002
FXUS61 KBOX 261431
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
1031 AM EDT SUN MAR 26 2023
SYNOPSIS
DRY AND MILD WEATHER TODAY BUT WITH A GUSTY WIND. HIGH PRESSURE
BUILDS IN TONIGHT WITH CLEAR AND COLD CONDITIONS. THE NEXT
SYSTEM BRINGS RAIN AND SNOW LATE ON MONDAY INTO TUESDAY AS LOW
PRESSURE TRACKS SOUTH OF NEW ENGLAND. APPEARS DRIER WEDNESDAY
THROUGH THURSDAY AS HIGH PRESSURE NUDGES IN. UNSETTLED LATE IN
THE WEEK AND HEADING INTO THE WEEKEND.
NEAR TERM /UNTIL 6 PM THIS EVENING/
1015 AM UPDATE:
MADE SMALL ADJUSTMENTS TO SKY COVER, DEWPOINTS AND WINDS/GUSTS
WITH THIS UPDATE BUT OVERALL THESE CHANGES WERE MINOR AND
FORECAST HOLDING UP WELL.
NOW THAT 0-2KM LAPSE RATES HAVE SWITCHED FROM STABLE TO
UNSTABLE, TRAPPED EARLY-DAY STRATUS AND AREAS OF MIST HAVE NOW
SCATTERED OUT FOR MANY (STILL CONTINUING NEAR NANTUCKET BUT
SHOULD DO SO IN SHORT ORDER). IN ITS PLACE IS VARIABLE BUT
INCREASING COVG OF STRATOCU CLOUDS PER DAY CLOUD PHASE RGB
SATELLITE IMAGERY (MORE NORTH AND WEST), ALONG WITH INCREASINGLY
GUSTY W/WNW WINDS.
ALREADY SEEING W/WNW GUSTS TO 35 MPH AT WORCESTER AIRPORT DUE
TO THE DEEPENING MIXED LAYER, WITH GUSTS AROUND 25-30 MPH BEING
FAIRLY COMMON. EXPECT SPEEDS TO INCREASE IN ALL AREAS BY LATE
MORNING TO MID AFTERNOON WITH WIND DIRECTIONS BECOMING MORE WNW
UPON PASSAGE OF A TROUGH NOW OVER EASTERN NY/WESTERN MA; STILL
A BIT OF A QUESTION HOW STRONG GUSTS MIGHT GET; GFS SHOWS A 850
MB JETCORE OF 45-NEAR 50KT ACROSS AREAS NORTH OF THE MASS PIKE
BY MID TO LATE AFTERNOON. IF MIXING CAN REACH THAT DEPTH WE
COULD REALIZE SOME GUSTS AT NEAR- ADVISORY LEVEL LATER THIS
AFTERNOON BUT IF WE DO IT WOULD BE FAIRLY SHORT LIVED AND
PREDOMINANTLY IN THE HIGHER TERRAIN IN WORCESTER COUNTY AND THE
NORTHERN BERKSHIRES.
ASIDE FROM THE GUSTINESS, OTHERWISE A PLEASANT SUNDAY WITH
MOSTLY SUNNY TO PARTLY CLOUDY CONDITIONS. NO CHANGES TO HIGHS
WHICH STILL LOOK ON TRACK.
PREVIOUS DISCUSSION...
WEAK LOW PRES IN VICINITY OF BUZZARDS BAY LIFTS NE INTO GULF OF
MAINE BY DAYBREAK WITH WIND SHIFT TO WEST. THE WIND SHIFT WILL
ADVECT LOW LEVEL DRY DRIER AIR INTO SNE WHICH WILL RESULT IN STRATUS
LIFTING AND PARTIAL CLEARING AROUND DAYBREAK, ALTHOUGH THE LOW
CLOUDS COULD LINGER A FEW MORE HOURS OVER OUTER CAPE AND NANTUCKET.
LOW AMPLITUDE UPPER TROUGH AXIS WILL BE OVER NEW ENG TODAY WITH
RESIDUAL COLD POOL ALOFT. 500 MB TEMPS AROUND -25C COMBINED WITH
SHALLOW LOW LEVEL MOISTURE WILL LEAD TO SCT-BKN STRATO-CU DEVELOPING
THIS MORNING, WITH MOST COVERAGE ACROSS NORTHERN MA, BUT EXPECT
DECREASING CLOUD COVER HERE MID/LATE AFTERNOON AS MOISTURE
DIMINISHES. OTHERWISE, MOSTLY SUNNY DAY FOR REST OF THE REGION.
