750
FXUS02 KWBC 301916
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
216 PM EST TUE DEC 30 2025
VALID 12Z FRI JAN 02 2026 - 12Z TUE JAN 06 2026
..GENERAL OVERVIEW
BROAD CYCLONIC FLOW ALOFT WILL BE IN PLACE ACROSS THE EASTERN HALF
OF THE COUNTRY FOR THE END OF THIS WEEK, WITH A DEEP LOW PRESSURE
SYSTEM CENTERED OVER HUDSON BAY AND ANOTHER OVER NEWFOUNDLAND. THIS
WILL HELP TO KEEP THE LAKE EFFECT SNOW MACHINE GOING DOWNWIND OF
THE GREAT LAKES ON FRIDAY BEFORE GRADUALLY DIMINISHING THROUGH THE
WEEKEND. MEANWHILE, AN UPPER-LEVEL RIDGE WILL INITIALLY BE IN
PLACE ACROSS THE INTERMOUNTAIN WEST, AND THEN REACH THE PLAINS OVER
THE WEEKEND. AN UNSETTLED WEATHER PATTERN EVOLVES ACROSS THE WEST
COAST BY THE END OF THE WEEK, WITH A WELL ORGANIZED STORM SYSTEM
REACHING CENTRAL AND NORTHERN CALIFORNIA INTO OREGON FRIDAY INTO
EARLY SATURDAY. ACROSS THE SOUTHERN TIER STATES, A WAVE OF LOW
PRESSURE DEVELOPS ALONG A FRONTAL BOUNDARY AND BRINGS HIGHER
RAINFALL CHANCES FROM THE DEEP SOUTH TO THE SOUTHEAST COAST FRIDAY
INTO SATURDAY. ANOTHER CLIPPER SYSTEM IS LIKELY TO CROSS THE UPPER
MIDWEST AND GREAT LAKES LATE THIS WEEKEND INTO EARLY NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE HAS REMAINED IN GOOD AGREEMENT WITH THE GENERAL
SYNOPTIC PATTERN ACROSS THE CONTINENTAL U.S. THROUGH THE END OF THE
WEEK AND INTO THE FIRST HALF OF THE WEEKEND, FEATURING BROAD MID
AND UPPER-LEVEL TROUGHING ACROSS THE CENTRAL TO EASTERN U.S. AND A
MID/UPPER-LEVEL RIDGE OVER THE WESTERN U.S. THE LATEST GUIDANCE
ALSO CONTINUES TO COME INTO BETTER AGREEMENT REGARDING A MID/UPPER
LEVEL SHORTWAVE INTERACTING WITH A LINGERING FRONTAL BOUNDARY FROM
THE SOUTH-CENTRAL TO SOUTHEASTERN U.S. GUIDANCE DOES WELL IN
DEPICTING A DEVELOPING SURFACE LOW OVER THE DEEP SOUTH ON FRIDAY
BEFORE TRACKING EASTWARD THROUGH THE SOUTHEAST AND OFF THE ATLANTIC
COAST FRIDAY INTO SATURDAY.
UNCERTAINTY INCREASES ACROSS THE WESTERN U.S. AS SEVERAL
SHORTWAVES GRADUALLY FLATTEN THE FLOW ALONG THE WEST COAST AND
DISPLACE THE RIDGE OVER THE INTERMOUNTAIN WEST EASTWARD INTO THE
PLAINS. A BLEND OF DETERMINISTIC AND ENSEMBLE GUIDANCE WAS UTILIZED
TO CREATE THE LATEST WPC FORECAST, WITH INCREASING WEIGHT PLACED
ON THE EC AND GEFS ENSEMBLE MEANS FOR DAY 5 AND BEYOND. THIS
MAINTAINED A GOOD BIT OF CONTINUITY AND STABILITY WHILE WAITING FOR
THE FINER SCALE DETAILS TO GET IRONED OUT WITH FUTURE CYCLES.
