446
FXUS61 KGYX 171504
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
1004 AM EST TUE DEC 17 2024
SYNOPSIS
A FRONT SWEEPS THROUGH THIS MORNING BRINGING AN END TO
PRECIPITATION FOR EVERYWHERE BUT THE MOUNTAINS. HIGHS PRESSURE
MOVES SOUTH OF THE AREA LATER TODAY INTO WEDNESDAY MORNING. A
THERE IS ANOTHER CHANCE FOR PRECIPITATION, WITH ACCUMULATING
SNOW EXPECTED AT LEAST IN THE MOUNTAINS. A VERY COLD AIR MASS
MOVES IN FOR FRIDAY INTO THE WEEKEND.
NEAR TERM /UNTIL 6 PM THIS EVENING/
UPDATE...MINOR CHANGES TO ADJUST FOR LATEST OBSERVATIONAL
TRENDS. WALKED PRECIP OUT SLIGHTLY FASTER THAN PREVIOUS
FORECAST...AND INCREASED POP SLIGHTLY IN THE UPSLOPE BEHIND IN
THE MTNS. ALSO ADDED SOME FLURRIES JUST DOWNWIND OF THE PEAKS
BASED ON FROUDE NUMBER FORECASTS ABOVE 1 BUT NOT QUITE REACHING
2.
PREVIOUSLY...FAST MOVING WAVE TRACKING ENE ACROSS THE INTL
BORDER ATTM, WITH TRIPLE POINT CROSSING THE CWA AS WELL. THE
BULK OF OUT PRECIP IS FALLING IN A BAND RAIN CROSSING THE CWA
NOW, WITH SOME LINGERING SHRA FOR A FEW HOURS BEHIND THIS BAND.
THERE ARE STILL A FEW HIGHLY LOCALIZED AREAS THAT ARE HOVERING
AROUND 32F, BUT MOST OF THE MORE SHELTERED AREAS HAVE PUSHED UP
INTO THE MID TO UPPER 30S, THANKS TO THE RAIN MIXING SOWN SOME
WARMER AIR. SO, WILL CANCEL THE ADVISORY BECAUSE THE TREND WILL
BE UPWARD TODAY, ONCE THE WE BRIEFLY GET INTO THE WARM SECTOR
AND WINDS SHIFT SW. I THINK THE SHOWERS CLEAR MUCH OF THE CWA BY
13-14Z, EXCEPT MAYBE THE FAR E ZONES AND THE MTNS, WHICH WILL
BE IN THE OCCLUSION UNTIL THE COLD FRONT MOVES THROUGH LATER
THIS MORNING. S OF THE MTNS SKIES SHOULD START TO CLEAR LATE
THIS MORNING WITH PARTLY SUNNY SKIES EARLY THIS AFTERNOON AND
EVENTUALLY MAINLY CLEAR SKIES LATER IN THE DAY, HIGHS RANGE FROM
THE LOW TO MID 40S IN THE S TO THE LOW TO MID 50S IN THE SOUTH,
SO QUITE MILD FOR DECEMBER.
SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/
AT LEAST LIGHT W FLOW WILL PERSIST TONIGHT, WHICH WILL PREVENT
TEMPS FORM FALLING TOO MUCH, ALONG WITH LINGERING CLOUDS IN THE
MTNS. LOWS RANGE FROM THE UPPER 20S N TO THE LOW 30S IN THE S
AS WEAK SFC RIDGE PASSES TO OUR S.
THE SFC RIDGE SHOULD HOLD THROUGH WED MORNING, BUT CLOUDS AND
EVENTUALLY PRECIP WILL OVERSPREAD THE CWA FROM THE W DURING THE
MID TO LATE AFTERNOON. HIGHS WILL BE LIMITED BY THE CLOUDS AND
WILL RANGE FROM THE MID 30S IN THE N TO LOW TO MID 40S IN THE S.
