566
FXUS02 KWBC 100717
PMDEPD
EXTENDED FORECAST DISCUSSION...AMENDED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
216 AM EST SAT FEB 10 2024
VALID 12Z TUE FEB 13 2024 - 12Z SAT FEB 17 2024
..GENERAL OVERVIEW
THE STORM SYSTEM THAT WILL BE TRACKING ACROSS THE SOUTHERN U.S. IN
THE SHORT RANGE FORECAST PERIOD IS FORECAST TO EXIT THE
MID-ATLANTIC COAST TUESDAY MORNING, WITH SNOW LIKELY CONTINUING
INTO TUESDAY AFTERNOON ACROSS SOUTHERN NEW ENGLAND BEFORE TAPERING
OFF LATER IN THE DAY. A QUASI-ZONAL FLOW PATTERN DEVELOPS ACROSS
MUCH OF THE NATION IN THE WAKE OF THIS STORM SYSTEM, AND A PATTERN
CHANGE IS EXPECTED TO EVOLVE BY THURSDAY ACROSS THE NORTH-CENTRAL
U.S. AS AN ARCTIC AIRMASS DROPS SOUTHWARD FROM WESTERN CANADA WITH
A RETURN TO BELOW NORMAL TEMPERATURES. MEANWHILE, AN UPPER LEVEL
RIDGE IS LIKELY TO BECOME ESTABLISHED OVER THE WEST COAST STATES
BY THE END OF THE WEEK, AND THIS WILL TEND TO LIMIT THE
PROGRESSION OF OFFSHORE PACIFIC STORM SYSTEMS UNTIL ABOUT SATURDAY
WHEN THE NEXT ROUND OF ORGANIZED PRECIPITATION MOVES INLAND ACROSS
CALIFORNIA. ELSEWHERE, SOME LIGHT SNOW SHOWERS ARE POSSIBLE FROM
THE NORTHERN ROCKIES TO THE UPPER MIDWEST WITH WEAK SHORTWAVE
PASSAGES, AND LAKE EFFECT SNOW ACROSS THE GREAT LAKES REGION
FRIDAY NIGHT INTO SATURDAY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE IS IN REASONABLY GOOD AGREEMENT
ACROSS THE CONTINENTAL U.S. ON TUESDAY, WITH A SLIGHTLY SLOWER
TREND WITH THE LOW EXITING THE EAST COAST. DIFFERENCES BECOME
EVIDENT BY WEDNESDAY WITH THE EXTENT OF TROUGH AMPLIFICATION OVER
THE NORTH-CENTRAL U.S. AND THE TIMING OF SHORTWAVE FEATURES IN THE
NORTHERN STREAM FLOW, AND ALSO WITH THE EXTENT OF THE RIDGE AXIS
ACROSS THE WEST COAST REGION. HOWEVER, THERE IS DECENT MODEL
AGREEMENT WITH THE DEVELOPING SOUTHERN STREAM TROUGH NEAR THE GULF
COAST LATE IN THE FORECAST PERIOD. THE USE OF THE ENSEMBLE MEANS
INCREASED TO ABOUT 50 PERCENT BY NEXT SATURDAY TO ACCOUNT FOR THE
GROWING MESOSCALE MODEL DIFFERENCES ELSEWHERE.
IN TERMS OF THE NBM, TEMPERATURES WERE REDUCED BY 2-5 DEGREES
ACROSS MUCH OF THE NORTH-CENTRAL U.S. GIVEN THE STRONGER SIGNAL
FOR AN ARCTIC SURFACE HIGH SETTLING IN, EVEN THOUGH THE GUIDANCE
HAS TRENDED COLDER COMPARED TO THIS TIME YESTERDAY. THE QPF WAS
ALSO RAISED ACROSS THE GENERAL VICINITY OF THE GREAT LAKES ON
FRIDAY FROM THE NBM GIVEN THE DECENT OVERALL SIGNAL FOR A LAKE
EFFECT SNOW EVENT.
..OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
WIDESPREAD SNOW WILL LIKELY BE ONGOING TUESDAY MORNING ACROSS MUCH
OF THE NORTHEAST U.S. AS THE SURFACE LOW CONTINUES TO DEEPEN UPON
EXITING THE COAST. SEVERAL INCHES OF SNOW IS EXPECTED, ESPECIALLY
ACROSS INTERIOR PORTIONS OF SOUTHERN NEW ENGLAND WHERE SNOW IS THE
PRIMARY PRECIPITATION TYPE THROUGHOUT THE EVENT. THE RAIN/SNOW
LINE COMES CLOSE TO THE MAJOR METROPOLITAN AREAS ALONG INTERSTATE
95 FROM PHILADELPHIA AND POINTS NORTHEAST, AND HERE THE FORECAST
IS MORE UNCERTAIN WHERE A CHANGEOVER FROM RAIN TO SNOW WILL TEND
TO LIMIT OVERALL ACCUMULATIONS. RAIN WILL BE THE MAIN
PRECIPITATION TYPE ACROSS EASTERN PORTIONS OF THE MID-ATLANTIC.
THE QUICK PROGRESSION OF THE SURFACE LOW SHOULD BRING AN END TO
MOST OF THE PRECIPITATION BY SUNSET TUESDAY, AND NO EXCESSIVE
RAINFALL AREAS ARE CURRENTLY WARRANTED FOR EITHER DAY 4 OR DAY 5
WITH JUST LIGHT TO MODERATE RAIN ACROSS WESTERN PORTIONS OF
WASHINGTON AND OREGON ON WEDNESDAY.
LOOKING AHEAD TO FRIDAY AND EARLY SATURDAY, A LOW PRESSURE SYSTEM
IS EXPECTED TO DEVELOP OVER THE WESTERN GULF AND ADVECT INCREASING
MOISTURE NORTHWARD AND OVER A DEVELOPING WARM FRONT, AND THIS WILL
LIKELY RESULT IN WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS
SOUTHERN TEXAS AND INTO THE CENTRAL GULF COAST REGION.
ADDITIONALLY, THE NEXT ROUND OF ORGANIZED PACIFIC MOISTURE IS
EXPECTED TO REACH THE WEST COAST ON FRIDAY AND RESULT IN MODERATE
TO HEAVY RAIN FOR THE NORTHERN HALF OF CALIFORNIA, AND SNOW FOR
THE HIGHER TERRAIN. FARTHER EAST, THE PROSPECTS FOR LAKE EFFECT
SNOW ARE INCREASING TO CLOSE OUT THE WORK WEEK WITH THE MUCH
COLDER AIRMASS CROSSING THE GREAT LAKES, WITH THE GREATEST
SNOWFALL LIKELY ACROSS CENTRAL AND NORTHERN MICHIGAN.
TEMPERATURES ARE EXPECTED TO BE GENERALLY 5 TO 15 DEGREES ABOVE
MID-FEBRUARY AVERAGES ACROSS MUCH OF THE MIDWEST REGION ON TUESDAY
AND WEDNESDAY WITH SLIGHTLY BELOW AVERAGE READINGS OVER THE DESERT
SOUTHWEST AND THE NORTHERN ROCKIES. GOING INTO LATE WEDNESDAY, A
STRONG COLD FRONT DROPPING SOUTH FROM WESTERN CANADA IS EXPECTED
TO HERALD THE ARRIVAL OF AN ARCTIC AIRMASS ACROSS THE NORTHERN
PLAINS AND BRING A RETURN TO BELOW AVERAGE TEMPERATURES FROM
MONTANA TO THE DAKOTAS AND NORTHERN MINNESOTA THROUGH THE END OF
THE WEEK, PERHAPS UP TO 20 DEGREES BELOW AVERAGE. MODELS HAVE
TRENDED COLDER BEHIND THIS FRONT COMPARED TO YESTERDAY, AND THINGS
MAY CONTINUE TO TREND COLDER IN FUTURE FORECAST UPDATES.
MEANWHILE, MUCH OF THE REMAINDER OF THE U.S. SHOULD HAVE
TEMPERATURES GENERALLY WITHIN 5 DEGREES OF CLIMATOLOGICAL AVERAGES
TO CLOSE OUT THE WORK WEEK, FOLLOWED BY COLDER CONDITIONS ACROSS
MUCH OF THE CENTRAL AND SOUTHERN PLAINS BY SATURDAY.
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 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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