507
FXUS02 KWBC 082000
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EST SAT NOV 8 2025
VALID 12Z TUE NOV 11 2025 - 12Z SAT NOV 15 2025
...FIRST WINTER-LIKE CHILL AND LAKE EFFECT SNOW EVENT OF THE
SEASON FOR MUCH OF THE CENTRAL AND EASTERN U.S. INTO EARLY NEXT
WEEK...
...AN ATMOSPHERIC RIVER WILL LIKELY IMPACT PORTIONS OF CALIFORNIA
BY MID TO LATE NEXT WEEK BRINGING A THREAT OF HEAVY RAINFALL...
..OVERVIEW
IT GENERALLY REMAINS THE CASE THAT AN ANOMALOUSLY DEEP UPPER
TROUGH WILL STILL BE OVER THE EASTERN U.S. TUESDAY, BRINGING
ANOTHER DAY OF WELL BELOW AVERAGE TEMPERATURES AND FREEZING
TEMPERATURES AS FAR SOUTH AS THE GULF COAST. THE DEPTH OF THE
TROUGH WILL EASE BY WEDNESDAY, BUT SOME TROUGHING WILL PERSIST IN
THE GREAT LAKES TO NORTHEAST AND LEAD TO ROUNDS OF LAKE EFFECT
PRECIPITATION, INCLUDING SNOW. UPPER RIDGING IN THE WEST IS
FORECAST TO SLOWLY MOVE TOWARD THE CENTRAL U.S. BRINGING MUCH
WARMER THAN AVERAGE TEMPERATURES. BY MID TO LATE NEXT WEEK, UPPER
TROUGHING WILL EDGE TOWARD THE WEST AND COULD DIRECT AN ATMOSPHERIC
RIVER, ESPECIALLY INTO CALIFORNIA. SOME ACTIVITY WILL WORK INLAND
NEXT FRIDAY/SATURDAY TO THE INTERMOUNTAIN WEST AND SOUTHWEST U.S..
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE REMAINS REASONABLY WELL CLUSTERED OVERALL THROUGH NEXT
WEEK, BUT RECENT MODEL AND ENSEMBLE MEMBERS HAVE OFFERED LESS THAN
STELLAR CYCLE TO CYCLE CONTINUITY WITH MAIN WEATHER FEATURE
PROGRESSIONS INTO LATER NEXT WEEK. HOWEVER, LATEST 00/06/12 UTC
CYCLE GUIDANCE CONTINUES TO CONVERGE ON A MORE SIMILAR SOLUTION,
BOLSTERING FORECAST CONFIDENCE INTO THESE LONGER TIME FRAMES,
ESPECIALLY AT MID-LARGER SCALES. ACCORDINGLY, THE WPC MEDIUM RANGE
PRODUCT SUITE WAS PRIMARITY DERIVED FROM A COMPOSITE BLEND OF
THE GFS/ECMWF/CANADIAN MODELS AND ENSEMBLES ALONG WITH WPC
CONTINUITY. THIS SOLUTION IS OVERALL IN LINE WITH GUIDANCE FROM
THE 13 UTC NATIONAL BLEND OF MODELS (NBM), BUT HAVE MANUALLY ADJUSTED
NBM GUIDANCE TO SHOW GREATER QPF/GREAT LAKE EFFECT ACTIVITY THROUGH
MIDWEEK AND SLIGHTLY COOLER TEMPS OVER AN ANOMALOUSLY COLD
SOUTHEAST.
..WEATHER/HAZARDS HIGHLIGHTS
UPPER TROUGHING OVER THE GREAT LAKES INTO THE NORTHEAST WILL
PERIODICALLY BE REINFORCED BY ADDITIONAL SHORTWAVE ENERGY RESULTING
IN CONTINUED LAKE EFFECT RAIN AND SNOW. SIGNIFICANT SNOWFALL
APPEARS PROBABLE ACROSS THE TUG HILL PLATEAU AND JUST TO THE LEE OF
THE LAKES. SNOW ACCUMULATIONS ARE ALSO LIKELY TUESDAY THROUGH
THURSDAY FROM NORTHWEST PA INTO CENTRAL/WESTERN NY AND INTO
NORTHERN NEW ENGLAND, LINGERING INTO FRIDAY IN COOLED FLOW.
MOST OTHER AREAS OF THE LOWER 48 WILL SEE DRY CONDITIONS NEXT
WEEK, UNTIL PRECIPITATION CHANCES INCREASE ALONG THE WEST COAST MID
TO LATE WEEK AS A PACIFIC SYSTEM APPROACHES. IT DOES SEEM LIKELY
THAT AN ATMOSPHERIC RIVER WILL MOVE INTO NORTHERN CA BY THURSDAY.
THERE WILL BE PRETTY STRONG CONVERGENCE AND UPPER SUPPORT WITH THIS
ATMOSPHERIC RIVER, AND THUS SOME HIGHER RAINFALL RATES. THE SYSTEM
LOOKS PROGRESSIVE ENOUGH TO LIMIT THE DURATION OF HEAVIER
RAINFALL TO A DEGREE, BUT THE SETUP WOULD SEEM TO SUPPORT A THREAT
OF EXCESSIVE RAINFALL LATER NEXT WEEK TO MONITOR. GREATER
UNCERTAINTY EXISTS FOR DAY 6 AND 7 OVER SOUTHERN CA AS THIS WILL
DEPEND ON THE EVOLUTION/TIMING OF THE TROUGH AND POSSIBLE EMBEDDED
CLOSED LOW, BUT CONFIDENCE ON LOCAL DETAILS ARE SLOWLY IMPROVING.
ONE MORE COLD DAY IS EXPECTED ACROSS THE EAST ON TUESDAY, WITH
HIGHS 10-20 DEGREES BELOW AVERAGE AND LOWS TUESDAY MORNING BELOW
FREEZING AS FAR SOUTH AS THE GULF COAST. IN FACT, WITH A HIGH
PRESSURE OVERHEAD RESULTING IN LIGHT WINDS AND CLEAR SKIES, LOW
TEMPERATURES OVER PORTIONS OF THE SOUTHEAST COULD END UP A BIT
BELOW NBM VALUES TUESDAY AND WEDNESDAY MORNING, AS SHOULD BE IDEAL
RADIATIONAL COOLING RESULTING IN A WIDESPREAD FROST/FREEZE THREAT.
MEANWHILE STRONG UPPER RIDGING IN THE WEST WILL RESULT IN ABOVE
AVERAGE TEMPERATURES GENERALLY BY AROUND 10-15 DEGREES TUESDAY INTO
WEDNESDAY. THESE WARMER THAN AVERAGE TEMPERATURES ARE FORECAST TO
SPREAD EAST INTO THE PLAINS AND EVENTUALLY THE MISSISSIPPI VALLEY
AS THE WEEK PROGRESSES AS THE RIDGE SHIFTS EAST. BY THURSDAY INTO
SATURDAY HIGHS IN THE 60S AND 70S OVER PORTIONS OF THE PLAINS AND
MS VALLEY WILL BE APPROACHING 20 DEGREES ABOVE AVERAGE IN SPOTS.
TEMPERATURES SHOULD ALSO MODERATE IN THE EAST BY WEDNESDAY AND
BEYOND, WITH NEAR TO JUST SLIGHTLY BELOW AVERAGE TEMPERATURES.
CHENARD/TATE/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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