761
FXUS02 KWBC 081901
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 PM EST MON JAN 08 2024
VALID 12Z THU JAN 11 2024 - 12Z MON JAN 15 2024
...ANOTHER MAJOR STORM TO IMPACT THE EAST-CENTRAL TO EASTERN U.S.
WITH SNOW/RAIN/WIND THREATS AND AN ARCTIC BLAST ENVELOPS MUCH OF
THE NORTH-CENTRAL U.S....
..GENERAL OVERVIEW
IN THE WAKE OF THE DEPARTING SURFACE LOW EXITING THE NORTHEAST
U.S. LATE WEDNESDAY, AN IMPROVING WEATHER TREND COMMENCES GOING
INTO THURSDAY ACROSS THE EASTERN U.S. AS HIGH PRESSURE BRIEFLY
SETTLES IN ACROSS THE REGION. HOWEVER, THIS WILL BE RATHER SHORT
LIVED AS THE EXTREMELY ACTIVE WEATHER PATTERN CONTINUES WITH
ANOTHER POTENT LOW PRESSURE SYSTEM GETTING BETTER ORGANIZED ACROSS
THE SOUTH-CENTRAL U.S. BY FRIDAY MORNING IN RESPONSE TO AN
AMPLIFYING UPPER TROUGH APPROACHING FROM THE ROCKIES. THIS LOW
SHOULD TRACK IN THE GENERAL DIRECTION OF THE OHIO VALLEY AND GREAT
LAKES REGION BY SATURDAY WITH MORE BAD WEATHER EXPECTED FOR MANY
AREAS THAT WILL BE HAMMERED EARLIER IN THE WEEK. IN ADDITION, A
STRONG ARCTIC FRONT WILL HERALD THE COLDEST WEATHER OF THE SEASON
THUS FAR ACROSS MUCH OF THE NORTH-CENTRAL U.S. FOR THE SECOND HALF
OF THE WEEK AND INTO NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
FOR THE NEXT BIG SYSTEM DEVELOPING ACROSS THE SOUTHERN PLAINS
FRIDAY, THE MODELS ALL AGREE THAT A POTENT SOUTHERN STREAM
TROUGH/SHORTWAVE EXITING THE ROCKIES THURSDAY WILL BEGIN ACQUIRING
NEGATIVE TILT BY FRIDAY EVENING ACROSS THE MIDWEST, ALLOWING RAPID
SURFACE CYCLOGENESIS TO OCCUR DOWNSTREAM. GUIDANCE HAS ALSO SHOWN
A SIGNIFICANT STRONGER TREND WITH THE SURFACE LOW AS IT APPROACHES
THE GREAT LAKES, WITH BOTH THE GFS AND ECMWF INDICATING CENTRAL
PRESSURE CLOSE TO 970 MB OVER EASTERN MICHIGAN AND POTENTIAL FOR
TRIPLE POINT LOW DEVELOPMENT SATURDAY BY NEW ENGLAND. THE GUIDANCE
NOW AGREES BETTER ON A SHORTWAVE APPROACHING THE PACIFIC NORTHWEST
LATE SATURDAY THAT WILL EVENTUALLY MOVE INLAND ACROSS THE
INTERMOUNTAIN WEST/ROCKIES, EVENTUALLY DOWNSTREAM TOWARD THE
SOUTH. FOR THE WPC FRONTS/PRESSURES PROGS AND FORECAST WEATHER
GRIDS/THREATS, A MULTI-DETERMINISTIC MODEL BLEND ALONG WITH THE
NBM AND WPC CONTINUITY OFFERS A SOLID STARTING POINT IN THE
FORECAST PROCESS, WITH MORE WEIGHTING TOWARDS BEST CLUSTERED
GFS/ECMWF THEN GEFS/ECMWF ENSEMBLE MEANS OVER TIME, BUT FORECAST
PREDICTABILITY SEEMS TO HOLD ABOVE NORMAL THROUGH MEDIUM RANGE
TIME SCALES. FOR THE LAKE EFFECT SNOW LATER IN THE FORECAST
PERIOD, THE NBM AGAIN APPEARED TOO LOW WITH AMOUNTS, SO THE QPF
WAS ROUGHLY DOUBLED FOR THIS REGION.
