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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