111
FXUS02 KWBC 020733
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 AM EST TUE DEC 2 2025
VALID 12Z FRI DEC 05 2025 - 12Z TUE DEC 09 2025
...RECORD COLD LIKELY FOR THE CORN BELT/MIDWEST/MID-ATLANTIC
THROUGH FRIDAY...
..OVERVIEW
BROAD CYCLONIC FLOW WILL CONTINUE TO DOMINATE DURING MUCH OF THE
MEDIUM RANGE PERIOD ACROSS THE CONUS AS A RESULT OF UPPER LOWS
ANCHORED OVER CANADA AND ALASKA. THIS WILL FAVOR BELOW TO WELL
BELOW NORMAL TEMPERATURES FOR THE PLAINS TO THE EAST COAST, WITH
RECORD COLD LOWS (AND COLD HIGHS) LIKELY INTO FRIDAY FROM THE CORN
BELT TO PARTS OF THE MID-ATLANTIC. NEAR TO ABOVE NORMAL
TEMPERATURES ARE FAVORED FOR THE WESTERN STATES DOWNSTREAM OF THE
CORE OF THE UPPER RIDGE. WITH THE UPPER TROUGH TOUCHING THE GULF
COAST LATE THIS WEEK, A FRONTAL SYSTEM THERE WILL MOVE EASTWARD AND
PROMOTE AN AREA OF LOCALLY HEAVIER RAIN ALONG THE I-10 CORRIDOR.
TREND BY THE WEEKEND CONTINUES TO BE FOR A FLATTER SYSTEM TO EXIT
OUT TO SEA THEREAFTER, BUT SOME GENERALLY LIGHT WINTRY
PRECIPITATION IS POSSIBLE ON ITS NORTHERN SIDE. A COUPLE OF CLIPPER
SYSTEMS WILL IMPACT THE NORTHERN TIER STATES AS WELL THROUGH THE
PERIOD.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT SYNOPTICALLY, BUT PLENTY
OF UNCERTAINTY IN THE DETAILS WHICH IMPACTS SENSIBLE WEATHER
GRIDS. THERE ARE SOME DIFFERENCES ACROSS THE MIDWEST THIS WEEKEND
WITH SOME WEAK SHORTWAVES, AND THEN THE CMC IS SHARPER WITH A
SHORTWAVE DOWN TOWARDS THE GULF COAST EARLY NEXT WEEK. SOME
UNCERTAINTY WITH TIMING OF UPPER RIDGING IN THE WEST AS WELL. EVEN
SO, A GENERAL MODEL BLEND SUFFICED FOR THE FIRST HALF OF THE
PERIOD, WITH INCREASING WEIGHTING OF THE ENSEMBLE MEANS ON DAYS 6
AND 7. THIS MEANT THE 01Z NBM WAS A GOOD STARTING POINT FOR MOST OF
THE SENSIBLE WEATHER GRIDS, BUT DID HAVE TO SUPPLEMENT THE QPF
GRIDS WITH DETERMINISTIC GUIDANCE TO INCREASE COVERAGE OF LIGHT
PRECIPITATION ASSOCIATED WITH THE SYSTEMS THROUGH THE NORTHERN
PLAINS AND MIDWEST.
..WEATHER/HAZARDS HIGHLIGHTS
HEAVY RAIN ALONG A FRONTAL BOUNDARY WILL SPREAD INTO THE SOUTHEAST
FRIDAY AND POSSIBLY INTO SATURDAY. THE WPC DAY 4/FRIDAY ERO
CONTINUES TO SHOW A MARGINAL RISK ACROSS PARTS OF THE SOUTHEAST
ALONG THE FRONTAL BOUNDARY WHICH MAY STALL FOR A PERIOD OF TIME
ALLOWING FOR SOME TRAINING OF STORMS. INSTABILITY MAY BE LACKING
OVERALL WHICH SHOULD LIMIT THE FLASH FLOOD THREAT TOWARD THE I-10
CORRIDOR. BY SATURDAY, SOME MODERATE TO HEAVY RAIN MAY LINGER
ACROSS NORTHERN FLORIDA AND SO A MARGINAL RISK WAS RAISED ON THE
DAY 5/SATURDAY ERO FOR THAT AREA. THE WHOLE SYSTEM WILL LIFT OUT TO
SEA BY SUNDAY, BUT MAY STILL SPREAD SOME LIGHT PRECIPITATION
(RAIN/SNOW) ON ITS NORTHERN SIDE ACROSS THE MID-ATLANTIC AND
PERHAPS NEW ENGLAND. OVER THE PAC NW, SEVERAL PACIFIC SYSTEMS WILL
PUSH INTO WESTERN CANADA DURING THE PERIOD WITH RAIN/SNOW OVER
WA/OR AND EASTWARD TO THE NORTHERN/CENTRAL ROCKIES. SOME CLIPPER
LIKE SYSTEMS WILL BRING RAIN AND SNOW TO PARTS OF THE MIDWEST AND
GREAT LAKES AS WELL.
SURGES OF BELOW AVERAGE TEMPERATURES CONTINUE FOR THE CENTRAL AND
EASTERN U.S. INTO LATE WEEK AS THE SPRAWLING LOW OVER HUDSON BAY
PERSISTS. A SURGE FROM THE NORTHERN PLAINS THROUGH THE NORTHEAST
OCCURS INTO FRIDAY WITH LOW TEMPERATURES OF 5 TO 20 DEGREES BELOW
ZERO, WHICH WILL LIKELY SET DAILY RECORD LOWS. HIGH TEMPERATURES IN
THE TEENS AND LOW 20S ON THURSDAY WILL ALSO SET DAILY RECORDS FOR
COLD HIGH TEMPERATURES. THE NEXT COLD SURGE MAY FOLLOW THE SAME
PATH BUT PERHAPS BE OF LESSER MAGNITUDE THIS WEEKEND. THE WEST WILL
SEE ABOVE NORMAL TEMPERATURES (ESPECIALLY THE GREAT BASIN) LATE
WEEK THROUGH THIS WEEKEND, EXPANDING INTO THE ROCKIES AND POSSIBLY
THE PLAINS BY NEXT TUESDAY.
SANTORELLI
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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