P-TYPE AT THE START COULD BE EITHER RA OR SN IN THE MTNS, BUT
SHOULD GO OVER TO SNOW QUICKLY THANKS TO WET BULB EFFECT. IN THE
S, IT LIKELY STARTS AS RAIN, AND STAYS THAT WAY INTO THE
EVENING. INTERESTING THING ABOUT THE SYSTEM, IS THAT IT LOOKS
RATHER WEAK FROM A SYNOPTIC PERSPECTIVE, WITH WEAKER AND FAST
MOVING WAVE AT 500 MB, BUT IT GETS QUITE A KICK FROM BEING
BENEATH RIGHT ENTRY REGION OF STRENGTHENING JET IN THE 200-300
MB LAYER, PRODUCING STRONG UVV THAT CROSSES THE CWA MAINLY WED
EVENING AND EXITING THE AREA SHORTLY AFTER MIDNIGHT. IN THE N
THIS WILL A QUICK BURST OF SNOW BUT COULD SEE ADVISORY LEVELS IN
THIS SHORT WINDOW. IN SE NH AND ALONG THE IMMEDIATE IT WILL
LIKELY BE ALL RAIN. THE QUESTION AT THIS PINT IS HOW MUCH DO THE
JET DYNAMICS AFFECT THE COLD AIR AT LOWER LEVELS AND CAN THEY
PULL COLD AIR TOWARD THE COAST PRODUCING A FEW INCHES OF SNOW
INTO THE I INTERIOR PARTS OF THE COASTAL COUNTIES, OR DOES THE
BULK OF THE SNOW STAY AROUND OR N OF A KCON-KLEW-KAUG LINE?
WHATEVER HAPPENS IT’LL ALL BE OVER BEFORE THE THU MORNING
COMMUTE.
LONG TERM /THURSDAY THROUGH MONDAY/
05Z LONG TERM FORECAST UPDATE... LITTLE CHANGE IN THE LATEST
ENSEMBLE AND DETERMINISTIC GUIDANCE FOR A MID-WEEK QUICK HITTING
SHOT OF PRECIPITATION ON WEDNESDAY NIGHT. THIS COULD BRING A
COUPLE INCHES OF SNOW FOR AREAS AWAY FROM THE COAST WITH A
RAIN/SNOW MIX ALONG THE COAST. BEHIND THIS SYSTEM COOLER
TEMPERATURES WILL PREVAIL ALONG WITH PERHAPS SOME SNOW SHOWERS
AT TIMES.
PREVIOUSLY...
OVERVIEW...
AN ACTIVE PATTERN CONTINUES THROUGH THE MIDDLE AND LATER PORTIONS OF
THE WORK WEEK WITH MULTIPLE CHANCES FOR RAIN OR SNOW. COLD WEATHER
RETURNS FOR THE END OF THE WEEK AND NEXT WEEKEND AS A TROUGH DEEPENS
ACROSS THE NORTHEAST.
DETAILS...
MILD WEATHER PRECEDES A SYSTEM ON WEDNESDAY WITH HIGHS MAINLY
IN THE 40S OUTSIDE OF THE HIGHER TERRAIN. A SHORTWAVE SWINGS
THROUGH THE OHIO VALLEY AND BY WEDNESDAY LOW PRESSURE DEEPENS AS
IT LIKELY TRACKS ACROSS OR JUST SOUTH OF SOUTHERN NEW ENGLAND.
WITH A LACK OF COLD AIR IN PLACE, A RAIN/SNOW LINE IS EXPECTED
TO SET UP ACROSS THE COASTAL PLAIN WEDNESDAY NIGHT AND INTO
EARLY THURSDAY. INTERIOR AND NORTHERN AREAS STAND THE BEST
CHANCE TO PICK UP A LIGHT TO MODERATE SNOWFALL, WHILE THE COAST
AND SOUTHERN NH LOOKS TO BE MOSTLY RAIN AT THIS POINT. THE
SYSTEM MOVES AWAY THURSDAY MORNING, WITH HIGHS RANGING FROM NEAR
30 ACROSS THE NORTH, TO THE MID 40S ALONG THE COAST.
SEASONABLY COOL AIR RETURNS FOR FRIDAY, WITH HIGHS RANGING FROM THE
LOW 20S ACROSS THE NORTH, TO THE MID 30S ALONG THE COASTLINE. WITH
COLD AIR IN PLACE, WE THEN WATCH THE NEXT POTENTIAL SYSTEM FOR
LATE FRIDAY AND FRIDAY NIGHT.
