336
FXUS61 KBOX 210508
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
1208 AM EST FRI FEB 21 2025
SYNOPSIS
A DISTANT OCEAN STORM WILL BRUSH THE CAPE/ISLANDS WITH SOME
LIGHT SNOW LATER THIS AFTERNOON INTO TONIGHT. BLUSTERY AND COLD
FRIDAY WITH THE DEPARTURE OF THE OCEAN STORM AND THE BUILDING
HIGH PRESSURE SYSTEM TO THE WEST. DRIER CONDITIONS CONTINUES INTO
THIS WEEKEND, WITH TEMPERATURES MODERATING TO NEAR NORMAL.
EARLY NEXT WEEK, SIGNS OF SOME UNSETTLED CONDITIONS AND
SLIGHTLY ABOVE NORMAL TEMPERATURES.
NEAR TERM /THROUGH TODAY/
300 PM UPDATE...
KEY MESSAGES...
* PERIODS OF LIGHT SNOW THIS EVENING & EARLY TONIGHT TOWARDS
THE CAPE/ISLANDS
* LESS SNOWFALL THAN EARLIER EXPECTED
CHANGES FROM PREVIOUS FORECAST...
ALL 12Z GUIDANCE HAS TRENDED TOWARD LESS QPF/SNOWFALL FOR
TONIGHT, AS OCEAN LOW DEPARTS OUT TO SEA. LATEST TRENDS ON RADAR
AND SATELLITE SUPPORT THIS AS WELL. THUS, WE HAVE DROPPED THE
WINTER WEATHER ADVISORY FOR NANTUCKET, AS WE ARE NOW ONLY
EXPECTING AN INCH OR TWO OF SNOW THERE. CAPE COD AND MARTHAS
VINEYARD, ONLY EXPECTING A COATING TO AN INCH LIKELY. ELSEWHERE,
OTHER THAN JUST A FEW FLURRIES, DRY WEATHER EXPECTED TONIGHT.
TONIGHT...
AS MENTIONED ABOVE LESS QPF/SNOWFALL EXPECTED TONIGHT THAN
EARLIER MODEL RUNS. THE WEST TO EASTERLY FLOW ALOFT, PRECLUDES
DEEP MOISTURE OFFSHORE FROM ADVECTING NORTHWARD. THIS SHOWS UP
ON MODEL SOUNDINGS, WITH THE COLUMN STRUGGLING TO COMPLETELY
SATURATE. SO DESPITE MODEST FORCING FOR ASCENT ASSOCIATED WITH
INVERTED TROUGH EXTENDING NORTHWEST OF THE CYCLONE INTO THE
SOUTH COAST AND ISLANDS, DEEP LAYER MOISTURE IS LACKING AND
BRIEF. THEREFORE, SNOW ACCUMULATIONS WILL BE LIMITED WITH MUCH
OF IT COMING FROM OCEAN EFFECT SNOW (OES) BANDS, ONCE NORTHERLY
FLOW INCREASES 00Z-06Z ACROSS THE CAPE AND ISLANDS. ONLY A
COATING TO AN INCH IS LIKELY HERE, WITH PERHAPS UP TO 2 INCHES
ON NANTUCKET. JUST LOTS OF CLOUDS AND SCATTERED FLURRIES
ELSEWHERE.
LATER TONIGHT, AS OFFSHORE LOW RAPIDLY DEEPENS EAST OF GEORGES
BANKS, NW GRADIENT AND CAA INCREASES AND RESULTS IN NW WINDS 15-25
MPH, UP TO 35 MPH ACROSS THE CAPE AND ISLANDS GIVEN THE DEEPER
BOUNDARY LAYER OVER THE WATER. ANOTHER CHILLY NIGHT, LOWS IN THE
TEENS, BUT FEELING COLDER GIVEN THE BLUSTERY NW WINDS THAT
DEVELOP LATE.
SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/
300 PM UPDATE...
KEY MESSAGES...
* DRY, BUT COLD AND BLUSTERY
FRIDAY...
DRY BUT COLD NW FLOW, WITH SURFACE WINDS 15-25 MPH. HIGHS ONLY
IN THE UPPER 20S TO LOWER 30S, BUT WILL FEEL COLDER GIVEN THE
BLUSTERY NW WINDS. THERE WILL BE SOME INEFFECTIVE SUNSHINE MIXED
AT TIMES WITH SCT-BKN STRATO-CU.
FRIDAY NIGHT...
DRY WEATHER CONTINUES, BUT ALSO REMAINING BLUSTERY AND COLD. NW
WINDS 10-15 MPH, BUT GUSTING UP TO 25 MPH ACROSS THE CAPE AND
ISLANDS. A COLD NIGHT WITH LOWS IN THE SINGLE DIGITS ACROSS
NORTHWEST MA, TO THE TEENS ELSEWHERE. COLDER WIND CHILLS GIVEN
THE NW BREEZE. MOSTLY CLEAR CONDITIONS.
