477
FXUS61 KBOX 192111
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
411 PM EST WED FEB 19 2025
SYNOPSIS
A DISTANT OCEAN STORM WILL BRUSH THE FAR SOUTHEAST NEW ENGLAND COAST
WITH SOME ACCUMULATING SNOW THURSDAY INTO THURSDAY NIGHT. BREEZY AND
COLD FOR FRIDAY WITH THE DEPARTURE OF A COASTAL LOW AND THE BUILDING
HIGH PRESSURE SYSTEM TO THE WEST. DRIER CONDITIONS AS WELL CONTINUES
INTO THIS WEEKEND WITH NEAR NORMAL TEMPERATURES. EARLY NEXT WEEK
SIGNS OF SOME UNSETTLED CONDITIONS AND SLIGHTLY ABOVE NORMAL
TEMPERATURES.
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/
KEY MESSAGES...
* VERY COLD WITH BELOW NORMAL TEMPS TONIGHT.
OUR DRY WEATHER CONTINUES OVERNIGHT THANKS TO A LINGERING RIDGE OF
HIGH PRESSURE EXTENDING FROM THE GREAT LAKES. EXPECTING A GOOD
AMOUNT OF CLEAR SKIES OVERNIGHT, THOUGH HIGH CLOUDS ASSOCIATED WITH
THE OFFSHORE STORM WILL MOVE OVER THE SOUTH COAST. THIS MAY LIMIT
RADIATIONAL COOLING A BIT BUT OVERALL A CLEAR, CALM NIGHT WILL ALLOW
FOR TEMPS TO DROP WELL BELOW NORMAL, INTO THE SINGLE DIGITS AND LOW
TEENS.
SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/
KEY MESSAGES...
* A STORM PASSES WELL OFFSHORE BRINGING SNOW TO THE CAPE AND ISLANDS
THURSDAY AFTERNOON AND OVERNIGHT.
* MOST LIKELY SNOW ACCUMS...1-3" FOR THE CAPE/MVY & 2-5" FOR ACK
THURSDAY A DEEP MID LEVEL TROUGH DIGS INTO THE GREAT LAKES
APPROACHING THE NORTHEAST WHILE OUT AHEAD OF IT A SURFACE LOW PASSES
WELL TO OUT SOUTHEAST, OUTSIDE OF THE 70/40 BENCHMARK. GUIDANCE HAS
BEEN GENERALLY IN AGREEMENT THE LAST 48 HOURS OR MORE THAT THIS
SYSTEM MERELY MAKES A GLANCING BLOW TO SOUTHERN NEW ENGLAND. THE
NORTHERN EXTENT OF THE PRECIP SHIELD CLIPS CAPE COD AND ESPECIALLY
THE ISLANDS AS THE NORTHERN STREAM UPPER LOW CAPTURES IT AND SWEEPS
IT QUICKLY OUT INTO ATLANTIC CANADA. GLOBAL GUIDANCE HAS SHIFTED THE
TRACK SLIGHTLY SOUTHEAST REDUCING ACCUMULATION AMOUNTS EVEN FURTHER,
WHILE THE NAM CONTINUES TO BE OUT ON ITS OWN WITH MUCH HIGHER
TOTALS. FOR WHAT IT'S WORTH, WHILE THE NAM INDICATES AS MUCH AS 8
INCHES OF SNOW FOR NANTUCKET EPS AND GEFS ENSEMBLE GUIDANCE SHOWS
ONLY A 10-30% CHANCE OF EVEN SEEING 3 INCHES OF SNOW. THIS IS ON PAR
WITH OTHER HI-RES GUIDANCE, SO THE FORECAST HAS BEEN BASED ON THESE
MODELS. GENERALLY THINKING A 1 TO 3 INCH EVENT FOR CAPE COD IS
POSSIBLE WITH 2 TO 5 INCHES FOR NANTUCKET BETWEEN SYNOPTIC FORCING
AND OCEAN ENHANCEMENT THANKS TO NORTHERLY FLOW OVER THE RELATIVELY
WARM WATERS. AIR TEMPERATURES WILL ONLY REACH THE UPPER 20S AND LOW
30S ON THURSDAY. SNOW BEGINS THURSDAY AFTERNOON AND COMES TO AN END
BEFORE SUNRISE ON FRIDAY. LOW TEMPERATURES WILL BE WARMER THAN THE
PREVIOUS NIGHT, IN THE TEENS AND 20S.
LONG TERM /FRIDAY THROUGH WEDNESDAY/
KEY MESSAGES
* GRADUAL UPTICK IN TEMPERATURES BETWEEN FRIDAY AND EARLY NEXT WEEK
* PERIOD OF GUSTY NORTHWEST WINDS TO 30 MPH ON FRIDAY AS A COASTAL
LOW PASSES SOUTHERN NEW ENGLAND TO THE SOUTHEAST
* DRY CONDITIONS THROUGH MONDAY BUT A COASTAL LOW MAY BRING
ADDITIONAL PRECIPITATION TUE/WED. LOW CONFIDENCE.
