860
FXUS02 KWBC 161831
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
131 PM EST THU NOV 16 2023
VALID 12Z SUN NOV 19 2023 - 12Z THU NOV 23 2023
..PATTERN OVERVIEW
THE MEDIUM RANGE PERIOD BEGINS WITH SPLIT FLOW ACROSS THE CONUS AS
THE HOLIDAY WEEK BEGINS. SYSTEMS IN THE NORTHERN STREAM WILL TRACK
ACROSS CENTRAL/SOUTHERN CANADA/U.S. NORTHERN TIER WHILE A
POTENTIAL CLOSED LOW DEVELOPS AND TRACKS THROUGH THE CENTRAL AND
EAST-CENTRAL U.S. AROUND MONDAY-TUESDAY. TOWARDS THE MIDDLE TO
LATTER PART OF NEXT WEEK, MODELS SEEM TO BE TRENDING TOWARDS THESE
TWO STREAMS COMBINING RESULTING IN A LARGE AND DEEP UPPER LOW
OVER/NEAR THE GREAT LAKES. THIS SHOULD FUEL AN EMERGING WET
PATTERN FROM THE CENTRAL PLAINS, INTO THE SOUTH, AND EVENTUALLY
INTO THE NORTHEAST SUNDAY-TUESDAY.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
MODEL AND ENSEMBLE GUIDANCE CONTINUE TO BE IN RELATIVELY GOOD
AGREEMENT, ALLOWING FOR A PURELY DETERMINISTIC MODEL BLEND THROUGH
TUESDAY BETWEEN THE LATEST RUNS OF THE GFS, ECMWF, AND CMC (THE
00Z UKMET WAS A LITTLE FAST THAN THE BETTER CONSENSUS). THERE ARE
SOME LINGERING DIFFERENCES IN THE DETAILS, WHICH SHOWS UP MOST
PROMINENTLY IN THE QPF FORECASTS, BUT THE NATIONAL BLEND OF MODELS
SEEMED TO DO A GOOD JOB SMOOTHING THESE OUT. BY
WEDNESDAY-THURSDAY, THERE IS GROWING SPREAD AND A TREND TOWARDS
MORE COMBINED NORTHERN/STREAM SOUTHERN STREAM FLOW. STILL A FEW
LINGERING TIMING DIFFERENCES AND RUN TO RUN VARIABILITY THOUGH,
AND SO THE WPC LATE WEEK PROGS WERE BASED MORE ON THE ENSEMBLE
MEANS. OVERALL, MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS WPC
FORECAST.
..WEATHER/HAZARDS HIGHLIGHTS
HEAVY RAINFALL POTENTIAL WILL INCREASE ACROSS THE SOUTH-CENTRAL TO
EASTERN U.S. FOR THE UPCOMING HOLIDAY WEEK AS A MAIN LOW PRESSURE
SYSTEM DEEPENS AND TRACKS ACROSS THE REGION. THE LOW WILL DEVELOP
IN THE LEE OF THE ROCKIES OVER THE CENTRAL/SOUTHERN PLAINS ON
SUNDAY AND MOVE TO THE EAST-CENTRAL STATES EARLY NEXT WEEK BEFORE
CURVING TOWARDS THE NORTHEAST MID-WEEK. THE TIGHTENING PRESSURE
GRADIENT AS THE LOW SPINS UP WILL LIKELY PRODUCE A PERIOD OF HIGH
WINDS ACROSS THE HIGH PLAINS EARLY NEXT WEEK AND INSTABILITY AHEAD
OF THE SYSTEM COULD BRING SEVERE WEATHER POTENTIAL TO PARTS OF THE
CENTRAL PLAINS AND CENTRAL GULF COAST SUNDAY-MONDAY, AS
HIGHLIGHTED BY THE LATEST OUTLOOKS FROM THE STORM PREDICTION
CENTER. THERE IS ALSO A SIGNAL FOR ORGANIZED AND POSSIBLY HEAVY
RAINFALL BY MONDAY WITH FOCUS OVER THE CENTRAL GULF COAST STATES
REGION. A WPC EXCESSIVE RAINFALL OUTLOOK MARGINAL RISK AREA WAS
MAINTAINED TO ADDRESS THIS EMERGING THREAT. AMPLE MOISTURE WILL
STREAM INTO THE SOUTHERN AND EASTERN U.S. AHEAD OF THE SYSTEM AS
IT WORKS DOWNSTREAM, SO DESPITE PROGRESSION OVER TIME MAY LEAD TO
SOME LOCALIZED RUNOFF ISSUES IN THE VICINITY OF THE
CENTRAL/SOUTHERN APPALACHIANS ON MONDAY AND THE MID-ATLANTIC AND
NORTHEAST ON TUESDAY. URBAN FLOODING POTENTIAL MAY BE A CONCERN
ESPECIALLY FOR THE METRO AREAS UP THROUGH MID-ATLANTIC AND THE
NORTHEAST. THERE IS SOME POSSIBILITY FOR SNOW ON THE NORTHERN
PERIPHERY OF THIS PRECIPITATION SHIELD.
IN THE WEST, UNSETTLED WEATHER INCLUDING A BURST OF MOUNTAIN SNOWS
IS EXPECTED SUNDAY AS NORTHERN STREAM UPPER TROUGH ENERGY DIGS
THROUGH THE NORTH-CENTRAL INTERMOUNTAIN WEST/ROCKIES. AN AMPLIFIED
UPPER RIDGE WILL THEN BUILD OVER THE WEST COAST EARLY NEXT WEEK,
RESULTING IN MORE STABLE AND DRY WEATHER. HOWEVER, UPSTREAM
PACIFIC SYSTEM ENERGIES MAY WORK INTO THIS RIDGE ENOUGH TO BRING
ANOTHER OPPORTUNITY FOR ORGANIZED PRECIPITATION INTO THE PACIFIC
NORTHWEST NEXT WEDNESDAY-THURSDAY.
SANTORELLI/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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