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
3 PM UPDATE...
KEY MESSAGES:
* MODERATING TEMPERATURES FOR MUCH OF NEXT WEEK
* PERHAPS A STORM SYSTEM BRINGING A WINTRY MIX TOWARD THE END OF THE
WEEK
12Z SUITE OF GUIDANCE STILL POINTING TO A RATHER QUIET PERIOD FROM
SUNDAY THROUGH THURSDAY. UPPER LEVEL FLOW WILL BE GENERALLY ZONAL
FOR MUCH OF THE TIME, ALLOWING AN AIRMASS ORIGINATING IN THE PACIFIC
TO WORK IT'S WAY ACROSS THE COUNTRY. THAT MEANS MODERATING
TEMPERATURES. STUCK WITH THE NBM GUIDANCE, WHICH HAS MID TO UPPER
40S FOR MOST OF THE AREA TUESDAY THRU THURSDAY, HOWEVER THERE ARE
SUGGESTIONS IN THE LONG RANGE ENSEMBLE GUIDANCE THAT TEMPERATURES
ABOVE 50F ARE POSSIBLE. THE EURO IS WARMEST FOR TUESDAY & WEDNESDAY,
AND SUGGESTING A 10-20% OF SEEING 50F+ ACROSS INTERIOR EASTERN MA
INTO NORTHERN RI AND CENTRAL CT. ON THURSDAY, THE CANADIAN AND GFS
ENSEMBLES START TO SHOW A 50F POTENTIAL SIGNAL, WITH THE EURO
SHOWING UPWARD OF A 40% CHANCE OF SEEING THOSE "WARM" TEMPERATURES.
ALTHOUGH MANY RIVERS HAVE SOME PARTIAL ICE COVER ACROSS THE REGION,
THIS KIND OF MODERATE TEMPERATURES DURING THE DAY AND AROUND
FREEZING AT NIGHT WILL RESULT IN A NICE ORDERLY SLOW MELT OF THE
ICE. THUS, AT THIS POINT, WE ARE NOT CONCERNED FOR ANY SIGNIFICANT
ICE JAM FLOODING. PRECIPITATION WILL BE MINIMAL THROUGH THURSDAY,
ALTHOUGH THERE ARE A COUPLE OF SHORTWAVES THAT RIPPLE THROUGH THE
ZONAL FLOW. HOWEVER THE MODELS HAVE CONSIDERABLE SPREAD IN THE
TIMING, SO 20-30% POPS ARE IN THE FORECAST FROM MONDAY INTO EARLY
WEDNESDAY. TEMPERATURES SHOULD BE MILD ENOUGH THAT MOST PRECIP IS IN
THE FORM OF LIGHT RAIN WITH ANY LIGHT SNOW CONTAINED TO HIGHER
ELEVATIONS. A STRONGER SYSTEM APPROACHES FOR THE END OF THE WEEK.
CONSIDERABLE UNCERTAINTY AT THIS POINT IN TIMING, TRACK, TEMPERATURE
PROFILES ETC. SO BEST COURSE OF ACTION AT THIS POINT IS TO STICK
WITH A MODEL BLEND WHICH GIVES US SNOW INLAND/RAIN CLOSER TO THE
COAST TYPE OF SCENARIO ANYTIME BETWEEN LATE THURSDAY THROUGH EARLY
SATURDAY.
AVIATION /05Z FRIDAY THROUGH TUESDAY/
FORECAST CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
THROUGH 12Z... HIGH CONFIDENCE.
VFR. FEW AREAS OF -SN OVER THE ISLAND THROUGH 09Z, OTHERWISE
DRY. NW WINDS 8-12 KNOTS, GUSTING 20-25 KNOTS.
FRIDAY AND FRIDAY NIGHT... HIGH CONFIDENCE.
VFR AND DRY. GUSTY NW WINDS 10-20 KNOTS WITH GUSTS 25-30 KNOTS,
HIGHEST OVER CAPE COD AND ISLANDS.
SATURDAY... HIGH CONFIDENCE.
VFR. LIGHT NW WINDS BECOME W 5-10 KNOTS.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/...
FRIDAY NIGHT THROUGH SATURDAY: VFR. BREEZY.
SATURDAY NIGHT THROUGH SUNDAY NIGHT: VFR.
MONDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE.
MARINE
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
KEY MESSAGES...
* LIGHT FREEZING SPRAY TONIGHT THROUGH FRIDAY NIGHT
* NW WINDS 20-25 KT LATE TONIGHT INTO FRIDAY
THRU FRIDAY NIGHT...
A DEVELOPING GALE CENTER SOUTH OF GEORGES BANK TONIGHT RACES OUT
TO SEA. IN ITS WAKE, NW WINDS 20-25 KT DEVELOPS ACROSS THE RI/MA
WATERS LATER TONIGHT AND CONTINUES INTO FRI. THIS WILL BE
ACCOMPANIED BY LIGHT FREEZING SPRAY AND PERIODS OF LIGHT SNOW
THIS EVENING. OTHERWISE, DRY WEATHER PREVAILS.
OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/...
SATURDAY THROUGH SUNDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY
APPROACHING 5 FT.
SUNDAY NIGHT THROUGH MONDAY: WINDS LESS THAN 25 KT.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST SATURDAY FOR ANZ231-250-
254>256.
SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR
ANZ232>235-237-251.
SYNOPSIS...NASH/NOCERA
NEAR TERM...NOCERA
SHORT TERM...NOCERA
LONG TERM...NASH
AVIATION...DOOLEY/NASH/NOCERA
MARINE...NASH/NOCERA
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