MODELS CONTINUE TO DIVERGE GREATLY ON THIS SYSTEM FROM RUN TO RUN,
AND SOMEWHAT BETWEEN DIFFERENT MODEL SUITES. THE OVERALL SET UP
FEATURES AN ALBERTA CLIPPER MOVING EASTWARD THROUGH THE GREAT LAKES,
AS RICH MOISTURE MOVES NORTHWARD OFF THE EAST COAST. THE
DISCREPANCY CONTINUES TO BE WHETHER OR NOT THESE TWO FEATURES
PHASE IN TIME TO BRING A SIGNIFICANT SNOWFALL TO THE AREA. AT
THIS POINT THE MODELS ARE SUGGESTING THIS DOES NOT HAPPEN IN
TIME, WITH ATLANTIC CANADA SEEING THE BRUNT OF A POWERFUL LOW
PRESSURE SYSTEM. HOWEVER, THIS DOESN'T MEAN IT SHOULD BE RULED
OUT YET, AS WE'RE STILL ABOUT 5 DAYS OUT. IT WOULD ONLY TAKE A
SLIGHTLY MORE AMPLIFIED SHORTWAVE TO PHASE SOONER AND BRING A
MORE SIGNIFICANT SNOWFALL TO THE AREA. ONE MODEL THAT DOES SHOW
THIS HAPPENING A LITTLE SOONER AND BRINGING SNOW IT AT LEAST
EASTERN AREAS IS THE NEW EURO AIFS MODEL. IT'S STILL TOO EARLY
TO KNOW IF THIS IS JUST AN OUTLIER, OR THE START OF A TREND, BUT
WE'LL NEED TO CONTINUE TO WATCH THIS SYSTEM FOR A COUPLE MORE
DAYS BEFORE A HIGHER CONFIDENCE OUTCOME CAN BE REACHED.
REGARDLESS OF THE DEVELOPMENT OF THE COASTAL LOW, AT LEAST SOME SNOW
SHOWER ACTIVITY IS POSSIBLE LATE FRIDAY AS THE CLIPPER MOVES THROUGH
NEW ENGLAND. BEHIND THIS SYSTEM, ARCTIC AIR POURS INTO NEW ENGLAND
FOR NEXT WEEKEND, BRINGING THE COLDEST TEMPERATURES OF THE SEASON SO
FAR. HIGHS IN THE TEENS AND 20S WITH LOWS IN THE SINGLE DIGITS TO
BELOW ZERO LOOK INCREASINGLY LIKELY. IF THERE DOES END UP BEING A
MORE WIDESPREAD SNOW COVER THESE TEMPERATURES WOULD GO EVEN LOWER,
SO THIS IS ONE MORE REASON TO KEEP MONITORING THE FRIDAY SYSTEM.
AVIATION /15Z TUESDAY THROUGH SATURDAY/
SHORT TERM...IFR-LIFR WILL LIKELY LINGER AT MOST TERMINALS UNTIL
13-14Z, BUT SHOULD SEE IMPROVEMENT TO MVFR THROUGH THE MORNING
AND VFR BY AFTERNOON, WHICH WILL PERSIST THROUGH WED MIDDAY AT
LEAST. WILL START TO SEE FLIGHT RESTRICTIONS RETURN IN RA/SN
SOMETIME WED AFTERNOON.
LONG TERM...VFR CONDITIONS ON WEDNESDAY GIVE WAY TO IFR TO LIFR
AND RESTRICTIONS WEDNESDAY NIGHT WITH RAIN SOUTH AND SNOW
NORTH. MVFR TO VFR RETURNS FOR THURSDAY AND INTO FRIDAY.
CONDITIONS THEN BECOME DEPENDENT ON THE TRACK OF A STORM FOR
LATE FRIDAY AND FRIDAY NIGHT, WITH COASTAL TERMINALS SEEING THE
GREATEST CHANCE FOR RESTRICTIONS. VFR THEN LIKELY RETURNS FOR
NEXT WEEKEND.
MARINE
SHORT TERM...AFTER A BRIEF PERIOD OF GALE FORCE GUSTS...WINDS
HAVE SHIFTED TO WESTERLY AND ARE BEGINNING TO DIMINISH. I
DROPPED THE GALE WARNING IN FAVOR OF A SCA THRU THE DAY...AND
DROPPED THE SCA IN CASCO BAY. WINDS SHOULD GENERALLY GUST AROUND
25KT THRU TODAY WITH SEAS GRADUALLY DIMINISHING OUTSIDE OF THE
BAYS. CONDS EXPECTED TO STAY SUB-SCA ON WED INTO WED NIGHT.
LONG TERM...LOW PRESSURE CROSSES THE WATERS WEDNESDAY NIGHT,
WITH WESTERLY WINDS POSSIBLY BRINGING SCA CONDITIONS BEHIND THE
SYSTEM ON THURSDAY. CONDITIONS THEN BECOME DEPENDENT ON THE
TRACK OF A DEVELOPING COASTAL LOW LATE FRIDAY. NORTHERLY GALES
AND ARCTIC SEA SMOKE ARE THEN POSSIBLE OVER THE WEEKEND.
GYX WATCHES/WARNINGS/ADVISORIES
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ150-
152-154.
SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ151.
NEAR TERM...LEGRO
SHORT TERM...CEMPA
LONG TERM...CLAIR/TUBBS
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