210
FXUS02 KWBC 210659
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 AM EST SAT JAN 21 2023
VALID 12Z TUE JAN 24 2023 - 12Z SAT JAN 28 2023
...MIDWEEK STORM TO SPREAD A HEAVY RAIN/SEVERE WEATHER THREAT TO
THE SOUTH EARLY NEXT WEEK, WORKING UP THE EASTERN SEABOARD MIDWEEK
ALONG WITH A HEAVY SNOW THREAT FROM THE CENTRAL ROCKIES/PLAINS
THROUGH THE INTERIOR NORTHEAST...
..SYNOPTIC OVERVIEW
THE WEATHER PATTERN IS EXPECTED TO BE ACTIVE BUT PROGRESSIVE
ACROSS MUCH OF THE NATION GOING INTO NEXT WEEK WITH THE MONDAY
STORM SYSTEM OVER THE NORTHEAST EXITING THE REGION BY EARLY
TUESDAY. THE NEXT AND POTENTIALLY MORE IMPACTFUL LOW PRESSURE
SYSTEM WILL BE GATHERING STRENGTH ACROSS THE GULF COAST EARLY IN
THE WEEK AND THEN TRACK IN A GENERAL NORTHEASTERLY DIRECTION
ACROSS THE OHIO VALLEY AND THEN THE NORTHEAST U.S. BY THURSDAY. A
BUILDING WEST COAST/WESTERN CANADA UPPER RIDGE AS A +PNA PATTERN
TRIES TO DEVELOP WILL HERALD A RETURN TO COLDER CONDITIONS ACROSS
MUCH OF THE CENTRAL AND EASTERN U.S. AS A BROAD UPPER TROUGH
DEVELOPS DOWNSTREAM OF THIS RIDGE THROUGH THE END OF THE WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z GUIDANCE HAS IMPROVED ITS OVERALL SYNOPTIC SCALE DEPICTION
ACROSS THE CONTINENTAL U.S. THROUGH THE MIDDLE OF THE WEEK,
ALTHOUGH THE 00Z CMC WAS NOT AVAILABLE AT THE TIME OF THIS
WRITING. THE UKMET/GFS/ECMWF ARE IN RELATIVELY CLOSE AGREEMENT
WITH THE LOW TRACK THROUGH THURSDAY, AND THE 12Z CMC IS GENERALLY
NORTHWEST OF THE 00Z MODEL CONSENSUS. FORECAST UNCERTAINTY
INCREASES GOING INTO FRIDAY AND SATURDAY AS THE UPPER RIDGE
EVENTUALLY BREAKS DOWN BY SHORTWAVE ENERGY FROM THE GULF OF ALASKA
IMPINGING UPON IT. AT THE TIME OF THE FRONTS/PRESSURES CREATION,
THE 18Z GFS DIFFERED CONSIDERABLY FROM THE MODEL CONSENSUS FOR
DAYS 6 AND 7, SO IT WAS NOT USED BEYOND THURSDAY. A GENERAL
DETERMINISTIC MODEL BLEND SUFFICED AS A STARTING POINT THROUGH
WEDNESDAY, AND AN INCREASE OF THE ENSEMBLE MEANS UP TO ABOUT 60%
BY SATURDAY WAS INCORPORATED TO ACCOUNT FOR INCREASING MESOSCALE
UNCERTAINTIES.
..WEATHER/HAZARD HIGHLIGHTS
AFTER THE DEPARTURE OF THE EAST COAST STORM SYSTEM MONDAY,
ATTENTION TURNS TO THE NEXT MAJOR STORM SYSTEM THAT IS FORECAST TO
DEVELOP OVER TEXAS ON TUESDAY AND THEN TRACK NORTHEAST ACROSS THE
OHIO VALLEY AND THEN THE GREAT LAKES THROUGH WEDNESDAY NIGHT, AND
THEN REACHING THE NORTHEAST U.S. BY THURSDAY AS A NEW SURFACE LOW
LIKELY DEVELOPS NEAR THE COAST. THE BEST HEAVY RAINFALL POTENTIAL
EXISTS ACROSS EASTERN TEXAS, LOUISIANA, AND INTO MISSISSIPPI ON
TUESDAY, WHERE A SLIGHT RISK OF EXCESSIVE RAINFALL IS NOW IN
EFFECT FOR THE DAY 4 PERIOD WITH THE POTENTIAL FOR SOME 2 INCH
RAINFALL TOTALS, SOME OF WHICH MAY FALL WITHIN A RELATIVELY SHORT
PERIOD OF TIME. AREAS FROM SOUTHERN LOUISIANA TO THE FLORIDA
PANHANDLE WILL ALSO BE IN A FAVORABLE KINEMATIC AND THERMODYNAMIC
ENVIRONMENT FOR POTENTIAL SEVERE WEATHER PER RECENT SPC OUTLOOKS.
THERE WILL LIKELY BE A NOTEWORTHY SWATH OF WINTRY WEATHER FROM THE
TEXAS PANHANDLE AND EXTENDING NORTHEAST ACROSS NORTHERN OKLAHOMA
AND SOUTHERN KANSAS ON TUESDAY, AND THEN ACROSS THE OZARKS AND
PORTIONS OF THE OHIO VALLEY WHERE SEVERAL INCHES OF SNOW
ACCUMULATION WILL BE POSSIBLE. HEAVY SNOW IS LOOKING MORE LIKELY
ACROSS INTERIOR PORTIONS OF THE NORTHEAST U.S. AS THE SECONDARY
LOW DEVELOPS, AND HEAVY RAIN AND WIND NEAR THE COAST AS THE LOW
CONTINUES TO INTENSIFY.
TEMPERATURES ARE EXPECTED TO GENERALLY BE ON THE ORDER OF 10 TO 20
DEGREES BELOW AVERAGE FROM THE INTERMOUNTAIN WEST TO THE CENTRAL
PLAINS FOR EARLY IN THE WEEK, AND SLIGHTLY ABOVE AVERAGE ACROSS
MOST OF THE EASTERN U.S. BY THE END OF THE WEEK, MOST AREAS
ACROSS THE NATION SHOULD BE NEAR AVERAGE TO 10 DEGREES BELOW
AVERAGE AS BROAD UPPER TROUGH AND CYCLONIC FLOW ALOFT KEEP ANY
ANOMALOUS WARMTH AT BAY. ALTHOUGH A COLDER PATTERN IS COMING,
THERE IS NO IMMINENT SIGN OF ANY MAJOR ARCTIC AIRMASSES SURGING
SOUTH FROM CANADA.
HAMRICK
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, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES 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
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