121
FXUS61 KBOX 170021
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
721 PM EST MON DEC 16 2024
SYNOPSIS
A PERIOD OF STEADY RAIN IS EXPECTED LATE TONIGHT INTO EARLY
TUESDAY MORNING, WITH THE REST OF THE DAY TURNING OUT DRY AND
UNSEASONABLY MILD. THERE IS THE POTENTIAL FOR MORE UNSETTLED
WEATHER WEDNESDAY AFTERNOON INT THURSDAY, AND PERHAPS AGAIN
FRIDAY INTO SATURDAY. ANOTHER SHOT OF VERY COLD AIR COULD ARRIVE
BY THIS WEEKEND.
NEAR TERM /UNTIL 6 AM TUESDAY MORNING/
* SPOTTY LIGHT RAIN AND DRIZZLE THIS EVENING.
* WIDESPREAD RAIN ARRIVES OVERNIGHT.
TWEAKED RAINFALL CHANCES AND TIMING THIS EVENING BASED ON
OBSERVED RADAR TRENDS. RAINFALL THIS EVENING HAS BEEN LIGHT,
WITH MOST SURFACE REPORTS REPORTING TRACE AMOUNTS. ISSUED A
SPECIAL WEATHER STATEMENT EARLIER THIS EVENING TO HIGHLIGHT THE
POSSIBILITY OF SOME LIGHT ICING ACROSS PORTIONS OF THE CT RIVER
VALLEY THROUGH ABOUT 8 PM. TEMPERATURES HAVE ALREADY BEGUN TO
RISE WITH WARM AIR ADVECTION UNDERWAY. EXPECTING TEMPERATURES TO
BE SAFELY ABOVE FREEZING BY THEN, ENDING THE THREAT OF ICING.
WILL BE MONITORING THIS CLOSELY, AND EXTEND THE STATEMENT IF
NEEDED.
OTHERWISE, OVERALL THEME OF THE FORECAST REMAINED ON TRACK.
STILL EXPECTING A WIDESPREAD RAINFALL TO DEVELOP OVERNIGHT.
PREVIOUS DISCUSSION...
A GRAY WINTER DAY CONTINUES THIS AFTERNOON FOR SOUTHERN NEW
ENGLAND WITH TEMPERATURES LIMITED TO THE 30S AND LOW 40S. WHILE
MUCH OF THE REGION ISN'T ACTIVELY SEEING WET WEATHER, SPOTTY
RAIN SHOWERS AND DRIZZLE WILL CONTINUE OFF AND ON THROUGH THE
AFTERNOON/EVENING BETWEEN FORCING FEATURES. A STALLED BOUNDARY
IS PROVIDING SOME BETTER FORCING FOR RAIN SHOWERS ALONG AND JUST
SOUTH OF THE SOUTH COAST OF RI/CT AND THIS IS WHERE WE STAND THE
BEST CHANCE OF SEEING MORE APPRECIABLE RAIN THIS AFTERNOON
AHEAD OF THE BETTER WARM FRONTAL FORCING TONIGHT.
THIS WARM FRONT SITTING OFFSHORE WILL LIFT NORTH OVERNIGHT
HERALDING THE RETURN OF MUCH MILDER TEMPERATURES, BY SUNRISE
THOSE IN RI AND EASTERN MA SHOULD BE SITTING IN THE LOWER TO
MID 50S. ACCOMPANYING THOSE WARM TEMPERATURES WILL BE A
WIDESPREAD SHIELD OF RAIN MOVING IN ON WARM FRONTAL LIFT AND THE
EMERGING LOW LEVEL JET WHICH WILL SQUEEZE OUT A QUICK QUARTER TO
HALF INCH OF RAIN. ENSEMBLES SHOW ESSENTIALLY NO CHANCE OF MORE
THAN A HALF INCH OF RAIN, SAVE FOR SOME 30-40% CHANCES ALONG
COASTAL RHODE ISLAND.
SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/
KEY MESSAGES...
* DRYING OUT AND MUCH WARMER TUESDAY.
