673
FXUS61 KGYX 291907
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
207 PM EST SAT NOV 29 2025
SYNOPSIS
SNOWSTORM OVER THE MID MISSISSIPPI VALLEY TODAY WILL CONTINUE TO
TRACK THROUGH THE GREAT LAKES AND INTO CANADA BY SUNDAY. THIS
WILL BRING A POTENTIAL FOR SNOW SHOWERS ACROSS MOST OF THE AREA
ESPECIALLY LATER IN THE DAY, WITH MOUNTAIN SNOW SHOWERS
CONTINUING INTO EARLY MONDAY. WE ONLY GET A BRIEF BREAK FROM
WINTER WEATHER HOWEVER AS THE NEXT STORM WILL QUICKLY ARRIVE
TUESDAY. THIS LOOKS LIKE THE FIRST WIDESPREAD SNOWFALL FOR AREAS
SOUTH OF THE MOUNTAINS. IT IS TIME TO GET THOSE PLOWS, SNOW
THROWERS, AND SHOVELS READY. ONCE THAT STORM EXITS THE REGION
WEDNESDAY, THE REST OF THE WEEK WILL BE COOL AND BREEZY WITH
MOUNTAIN SNOW SHOWERS LINGERING.
NEAR TERM /THROUGH TONIGHT/
NW BREEZE CONTINUES THIS AFTERNOON AS PRESSURE GRADIENT
SLACKENS AND HIGH PRESSURE NUDGES NORTHEAST. THE SAME CAN BE
SAID FOR REMAINING LIGHT SNOW NW OF THE MOUNTAINS AND NEAR THE
US/CAN BORDER. BY THE EVENING, BOTH SHOULD SUBSIDE.
HIGH PRESSURE WILL QUICKLY CROSS OVERNIGHT WITH INCREASING
CIRRUS. IT WILL TAKE MOST OF THE NIGHT FOR THIS TO THICKEN AND
LOWER. DEPENDING ON WHEN WINDS LIGHTEN AND DAYTIME CLOUDS
DISSIPATE LATE THIS AFTERNOON, TEMPS THIS EVENING WILL EASILY
COOL ALONG THE COAST AND INTERIOR. OVERNIGHT LOWS MAY BE
REALIZED SHORTLY AFTER MIDNIGHT WHILE CIRRUS OVERTAKES THE
FORECAST AREA.
SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/
LOW PRESSURE OVER THE GREAT LAKES SUNDAY MORNING WILL ACCELERATE
NE THROUGH ONTARIO AND QUEBEC. ONSHORE FLOW, CHANNELED BEHIND
THE EXITING HIGH PRES AND INCOMING LOW WILL BRING WARM, MOIST
AIR INLAND AS THE DAY PROGRESSES. WHILE COLD AHEAD OF THIS
SYSTEM, WINDS WON'T BE CONDUCIVE FOR CAD, BRINGING 40S ACROSS
THE INTERIOR INTO THE AFTERNOON AND EVENING.
THAT SAID, SNOW SHOULD BE THE SUPPORTED PRECIP TYPE ACROSS THE
FORECAST AREA THROUGH THE MORNING. MOISTURE PROFILES SUPPORT
SPOTS OF LIGHT SNOW OR SNOW SHOWERS THROUGH NOON. AFTER, THE
RAIN/SNOW LINE MARCHES INLAND AS PRECIP RATES INCREASE. THE
SYSTEM WILL BE MOVING QUICK ENOUGH TO KEEP ABOVE FREEZING TEMPS
FROM WORKING NW OF THE MOUNTAINS MOST OF THE EVENT, SO ALL SNOW
IS EXPECTED HERE. ACCUMULATIONS OF 1 TO 3 INCHES WILL BE
POSSIBLE, WITH THE GREATER AMTS OUTSIDE OF THE VALLEYS AND AT
ELEVATION. SNOW RATES MAY BE IMPRESSIVE, WITH HEALTHY OMEGA
WITHIN THE SNOW GROWTH REGION. HREF 1HR SNOWFALL HIGHLIGHTS THE
HIGHER TERRAIN WITH LIKELY PROBABILITIES OF AROUND 1 IN/HR. THIS
IS LESS LIKELY IN THE VALLEYS WITH MORE MILD TEMPS AND LOWER
RATIOS.
PRECIP RATES FOR THE CWA PEAK DURING THE MID TO LATE AFTERNOON.
AGAIN, AT THIS TIME, MUCH OF THE POPULATION CORRIDOR WILL BE
RAIN, WITH POINTS NORTH OF THE WHITES SNOW.
STEADY PRECIP PULLS NE AFTER 8PM AS RH ALOFT DRIES AND BRINGS
ABOUT LIGHTER AND SPOTTY PRECIP. W WINDS AGAIN KEEP MTN SNOW
SHOWERS GOING AS CAA BEGINS. OVERNIGHT LOWS QUICKLY RETRACE
COOLER, BACK INTO THE 20S TO AROUND 30.
