835
FXUS02 KWBC 211901
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
201 PM EST SAT JAN 21 2023
VALID 12Z TUE JAN 24 2023 - 12Z SAT JAN 28 2023
...HEAVY RAIN/SEVERE WEATHER THREAT FOR THE SOUTH TUESDAY TO THE
EASTERN SEABOARD MIDWEEK ALONG WITH A HEAVY SNOW THREAT OVERTOP
FROM THE SOUTH-CENTRAL PLAINS TO THE MIDWEST AND INTERIOR
NORTHEAST LINGERING INTO THURSDAY...
..SYNOPTIC OVERVIEW
THE WEATHER PATTERN WILL REMAIN QUITE STORMY AND PROGRESSIVE
ACROSS MUCH OF THE NATION GOING NEXT WEEK ON THE HEELS OF A LEAD
MONDAY STORM SYSTEM EXITING THE NORTHEAST BY TUESDAY. THE NEXT
IMPACTFUL LOW PRESSURE STORM 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 FROM THE WEST TO 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
RECENT GUIDANCE HAS IMPROVED ITS OVERALL SYNOPTIC SCALE DEPICTION
ACROSS THE CONTINENTAL U.S. INTO MID-LATER NEXT WEEK. A COMPOSITE
BLEND OF GFS/ECMWF/UKMET/CANADIAN GUIDANCE ALONG WITH WPC
CONTINUITY SEEMS TO OFFER GOOD PREDICTABILITY AND A REASONABLE
FORECAST BASIS. SYSTEM ORGANIZATION DECREASES AND FORECAST
UNCERTAINTY INCREASES INTO FRIDAY AND SATURDAY AS THE EASTERN
PACIFIC UPPER RIDGE INTERACTS WITH SHORTWAVE ENERGY FROM THE GULF
OF ALASKA. THIS LEADS TO QUITE VARIED DIGGING OF ENERGIES
DOWNSTREAM INTO THE WEST AND SUBSEQUENTLY THE CENTRAL AND EASTERN
STATES. PREFER AN ENSEMBLE MEAN SOLUTION ON THE MORE AMPLIFIED
SIDE OF THE FULL ENVELOPE OF GUIDANCE CONSIDERING THE LEAD-IN
AMPLITUDE OF THE EASTERN PACIFIC UPPER RIDGE THAT MAY PROVE SLOW
TO BE DISLODGED. THIS SCENARIO SEEMED BEST SHOWN BY ECMWF
ENSEMBLES AT TIME OF PRODUCT CREATION. SINCE THEN, THE 12 UTC
MODELS HAVE STRONGLY TRENDED TOWARD DIGGING ENERGIES MORE SHARPLY
DOWN OVER THE WEST COAST TO THE LEE OF SET RIDGE.
..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
SOUTHERN HIGH PLAINS AND EXTENDING NORTHEAST ACROSS NORTHERN
OKLAHOMA AND SOUTHERN KANSAS ON TUESDAY, AND THEN OUT ACROSS THE
MID-MS AND OHIO VALLEYS/EASTERN GREAT LAKES WHERE A SWATH OF
ENHANCED WRAPBACK SNOWS WILL BE POSSIBLE. HEAVY SNOW IS THEN
LIKELY ACROSS THE APPALACHIANS THROUGH INTERIOR AREAS OF THE
NORTHEAST AS THE SECONDARY LOW DEVELOPS, WITH HEAVY RAIN/WIND UP
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/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, 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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