335
FXUS02 KWBC 240807
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
307 AM EST WED DEC 24 2025
VALID 12Z SAT DEC 27 2025 - 12Z WED DEC 31 2025
..OVERVIEW
LEADING AND INITALLY AMPLIFIED UPPER RIDGING WILL SHIFT THROUGH
THE EAST-CENTRAL U.S. INTO THE WEEKEND, AS SPLIT UPPER TROUGHING
SHIFTS INLAND OVER THE WEST TO BRING AN END TO A VERY WET PERIOD,
ESPECIALLY IMPACTING CALIFORNIA. ACROSS THE CENTRAL TO EAST-CENTRAL
U.S., EXPECT UNSEASONABLE WARMTH WITH RECORD TEMPERATURES INTO THE
WEEKEND BEFORE STARK FRONTAL PASSAGE. THE COLDER NORTHERN TIER
WILL HAVE SEVERAL PLOWABLE SNOW CHANCES FROM THE GREAT LAKES TO THE
NORTHERN MID-ATLANTIC/NORTHEAST WITH ADVENT OF NORTHERN STREAM
UPPER TROUGHING AND WAVY FRONTAL SYSTEMS. EXPECT ENHANCED LAKE
EFFECT SNOWS SUNDAY/MONDAY IN STRONG COLD FLOW IN THE WAKE OF MAIN
LOW PASSAGE.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS AND ENSEMBLE FORECAST SPREAD STILL SEEMS MANAGEABLE THROUGH
MEDIUM RANGE TIME SCALES IN A SPLIT FLOW PATTERN OVER THE LOWER 48
HIGHLIGHTED BY AN ENERGETIC AND STEADILY PROGRESIVE NORTHERN
STREAM AND SEPARATED/SLOWER SOUTHERN STREAM. WHILE PREDICTABILITY
HAS IMPROVED WITH THE EVOLUTION OF THIS PATTERN OVER MUCH OF THE
NEXT WEEK, REMAINING DIFFERENCES CAN BE PARTIALLY MITIGATED AS
CONSISTENT WITH UNCERTAINTY WITH USAGE OF A COMPOSITE BLEND OF BEST
CLUSTERED GUIDANCE OF THE GFS/ECMWF AND GEFS/ECMWF ENSEMBLE MEANS,
ALBEIT WITH GREATER LINGERING UNCERTAINTIES STILL ASSOCIATED
WITH THE HANDLING OF SOUTHERN STREAM UPPER TROUGHING OVER/OFF THE
SOUTHWEST U.S. INTO NEXT WEEK. EVEN SO, THE WPC SOLUTION MAINTAINS
GOOD PRODUCT CONTINUITY IN LINE WITH THE NATIONAL BLEND OF MODELS.
..WEATHER/HAZARDS HIGHLIGHTS
LEADING SHALLOW SHORTWAVES MOVING THROUGH THE NORTHERN TIER AND
ASSOCIATED SURFACE SYSTEM REFLECTION AND POSSIBLE FLOW
AMPLIFICATION WITH THE DIGGING OF NORTHERN STREAM UPPER TROUGHING
INTO THE LOWER 48 WILL BRING SOME PRECIPITATION CHANCES TO THE
GREAT LAKES THROUGH THE NORTH-CENTRAL APPALACHIANS AND NORTHERN
MID-ATLANTIC/NORTHEAST TO INCLUDE CHANCES FOR ENHANCED SNOW/ICE.
TEMPERATURES WILL CONTINUE TO BE ANOMALOUSLY WARM FROM THE CENTRAL
TO EAST-CENTRAL U.S. MID-LOWER LATITUDES INTO SATURDAY. DAYTIME
HIGHS 25-30+ DEGREES ABOVE NORMAL MAY SET DAYTIME AND WARM MORNING
LOW RECORDS. THE AIRMASS MOVES EAST WITH TIME AND MODERATES. THIS
AIRMASS WILL BE IN STARK CONTRAST WITH SUBSEQUENT COLDER FLOW
SET TO DROP ACROSS THE CENTRAL AND EASTERN U.S. WITH NORTHERN
STREAM UPPER TROUGH AMPLIFICATION AND FRONTAL SYSTEM AND DEEPENED
LOW PASSAGE AND LEADING/WRAPPING ORGANIZED PRECIPITATION. OUT
WEST, TEMPERATURES SHOULD MODERATE TOWARDS NORMAL THIS WEEKEND,
WITH ANOTHER WARMUP POSSIBLE EARLY NEXT WEEK WITH UPPER RIDGING.
LATER UPSTREAM, THERE IS SOME GUIDANCE SIGNAL FAVORING RE-EMERGING
HEAVIER PRECIPITATION CHANCES INTO THE PACIFIC NORTHWEST/NORTHWEST
WITH RENEWED/WINDY ONSHORE FLOW IN ABOUT A WEEK LENDING INTO THE
CLIMATE PREDICTION CENTER'S WEEK 2 FORECAST TO RING IN 2026.
SCHICHTEL
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