843
FXUS02 KWBC 181829
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
129 PM EST SUN JAN 18 2026
VALID 12Z WED JAN 21 2026 - 12Z SUN JAN 25 2026
...PERSISTENT UPPER LEVEL TROUGHING WILL KEEP FRIGID TEMPERATURES
IN PLACE FOR THE NORTH-CENTRAL U.S. THROUGH NEXT WEEKEND...
19Z UPDATE: THE 12Z MODEL GUIDANCE SUITE FEATURES GOOD OVERALL
SYNOPTIC SCALE AGREEMENT THROUGH THURSDAY ACROSS THE CONTINENTAL
U.S., WITH A GENERAL MODEL BLEND USED FOR FRONTS AND PRESSURES
THROUGH THAT TIME. THE 12Z GFS STARTS DIVERGING FROM THE CONSENSUS
BY FRIDAY AND INTO THE WEEKEND WITH THE UPPER LOW FARTHER EAST
NEAR SOUTHERN CALIFORNIA, IN CONTRAST TO THE MORE OFFSHORE 6Z GFS
AND NON-NCEP GUIDANCE. THERE ARE ALSO DIFFERENCES WITH FRONTAL
BOUNDARY LATITUDINAL PLACEMENT ACROSS THE SOUTHERN PLAINS BY
SATURDAY, WITH THE 12Z GFS COMING INTO BETTER ALIGNMENT COMPARED TO
THE MORE NORTHERN 6Z PLACEMENT. MODEL CONFIDENCE AND RUN-TO-RUN
CONTINUITY SUFFERS MORE BY SUNDAY WITH THE EXTENT OF UPPER LEVEL
TROUGHING ACROSS THE MIDWEST/GREAT LAKES/NORTHEAST, WITH AN
ENSEMBLE MEAN APPROACH A SUGGESTED STARTING POINT. IN TERMS OF THE
NBM, THE MAJORITY OF THE DETERMINISTIC GUIDANCE WAS A LITTLE LOWER
WITH TEMPERATURES ACROSS THE CENTRAL AND EASTERN U.S. FOR THE
SECOND HALF OF THE FORECAST PERIOD, SO THE NBM WAS BLENDED WITH
ABOUT HALF OF THE SLIGHTLY COLDER AUTO BLEND, WITH MOST READINGS
ABOUT 1-3 DEGREES LOWER THAN NBM AS A RESULT. THERE WAS A SLIGHT
INCREASE IN QPF FOR LAKE EFFECT SNOWS, AND A MODEST DECREASE FROM
THE WIDESPREAD HEAVIER QPF FROM THE NBM EXTENDING FROM THE ARKLATEX
TO THE MID-ATLANTIC TO BE MORE IN LINE WITH THE DETERMINISTIC
CONSENSUS. THE PREVIOUS FORECAST DISCUSSION IS APPENDED BELOW.
HAMRICK
------------------------
..OVERVIEW
AN AMPLIFIED PATTERN ALOFT WILL BE IN PLACE MIDWEEK, WITH RIDGING
OVER THE WEST COAST AND DEEP TROUGHING OVER THE CENTRAL AND EASTERN
U.S., WITH THE LATTER CAUSING BELOW AVERAGE TEMPERATURES. THIS
PATTERN WILL ALSO BE FAVORABLE FOR LAKE EFFECT SNOW THAT COULD
BECOME HEAVY. THE TROUGH MAY BROADEN WESTWARD MID- AND LATE WEEK
WHILE BECOMING SHALLOWER TO THE EAST. GULF MOISTURE IS FORECAST TO
RETURN TO THE SOUTHEASTERN QUADRANT OF THE U.S. WEDNESDAY-THURSDAY.
