350
FXUS02 KWBC 090701
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM EST TUE JAN 09 2024
VALID 12Z FRI JAN 12 2024 - 12Z TUE JAN 16 2024
...ANOTHER MAJOR STORM TO IMPACT THE EAST-CENTRAL TO EASTERN U.S.
WITH SNOW/RAIN/WIND THREATS FOLLOWED BY AN ARCTIC BLAST THROUGH
MUCH OF THE NORTH-CENTRAL U.S....
..GENERAL OVERVIEW
AN UPPER TROUGH OVER THE GREAT PLAINS WILL AMPLIFY WHILE IT
PROPAGATES THROUGH THE MIDWEST AND INTO SOUTHEASTERN CANADA THIS
WEEKEND. AT THE SURFACE, CYCLONGENISIS AND A RAPIDLY INTENSIFYING
MID-LATITUDE CYCLONE WILL TAKE SHAPE OVER THE SOUTHERN PLAINS AND
LOWER MISSISSIPPI VALLEY ON FRIDAY. THIS SYSTEM WILL CONTINUE TO
INTENSIFY AS IT MOVES INTO THE MIDWEST AND NORTHEAST ON SATURDAY.
MEANWHILE, A POTENT UPPER LOW WILL BREAK-DOWN AN EAST PACIFIC
RIDGE AND MAKE ITS WAY INTO THE NORTHWEST THIS WEEKEND. ARCTIC
HIGH PRESSURE WILL BUILD IN ACROSS THE CENTRAL U.S. BEHIND THE
DEPARTING STORM IN THE EAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST NUMERICAL MODELS ARE QUITE DISPERSED IN THEIR HANDLING
OF THE OVERALL EVOLUTION OF THE SYNOPTIC PATTERN OVER THE LOWER 48
DURING THE MEDIUM RANGE PERIOD. THERE'S PLENTY OF RUN-TO-RUN
VARIANCE IN THE DETERMINISTIC EURO WITH RESPECT TO THE INCOMING
EAST PAC LOW ON DAY 3. THE 12Z UKMET/CMC AND 18Z GFS ARE ALSO ALL
OVER THE PLACE WITH THEIR PLACEMENTS OF THAT SYSTEM SO THIS
SYSTEM'S DETAILS ARE YET TO BE CONSIDERED CERTAIN. THE MODELS ARE
IN REASONABLE AGREEMENT ABOUT THE EVOLUTION OF THE WOUND UP
EASTERN U.S. STORM THROUGH DAY 5. A GENERAL MODEL BLEND CONSISTING
OF THE 12Z EC/UKMET/CMC AND 18Z GFS WERE UTILIZED ON DAY 3. THE
UKMET WAS REMOVED ON DAY 4 DUE TO ITS SIGNIFICANT DIVERGENCE FROM
THE REST OF THE GUIDANCE REGARDING THE SHORTWAVE ENERGY IN THE
EAST PAC/NORTHWEST U.S.. THE CANADIAN IS DROPPED FROM THE DAY 5
BLEND IN PLACE OF THE 12Z ECE AND 18Z GEFS BECAUSE IT (CMC) HAS
THE PARENT LOW CENTERED OVER THE UPPER MIDWEST WHILE THE EC AND
GFS AND CANADIAN ENSEMBLE HAVE IT MUCH FARTHER NORTH IN CANADA.
THE CANADIAN ENSEMBLE IS INTRODUCED BRIEFLY ON DAY 6 AND REMOVED
ON DAY 7.
..WEATHER/HAZARDS HIGHLIGHTS
THE ACTIVE PERIOD CONTINUES THROUGH THE WEEKEND, BEGINNING WITH
YET ANOTHER MAJOR STORM OVER THE EAST-CENTRAL TO EASTERN U.S. THIS
FRIDAY. A DEEP MID-LATITUDE CYCLONE WILL PRODUCE A SWATH OF HEAVY
SNOW FROM EASTERN MISSOURI THROUGH THE GREAT LAKES ON FRIDAY, AND
INTO NEW ENGLAND ON FRIDAY NIGHT WITH LINGERING LAKE EFFECT SNOW
OCCURING ON THE BACKSIDE OF THE ARCTIC COLD FRONT DOWNWIND LAKES
ERIE AND ONTARIO ON SATURDAY. SOME LIGHT TO MODERATE SNOW MAY
OCCUR DOWN THROUGH THE CENTRAL APPALACHIANS ON FRIDAY AS WELL. IN
THE WARM SECTOR OF THIS DYNAMIC SYSTEM, RAIN SHOWERS AND SCATTERED
THUNDERSTORMS ARE LIKELY. SOME HEAVY RAINFALL IS POSSIBLE OVER
PARTS OF THE CENTRAL MIDWEST FRIDAY AFTERNOON WHERE SOME
INSTABILITY MAY CREEP IN LEADING TO THE THREAT OF EXCESSIVE
RAINFALL. THIS THREAT IS MARGINAL (AT LEAST 5%). AS THE SYSTEM
PROGRESSES EASTWARD FRIDAY NIGHT THE NORTHEAST/SOUTHERN NEW
ENGLAND COAST MAY BECOME AN AREA OF FOCUSED HEAVY RAINFALL. A
SLIGHT RISK OF EXCESSIVE RAINFALL IS IN EFFECT FOR AN AREA
ENCOMPASSING THE I-95 CORRIDOR BETWEEN BALTIMORE AND WESTERN RHODE
ISLAND WHERE FAVORABLE JET DYNAMICS AND MOISTURE FLUX WILL BE
PRESENT. HEAVY RAINFALL OVER EXISTING SNOWPACK IN NORTHEASTERN
PENNSYLVANIA INTO NORTHERN NEW JERSEY, SOUTHERN NEW YORK AND
SOUTHERN NEW ENGLAND MAY ALSO CONTRIBUTE TO THE FLASH FLOODING
THREAT.
KEBEDE
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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