SOUNDINGS SHOW A WELL MIXED BOUNDARY LAYER UP TO ABOUT 850 MB SO
EXPECT GUSTY WINDS DEVELOPING WITH WNW GUSTS TO 25-35 MPH AND UP TO
40 MPH OVER THE HIGHER ELEVATIONS. TEMPS AT 850 MB THIS AFTERNOON 0
TO -4C FROM S TO N WHICH SUPPORT HIGHS RANGING FROM UPPER 40S HIGHER
TERRAIN TO UPPER 50S ACROSS CT/RI AND SE MA.
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/
TONIGHT...
HIGH PRES BUILDS IN FROM THE WEST TONIGHT. DRY AIRMASS WITH CLEAR
SKIES AND DIMINISHING WIND WILL LEAD GOOD RADIATIONAL COOLING
OVERNIGHT. LEANED TOWARD COLDER MOS GUIDANCE FOR LOW TEMPS,
GENERALLY MID/UPPER 20S WESTERN MA TO 30-35 ELSEWHERE.
MONDAY...
FAST MOVING FLOW ALOFT WILL BRING NEXT SHORTWAVE TOWARD NEW ENG FROM
THE OHIO VALLEY. SUNSHINE TO START THE DAY, THEN CLOUDS INCREASE AND
THICKEN IN THE AFTERNOON. MUCH OF THE GUIDANCE HAS TRENDED QUICKER
AND MORE AGGRESSIVE WITH PRECIP DEVELOPING AND MOVING INTO SNE LATE
IN THE DAY AS DEEPENING MOISTURE PLUME MOVES IN FROM THE WEST AHEAD
OF THE SHORTWAVE. WE INTRODUCED POPS ACROSS SW HALF OF SNE BUT
FORECAST CONFIDENCE LOWER THAN WHAT WE WOULD LIKE FOR A DAY 2
FORECAST GIVEN THE INCONSISTENCY AMONG THE GUIDANCE SUITE. WHILE
TEMPS ALOFT ARE COLD, BOUNDARY LAYER IS TOO WARM AND SUPPORTS RAIN
BUT TRANSITIONING TO SNOW TOWARD EVENING OVER THE HIGHER ELEVATIONS.
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/
HIGHLIGHTS...
* RAIN CHANGING OVER TO SNOW ACROSS THE INTERIOR LATE MON INTO EARLY
TUE. ELSEWHERE WILL BE A COLD RAIN. LIGHT ACCUMULATIONS POSSIBLE
ACROSS THE HIGHER TERRAIN. PRECIP TAPERS OFF LATE TUE. LOW
CONFIDENCE IN THE FORECAST.
* DRIER ON WED BEFORE A COLD FRONT CROSSES THE REGION LATE WED INTO
THU. DRIER LATE THU INTO EARLY FRI.
* UNSETTLED LATE IN THE WEEK AND HEADING INTO THE WEEKEND.
* TEMPS WILL BE NEAR TO ABOVE NORMAL FOR MUCH OF THE WEEK.
MONDAY NIGHT THROUGH TUESDAY...
A SHORTWAVE TROUGH WILL BE OVER THE MID ATLANTIC LATE ON MON. THE
TROUGH WILL LIFT OFFSHORE BY EARLY TUE. ANOTHER SHORTWAVE WILL LIFT
QUICKLY IN BEHIND THE DEPARTING TROUGH FROM THE OH VALLEY INTO TUE
BEFORE MOVING OFFSHORE LATE IN THE DAY. IN RESPONSE TO THESE
FEATURES A LOW MOVES FROM THE MID ATLANTIC TO SOUTH OF OUR REGION
BEFORE MOVING OFFSHORE.
CONFIDENCE IN THIS PARTICULAR PERIOD IS LOWER THAN WOULD LIKE
ESPECIALLY GIVEN WE ARE TALKING THE DAY 2.5-3 WINDOW. THERE HAS BEEN
CONSIDERABLE UNCERTAINTY IN DETERMINISTIC AND ENSEMBLE GUIDANCE OVER
THE PAST SEVERAL DAYS. THIS IS ESSENTIALLY DUE TO GUIDANCE HAVING
TROUBLE HANDLING CONVECTIVE ACTIVITY OVER THE SOUTHEASTERN US AND OH
VALLEY AND ITS INTERACTION WITH THE TROUGHS. THIS IMPACTS THE TIMING
AND INTENSITY OF THE SYSTEM AS IT MOVES THROUGH.