THEN PRECIPITATION COULD OVERSPREAD MUCH OF THE EASTERN HALF OF
THE U.S. FRIDAY AND INTO NEXT WEEKEND, INCLUDING UNCERTAIN
POTENTIAL FOR ORGANIZED WINTRY PRECIPITATION ACROSS THE MIDDLE
MISSISSIPPI TO OHIO VALLEYS AND POSSIBLY THE NORTHEAST. ALSO FRIDAY
INTO THE WEEKEND, ANOTHER ROUND OF UPPER TROUGHING AND ARCTIC
SURFACE HIGH PRESSURE WILL EXPAND INTO THE NORTH-CENTRAL U.S. AND
BRING BITTERLY COLD TEMPERATURES WELL BELOW 0F TO THE NORTHERN
PLAINS AND UPPER MIDWEST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE IS IN GOOD AGREEMENT FOR THE LARGE AMPLIFIED TROUGH
FOR AREAS EAST OF THE ROCKIES INTO WEDNESDAY, WITH RIDGING ATOP
THE WEST COAST. MODEL CONSENSUS IS INCREASING WITH THE ENERGY
MOVING THROUGH THE BASE OF THE TROUGH ACROSS THE NORTHERN PLAINS
EARLY WEDNESDAY AND THE OHIO VALLEY EARLY THURSDAY, FOR BETTER
AGREEMENT IN FRONTAL TIMING AND PRECIPITATION DISTRIBUTION COMPARED
TO A DAY AGO (THOUGH POSSIBLY MULTIPLE WAVES OF FRONTS MAKE IT
TRICKY). AS THIS ENERGY LIFTS OUT LATE WEEK, THE TROUGH SHOULD
FLATTEN AND LEAD TO MORE ZONAL FLOW ACROSS THE SOUTH. BY SATURDAY
THERE IS SOME MODEL SPREAD WITH THE PRIMARY UPPER LOW EMBEDDED
WITHIN THE NORTHERN STREAM--THE 00Z ECMWF SEEMS ALONE FOR THE
DETERMINISTIC MODELS IN BRINGING IT EAST INTO SOUTHEAST
CANADA/NORTHEASTERN U.S. WHILE OTHER MODELS KEEP IT NEAR JAMES BAY
--BUT THE EC-AIFS IS SIMILAR TO THE ECMWF. THIS WOULD HAVE
IMPLICATIONS ON PRECIPITATION DISTRIBUTION INCLUDING WINTER WEATHER
IN THE OHIO VALLEY TO NORTHEAST LATE WEEK INTO THE WEEKEND FOR
EXAMPLE.
MEANWHILE THERE REMAINS A FAIR AMOUNT OF MODEL SPREAD BY LATER
WEEK WITH NORTHERN STREAM ENERGY DIGGING INTO THE NORTHWEST, PLUS
THE POSSIBILITY OF INTERACTION WITH A SOUTHERN STREAM EASTERN
PACIFIC UPPER LOW. THE PRIMARY OUTLIER WAS THE 12Z GFS, WHICH
SHOWED A FASTER SOUTHERN STREAM LOW TRACK COMBINED WITH STRONGER
NORTHERN STREAM ENERGY FOR PHASING A DEEP TROUGH IN THE WEST OVER
THE WEEKEND, UNLIKE OTHER GUIDANCE AND THE 18Z AND NOW 00Z GFS.
OTHER THAN THAT, IT BECOMES DIFFICULT TO PICK OUT ANY OUTLIERS AS
MULTIPLE SHORTWAVES MAY DEVELOP TROUGHING IN THE WEST, BUT WITH
UNCERTAINTIES IN DEPTH AND TIMING OF THE TROUGH. OVER THE WEEKEND
THE NEW 00Z GFS MOVES TROUGHING FARTHER EAST QUICKLY. IT JIVES
RELATIVELY WELL WITH THE EC-AIFS, WHILE THE AIGFS ON THE OTHER HAND
SHOWS TROUGHING ACROSS THE INTERIOR WEST AND LOOKS MORE LIKE THE
DETERMINISTIC ECMWF, DEMONSTRATING THE SPREAD.
OVERALL, THE WPC FORECAST WAS BASED ON A MULTI-MODEL BLEND EARLY
IN THE PERIOD, WITH INCREASING PROPORTIONS OF ENSEMBLE MEANS AS THE
PERIOD PROGRESSED AND SPREAD INCREASED.
..WEATHER/HAZARDS HIGHLIGHTS
SEVERAL DAYS OF LAKE EFFECT AND UPSLOPE FLOW SNOW ARE IN STORE
WITH THE MEAN WESTERLY WIND PATTERN ACROSS THE NORTHEASTERN
QUADRANT OF THE LOWER 48. A CLIPPER SYSTEM COULD ENHANCE GREAT
LAKES SNOW INTO WEDNESDAY-THURSDAY AND SPREAD LIGHTER SNOW TO THE
NORTHEAST THURSDAY. SNOW IS FORECAST TO BE HEAVIEST IN WESTERN NEW
YORK DOWNWIND OF LAKE ONTARIO FROM THE LAKE EFFECT/ENHANCED SNOW;
AFTER LIKELY HEAVY SNOW AMOUNTS TUESDAY (NOW IN THE SHORT RANGE
PERIOD), SEVERAL MORE INCHES OF SNOW ON WEDNESDAY AND THURSDAY ARE
POSSIBLE, POTENTIALLY PILING UP TO 1-3 FEET.