FRIDAY THROUGH MONDAY
A COASTAL LOW WILL BE DEPARTING THE SOUTH COASTAL WATERS EARLY
FRIDAY AFTER DUMPING A FEW INCHES OF SNOW ON THE CAPE ISLANDS. DEEP
NORTHWEST FLOW DEVELOPS BEHIND THE DEPARTING LOW SUPPORTING A
COLD/DRY PATTERN THROUGH THE FIRST HALF OF THE WEEKEND. EXPECT
CHILLY TEMPS ON FRIDAY WITH HIGHS RANGING FROM THE UPPER 20S TO LOW
30S. CAA PATTERN WILL SUPPORT A PERIOD OF GUSTY NORTHWEST WINDS ON
FRIDAY AFTERNOON. LATEST MODEL GUIDANCE SUPPORTS A 25 TO 35 KNOT LOW-
LEVEL JET BETWEEN 925 AND 850 HPA. THUS, SOME 30 MPH GUSTS ARE
LIKELY ON FRIDAY AFTERNOON.
A MID-LEVEL RIDGE BUILDING IN FROM THE WEST ON SATURDAY WILL BEGIN
AN UPWARD TREND IN TEMPERATURES THAT WILL CARRY THROUGH MONDAY. HIGH
TEMPS IN THE MID 30S ON SATURDAY WILL CLIMB TO THE LOW 40S ON
MONDAY. EXPECT DRY WEATHER AND MORE SUN THAN CLOUDS THROUGH THIS
TIME FRAME. GENERALLY A QUIET WEEKEND ACROSS THE REGION.
TUESDAY AND WEDNESDAY
UNCERTAINTY IN THE FORECAST GROWS SUBSTANTIALLY BY TUESDAY OF NEXT
WEEK WITH MODELS TRYING TO RESOLVE THE TRACK OF ANOTHER COASTAL LOW
PRESSURE SYSTEM. LATEST ENSEMBLES SUPPORT ANOTHER TRACK SOUTH AND
EAST OF SOUTHERN NEW ENGLAND, BUT CONFIDENCE IS VERY LOW AT THIS
TIME RANGE. ADDITIONALLY, LOW PRESSURE IS FORECAST TO BE DIGGING
DOWN FROM CANADA WHICH MAY ALSO SUPPORT THE POTENTIAL FOR SOME
UNSETTLED WEATHER. GIVEN THE UNCERTAINTY, WE HAVE LEANED ON THE NBM
FOR POPS FOR EARLY NEXT WEEK WITH A 20-30 PERCENT CHANCE OF
PRECIPITATION (FROZEN OR LIQUID) FOR TUESDAY. TEMPERATURES LOOK TO
REMAIN ON THE MILD SIDE WITH HIGHS IN THE 40S THROUGH THE MIDDLE OF
NEXT WEEK. STAY TUNED FOR FURTHER DETAILS.
AVIATION /21Z WEDNESDAY THROUGH MONDAY/
FORECAST CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
18Z TAF UPDATE...
THIS AFTERNOON AND TONIGHT...HIGH CONFIDENCE.
VFR. NW WINDS GUSTS OF 20 TO 25 KTS INTO EARLY AFTERNOON, BUT
SUBSIDING TO LESS THAN 15 KTS BY LATE AFTERNOON/EARLY EVENING.
WINDS WILL DECREASE FURTHER TONIGHT BECOMING CALM/LIGHT FROM THE
NW.
THURSDAY AND THURSDAY NIGHT...HIGH CONFIDENCE.
MAINLY VFR NEAR AND NORTHWEST OF THE BOSTON TO PROVIDENCE
CORRIDOR. A PERIOD OF MVFR AND LOCALIZED IFR CONDITIONS DEVELOP
THU AFTERNOON AND CONTINUE INTO THU NIGHT TOWARD THE CAPE AND
ISLANDS. THIS A RESULT OF A DISTANT OCEAN STORM AND THE
NORTHWEST EXTENT OF ITS SNOW SHIELD...WHICH SHOULD NOT GET TOO
MUCH FURTHER NORTHWEST THAN THE CAPE COD CANAL...PERHAPS
BRIEFLY GRAZING THE SOUTH COAST AND PARTS OF PLYMOUTH COUNTY.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK /FRIDAY THROUGH MONDAY/...
FRIDAY: VFR. WINDY WITH LOCAL GUSTS UP TO 30 KT.
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.
TONIGHT THROUGH THURSDAY...HIGH CONFIDENCE.
WINDS AND SEAS CONTINUE LOWER LATER THIS AFTERNOON AND DROP
BELOW SMALL CRAFT THRESHOLDS ACROSS ALL OUR WATERS BY EARLY
EVENING. HIGH PRESSURE THEN NOSES IN FROM THE WEST KEEPING WINDS
BELOW SMALL CRAFT THRESHOLDS TONIGHT INTO THU.
THURSDAY NIGHT...HIGH CONFIDENCE.
A DISTANT OCEAN STORM WILL INTENSIFY AND ALLOW THE PRESSURE GRADIENT
TO INCREASE. THIS WILL ALLOW NW WIND GUSTS OF 20-30 KNOTS TO DEVELOP
AND SMALL CRAFT HEADLINES WILL LIKELY BE NEEDED FOR MOST OF OUR
WATERS.
OUTLOOK /FRIDAY THROUGH MONDAY/...
FRIDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS
UP TO 25 KT. SEAS UP TO 5 FT. CHANCE OF FREEZING SPRAY.
FRIDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH
GUSTS UP TO 25 KT. SEAS UP TO 5 FT. CHANCE OF FREEZING SPRAY.
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...WINTER WEATHER ADVISORY FROM 9 AM THURSDAY TO 7 AM EST FRIDAY
FOR MAZ024.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ255-
256.
SYNOPSIS...BW/RM
NEAR TERM...BW
SHORT TERM...BW
LONG TERM...RM
AVIATION...BW/RM
MARINE...BW/RM
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