704
FXUS02 KWBC 060733
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 AM EST TUE JAN 6 2026
VALID 12Z FRI JAN 09 2026 - 12Z TUE JAN 13 2026
..OVERVIEW
THE MEDIUM RANGE PERIOD BEGINS FRIDAY WITH A DEEP TROUGH DIGGING
THROUGH THE WESTERN U.S., GRADUALLY PROGRESSING EAST WITH TIME AS
IT STRENGTHENS AND CLOSES OFF A LOW NEAR THE GREAT LAKES. THIS WILL
PROMOTE MODERATE TO HEAVY PRECIPITATION CHANCES ALONG AND AHEAD OF
THE ASSOCIATED FRONTAL BOUNDARY ACROSS THE EASTERN THIRD OF THE
COUNTRY. SOME WINTRY PRECIPITATION IS POSSIBLE ON THE BACKSIDE OF
THE SYSTEM INTO THE UPPER MIDWEST AND GREAT LAKES. AHEAD OF THIS
FRONT, RECORD HIGH TEMPERATURES ARE POSSIBLE ON FRIDAY FOR PORTIONS
OF THE EAST- CENTRAL TO EASTERN STATES. ONCE THE FRONT CLEARS THE
EAST COAST THIS WEEKEND, MUCH OF THE COUNTRY WILL BE DRY SUNDAY AND
MONDAY UNDERNEATH SPRAWLING HIGH PRESSURE.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST MODEL GUIDANCE CONTINUES TO SHOW REASONABLY GOOD
AGREEMENT ON THE LARGE SCALE PATTERN EVOLUTION INTO EARLY NEXT
WEEK, BUT STILL WITH CONSIDERABLE DIFFERENCES IN THE DETAILS WHICH
HAVE IMPLICATIONS ON SENSIBLE WEATHER. THE GUIDANCE HAS SHOWN
BETTER AGREEMENT IN RECENT RUNS WITH A DEEPENING TROUGH INTO THE
CENTRAL U.S. FRIDAY-SATURDAY. THE DIFFERENCES NOW ARE REALLY WITH
THE TIMING WHICH IS RELATED TO PHASING OF A COUPLE OF SHORTWAVES
WITHIN THE OVERALL PARENT TROUGH. THERE SEEMS TO BE A TREND TOWARDS
A BIT MORE PHASING AND SLOWER TROUGH PROGRESSION INTO THE MIDWEST
AND EVENTUALLY THE EAST, WHICH IS SUPPORTED BY THE AI GUIDANCE AS
WELL. GUIDANCE SHOWS THAT SOME ENERGY MAY BREAK OFF A RETROGRADE
WESTWARD SETTLING OVER THE NORTHERN BAJA PENINSULA BENEATH A
BUILDING ANOMALOUS RIDGE OVER THE WEST. THE TROUGH PROGRESSES INTO
THE EAST THIS WEEKEND WITH SOME GREATER TIMING UNCERTAINTIES
ARISING IMPACTING HOW QUICKLY THE FRONT AND PRECIPITATION MAY CLEAR
THE EAST. AFTER THIS, THE PATTERN MAY TURN MORE ZONAL BY EARLY
NEXT WEEK, THOUGH WITH UNCERTAINTY IN ANOTHER SHORTWAVE INTO THE
NORTHWEST AROUND MONDAY, WITH POSSIBLE CUTOFF/CLOSED LOW
DEVELOPMENT OVER/NEAR CALIFORNIA BY TUESDAY.
A GENERAL MODEL BLEND OF THE DETERMINISTIC GUIDANCE SEEMED TO WORK
WELL AS A STARTING POINT FOR THE DAY 3-5/FRIDAY-SUNDAY PERIOD.
AFTER THIS, GRADUALLY INCREASED THE ENSEMBLE MEAN WEIGHTING TO 50
PERCENT OF THE BLEND TO HELP MITIGATE THE GREATER DIFFERENCES WHICH
ARISE LATE PERIOD. GENERALLY MAINTAINED GOOD AGREEMENT WITH THE
PREVIOUS WPC FORECAST IN TERMS OF THE TROUGH THROUGH THE CENTRAL
AND EASTERN U.S..
