698
FXUS02 KWBC 261908
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
208 PM EST FRI DEC 26 2025
VALID 12Z MON DEC 29 2025 - 12Z FRI JAN 02 2026
..OVERVIEW
A BROAD UPPER RIDGE/TROUGH PATTERN ACROSS THE LOWER 48 TO START NEXT
WEEK WILL TRANSITION TO A MORE TYPICAL WAVELENGTH TROUGH/RIDGE/TROUGH
PATTERN. WITH THE PACIFIC LARGELY BLOCKED FROM INCOMING MOISTURE,
MOST OF THE CONUS WILL BE DRY EXCEPT FOR DOWNWIND OF THE GREAT
LAKES DUE TO LAKE-EFFECT SNOW. BY THE END OF THE PERIOD, THE STRONG
UPPER RIDGING INITIALLY OVER THE WEST COAST WILL BREAK DOWN AND
ALLOW BOTH NORTHERN STREAM AND SUBTROPICAL TROUGHING TO PUSH
INLAND, BRINGING ANOTHER ROUND OF RAIN AND MOUNTAIN SNOW TO MUCH OF
THE WEST BY THE END OF NEXT WEEK (BUT WITH MUCH LESS INTENSITY
THAN THE CURRENT EVENT).
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE APPEARS TO CAPTURE THE OVERALL EVOLUTION OF THE SYNOPTIC
PATTERN OVER THE CONUS REASONABLY WELL. A GENERAL MODEL BLEND
CONSISTING OF THE AVAILABLE DETERMINISTIC GUIDANCE WAS SUFFICIENT
THROUGH DAY 4. DETERMINISTIC 06Z GFS AND 00Z CMC WERE BLENDED
WITH THE ECE/GEFS MEANS ON DAY 5 TO RETAIN SOME DETAIL/SEPARATION OF
THE TWO CLOSED CIRCULATIONS OVER ONTARIO/QUEBEC. THE ENSEMBLE
MEANS WERE FAVORED BEYOND DAY 5 DUE TO A MORE SIMPLIFIED PATTERN
WITH DIFFLUENCE/TROUGHING IN THE WEST, RIDGING OVER THE CENTRAL
U.S., AND MEAN TROUGHING OVER THE EAST.
..WEATHER/HAZARDS HIGHLIGHTS
A VIGOROUS SYSTEM WILL KICK OFF THE PERIOD ON MONDAY THROUGH THE
GREAT LAKES AS IT RAPIDLY DEEPENS INTO SOUTHEASTERN ONTARIO/WESTERN
QUEBEC. THIS WILL BRING A WINTRY MIX OF SNOW/SLEET/FREEZING RAIN
TO THE NORTHEAST AS WARM AIR OVERRIDES THE COLD SURFACE AND LAKE
ENHANCED/EFFECT SNOW OVER THE GREAT LAKES AS THE LOW GENERATES
NORTHERLY TO NORTHWESTERLY FLOW. THE PATTERN WILL TURN QUIET
MIDWEEK WITH HIGH PRESSURE IN CONTROL, BUT CONTINUED CHANCE OF
LAKE EFFECT SNOW THAT WILL BE ENHANCED BY QUICK CLIPPER SYSTEMS
AND/OR MID-LEVEL TROUGHS. BY THU/FRI, THE WEST WILL SEE AN INCREASE
IN PRECIPITATION AS A FRONT FROM THE PACIFIC COMES INTO THE PACNW
AND A WEAKENING OCCLUDED SYSTEM OUT OF THE SUBTROPICAL PACIFIC
MOVES INTO CALIFORNIA AND THE SOUTHWEST. THE MOISTURE ANOMALIES
WILL INCREASE, ACTUAL RAINFALL AMOUNTS APPEAR TO BE MODEST AT THIS
TIME. HOWEVER, GIVEN THE RECENT VERY HEAVY RAINFALL OVER MUCH OF
CALIFORNIA, THIS SYSTEM BEARS WATCHING.
TEMPERATURES WILL BE SOMEWHAT VARIABLE OVER THE LOWER 48, BUT
GENERALLY COLDER THAN NORMAL AROUND THE GREAT LAKES INTO THE
NORTHEAST DUE TO THE PERSISTENT TROUGHING AND MILDER THAN NORMAL
OVER THE INTERIOR WEST/ROCKIES. WIDESPREAD RECORD COLD OR WARM
TEMPERATURES ARE NOT EXPECTED.
KEBEDE/FRACASSO
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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