BY MID MORNING TUESDAY MUCH OF THE RAIN HAS EXITED OR IS JUST
EXITING FAR EASTERN MA AS THE TRANSIENT SHORTWAVE EXITS EAST AND
MID LEVEL HEIGHTS BEGIN TO RISE. WHILE WE'LL START THE DAY
CLOUDY, INCREASINGLY DRIER AIR FILTERS IN AND AND THE AFTERNOON
SHOULD FEATURE PLENTY OF SUN ACROSS SNE. VERY WARM TEMPERATURES
WILL ACCOMPANY THE SUN AS THE MILD S/SW FLOW CONTINUES THROUGH
PART OF THE DAY, RESULTING IN HIGH TEMPERATURES IN THE MID TO
UPPER 50S. FOR COMPARISON, THE AVERAGE WOULD BE THE LOW TO MID
40S. A COLD FRONT WILL DROP IN FROM NW TO SE LATE IN THE DAY
BRINGING COOLER TEMPERATURES TO THE INTERIOR BY LATE TUE AND FOR
SOUTHEAST MA OVERNIGHT, THOUGH EVEN THESE LOWS (30S) WILL BE A
BIT ABOVE NORMAL. THE OVERNIGHT HOURS WILL BE QUIET AS SURFACE
HIGH PRESSURE MOVES OVERHEAD WITH WEAK RIDGING IN THE MID
LEVELS.
LONG TERM /WEDNESDAY THROUGH MONDAY/
KEY MESSAGES:
* ACTIVE WEATHER PATTERN THROUGH THIS WEEKEND, FEATURING THE
PASSAGE OF SEVERAL SYSTEMS ACCOMPANIED BY PERIODS OF
PRECIPITATION.
* ARCTIC AIR MOVES INTO REGION BY END OF THIS WEEK, BRINGING
BELOW NORMAL TEMPERATURES FOR THIS WEEKEND.
LATEST GUIDANCE SUITE DOES NOT SHOW THE ACTIVE PATTERN SETTLING
DOWN MUCH. HAVE MODERATE CONFIDENCE IN THE DETAILS INTO
THURSDAY, THEN CONFIDENCE IN THE DETAILS, SUCH AS TIMING AND
LOCATION, LOWERS INTO THIS WEEKEND. THE OVERALL THEME LOOKS
CONSISTENT, BUT THE TIMING MAY CHANGE WITH LATER FORECASTS.
GENERALLY EXPECTING TWO ROUNDS OF PRECIPITATION DURING THIS PART
OF THE FORECAST. THE FIRST LOOKS TO BE SOMETIME WEDNESDAY
AFTERNOON INTO THURSDAY MORNING, AND THE SECOND SOME TIME FRIDAY
INTO SATURDAY. EXPECTING MAINLY RAINFALL WITH THIS FIRST EVENT,
WITH SNOW POSSIBLE ACROSS THE HIGHER TERRAIN OF WESTERN AND
CENTRAL MA, ESPECIALLY AT NIGHT. A SIMILAR SITUATION FOR THE
LATE WEEK SYSTEM, WHERE A MIX OF RAIN AND SNOW IS POSSIBLE. SNOW
APPEARS TO BE MORE LIKELY ACROSS THE INTERIOR, BUT WHERE THE
RAIN/SNOW LINE SETS UP IS STILL UNCERTAIN. SOUTHERN NEW ENGLAND
LOOKS TO BE SANDWICHED BETWEEN A LOW PRESSURE MOVING FROM THE
GREAT LAKES INTO CANADA AND AN OFFSHORE LOW PRESSURE. STILL A
LOT OF THINGS TO BE RESOLVED WITH LATER FORECASTS THIS WEEK.
ABOVE NORMAL TEMPERATURES EXPECTED INTO THURSDAY, THEN SHOULD
TREND BELOW NORMAL BY FRIDAY INTO THIS WEEKEND.
AVIATION /00Z TUESDAY THROUGH SATURDAY/
FORECAST CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TONIGHT...MODERATE CONFIDENCE
CONDITIONS WILL LOWER TO MAINLY IFR LEVELS. WHILE A FEW
SCATTERED SHOWERS ARE POSSIBLE THIS EVENING, A PERIOD OF STEADY
RAIN SHOULD IMPACT THE AREA LATE TONIGHT INTO EARLY TUE MORNING.
