607
FXUS02 KWBC 040758
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EST SUN JAN 4 2026
VALID 12Z WED JAN 07 2026 - 12Z SUN JAN 11 2026
..OVERVIEW
QUASI-ZONAL FLOW OVER THE CONUS (WITH PROGRESSIVE NORTH-CENTRAL TO
NORTHEASTERN U.S. CLIPPER SYSTEMS) AT THE START OF THE MEDIUM
RANGE PERIOD WEDNESDAY WILL TURN INCREASINGLY MORE AMPLIFIED BY
LATE WEEK INTO NEXT WEEKEND. SOUTHERN STREAM TROUGHING OFF THE WEST
COAST SHOULD CLOSE OFF INTO AN UPPER LOW, WHICH BY WEDNESDAY,
SHOULD BE SITUATED OFF THE SOUTHERN CALIFORNIA COAST. THIS SHOULD
PROGRESS EASTWARD AND WEAKEN WITH TIME AS IT MOVES ACROSS THE
SOUTHERN PLAINS AND PHASES WITH ADDITIONAL ENERGY INTO THE WEST BY
FRIDAY. THIS SHOULD HELP DEVELOP A DEEP TROUGH WHICH MOVES FROM THE
WEST TO THE EAST BY THE END OF NEXT WEEKEND. THE PATTERN WILL
ALLOW FOR AN INCREASE IN PRECIPITATION COVERAGE ACROSS THE CENTRAL
TO EASTERN U.S. LATER THIS WEEK, WHILE SHIFTING WELL ABOVE NORMAL
TEMPERATURES FROM THE PLAINS/MISSISSIPPI VALLEY INTO THE EAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THERE IS GENERAL AGREEMENT ON THE LARGE SCALE PATTERN, BUT STILL A
LOT OF UNCERTAINTY IN THE DETAILS IMPACTING SENSIBLE WEATHER AND
FRONTAL TIMINGS AND PLACEMENT. THE SOUTHERN STREAM CLOSED LOW OFF
CALIFORNIA IS SHOWING BETTER AGREEMENT THAN PREVIOUS DAYS, AND
CONTINUE TO FAVOR THE SLIGHTLY SLOWER GFS/ECMWF AND AI GUIDANCE
OVER THE CMC AND UKMET. THE NEW 00Z CMC TONIGHT DID TREND SLOWER
THAN THE 12Z RUN YESTERDAY SO THAT INCREASING CONFIDENCE IN THE
PREFERRED BLEND.
AFTER THIS, MODELS AGREE THAT ADDITIONAL STRONG VORTICITY WILL
DROP INTO THE NORTHWEST MID TO LATE WEEK, WITH A DEEPENING TROUGH
DEVELOPING OVER THE INTERIOR WEST AS IT PHASES WITH THE SOUTHERN
STREAM LOW. THERE REMAINS A TON OF UNCERTAINTY THOUGH WITH
INDIVIDUAL SHORTWAVES/PIECES OF ENERGY WITHIN THE LARGER TROUGH.
THE ESPECIALLY IMPACTS THE RESULTING SURFACE LOW TRACK TIMING FROM
THE CENTRAL U.S. INTO THE GREAT LAKES/NORTHEAST (WITH POSSIBLE
WINTRY PRECIP ON ITS NORTH/WEST SIDE). MODEL RUN TO RUN VARIABILITY
IS HIGH WITH THIS LOW SO LOW CONFIDENCE FORECAST RIGHT NOW ON ITS
PLACEMENT AND STRENGTH. THIS MAY BE RELATED TO ADDITIONAL UPSTREAM
ENERGY INTO THE TROUGH NEXT FRIDAY. THE ECMWF HAD BEEN AN OUTLIER
WITH BRINGING THIS INTO THE NORTHWEST RATHER THAN THE NORTHERN
PLAINS, BUT THE NEW 00Z RUN DID TREND MORE IN LINE. EITHER WAY,
THIS REINFORCES TROUGHING ACROSS THE EAST-CENTRAL U.S. NEXT
WEEKEND, WITH TIMING STILL A CONCERN. WPC LEANED MORE HEAVILY ON
THE ENSEMBLE MEANS FOR THE LATE PERIOD FORECAST, WITH SOME
DETERMINISTIC GFS WHICH WAS THE CLOSEST TO THE ENSEMBLE MEANS.