..WEATHER/HAZARDS HIGHLIGHTS
AMPLE GULF MOISTURE (WITH HIGHLY ANOMALOUS VALUES ABOVE THE 95TH
PERCENTILE) WILL STREAM AHEAD OF THE CENTRAL U.S. TROUGH TO PRODUCE
WIDESPREAD RAIN FROM THE GULF COAST TO THE OHIO VALLEY, MID-
ATLANTIC, AND NORTHEAST FRIDAY INTO SATURDAY. MODELS ARE SHOWING AN
INCREASING SIGNAL FOR HEAVY TO EXCESSIVE RAINFALL POTENTIAL,
PARTICULARLY FRIDAY ACROSS PORTIONS OF THE TENNESSEE VALLEY. GIVEN
THE ANOMALOUS MOISTURE AND SOME INSTABILITY (ESPECIALLY SOUTH) WENT
AHEAD WITH A SLIGHT RISK UPGRADE FOR THE DAY 4/FRIDAY ERO PERIOD
FROM NORTHEAST MISSISSIPPI TO CENTRAL TENNESSEE WHERE MODEL 24-HOUR
QPFS SHOW SUPPORT FOR 2-4+ INCHES OF RAIN AND SOME POTENTIAL FOR
TRAINING ALONG THE INITIALLY SLOW TO MOVE BOUNDARY. BY SATURDAY,
THE PRECIPITATION MOVES INTO THE EAST AND THE FRONTAL BOUNDARY
SHOULD BE PROGRESSIVE ENOUGH BY THAT TIME TO PRECLUDE A RISK AREA
ON THE DAY 5 ERO AT THIS TIME. PRECIPITATION SHOULD CLEAR THE COAST
BY SUNDAY, WITH SOME POSSIBLE SHOWERS LINGERING ACROSS FLORIDA.
ON THE COLD SIDE OF THIS SYSTEM, THERE IS THE POTENTIAL FOR
ACCUMULATING SNOW FROM THE CENTRAL PLAINS TO THE UPPER MIDWEST AND
NORTHERN GREAT LAKES FRIDAY INTO SATURDAY. DETAILS WILL NEED TO BE
SORTED OUT IN THE COMING DAYS, BUT THE SIGNAL FOR A SWATH OF AT
LEAST A FEW INCHES, WITH LOCALLY HIGHER AMOUNTS, WILL NEED TO BE
CAREFULLY EVALUATED WITH FUTURE MODEL CYCLES. LAKE EFFECT SNOWS MAY
CONTINUE INTO SUNDAY DOWNWIND OF FAVORABLE LOCATIONS AS A WEAK
CLIPPER SYSTEM MOVES THROUGH. AFTER THIS THOUGH, MUCH OF THE
COUNTRY WILL BE DRY WITH THE EXCEPTION OF THE FAR WESTERN
WASHINGTON AND POSSIBLY PARTS OF THE SOUTHERN PLAINS NEXT MONDAY.
TEMPERATURES ARE LIKELY TO BE WELL ABOVE AVERAGE ACROSS THE
EASTERN THIRD OF THE COUNTRY FRIDAY INTO SATURDAY AHEAD OF THE BIG
TROUGH, WITH TEMPERATURE ANOMALIES OF 15 TO 25 DEGREES ABOVE
NORMAL. DAILY RECORDS FOR WARM LOWS AND HIGHS COULD BE SET ACROSS
THE SOUTHERN TIER AND INTO PARTS OF THE MID-ATLANTIC. TEMPERATURES
WILL RETURN TO NORMAL FROM WEST TO EAST FOLLOWING THE FRONTAL
PASSAGE. MEANWHILE THE WEST/SOUTHWEST MAY START BELOW NORMAL BUT
SHOULD TREND WARMER WITH TIME AS A RIDGE DEVELOPS OVER MUCH OF THE
REGION. THIS RIDGE WILL ALSO BUILD INTO THE NORTH-CENTRAL U.S. BY
THE WEEKEND WITH ABOVE TO WELL ABOVE TEMPERATURES RETURNING TO THAT
REGION.
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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