304
FXUS02 KWBC 050800
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EST MON JAN 5 2026
VALID 12Z THU JAN 08 2026 - 12Z MON JAN 12 2026
..OVERVIEW
THE PATTERN OVER THE CONUS WILL BE INCREASINGLY AMPLIFIED BY THE
START OF THE MEDIUM RANGE PERIOD ON THURSDAY AS A SOUTHERN STREAM
UPPER LOW/SHORTWAVE PHASES WITH STRONG NORTHERN STREAM ENERGY INTO
THE NORTHWEST. THIS WILL DEVELOP A DEEP TROUGH THAT MOVES FROM THE
WEST THURSDAY INTO THE CENTRAL U.S. FRIDAY AND MORE SLOWLY TOWARD
THE EAST NEXT WEEKEND. THE PATTERN WILL ALLOW FOR AN INCREASE IN
PRECIPITATION COVERAGE ACROSS THE CENTRAL TO EASTERN U.S., WITH
WELL ABOVE NORMAL TEMPERATURES AHEAD OF IT FROM THE EAST-CENTRAL
U.S. TO THE EAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THERE REMAIN SOME MINOR TIMING AND DETAIL DIFFERENCES REGARDING
THE PHASING OF THIS SHORTWAVE OVER NORTHERN MEXICO AND THE LARGER
SCALE TROUGH/NORTHERN SCALE ENERGY OVER THE WEST ON THURSDAY, BUT A
MULTI-MODEL BLEND SEEMED TO BE A GOOD STARTING POINT. THIS
PROGRESSES AS AN AMPLIFIED TROUGH THROUGH THE CENTRAL U.S. ON
FRIDAY, AND THE MAIN OUTLIER IS THE UKMET WHICH IS SLOWER AND PULLS
TROUGHING FARTHER WEST (SOMETHING THE ECMWF WAS DOING YESTERDAY).
THERE IS BETTER CONSENSUS FOR A MORE PROGRESSIVE TROUGH, AS SHOWN
BY THE EC, GFS, AND CMC. DIFFERENCES IN THE TIMING OF THIS TROUGH
HOWEVER DO INCREASE BY SUNDAY-MONDAY, SEEMINGLY DUE TO ADDITIONAL
ENERGY THAT DROPS INTO THE TROUGH NEXT WEEKEND. THROUGH THE 12Z
GUIDANCE, THE GFS AND CMC WERE BOTH NOTICEABLY FASTER THAN THE
ECMWF (AND THE AI-GUIDANCE AND ENSEMBLES), EXITING THE EAST COAST
BY MONDAY, WHILE THE ECMWF KEPT IT OVER THE EAST LONGER. HOWEVER,
BOTH THE NEW 00Z CMC AND GFS SLOWED DOWN, WHILE THE ECMWF SPED UP
QUITE A BIT. SO, VERY LOW CONFIDENCE FORECAST AND A LOT OF
VARIABILITY ON THIS WHICH WOULD IMPACT HOW QUICKLY THE FRONT AND
ASSOCIATED PRECIPITATION CLEAR THE COAST. THE 01Z NBM SEEMED TO
SERVE A GOOD STARTING POINT FOR THIS RIGHT NOW AMIDST THE
UNCERTAINTY.
THE WPC FORECAST TONIGHT USED A NON UKMET BLEND FOR DAYS 3 AND 4.
BY DAY 5 AND BEYOND, GRADUALLY INCREASED THE ENSEMBLE MEAN
WEIGHTING TO 70 PERCENT OF THE BLEND TO HELP MITIGATE LATE PERIOD
DIFFERENCES.
..WEATHER/HAZARDS HIGHLIGHTS
PRECIPITATION ACROSS THE WEST WILL BE ONGOING AS THE PERIOD
STARTS, BUT SHOULD WIND DOWN FRIDAY. SOME HEAVY SNOW IS POSSIBLE IN
THE HIGHER TERRAIN.
AS THE SHORTWAVE AND THE LARGER SCALE TROUGH OVER THE WEST PHASE
INTO THURSDAY, THE COMBINED TROUGH SHOULD TAP INTO GULF MOISTURE,
ALLOWING FOR WIDESPREAD PRECIPITATION FROM THE MISSISSIPPI VALLEY
INTO THE OHIO VALLEY. A FAVORABLE UPPER JET, MOISTURE ANOMALIES
OVER THE 90TH PERCENTILE FOR THIS TIME OF THE YEAR, AND SOME
INSTABILITY REACHING AS FAR NORTH AS THE OHIO VALLEY WILL SUPPORT
CONVECTION IN THIS REGION. MODEL 24-HOURLY QPFS SHOW 1-3 INCHES OF
RAIN, WITH LOCALLY HIGHER AMOUNTS, SUPPORTING AT LEAST A MARGINAL
RISK FOR THE THURSDAY/DAY 4 ERO. RAIN RATES WILL NEED TO OVERCOME
THE ANTECEDENT DRY CONDITIONS, WHICH MAY LIMIT THE OVERALL RISK, AT
LEAST INITIALLY. THE SYSTEM WILL TRACK INTO THE TENNESSEE
VALLEY/MID- ATLANTIC/OHIO VALLEY ON FRIDAY, AND ANOTHER MARGINAL
RISK IS PLACED ACROSS THE TENNESSEE VALLEY WHERE MODEL QPFS ARE
HIGHEST RIGHT NOW AND WHERE THE FRONT MAY BE SLIGHTLY SLOWER TO
PROGRESS THROUGH. PRECIPITATION MOVES INTO THE EAST BY SATURDAY,
LIKELY CLEARING THE COAST IN TIME FOR SUNDAY. MUCH OF THE COUNTRY
LOOKS DRY BY SUNDAY, WITH THE EXCEPTION OF MAYBE FLORIDA AND LAKE
EFFECT SNOWS ACROSS THE GREAT LAKES.
ON THE BACKSIDE OF THIS SYSTEM, WINTRY PRECIPITATION REMAINS
POSSIBLE. WHILE THE DETAILS ARE STILL UNCERTAIN DEPENDING ON THE
TRACK AND TIMING OF THE SURFACE LOW PRESSURE SYSTEM, ACCUMULATING
SNOW CHANCES ARE INCREASING ACROSS PORTIONS OF THE NORTHERN/CENTRAL
PLAINS INTO THE MIDWEST THURSDAY NIGHT INTO FRIDAY AND FOR THE
UPPER GREAT LAKES REGION FRIDAY INTO SATURDAY. IT IS NOT LOOKING
LIKE A PARTICULARLY HAZARDOUS EVENT AT THIS TIME, BUT AT LEAST A
FEW INCHES OF SNOW IS POSSIBLE.
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 25 DEGREES ABOVE AVERAGE WILL BE WIDESPREAD
FROM THE CENTRAL U.S. TO THE EAST THURSDAY AND FRIDAY. DAILY
RECORDS FOR WARM LOWS AND HIGHS COULD BE SET ACROSS THE SOUTHERN
TIER. 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 AND THE EAST
NEXT SUNDAY BEHIND A POTENT COLD FRONT JUST AHEAD OF THE UPPER
TROUGH. A BUILDING RIDGE BEHIND THIS MAY BRING ABOVE NORMAL
TEMPERATURES BACK INTO THE NORTH-CENTRAL U.S. BY NEXT MONDAY.
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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