401
FXUS61 KGYX 202034
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
334 PM EST FRI DEC 20 2024
SYNOPSIS
LOW PRESSURE DEVELOPS OFF THE NEW ENGLAND COASTLINE TONIGHT,
BRINGING A PERIOD OF LIGHT SNOW. VERY COLD AIR MOVES INTO NEW
ENGLAND SATURDAY NIGHT AND SUNDAY. AFTER A DRY MONDAY, MORE
LIGHT SNOW WILL ARRIVE MONDAY NIGHT AND TUESDAY FROM A CLIPPER
TYPE SYSTEM. HIGH PRESSURE WILL THEN REBUILD OVER THE REGION
WEDNESDAY AND THURSDAY.
NEAR TERM /THROUGH TONIGHT/
LOW PRESSURE HAS EMERGED OFF THE MID-ATLANTIC COAST AND WILL
LIFT TO THE NORTHEAST AND DEEPEN THROUGH TONIGHT ALONG WITH ITS
ASSOCIATED 500MB SHORTWAVE TROUGH. THIS WILL BRING INCREASING
CHANCES FOR LIGHT SNOW AS WE GO INTO THE EVENING AND TONIGHT AND
COULD MAKE FOR SOME SLICK ROADWAYS FOR THE EVENING COMMUTE,
ESPECIALLY ACROSS SOUTHWEST ME AND SOUTHERN NH WHERE IT'S
ALREADY SNOWING.
THE FORECAST TRACK OF THE LOW WILL KEEP THE HIGHER QPF SOUTH AND
EAST OF THE REGION BUT STILL ENOUGH QPF TO WHERE AREAS ALONG THE
COAST COULD SEE 1-2" OF FLUFFY SNOW AS WELL AS PORTIONS OF
INLAND SOUTHERN NH. ACROSS THE INTERIOR, GENERALLY LESS THAN AN
INCH OF SNOW IS FORECAST.
AN AREA TO WATCH FOR ENHANCED TOTALS THIS EVENING IS ACROSS
SOUTHEAST NH AND FAR SW ME, WHERE OCEAN ENHANCEMENT/INCREASED
CONVERGENCE WITH AN INVERTED TROUGH COULD PRODUCE LOCALLY HIGHER
AMOUNTS OF 3-4" ALONG THE I-95 CORRIDOR FROM COASTAL YORK
SOUTHWARD THROUGH ROCKINGHAM COUNTY. GOING INTO TONIGHT, I DO
HAVE ANOTHER AREA OF 2-3" TOWARD THE MIDCOAST.
TOWARD THE AUGUSTA REGION, THERE IS SOME UNCERTAINTY ON THE
INLAND EXTENT OF MORE QPF, SO I HAVE COMPROMISED BETWEEN THE
WETTER ECMWF AND GFS WHICH YIELDS AROUND AN INCH FOR THE TIME
BEING. SNOW WILL TAPER OFF FROM WEST TO EAST THROUGH THE COURSE
OF THE OVERNIGHT HOURS.
SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/
LIGHT SNOW COULD LINGER ACROSS THE MIDCOAST FOR A BRIEF PERIOD
BEYOND SUNRISE SATURDAY BUT WILL COME TO AN END AS THE RESPONSIBLE
LOW BEGINS TO LIFT UP INTO THE CANADIAN MARITIMES. IN THE UPPER
LEVELS, A 500MB TROUGH WILL BE JUST WEST OF THE REGION TO START THE
BUT WILL GRADUALLY SLIDE EASTWARD THROUGH THE DAY. COMBINING WITH
LOW-LEVEL UPSLOPE FLOW, I'M EXPECTING PRETTY HIGH COVERAGE OF
UPSLOPE SNOW SHOWERS IN THE MOUNTAINS, AND INCREASING FROUDE NUMBERS
WILL RESULT IN A CHANCE TO SEE SOME OF THESE DOWNWIND WITH UPPER
SUPPORT. AT THE VERY LEAST, SKIES SHOULD STAY ON THE CLOUDIER SIDE
SOUTH OF THE MOUNTAINS. IT WILL ALSO BE SOMEWHAT BREEZY WITH GUSTS
UP TO 25 MPH, AND WITH TEMPERATURES ONLY REACHING MID 20S TO LOW
30S, IT WILL FEEL PRETTY CHILLY WITH WIND CHILLS LIKELY STAYING IN
THE TEENS.
SATURDAY NIGHT IS SHAPING UP TO BE A COLD ONE. HIGH PRESSURE WILL
START TO BUILD IN FROM THE WEST, BUT THE PRESSURE GRADIENT LOOKS TO
REMAIN TIGHT ENOUGH TO KEEP WINDS UP THROUGH THE NIGHT, AND
TEMPERATURES WILL CONTINUE TO FALL WITH COLD AIR ADVECTION. SINGLE
DIGIT SUBZERO WINDS CHILLS ARE POSSIBLE SOUTH OF THE MOUNTAINS WHILE
THE MOUNTAINS POTENTIALLY FALL AS LOW -10F TO -20F (EVEN LOWER AT
HIGHER ELEVATIONS).
