509
FXUS02 KWBC 061859
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 PM EST SAT JAN 06 2024
VALID 12Z TUE JAN 09 2024 - 12Z SAT JAN 13 2024
...INTENSE LOW PRESSURE TO BRING WIDESPREAD RAIN, WIND, AND SNOW
FOR MUCH OF THE EASTERN HALF OF THE NATION THROUGH WEDNESDAY,
FOLLOWED BY AN ARCTIC AIRMASS SETTLING SOUTH FROM THE NORTHERN
PLAINS...
..GENERAL OVERVIEW
THE WEATHER PATTERN ACROSS THE CONTINENTAL U.S. WILL CONTINUE TO
BE EXTREMELY ACTIVE WITH MULTIPLE HIGH IMPACT WEATHER EVENTS
EXPECTED NEXT WEEK. THE FIRST AND BIGGEST EVENT WILL BE THE
RAPIDLY DEEPENING SURFACE LOW ACROSS THE SOUTH-CENTRAL U.S. THAT
WILL QUICKLY REACH THE GREAT LAKES AND NORTHEAST BY WEDNESDAY
MORNING, WITH WIDESPREAD HEAVY RAIN AND STRONG WINDS ACCOMPANYING
IT, AND POTENTIAL BLIZZARD CONDITIONS NORTHWEST OF THE LOW TRACK.
ONCE THIS STORM DEPARTS, AN ARCTIC FRONT WILL HERALD THE ARRIVAL
OF THE COLDEST TEMPERATURES SO FAR THIS SEASON ACROSS THE
NORTH-CENTRAL U.S. WITH A PATTERN TRANSITION EMERGING. THERE ARE
ALSO INCREASING PROSPECTS FOR ANOTHER WELL ORGANIZED STORM SYSTEM
TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION BY THE END OF THE
WEEK THAT COULD VERY WELL PRODUCE MORE IMPACTFUL WEATHER FOR THE
EASTERN U.S. BY SATURDAY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
RECENT MODEL GUIDANCE SUITES CONTINUE TO AGREE QUITE WELL ON THE
INTENSITY AND OVERALL EVOLUTION OF THE MAJOR EASTERN U.S. STORM
SYSTEM DURING THE TUESDAY-WEDNESDAY TIME PERIOD. THE MODELS AGREE
THAT THE LOW SHOULD BOTTOM OUT AT LEAST INTO THE HIGH 970S TO LOW
980S FOR PRESSURE, AND THAT RANGE SEEMS ACHIEVABLE GIVEN QUITE
FAVORABLE NEGATIVE UPPER TROUGH SUPPORT. WELL UPSTREAM FOR THE
NORTHEAST PACIFIC/GULF OF ALASKA SOURCED SYSTEM MOVING IN ACROSS
THE NORTHWESTERN U.S., SOME DIFFERENCES BECOME APPARENT AS THE
SHORTWAVE WORKS INLAND AND ESPECIALLY DOWNSTREAM INTO LATER NEXT
WEEK. EJECTING IMPULSES OFFER TIMING DIFFERENCES AND RUN TO RUN
CONTINUITY ISSUES OVER TIME, BUT THERE DOES SEEM TO BE A SLOWER
TREND OVERALL OVER THE PAST 24 HOURS FOR A MAIN TROUGH DIGGING
INTO AND COMING OUT FROM THE WEST SLATED TO BE A DRIVER FOR THE
NEXT WELL ORGANIZED STORM TO AFFECT THE CENTRAL TO EASTERN U.S.
HEADING INTO NEXT WEEKEND. OVERALL, THE WPC MEDIUM RANGE PRODUCT
SUITE WAS PRIMARILY DERIVED FROM A MULTI-DETERMINISTIC MODEL BLEND
ALONG WITH THE GENERALLY COMPATIBLE 13 UTC NBM AND WPC CONTINUITY
FOR TUESDAY INTO THURSDAY, ADDING SOME GEFS/ECMWF ENSEMBLE MEANS
TO THE AFOREMENTIONED BLEND AT THE EXPENSE OF THE MORE PROGRESSIVE
00/12 UTC CANADIAN SOLUTIONS INTO FRIDAY/SATURDAY.
..WEATHER/HAZARDS HIGHLIGHTS
CONFIDENCE REMAINS ABOVE NORMAL FOR A HIGHLY IMPACTFUL EVENT
SPANNING FROM TEXAS TO THE GREAT LAKES AND NORTHEAST U.S.
