671
FXUS02 KWNH 270802
PREEPD
PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
301 AM EST THU NOV 27 2025
VALID 12Z SUN NOV 30 2025 - 12Z THU DEC 04 2025
...IMPACTFUL WINTER STORM EXPECTED FROM THE MIDWEST TO THE GREAT
LAKES THIS WEEKEND WITH DISRUPTIONS TO TRAVEL LIKELY...
...ANOTHER QUICK-MOVING SYSTEM APPEARS TO BRING WIDESPREAD ENHANCED
RAINFALL EARLY TO MIDWEEK ACROSS THE SOUTH AND SOUTHEAST WITH
UNCERTAIN NORTHERN EXTENT OF THE WINTER WEATHER POTENTIALS...
..OVERVIEW WITH GUIDANCE/PREDICTABILITY ASSESSMENT
MUCH OF THE CONCERN DURING THE MEDIUM-RANGE PERIOD HAS TO DO WITH
THE TWO LOW PRESSURE SYSTEMS AS HIGHLIGHTED IN THE HEADLINES
ABOVE. THE FIRST SYSTEM OF CONCERN WILL BE ON THE TIMING OF A
DEVELOPING CYCLONE WITH LIKELY SNOW IMPACTS ACROSS THE GREAT LAKES
THIS HOLIDAY WEEKEND. THE ECMWF REMAINS THE SLOWEST GUIDANCE OF
TRACKING THIS SYSTEM ACROSS THE GREAT LAKES ON SUNDAY. THE EC-
AIFS, EC MEAN BOTH SUPPORT A SLIGHTLY FASTER FORWARD MOTION OF THIS
SYSTEM IN AGREEMENT WITH THE GFS, GEFS AND CMC. THE SLOW ECMWF
SOLUTION IS CONSIDERED AN OUTLIER AT THIS POINT.
MEANWHILE, ANOTHER TROUGH UPSTREAM DIVES SOUTHEAST THROUGH THE
WEST THIS WEEKEND THEN TURNS EASTWARD EARLY NEXT WEEK, TRIGGERING
THE DEVELOPMENT OF A WAVE OF LOW PRESSURE NEAR THE TAIL END OF THE
PREVIOUS FRONT NEAR THE GULF COAST EARLY NEXT WEEK. MODELS HAVE
GENERALLY TRENDED TOWARD A MORE INLAND TRACK ACROSS THE SOUTHEAST
THEREAFTER. THE GFS AND CMC ARE THE MOST AGGRESSIVE IN THIS
RESPECT. THE ECMWF HAS FOLLOWED SUIT TO SOME EXTENT TODAY BUT NOT
QUITE AS AGGRESSIVE AS THE GFS AND CMC. THE WPC MEDIUM-RANGE
FORECASTS REFLECT THIS GENERAL MODEL TREND. THEY ARE BASED ON A
GENERAL CONSENSUS OF 40% FROM THE 12Z ECMWF/EC MEAN, 40% FROM THE
12/18Z GFS/GEFS, AND 20% FROM THE 00Z CMC/CMC MEAN. THIS BLEND
YIELDED A SOLUTION RATHER COMPATIBLE WITH THE PREVIOUS WPC
FORECASTS.
..WEATHER/HAZARDS HIGHLIGHTS
THE MAIN WEATHER HEADLINES DURING THE MEDIUM RANGE PERIOD WILL
LIKELY COME FROM TWO LOW PRESSURE SYSTEMS. A DEEPENING LOW PRESSURE
SYSTEM WILL LIKELY TRACK ACROSS THE GREAT LAKES ON SUNDAY. MODERATE
TO HEAVY NEW SNOW TOTALS OF A FOOT IS POSSIBLE. THIS IS LIKELY TO
IMPACT THANKSGIVING WEEKEND TRAVEL, SO SEE WPC'S KEY MESSAGES FOR
FURTHER INFORMATION. SNOW IS FORECAST TO SPREAD INTO THE INTERIOR
NORTHEAST BY SUNDAY, BUT WILL GENERALLY RESULT IN LESS SNOW AS THE
LOW TRACK MOVES QUICKLY ACROSS SOUTHEASTERN CANADA.
