416
FXUS02 KWBC 201844
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
244 PM EDT SUN OCT 20 2024
VALID 12Z WED OCT 23 2024 - 12Z SUN OCT 27 2024
..GENERAL OVERVIEW
A GENERALLY BENIGN WEATHER PATTERN IS EXPECTED FOR MANY AREAS
ACROSS THE CONTINENTAL U.S. FOR THE MIDDLE OF THE WEEK TO BE
FEATURED WITH A SURFACE HIGH OVER THE EASTERN U.S., ACCOMPANIED BY
ABOVE AVERAGE TEMPERATURES AND CONTINUED DRY CONDITIONS FROM THE
MID- ATLANTIC TO THE SOUTHEAST U.S.. AN INCOMING TROUGH FROM THE
MIDWEST AND THE ASSOCIATED COLD FRONT WILL HERALD THE ARRIVAL OF
COOLER WEATHER TOWARDS THE END OF THE WEEK, BUT IT WILL HAVE
LIMITED MOISTURE TO WORK WITH SO RAINFALL AMOUNTS FROM THE GREAT
LAKES TO THE NORTHEAST WILL BE GENERALLY LIGHT TO OCCASIONALLY
MODERATE. THERE MAY BE ANOTHER CHANCE FOR SOME ORGANIZED RAINS
THERE AGAIN NEXT WEEKEND. MEANWHILE, THE NEXT PACIFIC STORM SYSTEM
IS EXPECTED TO APPROACH THE PACIFIC NORTHWEST LATE IN THE WEEK,
BRINGING A RETURN TO RAIN AND HIGH MOUNTAIN SNOW FROM NORTHERN
CALIFORNIA TO WASHINGTON STATE. AN UPPER RIDGE AND MILDER
TEMPERATURES ARE LIKELY AHEAD OF THIS PACIFIC STORM SYSTEM ACROSS
MUCH OF THE CENTRAL U.S.
..GUIDANCE/PREDICTABILITY ASSESSMENT
RECENT MODEL CYCLES HAVE STRUGGLED WITH THE FLOW PATTERN ACROSS
THE EASTERN PACIFIC AND INTO THE PACIFIC NORTHWEST, AND THIS IN
TURN AFFECTED THE AMPLITUDE AND POSITION OF BOTH UPPER RIDGE OVER
THE ROCKIES AND WESTERN HIGH PLAINS, AND ALSO THE EVOLVING CLOSED
LOW OFF THE NORTHWEST COAST AND ITS EVENTUAL EVOLUTION AS IT TRACKS
INLAND. THE 06 UTC GFS/GEFS AND 00 UTC ECMW/ECMWF ENSEMBLE MEANS
CONVERGED UPON A BETTER CLUSTERED SOLUTION OVER MEDIUM RANGE TIME
PERIODS, BOLSTERING FORECAST CONFIDENCE TO A DEGREE, PROBABLY
CLOSER TO AVERAGE LEVELS. A PREFERED COMPOSITE BLEND OF THESE
GUIDANCE PIECES ALSO SEEMS TO PROVIDE A SOLID FORECAST BASIS FOR
THE REST OF THE NATION ALONG WITH THE NBM, BUT LATEST 12 UTC
GUIDANCE RUN CLUSTERING IS NOT QUITE AS GOOD.
..WEATHER/HAZARDS HIGHLIGHTS
A LEADING COLD FRONT CROSSING THE GREAT LAKES/OHIO VALLEY AND INTO
THE NORTHEAST WEDNESDAY INTO THURSDAY WILL LIKELY HAVE JUST ENOUGH
MOISTURE AND LIFT TO PRODUCE SOME MAINLY LIGHT TO MODERATE
SHOWERS. LATER PERIOD SYSTEM APPROACH HAS MORE UNCERTAINTY, BUT
WOULD SUPPORT ANOTHER PERIOD OF ORGANIZED RAIN POTENTIAL THERE INTO
NEXT WEEKEND. IT SHOULD CONTINUE TO REMAIN DRY AND MOSTLY SUNNY
FOR AREAS FARTHER TO THE SOUTH ACROSS THE MID- ATLANTIC AND THE
SOUTHEAST U.S., WHERE THE VERY PLEASANT FALL WEATHER WILL CONTINUE
FOR A WHILE. THERE ARE CURRENTLY NO RISK AREAS IN THE DAY 4 AND DAY
5 EXCESSIVE RAINFALL OUTLOOKS.
THE PATTERN WILL BECOME FAVORABLE FOR THE RETURN OF PRECIPITATION
TO THE PACIFIC NORTHWEST LATE THIS WEEK INTO THE WEEKEND. HOWEVER
DESPITE SOME RECENT IMPROVEMENT IN THE AREA, THERE IS CONTINUED
MODEL SPREAD FOR A SYSTEM EXPECTED TO DEVELOP OVER THE EASTERN
PACIFIC BY MIDWEEK AND LIFT NORTHEASTWARD THEREAFTER. RAIN AND HIGH
ELEVATION NORTHERN CASCADES SNOW COULD COMMENCE AS EARLY AS LATE
THURSDAY PER THE FAST SIDE OF RECENT SPREAD, OR TAKE UNTIL LATE
FRIDAY OR SO ON THE SLOWER SIDE. CURRENTLY THIS LOOKS MORE LIKE A
BROAD PRECIPITATION EVENT RATHER THAN A FOCUSED ATMOSPHERIC RIVER,
BUT SOME LOCALLY ENHANCED TOTALS WILL BE POSSIBLE. LIGHTER
WEEKEND PRECIPITATION IS FORECAST TO REACH THE NORTHERN ROCKIES.
TEMPERATURES WILL FEEL MORE LIKE SEPTEMBER ACROSS AREAS FROM THE
CENTRAL U.S. INTO THE NORTHEAST MID-WEEK, WITH HIGHS RUNNING 10-20
DEGREES ABOVE AVERAGE FOR LATE OCTOBER. A MAIN COLD FRONT PUSHING
RAPIDLY SOUTHEASTWARD FROM THE NORTHERN PLAINS WILL BRING A RETURN
TO MORE SEASONABLE TO CONDITIONS FOR THE END OF THE WEEK. FROM
LATE WEEK INTO THE WEEKEND, A BUILDING WESTERN U.S. UPPER RIDGE
THAT PUSHES EASTWARD AHEAD OF THE PACIFIC STORM SYSTEM SHOULD
PROMOTE A WARMING TREND FIRST OVER THE INTERMOUNTAIN WEST AND
ROCKIES/WESTERN HIGH PLAINS, AND THEN COVERING MUCH OF THE CENTRAL
U.S. WHERE MANY AREAS SHOULD SEE HIGHS UPWARDS TO 10-15 DEGREES
ABOVE NORMAL.
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 (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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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