AT THIS POINT THE 00Z 12KM NAM IS A BIT OF AN OUTLIER BEING THE
SLOWEST WITH MUCH MORE QPF AND ACCUMULATING SNOW POTENTIAL ACROSS
OUR INTERIOR. GIVEN THE NAM 3KM SHOWS A MORE PROGRESSIVE FEEL LIKE
THE GFS/ECMWF/GEM AND EXPLICITLY RESOLVES CONVECTION AM THINKING
THIS IS THE MAIN REASON FOR THE DIFFERENCE. STILL WILL WANT TO KEEP
A CLOSE EYE ON HOW THINGS EVOLVE AS THERE HAS BEEN LITTLE RUN-TO-RUN
AND MODEL TO MODEL CONSISTENCY. DID OPT TO BUMP UP QPF AND SNOWFALL
AMOUNTS A BIT GIVEN THE SHIFT IN GUIDANCE. WE'VE NOW GOT ROUGHLY 60-
100 PERCENT PROBABILITIES OF 24 HR QPF AOA 0.1" PER THE GEFS/GEPS
AND EPS, WHICH IS A BIG JUMP FROM THE PREVIOUS. DUE TO THIS HAVE
BUMPED PRECIP CHANCES UP TO LIKELY MON NIGHT BEFORE GRADUALLY
TAPERING CHANCES OFF INTO EARLY TUE. THE CORRESPONDING 24 HR SNOW
AOA 1" WITH A 10:1 SLR IS ROUGHLY 10-70 PERCENT HEADING INTO TUE AM.
LOOKS LIKE BEST CHANCES ARE ACROSS THE HIGHER TERRAIN AT THIS POINT,
BUT WILL BE DEPENDENT ON THE PRECIP TIMING/INTENSITY. STAY TUNED AS
HOPEFULLY MODELS WILL COME INTO BETTER AGREEMENT LATER TODAY OR
TONIGHT.
EXPECT RAIN TO CHANGE OVER TO SNOW, BUT EVEN MASS FIELDS ARE ALL
OVER THE PLACE AT THIS POINT. HAVE STUCK TOWARD THE GFS/ECMWF/GEM
CONSENSUS AT THIS POINT, BUT THERE WOULD BE MORE ACCUMULATING SNOW
IF THE HEAVIER PRECIP COMES IN LATER. LOWS IN THE 30S ACROSS THE
REGION MON NIGHT HEADING INTO TUE. SHOULD SEE ANY LINGERING SNOW
CHANGE BACK OVER TO RAIN ON TUE AS PRECIP IS GRADUALLY WINDING DOWN.
HIGH TEMPS AROUND SEASONABLE WITH READINGS IN THE 40S TO LOW 50S.
LATE TUESDAY THROUGH WEDNESDAY...
AT THIS POINT GUIDANCE TRENDING TOWARD A DRIER FORECAST. A SHORTWAVE
RIDGE BUILDS FROM THE MID ATLANTIC/EASTERN GREAT LAKES LATE ON TUE
OFFSHORE BY WED AM, WHILE A SHORTWAVE TROUGH UNDERCUTS IT AND LIFTS
FROM THE MID ATLANTIC OFFSHORE TO THE SOUTH OF OUR REGION. A RIDGE
BUILDS ACROSS THE CENTRAL US ON WED, WHILE WE REMAIN UNDER CYCLONIC
FLOW. AT THIS POINT APPEARS THAT HIGH PRESSURE WILL NUDGE INTO OUR
REGION FROM THE OH/TN VALLEY THROUGH THIS PERIOD.
GUIDANCE OVERALL TRENDING IN A DRIER DIRECTION FOR THIS TIMEFRAME AS
HIGH PRESSURE BUILDS IN. THINK THIS IS THE DIRECTION TO GO AT THIS
POINT, BUT THERE ARE SEVERAL EPS MEMBERS STILL FEATURING A COASTAL
SYSTEM OF SOME SORT. THIS IS LIKELY A RESULT OF MORE CONVECTIVE
ACTIVITY INTERACTING WITH THE TROUGH UNDERCUTTING THE RIDGE. GIVEN
THE UNCERTAINTY DURING THE MON-TUE WINDOW DO NOT WANT TO COMPLETELY
RULE THIS OUT QUITE YET. FOR NOW HAVE SLIGHT CHANCES OF PRECIP WITH
NEAR TO ABOVE SEASONABLE TEMPERATURES.
LATE WEDNESDAY THROUGH THURSDAY...
A TROUGH LIFTS FROM THE CENTRAL GREAT LAKES/ONTARIO LATE ON WED INTO
QUEBEC BY EARLY THU. THE RIDGE BUILDS INTO THE MISSISSIPPI RIVER
VALLEY AND CENTRAL GREAT LAKES. A COLD FRONT CROSSES THE REGION AS
HIGH PRESSURE IS NUDGING IN FROM THE SOUTHEASTERN US.