LONG TERM /MONDAY THROUGH SATURDAY/
KEY MESSAGE: FIRST WIDESPREAD ACCUMULATING SNOWFALL POSSIBLE
FOR THE COAST AND SOUTHERN NH. GENERALLY COOLER THAN NORMAL
TEMPS THRU THE EXTENDED.
IMPACTS: ACCUMULATING SNOWFALL IS BECOMING MORE LIKELY FOR AT
LEAST PARTS OF THE AREA TUE INTO WED. HAZARDOUS TRAVEL
CONDITIONS ARE POSSIBLE...ESPECIALLY FOR THE EVENING COMMUTE
TUE.
FORECAST DETAILS: HIGH PRESSURE WILL BE BUILDING ACROSS THE
REGION MON. THIS WILL BRING A QUICK END TO ANY LINGERING SNOW
SHOWERS IN THE MTNS AS THE RIDGE AXIS CENTERS OVER THE AREA BY
THE EVENING. THAT COULD SET UP A VERY COLD OVERNIGHT INTO TUE
MORNING IF HIGH CLOUDINESS CAN HOLD OFF. WIDESPREAD TEMPS IN THE
TEENS AND SOME SINGLE DIGITS WOULD BE THE RESULT. EVEN IF CLOUD
COVER WERE FASTER THAN MODELED...LOW TEMPS WOULD BE MORE
AFFECTED IN THE NORTHERN VALLEYS WHERE READINGS WOULD BE CLOSER
TO 20.
HOWEVER MOST OF THE ATTENTION IN THIS PERIOD WILL BE ON THE
EVOLUTION OF THE SHORTWAVE TROF DIVING INTO THE PACIFIC
NORTHWEST THIS EVENING. CURRENT MODEL GUIDANCE HAS A FAST MOVING
BUT COLD STORM PASSING SOUTH OF THE FORECAST AREA. AND SO
CONFIDENCE IN OUR FIRST ACCUMULATING SNOWFALL IS STARTING TO
GROW.
THE THERMODYNAMIC EVOLUTION OF THE STORM IS ONE THAT AT THIS
TIME FAVORS A HYBRID BANDING STRUCTURE. THERE ARE ASPECTS OF
BOTH LATERALLY QUASI-STATIONARY BANDING AND PIVOTING BANDING.
THE UPPER LEVEL JET...ADVECTION...AND MID LEVEL STREAMLINES TEND
TO FAVOR THE QUASI-STATIONARY BANDING. WHILE THE Q VECTOR
FORECAST WOULD SUGGEST SOME POTENTIAL FOR A PIVOTING BAND. WITH
A LITTLE MORE SYNOPTIC SUPPORT FOR THE QUASI-STATIONARY
BAND...THAT MAY MEAN A SIGNIFICANT SNOWFALL FOR THIS TIME OF
YEAR UNDER THE BAND BUT A RATHER SHARP CUTOFF TO THE NORTHWEST
OF THAT. NBM POP AND TEMPS LOOK REASONABLE AT THIS TIME...WITH
LIKELY POP ACROSS THE SOUTHERN HALF OF THE FORECAST AREA AND AT
LEAST A HINT THAT THE COAST MAY BE WARM ENOUGH TO FLIP PTYPE TO
RAIN FOR A TIME.
GIVEN HOW FAR IN THE FUTURE THIS EVENT IS THERE ARE NOT NBM
FORECASTS FOR QPF FOR THE ENTIRE EVENT IN THE PUBLIC FORECAST.
HOWEVER THERE ARE SOME POTENTIAL CAUTION FLAGS TO BE AWARE OF AS
WE MOVE CLOSER IN TIME. MEDIAN QPF INTERNALLY CONTINUES TO BE A
FAIR BIT LOWER THAN MEAN...AND SUGGESTS THAT SEVERAL BIG HITS
FROM A FEW ENSEMBLE MEMBERS ARE DRAGGING THE MEAN UP. THAT WILL
PROBABLY NOT BE THE QPF WE WANT TO BASE THE EVENTUAL SNOWFALL
FORECAST OFF OF. THIS IS BACKED UP BY DESI FORECASTS SHOWING A
FAIRLY TYPICAL EFI VALUE...JUST OVER HALF THE ENSEMBLE MEMBERS
HAVING A HIGH THAN NORMAL SNOWFALL FOR THIS TIME OF YEAR...BUT A
SHIFT OF TAILS AROUND 1. THIS IS ANOTHER INDICATOR THAT MOST OF
THE GUIDANCE IS NOT EXTREME...BUT A FEW OF THE HIGHER END
SOLUTIONS ARE. FINALLY PERUSING THE CLUSTER ANALYSIS IN DESI AND
THERE IS A STRONG CONTINGENT OF MEMBERS AT OR BELOW MEAN QPF
ACROSS THE MAJOR ENSEMBLE SUITES. THERE ARE JUST ABOUT A THIRD
OF MEMBERS WETTER THAN MEAN QPF...OWING TO A DEEPER AND SHARPER
TROF AS IT SWINGS THRU THE OHIO VALLEY. SO THAT WILL BE
SOMETHING TO KEEP AN EYE ON LATER SUN.
