272
FXUS02 KWBC 100701
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM EST WED JAN 10 2024
VALID 12Z SAT JAN 13 2024 - 12Z WED JAN 17 2024
...ANOTHER MAJOR STORM TO IMPACT THE EASTERN U.S. WITH
SNOW/RAIN/WIND THREATS FOLLOWED BY AN ARCTIC BLAST THROUGH MUCH OF
THE CENTRAL U.S....
..OVERVIEW
AN UPPER LOW, RESPONSIBLE FOR THE EASTERN U.S. STORM, WILL
NEGATIVELY TILT ON SATURDAY THEN GET WOUND UP OVER SOUTHEASTERN
CANADA THROUGH THE MIDDLE OF NEXT WEEK. A CONVEYOR BELT OF
SHORTWAVE ENERGY WILL PIVOT ACROSS THE SOUTHERN PERIPHERY OF THE
NEWLY FORMED PARENT LOW, PROPAGATING THROUGH THE MIDWEST AND EAST
COAST. AN EAST PACIFIC SHORTWAVE TROUGH WILL LIKELY SWING THROUGH
THE WEST BY WAY OF THE PAC NW, FOLLOWED BY AN AMPLIFYING UPPER
RIDGE OVER THE WEST IN RESPONSE TO THE DEEPENING UPPER LOW IN
CANADA. SUCH A SETUP WILL FACILITATE THE DESCENT OF ARCTIC HIGH
PRESSURE OVER THE CENTRAL AND EASTERN U.S. THROUGH NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE NON 12Z UKMET GUIDANCE WERE IN REASONABLE AGREEMENT REGARDING
THE OVERAL EVOLUTION OF THE SYNOPTIC PATTERN OVER THE LOWER 48
WITH THE DEEPENING UPPER LOW OVER SOUTHEAST CANADA, THE AMPLIFYING
UPPER RIDGE OVER THE WEST IN RESPONSE AND A SHORTWAVE THROUGH THAT
PRECEEDS THAT RIDGE. FIRSTLY, ON DAY 3, THE 12Z AND 18Z GFS
DIVERGED A BIT FROM THE CLOSED LOW OVER THE GREAT LAKES THAT
PREVIOUS RUNS AS WELL AS THE CMC AND EC HAVE CONSISTENTLY
SIGNALLED OVER THE SEVERAL RUNS. THAT BEING SAID, REASONABLE
CLUSTERING WITH RESPECT TO THE EAST PAC SHORTWAVE BETWEEN THE
THREE OPERATIONAL MODELS' LATEST RUNS SUPPORTED A GENERAL MODEL
BLEND OF THEM ON DAY 3. THE 18Z GEFS WAS INTRODUCED INTO THE BLEND
A BIT EARLIER THAN USUAL TO ACCOUNT FOR VARIANCE IN THE HANDLING
OF THE EMERGING EAST PAC RIDGE AND A DISTURBANCE WITHIN THE
SOUTHERN EDGE OF THE AFOREMENTIONED UPPER LOW IN CANADA. THE 12Z
CMC WAS DROPPED FROM THE DAY 5 BLEND FOR THE 12Z ECE TO ACCOUNT
FOR DISPLACEMENT OF THE UPPER LOW FARTHER SOUTH IN THE 12Z CMC
COMPARED TO THE THE EC AND GFS SUITES. THE EUROPEAN AND GFS
DETERMINISTIC AND ENSEMBLE MEANS CLUSTER WELL ON DAY 6 SO THE DAY
5 BLEND IS CONTINUED. THE 12Z EC IS REPLACED WITH THE 12Z CMC ON
DAY 7 DUE TO OVERAMPLIFICATION OF THE WESTERN RIDGE COMPARED TO
THE OTHER GUIDANCE.
..WEATHER/HAZARDS HIGHLIGHTS
THE MISSISSIPPI VALLEY TO EAST COAST STORM WILL BE WELL UNDERWAY
BY SATURDAY WITH SNOW, RAIN AND WIND THREATS LIKELY FROM THE
MIDWEST TO THE EAST COAST. AN OCCLUDED SUB 980MB SURFACE LOW
CENTERED OVER THE UPPER MIDWEST WILL PRODUCE HEAVY SNOW AND STRONG
WINDS OVER THE MIDWEST AND GREAT LAKES WITH NORTHWESTERLY FLOW
OVER LAKES HURON, SUPERIOR AND MICHIGAN EARLY ON IN THE DAY
FOLLOWED BY LAKE EFFECT SNOW DOWNWIND OF LAKES ERIE AND ONTARIO
LATER ON IN THE DAY AND THROUGH SUNDAY AS THE SYSTEM DEPARTS INTO
THE CANADIAN MERETIME. LINGERING SNOW SHOWERS ARE ALSO POSSIBLE
OVER UPSLOPE PORTIONS OF THE CENTRAL APPALACHIANS ON SATURDAY.
SUSTAINED WINDS OF 20-30MPH AND GUSTS OF OVER 40MPH ARE POSSIBLE
FROM THE MIDWEST TO THE NORTHEAST ON SATURDAY. WINDS CALM DOWN
CONSIDERABLY ON SUNDAY ACROSS THE EAST. HEAVY RAINFALL IS EXPECTED
TO CONTINUE ACROSS THE NEW ENGLAND COAST SATURDAY MORNING INTO
AFTERNOON WITH A LOW-END MARGINAL EXCESSIVE RAINFALL RISK OVER THE
MAINE COAST.
IN THE WEST, SHORTWAVE ENERGY WILL SPREAD TROPICAL MOISTURE OVER
THE NORTHWEST ON SATURDAY. HEAVY TO EXCESSIVE RAINFALL IS POSSIBLE
FOR PORTIONS OF THE CENTRAL OREGON COAST DOWN INTO NORTHERN
CALIFORNIA WHERE A MARGINAL RISK IS IN EFFECT.
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page