EARLY-MID NEXT WEEK AS A SURFACE LOW BECOMES ANOMALOUSLY STRONG
WHILE LIFTING NORTHEAST TOWARDS THE EASTERN GREAT LAKES BY
WEDNESDAY MORNING. HEAVY RAINFALL WILL INDEED BE ONE OF THE THINGS
MAKING WEATHER HEADLINES AS A VERY STRONG LOW LEVEL JET ADVECTS
DEEP GULF OF MEXICO MOISTURE NORTHWARD ACROSS THE EAST COAST
STATES ON TUESDAY. WIDESPREAD 1-3 INCH RAINFALL TOTALS ARE LIKELY
FROM THE SOUTHERN APPALACHIANS TO SOUTHERN NEW ENGLAND, WITH
LOCALLY HIGHER AMOUNTS VERY POSSIBLE GIVEN HIGHLY FAVORABLE
ENSEMBLE PROBABILITIES. THE DAY 4 OUTLOOK CONTINUES WITH A SLIGHT
RISK AREA STRETCHED FROM THE SOUTHERN APPALACHIANS TO SOUTHERN NEW
ENGLAND, WHILE MAINTAINING AND SLIGHTLY NORTHWARD EXPANDING AN
EXISTING MODERATE RISK THREAT AREA FROM FAR EASTERN PENNSYLVANIA
AND NORTHERN NEW JERSEY INTO SOUTHEAST NEW YORK/CATSKILLS WHERE
THERE IS A STRONG SIGNAL FOR 2 TO 3+ INCH RAINFALL TOTALS DURING
THIS TIME WITH IMPRESSIVE IVT VALUES EXPECTED FROM THE WESTERN
ATLANTIC. PARTS OF THIS REGION MAY ALSO HAVE SOME SNOW ON THE
GROUND AT THE ONSET OF THIS EVENT, AND THIS WILL TEND TO BE AN
AGGRAVATING FACTOR IN THE FLOODING POTENTIAL ALONG WITH REDUCED
FLASH FLOOD GUIDANCE. A BROADER MARGINAL RISK AREA INCLUDES ALL
AREAS FROM SOUTHERN GEORGIA TO SOUTHERN NEW HAMPSHIRE.
IN ADDITION TO THE HEAVY RAINFALL WILL BE THE INCREASING THREAT OF
STRONG TO SEVERE THUNDERSTORMS IN THE WARM SECTOR OF THE LOW WHERE
THE BEST COMBINATION OF KINEMATICS AND INSTABILITY WILL EXIST, AND
THIS IS EXPECTED FROM NORTHERN FLORIDA TO SOUTHEASTERN NORTH
CAROLINA ON TUESDAY. ON THE NORTHWEST SIDE OF THE LOW WILL BE THE
INCREASING PROSPECTS FOR AN IMPACTFUL WINTER STORM FROM NORTHERN
MISSOURI TO MICHIGAN, AND GIVEN THE STRONG PRESSURE GRADIENT
EXPECTED, THERE WILL LIKELY BE SOME BLIZZARD CONDITIONS AT TIMES.
WIDESPREAD WINDY CONDITIONS ARE EXPECTED ACROSS MUCH OF THE
EASTERN HALF OF THE NATION TUESDAY AND GOING INTO WEDNESDAY WITH
WINDS GUSTING 30-50 MPH AT TIMES, AND PERHAPS EVEN HIGHER ACROSS
THE HIGHEST TERRAIN OF THE CENTRAL/SOUTHERN APPALACHIANS.
IN TERMS OF TEMPERATURES, AN ARCTIC BLAST IS EXPECTED FOR THE
NORTHERN PLAINS TO CLOSE OUT NEXT WEEK WITH WIDESPREAD SUBZERO
LOWS FOR THE DAKOTAS AND INTO MONTANA, AND HIGHS ONLY IN THE 0S
AND 10S FOR MANY OF THOSE SAME AREAS, WITH ANOMALIES UPWARD TO 30
DEGREES BELOW NORMAL. SOME SUBZERO HIGHS ARE LIKELY FOR NORTHERN
MONTANA INTO NORTH DAKOTA. UPSTREAM, A CONTINUED SERIES OF HIGHLY
DYNAMIC PACIFIC SYSTEMS WILL MAINTAIN AND PERIODICALLY REJUVENATE
A HIGHLY UNSETTLED/WINTRY NEXT WEEK FOR A GOOD PORTION OF THE
WEST. THERE IS A MODERATE TO LOCALLY HEAVIER PRECIPITATION SIGNAL
FOCUS TO SPREAD DOWN FROM THE PACIFIC NORTHWEST TO NORTH-CENTRAL
CALIFORNIA INTO THE SIERRA. THERE SHOULD ALSO BE WIDESPREAD
TERRAIN/MOUNTAIN FOCUSING SNOWS FURTHER INLAND ACROSS THE
INTERMOUNTAIN WEST INTO THE ROCKIES WITH CONTINUED SYSTEM
PROGRESSIONS.
LOOKING AHEAD TO THE NEXT FRIDAY-SATURDAY TIME PERIOD, IT IS STILL
LOOKING LIKELY THAT ANOTHER POTENTIALLY STRONG LOW PRESSURE SYSTEM
COULD AFFECT SIMILAR AREAS OF THE CENTRAL AND EASTERN U.S.
COMPARED TO THE LOW ON TUESDAY/WEDNESDAY, TRACKING FROM TEXAS TO
THE GREAT LAKES BASED ON THE LATEST GUIDANCE. THIS WOULD AGAIN
INCREASE THE POTENTIAL FOR STRONG THUNDERSTORMS/WINDS, HEAVY
RAINFALL, AND WINTER WEATHER TO CLOSE OUT THE WEEK, AND THIS WILL
CONTINUE TO BE MONITORED CLOSELY.
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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