S WINDS 5 TO 15 KNOTS AND WE DO EXPECT SOME GUSTS NEAR 25 KNOTS
TOWARD DAYBREAK ACROSS THE CAPE/ISLANDS. LLWS WILL ALSO BE AN
ISSUE FOR THE TERMINALS AS A MODEST LOW LEVEL JET DEVELOPS.
TUESDAY...MODERATE CONFIDENCE.
THE LAST OF THE REMAINING SHOWERS SHOULD EXIT THE SOUTHEAST NEW
ENGLAND COAST BY MID-MORNING OR SO ON TUE. OTHERWISE, MVFR-IFR
CONDITIONS EARLY IN THE MORNING SHOULD IMPROVE TO MAINLY VFR BY
MID AFTERNOON. THIS PROCESS MAY TAKE A FEW HOURS LONGER TOWARDS
THE CAPE AND ISLANDS.
TUESDAY NIGHT...HIGH CONFIDENCE.
VFR. W WINDS 5-10 KTS.
KBOS TAF...MODERATE CONFIDENCE IN TAF.
KBDL TAF... MODERATE CONFIDENCE IN TAF.
OUTLOOK /WEDNESDAY THROUGH SATURDAY/...
WEDNESDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. CHANCE RA.
WEDNESDAY NIGHT: MAINLY MVFR, WITH LOCAL IFR POSSIBLE. BREEZY.
RA.
THURSDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY. CHANCE
RA.
THURSDAY NIGHT: VFR.
FRIDAY: MVFR/IFR CONDITIONS POSSIBLE. CHANCE RA, SLIGHT CHANCE
SN.
FRIDAY NIGHT: MVFR/IFR CONDITIONS POSSIBLE. BREEZY. CHANCE SN,
RA LIKELY.
SATURDAY: MAINLY VFR, WITH AREAS IFR POSSIBLE. BREEZY. CHANCE
SN.
MARINE
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TONIGHT AND TUESDAY...HIGH CONFIDENCE.
A SHORTWAVE TROUGH PASSING TO OUR NORTH WILL INDUCE A MODEST
SOUTHWEST LOW LEVEL JET TONIGHT INTO TUE. DESPITE THE INVERSION
OVER THE RELATIVELY COOL WATERS, STILL EXPECT SW WIND GUSTS OF
20 TO 30 KNOTS TONIGHT INTO THE MIDDLE OF TUE AFTERNOON BEFORE
GRADUALLY STARTING TO DIMINISH. SMALL CRAFT HEADLINES POSTED
MOST WATERS TONIGHT INTO TUE.
TUESDAY NIGHT...HIGH CONFIDENCE.
W WINDS 15-20 KTS, DECREASING TOWARD SUNRISE. SEAS 2-5 FT
DECREASING THROUGH THE OVERNIGHT HOURS.
OUTLOOK /WEDNESDAY THROUGH SATURDAY/...
WEDNESDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING
5 FT. CHANCE OF RAIN.
WEDNESDAY NIGHT: WINDS LESS THAN 25 KT. LOCAL ROUGH SEAS. RAIN.
THURSDAY: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. CHANCE OF
RAIN.
THURSDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS
APPROACHING 5 FT.
FRIDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING 5 FT.
RAIN LIKELY.
FRIDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. RAIN
LIKELY, CHANCE OF SNOW. LOCAL VISIBILITY 1 TO 3 NM.
SATURDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS UP
TO 20 KT. AREAS OF ROUGH SEAS. CHANCE OF SNOW, CHANCE OF RAIN.
VISIBILITY 1 TO 3 NM.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST TUESDAY FOR ANZ231>235-237-
251.
SMALL CRAFT ADVISORY UNTIL 7 PM EST TUESDAY FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR ANZ254>256.
SYNOPSIS...BELK/BW
NEAR TERM...BELK/BW
SHORT TERM...BW
LONG TERM...BELK
AVIATION...BELK/BW
MARINE...BELK/BW
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