LONG TERM /SUNDAY THROUGH FRIDAY/
HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE NORTHEAST ON SUNDAY
FROM THE GREAT LAKES REGION. UPSLOPE CLOUDS WILL ALSO CONTINUE
ACROSS THE NORTHERN HIGHER TERRAIN WITH A FEW SCATTERED FLURRIES
POSSIBLE. H8 TEMPERATURES NEAR -20C WILL ALLOW FOR VERY COLD
CONDITIONS WITH AFTERNOON HIGH TEMPERATURES ONLY INTO THE SINGLE
NUMBERS AND TEENS IN MANY AREAS. A NORTHWESTERLY GRADIENT WILL LEAD
TO WIND CHILL VALUES REMAINING BELOW ZERO IN THE NORTH.
THE LARGE RIDGE OF HIGH PRESSURE WILL BEGIN TO CREST OVER THE REGION
SUNDAY NIGHT. MAINLY CLEAR SKIES, LIGHT WINDS AND LOW SURFACE DEW
POINTS WILL ALLOW FOR RADIATIONAL COOLING, ESPECIALLY IN AREAS THAT
HAVE A FRESH SNOWPACK. OVERNIGHT LOWS WILL DROP TO ZERO TO 10 BELOW
IN THE NORTH WITH SINGLE DIGITS IN THE SOUTH.
ANOTHER DRY AND MILDER DAY WILL FOLLOW ON MONDAY. A SOUTHWEST FLOW
AROUND THE PERIPHERY OF EXITING HIGH PRESSURE WILL ALLOW
FOR CHILLY, BUT MILDER TEMPERATURES IN THE TEENS AND 20S.
A CLIPPER TYPE SYSTEM WILL ALLOW FOR PRECIPITATION TO BREAK OUT
ACROSS THE REGION MONDAY NIGHT INTO TUESDAY. IT WILL BE PLENTY COLD
FOR AN ALL SNOW SITUATION. 12Z OPERATIONAL MODELS AND LATEST
ENSEMBLE SOLUTIONS SUGGEST THE POSSIBILITY OF PLOWABLE SNOW ON THIS
BUSY TRAVEL DAY. WILL CONTINUE TO DISCUSS IN OUR LATEST DSS PACKAGES.
THE MIDWEEK PERIOD NEXT WEEK LOOKS RELATIVELY DRY. HOWEVER, WILL
CONTINUE TO MONITOR ANOTHER CLIPPER TYPE SYSTEM WHICH MAY REDEVELOPS
OFF THE COASTLINE.
AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
SHORT TERM...LIGHT SNOW SHOWERS REMAIN IN THE FORECAST THROUGH TONIGHT,
PARTICULAR SOUTH AND EAST OF A MHT TO AUG LINE WITH THE HIGHER
POTENTIAL TOWARD THE COASTAL TERMINALS. MVFR TO IFR VISIBILITIES AND
CEILINGS ARE POSSIBLE WITH THIS ACTIVITY. CONDITIONS TREND TOWARD
VFR MOST SITES OVERNIGHT TONIGHT AND INTO SATURDAY, BUT SKIES
EXPECTED TO BE MOSTLY CLOUDY THROUGH THE DAY SAT WITH VFR CIGS
LINGERING ACROSS THE AREA WITH A COUPLE OF SNOW SHOWERS POSSIBLE.
THE EXCEPTION WILL BE AT LEB AND HIE, WITH OFF AND ON MVFR CEILINGS
AND HIGHER CHANCES OF SNOW SHOWERS. MAINLY VFR SATURDAY NIGHT.
LONG TERM...
A WEAK CLIPPER PASSES NORTH OF THE AREA TODAY AND TONIGHT,
WHILE ANOTHER LOW PASSES WELL OFFSHORE TONIGHT, BRING SOME SNOW
SHOWERS OR LIGHT SNOW. VERY COLD AIR MOVES INTO NEW ENGLAND
SATURDAY NIGHT AND SUNDAY. ALTHOUGH IT WILL GRADUALLY MODERATE
TO NEAR NORMAL BY THE MIDDLE OF NEXT WEEK, AS STRONG HIGH
PRESSURE SETTLES OVER THE REGION.
MARINE
SHORT TERM...LOW PRESSURE CONTINUES TO DEEPEN AS IT PASSES EAST
OF THE WATERS TONIGHT. THIS WILL KEEP SCA CONDITIONS ACROSS THE
WATERS THROUGH SATURDAY NIGHT WITH NORTHEAST WINDS THIS
EVENING, WHICH WILL SHIFT TO THE NORTH TONIGHT, AND THEN OUT OF
THE NORTHWEST SATURDAY THROUGH SATURDAY NIGHT.
LONG TERM...A NORTHWESTERLY GRADIENT WILL KEEP WINDS ABOVE SCA
THRESHOLDS SUNDAY INTO SUNDAY NIGHT. OTHERWISE CONDITIONS WILL
EASE INTO NEXT WEEK.
GYX WATCHES/WARNINGS/ADVISORIES
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EST SUNDAY FOR ANZ150-152-154.
SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 3 AM EST
SUNDAY FOR ANZ151-153.
NEAR/SHORT TERM...COMBS
LONG TERM...CANNON
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