..WEATHER/HAZARDS HIGHLIGHTS
UNFORTUNATELY, ANOTHER STRONG LOW PRESSURE SYSTEM IS FORECAST TO
RAPIDLY DEVELOP OVER THE SOUTH-CENTRAL U.S. BY THURSDAY NIGHT INTO
EARLY FRIDAY, AND THIS COULD AFFECT SIMILAR AREAS OF THE CENTRAL
AND EASTERN U.S. COMPARED TO THE LOW IN THE SHORT RANGE FORECAST
PERIOD, TRACKING FROM NORTHERN TEXAS TO THE OHIO VALLEY AND THEN
THE EASTERN GREAT LAKES BASED ON THE LATEST MODEL GUIDANCE. THERE
WILL LIKELY BE A BAND OF SIGNIFICANT SNOW EXTENDING FROM AT LEAST
MISSOURI TO MICHIGAN ASSOCIATED WITH THE DEFORMATION ZONE/WRAPPING
MOISTURE NORTHWEST OF THE SURFACE LOW, AND THE HIGHEST
PROBABILITIES OF THIS ARE GENERALLY SOUTHEAST OF THE HIGHEST
SNOWFALL TOTALS EXPECTED WITH THE SYSTEM EARLY IN THE WEEK. GIVEN
THE STRONG PRESSURE GRADIENT THAT WILL BE IN PLACE, MANY PLACES
COULD EXPERIENCE BLIZZARD CONDITIONS. WITH STRONG COLD AIR
ADVECTION IN THE WAKE OF THIS LOW PRESSURE SYSTEM, LAKE EFFECT
SNOW IS EXPECTED TO INCREASE DOWNWIND OF THE GREAT LAKES BY THE
WEEKEND, AND POTENTIALLY HEAVY AT TIMES. ADDITIONAL ROUNDS OF
HEAVY RAIN AND STRONG TO SEVERE THUNDERSTORMS ARE ALSO LIKELY FOR
MUCH OF THE SOUTH/SOUTHEAST GOING INTO FRIDAY, AND THEN SPREADING
QUICKLY NORTHEASTWARD ALONG THE EAST COAST GOING INTO FRIDAY NIGHT
AND SATURDAY. THIS RAINFALL WILL ALSO BE FALLING OVER HIGHLY
SATURATED SOILS OWING TO RECENT AND UPCOMING RAINFALL AND SNOWS,
AND GIVEN THE QPF SIGNAL FOR SOME 1-3+ INCH RAINFALL TOTALS ACROSS
PORTIONS OF THE MID-ATLANTIC AND NORTHEAST, A SLIGHT RISK OF
EXCESSIVE RAINFALL CERTAINLY SEEMS WARRANTED FOR THE DAY 5 PERIOD
ON FRIDAY/FRIDAY NIGHT FROM NORTHERN VIRGINIA TO WESTERN MA, AND A
BROADER MARGINAL RISK AREA EXTENDING SOUTHWARD ALONG THE SPINE OF
THE APPALACHIANS AND A SEPARATE AREA ACROSS PORTIONS OF KY AND TN.
IN TERMS OF TEMPERATURES, AN ARCTIC BLAST IS EXPECTED FOR THE
NORTHERN PLAINS/ROCKIES TO CLOSE OUT THE WEEK WITH WIDESPREAD
DOUBLE DIGIT SUBZERO LOWS FOR THE DAKOTAS AND INTO MONTANA, AND
SOME SUBZERO HIGHS, WITH ANOMALIES AS MUCH AS 35 DEGREES BELOW
NORMAL AND THE POTENTIAL FOR SOME DAILY RECORD LOWS. THE ARCTIC
AIRMASS WILL ALSO DROP SOUTHWARD WEST OF THE CONTINENTAL DIVIDE
THROUGHOUT THE CENTRAL AND NORTHERN INTERMOUNTAIN WEST, AND ALSO
SPREAD DOWN ACROSS THE CENTRAL TO EAST-CENTRAL U.S. OVER TIME, BUT
MODIFIED AS IT PROGRESSES SOUTHEASTWARD.
UPSTREAM, A CONTINUED SERIES OF HIGHLY DYNAMIC GULF OF
ALASKA/WESTERN CANADIAN AMPLIFYING SYSTEMS WILL MAINTAIN AND
PERIODICALLY REJUVENATE A HIGHLY UNSETTLED AND WINTRY PATTERN LATE
THIS WEEK FOR A GOOD PORTION OF THE WEST. THERE IS A STRONG
SIGNAL IN THE GUIDANCE FOR THIS SHORTWAVE ENERGY TO SPREAD DOWN
FROM THE PACIFIC NORTHWEST TO NORTH-CENTRAL CALIFORNIA INTO THE
SIERRA. THERE IS A MODERATE TO LOCALLY HEAVY RAINFALL SIGNAL FOR
COASTAL OREGON/NORTHERN CALIFORNIA TO MONITOR OUTLINED BY A DAY
5/FRIDAY ERO MARGINAL THREAT AREA. THERE SHOULD ALSO BE WIDESPREAD
TERRAIN/MOUNTAIN ENHANCED SNOWS FARTHER INLAND ACROSS THE NORTHERN
INTERMOUNTAIN WEST INTO THE ROCKIES WITH CONTINUED SYSTEM
PROGRESSIONS. THIS ENERGY IS SLATED IN LESS CERTAIN FORM TO WORK
INCREASINGLY DOWNSTREAM IN A SOUTHERN STREAM INTO THE
SOUTH-CENTRAL U.S. IN AN EMERGING PCPN PATTERN.
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 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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