GULF MOISTURE IS FORECAST TO REACH SOUTHERN TEXAS INTO THE LOWER
MISSISSIPPI VALLEY ON WEDNESDAY AND POOL ALONG A FRONT, PRODUCING
MODERATE TO POSSIBLY HEAVY RAIN. A MARGINAL RISK OF EXCESSIVE
RAINFALL HAS BEEN INTRODUCED FOR PORTIONS OF SOUTHEAST TEXAS INTO
SOUTHWESTERN LOUISIANA ON DAY 4/WEDNESDAY, WHERE RECENT MODEL
GUIDANCE IS DEPICTING THE POTENTIAL FOR SOME 1-2+ INCH RAINFALL
TOTALS, WHICH COULD BE ENOUGH TO CAUSE MAINLY NUISANCE LEVEL URBAN
FLOODING IF THIS HAPPENS IN A SHORTER PERIOD OF TIME. THE
MITIGATING FACTOR WILL BE THE LIMITED INLAND EXTENT OF HIGHER
INSTABILITY, WITH MOST OF IT REMAINING OVER THE COASTAL WATERS.
MODERATE RAIN IS FORECAST TO SPREAD INTO THE ARK- LA- TEX TO LOWER
MISSISSIPPI VALLEY WEDNESDAY AND ACROSS THE GULF COAST INTO FLORIDA
ON THURSDAY, BUT WITH RAIN AMOUNTS WELL BELOW ANY EXCESSIVE
RAINFALL THREAT. THEN FOR FRIDAY, ANOTHER ROUND OF PRECIPITATION IS
FORECAST TO SPREAD ACROSS THE LOWER/MIDDLE MISSISSIPPI VALLEY INTO
THE TENNESSEE AND OHIO VALLEYS AND MOVE EAST INTO NEXT WEEKEND.
NORTHERN AREAS OF THIS PRECIPITATION SHIELD LIKE THE MID-
MISSISSIPPI AND OHIO VALLEYS INTO THE NORTHEAST COULD SEE WINTER
WEATHER AS MOISTURE OVERRUNS INCOMING COLD AIR. SNOW AND/OR ICE ARE
BOTH POSSIBLE, BUT THERE IS AMPLE UNCERTAINTY WITH PRECIPITATION
COVERAGE, TYPES, AND AMOUNTS AT THIS POINT, SO STAY TUNED FOR
FORECAST UPDATES. MEANWHILE, THE PACIFIC NORTHWEST INTO THE
NORTHERN ROCKIES CAN EXPECT INCREASING PRECIPITATION THURSDAY AND
PERSISTING INTO FRIDAY-SATURDAY DUE TO ENERGY ALOFT.
BELOW AVERAGE TEMPERATURES ARE EXPECTED ACROSS THE EASTERN U.S.
WEDNESDAY, PARTICULARLY WITH CHILLY MORNING LOWS. ELSEWHERE
TEMPERATURES SHOULD BE GENERALLY NEAR TO SLIGHTLY ABOVE AVERAGE FOR
MIDWEEK. THEN REPEATED ROUNDS OF REINFORCING TROUGHING ARE
FORECAST ACROSS THE NORTHERN TIER INTO LATE WEEK, WHILE A COLD
SURFACE HIGH SINKS IN FROM CANADA AND PUSHES A STRONG COLD FRONT
SOUTH ACROSS THE PLAINS AND VICINITY. BY FRIDAY, THE NORTHERN
PLAINS TO UPPER MIDWEST SHOULD SEE WELL BELOW AVERAGE TEMPERATURES,
WHERE EVEN HIGHS MAY STAY UNDER 0F. OVER THE WEEKEND, THE COLD IS
FORECAST TO REMAIN ACROSS THE NORTHERN TIER AND SPREAD SOUTH ACROSS
MUCH OF THE CENTRAL U.S. AND EAST INTO THE GREAT LAKES/NORTHEAST.
THERE IS UNCERTAINTY IN HOW FAR SOUTH THE COLD FRONT REACHES AFTER
A WARMER THAN AVERAGE SPELL IN THE SOUTHERN PLAINS FRIDAY AND THE
SOUTHEAST SATURDAY.
TATE/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
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