FINALLY, MUCH OF THE GUIDANCE IS SUGGESTIVE OF ANOTHER CLIPPER
SYSTEM DROPPING SOUTHEASTWARD ACROSS THE UPPER MIDWEST, GREAT
LAKES, AND THE NORTHEAST SUNDAY INTO MONDAY. THE BLEND OF THE
DETERMINISTIC GFS/ECMWF AND ENSEMBLE MEANS REPRESENTED TIMING
DIFFERENCES WELL AND THE WPC QPF FORECAST WAS ONCE AGAIN INCREASED
ACROSS THIS REGION AS THE NBM REMAINED RATHER DRY.
..WEATHER/HAZARDS HIGHLIGHTS
A MORE ACTIVE WEATHER PATTERN DEVELOPS ALONG THE WEST COAST BY
FRIDAY AS A ORGANIZED LOW PRESSURE SYSTEM LIFTS NORTHWARD WITH A
COLD FRONT REACHING THE CALIFORNIA COAST. AN ATMOSPHERIC RIVER WILL
LIKELY AFFECT THE NORTHERN CALIFORNIA COAST AND MOVE INLAND
THROUGH SATURDAY AFTERNOON, BRINGING THE POTENTIAL FOR 2 TO 4
INCHES OF RAINFALL FOR THE LOWER ELEVATIONS, WITH A SECONDARY
MAXIMA FOR THE EASTERN FOOTHILLS OF THE NORTHERN SIERRA NEVADA. A
MARGINAL RISK AREA WILL BE VALID HERE FOR BOTH FRIDAY AND SATURDAY,
WITH POSSIBLE FUTURE UPGRADES TO SLIGHT RISK IN LATER OUTLOOKS IF
TRENDS CONTINUE HEAVIER IN FUTURE MODEL CYCLES.
ELSEWHERE ACROSS THE COUNTRY, AN AREA OF LOW PRESSURE IS EXPECTED
TO DEVELOP ACROSS THE DEEP SOUTH ON FRIDAY BEFORE EXITING THE
SOUTHEAST COAST ON SATURDAY. THIS QUICK-MOVING SYSTEM WILL PRODUCE
A CORRIDOR OF MODERATE RAINFALL AND SOME THUNDERSTORMS FROM
MISSISSIPPI EASTWARD TO THE CAROLINAS. ANOTHER CLIPPER TYPE SYSTEM
IS LIKELY TO TRACK FROM THE UPPER MIDWEST, TO THE GREAT LAKES, TO
THE INTERIOR NORTHEAST, AND ACROSS NEW ENGLAND SUNDAY INTO MONDAY.
THIS WEAKLY ORGANIZED SYSTEM IS EXPECTED TO PRODUCE A SWATH OF
MAINLY LIGHT SNOW AND PERHAPS SOME MIXED WINTRY PRECIPITATION ALONG
THE SOUTHERN PORTION OF THE TRACK; HOWEVER, IT IS NOT CURRENTLY
EXPECTED TO BE AN IMPACTFUL SYSTEM. IN THE WAKE OF THE CLIPPER,
SOME MINOR LAKE EFFECT AND UPSLOPE SNOWFALL IS LIKELY DOWNWIND OF
THE GREAT LAKES AND ACROSS PORTIONS OF THE CENTRAL APPALACHIANS ON
TUESDAY.
IN TERMS OF TEMPERATURES, THERE WILL LIKELY BE A LITTLE BIT OF AN
ABATEMENT OF THE COLD TEMPERATURES ACROSS THE NORTHERN TIER STATES
AS THE UPPER TROUGH FLATTENS SOME AND THE AIRMASS MODIFIES, WITH
READINGS SLIGHTLY BELOW NORMAL AND THE GREATEST ANOMALIES LIKELY
OVER NORTHERN NEW ENGLAND. ABOVE AVERAGE TEMPERATURES ARE EXPECTED
TO ENCOMPASS A LARGE PORTION OF THE U.S. FROM THE INTERMOUNTAIN
WEST TO THE PLAINS AND DEEP SOUTH, AND CLOSER TO AVERAGE FROM THE
OHIO VALLEY TO THE MID-ATLANTIC REGION.
MILLER/HAMRICK
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page