE EAST-CENTRAL U.S. WILL
MODERATE THIS WEEKEND AS AMPLIFIED UPPER TROUGHING FINALLY LIFTS
OUT, BUT NOT BEFORE RENEWED LAKE EFFECT AND BROADER SOUTHERN
CANADA TO NORTHERN NORTHEAST SNOWS WITH WINDY CLIPPER PASSAGE.
MEANWHILE, MOIST RETURN FLOW FROM THE GULF OF MEXICO WITH
RETREATING HIGH PRESSURE WILL SUPPORT EMERGING ENHANCED RAIN
CHANCES SET TO SPREAD FROM THE WEST-CENTRAL GULF COAST STATES UP
THROUGH THE APPALACHIANS THIS WEEKEND INTO EARLY NEXT WEEK, ALBEIT
WITH UNCERTAINTY ON THE TIMING AND INLAND EXTENT OF THE RAIN. NO
THREAT AREAS ARE CURRENTLY DENOTED ON THE WPC DAY 4/5 (FRI-SAT) EXCESSIVE
RAINFALL OUTLOOK AREAS, BUT THIS IS PREDICATED ON AMPLE VARIANCES
IN FLOW TRANSITION AND WITH A NOTION THAT HEAVIER INLAND FOCUS MAY
BE DELAYED INTO LATER WEEKEND/EARLY NEXT WEEK AS AIDED BY UNCERTAIN
SOUTHERN STREAM UPPER ENERGY EJECTION FROM THE SOUTHWEST/BAJA AND
EFFECT OF POSSIBLE WAVY APPROACH OF EARLY NEXT WEEK COLD FRONT.
UPSTREAM, MODERATE TO TERRAIN ENHANCED PRECIPITATION WILL DEVELOP
THIS WEEKEND OVER THE PACIFIC NORTHWEST WITH ENERGETIC UPPER TROUGH
PASSAGE AND LEAD MOISTURE FEED. TERRAIN ENHANCED SNOWS WILL SPREAD
ACROSS THE NORTHWEST TO THE NORTH-CENTRAL ROCKIES WITH SYSTEM AND
UNSETTLING COLD FRONTAL PASSAGE OVER THE WEST INTO NEXT WEEK.
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 (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page