OTHERWISE THE REGION WILL REMAIN NEAR TO BELOW NORMAL TEMPS AND
EMBEDDED IN THE WESTERLY FLOW. THIS WILL LEAD TO UPSLOPE SNOW
SHOWERS ACTIVITY THRU THE REMAINDER OF THE PERIOD...WITH PASSING
SHORTWAVES INCREASING THE COVERAGE OF SHOWER ACTIVITY.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
SHORT TERM...VFR THIS EVENING AND OVERNIGHT. CIRRUS WILL SLOWLY
THICKEN AND LOWER INTO SUNDAY MORNING. MVFR CEILINGS BECOME MORE
LIKELY BY MID MORNING AS SHSN BEGIN. WARMING TEMPERATURES WILL
BRING RA MIXING TO COAST AND THEN INLAND TOWARDS LEW/AUG/CON/MHT
BY AROUND NOON. PRECIP RATES INCREASE IN THE AFTERNOON, WITH IFR
CEILINGS SPREADING INLAND. EXPECT LOWERED VIS WHERE SNOW RATES
INCREASE, MOST CONSISTENT IN THE MOUNTAINS. PASSING FRONTAL
FEATURE IN THE AFTERNOON WILL LOWER COASTAL SITES TO IFR BEFORE
BEGINNING AN IMPROVING TREND AFTER 00Z, GRADUALLY TO VFR BY 12Z
MON.
LONG TERM...VFR CONDITIONS THRU TUE MORNING WILL GIVE WAY
QUICKLY TO AREAS OF IFR IN SNOWFALL AND MAYBE LOW CIGS IN RAIN
NEAR THE IMMEDIATE COASTLINE. THERE ARE SOME QUESTIONS ABOUT HOW
FAR INLAND SNOWFALL WILL MAKE IT AND THUS HOW FAR IFR
CONDITIONS EXTEND...SO THIS PLACES THE LOWEST CONFIDENCE AT TAF
SITES LIKE LEB AND HIE. ONCE NORTHWEST WINDS ARRIVE LATE TUE
INTO WED...VFR CONDITIONS RETURN TO THE COAST AND SOUTHERN NH
BUT MVFR CIGS WILL DEVELOP IN THE MTNS. LEB AND HIE WILL SEE
THOSE THRU WED...BUT PERIODS OF MVFR ARE POSSIBLE INTO FRI AS
WELL AS UPSLOPE SNOW SHOWERS ACTIVITY WAXES AND WANES.
MARINE
SHORT TERM...GUSTY WINDS CONTINUE THIS AFTERNOON, BUT SUBSIDE
THIS EVENING. NEXT SYSTEM ON SUNDAY WILL BRING A PERIOD OF GALES
TO MOST OF THE COASTAL WATERS. PEAK GUSTS MAY BE SHORT LIVED
WITH A PASSING COLD FRONT, BUT LOW LEVEL JET SUPPORTS GALES
OVERNIGHT AND INTO EARLY MON MORNING. EXPECT A W WIND SHIFT
SUNDAY EVENING WITH THIS FRONT, BECOMING NW MONDAY MORNING. WITH
THE ADDED WIND, WAVE HEIGHTS INCREASE QUICKLY SUNDAY AFTERNOON,
BUILDING 8 TO 10 FT TOWARDS THE MIDCOAST COASTAL WATERS.
LONG TERM...GUSTY WINDS WILL DIMINISH RATHER QUICKLY AS HIGH
PRESSURE BUILDS INTO THE AREA. NORTHEAST WINDS WILL INCREASE ON
TUE AS THE NEXT STORM PASSES OUTSIDE OF THE GULF OF MAINE...BUT
AS IT DEPARTS INTO THE NORTHWEST ATLANTIC NORTHWEST WINDS WILL
INCREASE AND GALE FORCE GUSTS ARE POSSIBLE OUTSIDE OF THE BAYS
ON WED. GUSTY WINDS WILL GENERALLY LINGER THRU THE REST OF THE
WORK WEEK AND AT LEAST SCA CONDITIONS ARE ANTICIPATED FOR MOST
OF THAT TIME.
GYX WATCHES/WARNINGS/ADVISORIES
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR
ANZ150>154.
GALE WARNING FROM 4 PM SUNDAY TO 10 AM EST MONDAY FOR ANZ150-
152.
GALE WARNING FROM 4 PM TO 10 PM EST SUNDAY FOR ANZ151.
NEAR TERM...CORNWELL
SHORT TERM...CORNWELL
LONG TERM...LEGRO
AVIATION...CORNWELL/LEGRO
MARINE...CORNWELL/LEGRO
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