..WEATHER/HAZARDS HIGHLIGHTS
A CLIPPER SYSTEM MOVING INTO THE NORTHEAST ON WEDNESDAY WILL
SPREAD SOME PRECIPITATION THERE, INCLUDING POSSIBLE LIGHT FREEZING
RAIN AND LIGHT TO MODERATE SNOW IN SOME AREAS. MEANWHILE, THE
CLOSED LOW INITIALLY OFF SOUTHERN CALIFORNIA SHOULD SPREAD SOME
PRECIP ACROSS THE SOUTHWEST, BUT HEAVY RAINFALL IS NOT ANTICIPATED.
PRECIPITATION (RAIN AND MOUNTAIN SNOW) WILL BE SPREAD ACROSS MUCH
OF THE WEST AS THE FIRST SURGE OF ENERGY MOVES INTO THE REGION MID-
WEEK. SOME HEAVY SNOW IS POSSIBLE FOR PARTS OF THE CASCADES OR
NORTHERN ROCKIES.
AS THE SHORTWAVE AND THE LARGER SCALE TROUGH OVER THE WEST PHASE
LATE WEDNESDAY INTO THURSDAY, THE COMBINED TROUGH SHOULD TAP INTO
GULF MOISTURE, LEADING TO RAIN CHANCES EXPANDING ACROSS THE SOUTH-
CENTRAL PLAINS AND MISSISSIPPI VALLEY WEDNESDAY NIGHT AND PRESSING
EAST INTO THE MIDWEST AND OHIO/TENNESSEE VALLEYS THURSDAY- FRIDAY
AND EVENTUALLY THE EAST FRIDAY-SATURDAY. FOR THURSDAY, MOISTURE
ANOMALIES AND SOME INSTABILITY, WITH SUPPORT FROM MODEL QPFS, DO
SUPPORT A MARGINAL RISK IN THE THURSDAY ERO, BUT DRY ANTECEDENT
CONDITIONS MAY LIMIT THE OVERALL THREAT. WINTRY PRECIPITATION
REMAINS POSSIBLE ON THE WESTERN AND NORTHERN SIDES OF THE
PRECIPITATION SHIELD IN THE NORTHERN/CENTRAL PLAINS TO MIDWEST, BUT
THIS WILL BE HIGHLY DEPENDING ON THE UNCERTAIN TRACK AND TIMING OF
THE SURFACE LOW PRESSURE SYSTEM.
TEMPERATURES ARE LIKELY TO BE WELL ABOVE AVERAGE ACROSS THE
ENTIRETY OF THE COUNTRY EAST OF THE ROCKIES BY MIDWEEK. TEMPERATURE
ANOMALIES OF 15 TO 30 DEGREES ABOVE AVERAGE WILL BE WIDESPREAD
ACROSS THE CENTRAL U.S. BY WEDNESDAY AND SOME DAILY RECORDS FOR
WARM LOWS AND HIGHS COULD BE SET. UNSEASONABLY WARM TEMPERATURES
WILL GRADUALLY EXPAND AND SPREAD EASTWARD LATER IN THE WEEK WITH
SOME MODERATION FROM THE MIDWEST INTO THE EAST. MEANWHILE THE
WEST/SOUTHWEST SHOULD BE NEARER TO NORMAL OR SLIGHTLY BELOW AS THE
PATTERN TURNS MORE AMPLIFIED AND TROUGHING DEVELOPS, AND
TEMPERATURES ARE LIKELY TO MODERATE BACK TO NORMAL INTO THE PLAINS
AND MISSISSIPPI VALLEY BY SATURDAY.
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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