NOT OUT OF THE QUESTION THE COLD FRONT COULD BRING US SOME SHOWER
ACTIVITY LATE ON WED INTO EARLY THU, BUT AT THIS POINT HAVE STUCK
WITH A DRIER FORECAST AS HIGH PRESSURE REMAINS OVER OUR REGION
THROUGH THU. NEAR SEASONABLE TEMPS EXPECTED.
FRIDAY THROUGH SATURDAY...
HAVE STUCK WITH THE NBM FOR THIS TIMEFRAME. THIS WILL BE OUR NEXT
OPPORTUNITY FOR MORE WIDESPREAD RAIN SHOWERS AND PERHAPS A FEW
THUNDERSTORMS. WILL HAVE A TROUGH LIFT FROM THE FOUR CORNERS REGION
EARLY ON FRI INTO THE GREAT LAKES BY LATE FRI/SAT. THIS COULD ALSO
BE OUR NEXT OPPORTUNITY FOR GUSTY WINDS AS NAEFS SHOWS WINDS OF 2-3
STD ABOVE CLIMATOLOGY DURING THIS PERIOD.
AVIATION /14Z SUNDAY THROUGH THURSDAY/
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
15Z TAF UPDATE:
TODAY: HIGH CONFIDENCE.
VFR. INCREASING W TO WNW GUSTS 25 TO 35 KT, PEAKING 16-22/23Z.
GUSTS DIMINISH TO SUSTAINED WINDS AROUND 10 KT AFTER 22/23Z.
TONIGHT...HIGH CONFIDENCE.
VFR WITH W WINDS DIMINISHING. BECOMING LIGHT AND VARIABLE LATE.
MONDAY...MODERATE CONFIDENCE.
VFR IN THE MORNING, THEN LOWERING CIGS WITH RAIN POSSIBLY
MOVING INTO THE REGION FROM THE SW BY LATE IN THE DAY, BUT
TIMING IS UNCERTAIN.
KBOS TERMINAL...HIGH CONFIDENCE. VFR THRU TONIGHT. W GUSTS
25-30 KT SHOULD CONTINUE THRU ABOUT 17-18Z SUN, THEN TURN WNW AT
SIMILAR SUSTAINED AND GUST SPEEDS UNTIL SUNDOWN. OUTSIDE CHANCE
THAT GUSTS EARLY TO MID-AFTN COULD REACH 35 KT.
KBDL TERMINAL...HIGH CONFIDENCE. VFR THRU TONIGHT. SW
GUSTS TO 20-25 KT THRU MIDDAY, THEN BECOME W/WNW 25 KT EARLY TO
MID-AFTN. GUSTS EASE AFTER SUNDOWN.
OUTLOOK /MONDAY NIGHT THROUGH THURSDAY/...
MONDAY NIGHT: MAINLY VFR, WITH AREAS MVFR POSSIBLE. CHANCE RA,
SLIGHT CHANCE SN.
TUESDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. SLIGHT CHANCE
RA.
TUESDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. SLIGHT
CHANCE RA, SLIGHT CHANCE SN.
WEDNESDAY: VFR. BREEZY. SLIGHT CHANCE RA, SLIGHT CHANCE SN.
WEDNESDAY NIGHT THROUGH THURSDAY: VFR. BREEZY.
MARINE
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
OVERALL HIGH CONFIDENCE THROUGH MON.
SMALL CRAFT ADVISORIES POSTED FOR ALL WATERS FOR WEST WIND GUSTS 25-
30 KT, DEVELOPING THIS MORNING AND PERSISTING THROUGH THE AFTERNOON.
WINDS GRADUALLY DIMINISH TONIGHT AS HIGH PRES BUILDS IN FROM THE
WEST. MOSTLY LIGHT WINDS MONDAY UNDER HIGH PRES.
OUTLOOK /MONDAY NIGHT THROUGH THURSDAY/...
MONDAY NIGHT: WINDS LESS THAN 25 KT. CHANCE OF RAIN.
TUESDAY THROUGH WEDNESDAY: WINDS LESS THAN 25 KT. SLIGHT CHANCE
OF RAIN.
WEDNESDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH
GUSTS UP TO 25 KT. AREAS OF SEAS APPROACHING 5 FT. SLIGHT
CHANCE OF RAIN.
THURSDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH
GUSTS UP TO 25 KT. SEAS UP TO 5 FT.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ230-
235-237.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
ANZ231>234-236.
SMALL CRAFT ADVISORY UNTIL 8 AM EDT MONDAY FOR ANZ250-254>256.
SMALL CRAFT ADVISORY UNTIL 2 AM EDT MONDAY FOR ANZ251.
SYNOPSIS...KJC/BL
NEAR TERM...KJC/BL/LOCONTO
SHORT TERM...KJC
LONG TERM...BL
AVIATION...KJC/BL/LOCONTO
MARINE...KJC/BL/LOCONTO
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