AN AREA OF SNOW ASSOCIATED WITH THE NEXT SHORTWAVE DIGGING ACROSS
THE WESTERN U.S. SHOULD BE REACHING THE GREAT BASIN ON SUNDAY
FOLLOWED BY THE CENTRAL ROCKIES ON MONDAY. HOW MUCH THIS SHORTWAVE
INTERACTS WITH THE TAIL END OF THE PREVIOUS FRONT EXTENDING
NEAR/ALONG THE GULF COAST COULD DETERMINE HOW FAR NORTH A LOW
PRESSURE WAVE WILL EVENTUALLY TRACK AND HOW MUCH GULF MOISTURE WILL
BE DRAWN INTO THE EASTERN U.S. THROUGH MIDWEEK NEXT WEEK. IT
APPEARS THAT THE CENTRAL GULF COAST REGION WILL BE THE PRIME
LOCATION OF SEEING HEAVY RAIN FROM THIS DEVELOPING SYSTEM, ALTHOUGH
THE SPEED OF MOTION OF THIS SYSTEM WILL PROBABLY LIMIT THE TOTAL
RAINFALL AMOUNTS. WITH THESE IN MIND, A MARGINAL RISK OF HEAVY
RAIN HAS BEEN INTRODUCED FROM THE CENTRAL GULF COAST INTO PORTIONS
OF THE DEEP SOUTH FOR DAY 5. MEANWHILE, THE NORTHERN EXTENT OF THIS
DEVELOPING SYSTEM WILL LIKELY HAVE WINTRY WEATHER CONCERNS BUT
UNCERTAINTIES REMAIN TOO HIGH TO BE MORE SPECIFIC ON THE DETAILS
THUS FAR. A MORE INLAND/NORTHERN TRACK WOULD BRING WINTRY
PRECIPITATION FARTHER NORTH TO PERHAPS NEW ENGLAND. THE NEW 00Z
ECMWF APPEARS TO SUPPORT THIS SCENARIO.
FOLLOWING A ROUND OF SNOW THIS WEEKEND FROM THE GREAT BASIN TO THE
CENTRAL ROCKIES, ADDITIONAL ENERGY MOVING ACROSS THE NORTHWEST
SHOULD SUPPORT LOWER ELEVATION RAIN AND HIGHER ELEVATION SNOW IN
THE PACIFIC NORTHWEST TO INTERMOUNTAIN WEST AND ROCKIES BY TUESDAY-
WEDNESDAY.
WIDESPREAD AND PERSISTENT BELOW AVERAGE TEMPERATURES FOR THIS TIME
OF YEAR CAN BE EXPECTED FOR THE CENTRAL U.S. IN PARTICULAR THROUGH
MOST OF THE FORECAST PERIOD AS ARCTIC AIR SPILLS SOUTH. THE
COLDEST ANOMALIES FOR BOTH HIGHS AND LOWS (AROUND 15-25 DEGREES
BELOW NORMAL) ARE FORECAST OVER THE NORTHERN HIGH PLAINS SATURDAY,
SPREADING ACROSS THE REST OF THE PLAINS AND MISSISSIPPI VALLEY
SUNDAY, AND INTO THE MIDWEST MONDAY- TUESDAY GIVEN THE SNOW COVER
THERE. LOWS ARE LIKELY TO BE BELOW 0F IN THE NORTHERN PLAINS TO
MINNESOTA SUNDAY-MONDAY, WITH HIGHS IN THE TEENS. ROUNDS OF COOLER
THAN AVERAGE TEMPERATURES ARE LIKELY IN THE EAST AS WELL, BUT WITH
ANOMALIES CLOSER TO 5-15 DEGREES BELOW NORMAL, ASIDE FROM FLORIDA
THAT SHOULD BE WARMER THAN AVERAGE BY A FEW DEGREES. THE ROCKIES
WESTWARD SHOULD BE NEAR NORMAL TO A BIT ABOVE FOR MOST OF THE
PERIOD.
KONG/TATE
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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