428
FXUS61 KBOX 121844
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
244 PM EDT WED AUG 12 2026
WHAT HAS CHANGED
GROWING RISK FOR LATE EVENING AND OVERNIGHT SHOWERS AND STORMS
MAINLY SOUTH OF THE MASS PIKE, BUT SEVERE WEATHER ISN'T
ANTICIPATED FROM THESE STORMS.
KEY MESSAGES
- SHOWERS AND THUNDERSTORMS MOVE EAST-SOUTHEAST FROM NY AFTER
MIDNIGHT AND OVERNIGHT MAINLY FOR AREAS SOUTH OF THE MASS
PIKE. TURNING MORE HUMID TOO.
- EARLY CLOUD COVER THURSDAY DISSIPATES, BUT ISOLATED TO WIDELY
SCATTERED SHOWERS/WEAKER STORMS DEVELOP ACROSS NORTHERN MA.
- BECOMING COOLER AND LESS HUMID FRIDAY THROUGH SATURDAY NIGHT.
A PERIOD OF SHOWERS AND POSSIBLE THUNDERSTORMS SUNDAY
AFTERNOON INTO MONDAY NIGHT. DRY WEATHER SHOULD RETURN TUESDAY
AND WEDNESDAY.
DISCUSSION
KEY MESSAGE 1...SHOWERS AND THUNDERSTORMS MOVE EAST-SOUTHEAST FROM
NY AFTER MIDNIGHT AND OVERNIGHT MAINLY FOR AREAS SOUTH OF THE MASS
PIKE. TURNING MORE HUMID TOO.
SEASONABLY MILD WITH TOLERABLE HUMIDITY LEVELS CURRENTLY AS OF
WEDNESDAY AFTERNOON, BUT WE'RE LOOKING AT SOME CHANGES TO OUR
AIRMASS OVER THE NEXT 12-24 HOURS. COUPLE WEAK IMPULSES IN BROAD WNW
FLOW ALOFT ARE CONTRIBUTING TO SCATTERED SHOWERS WITH A FEW
THUNDERSTORMS. ONE IS WORKING THROUGH FAR NORTHEAST ONTARIO,
RESPONSIBLE FOR THE AREA OF SHOWERS AND STORMS OVER VT/NORTHERN NY.
THESE SHOULD PASS TO OUR NORTH BUT A COUPLE COULD CLIP PART OF ESSEX
COUNTY AND THE NORTH SHORE THROUGH SUNDOWN.
THE MORE SIGNIFICANT FEATURE TO SOUTHERN NEW ENGLAND COMES IN THE
FORM OF A WEAK IMPULSE ON WATER VAPOR IMAGERY NEAR THE NORTHERN
PORTION OF LAKE MICHIGAN, WHICH IS CURRENTLY HELPING TO PRODUCE
SCATTERED SHOWERS AND STORMS WHEN COUPLED WITH ISENTROPIC ASCENT
ASSOCIATED WITH A SURFACE WARM FRONT/HIGHER DEWPOINTS IN THE MID 60S
OVER GREATER TORONTO AND BUFFALO NY AREAS. NBM AND CAMS WERE
PREVIOUSLY SLOW TO RESOLVE THESE, BUT THE PAST FEW CYCLES HAVE SHOWN
MORE OF A RISK FOR SHOWERS AND STORMS MORE CONCENTRATED ALONG AND
SOUTH OF THE MASS PIKE AND PARTICULARLY FOR THE HARTFORD-PROVIDENCE-
SOUTHEAST MA AREA AROUND/AFTER MIDNIGHT AND INTO OVERNIGHT. MID-
LEVEL LAPSE RATES AROUND 6 TO 6.5 C/KM BUT WITH DEWPOINTS RISING
INTO THE MID 60S, MOST-UNSTABLE CAPE VALUES RISE TO ABOUT 1000-1200
J/KG IN THE CT-RI AREA. EXPECT A FEW THUNDERSTORMS TO BE AROUND BUT
SHOULD BE ELEVATED, WITH A COUPLE STRONGER STORMS CAPABLE OF
FREQUENT LIGHTNING, PEA TO DIME SIZE HAIL AND WIND GUSTS AROUND 40
MPH AS THEY MOVE OFF TOWARD THE SOUTHEAST AT A FAIRLY GOOD CLIP
GIVEN FAST WNW WINDS ALOFT. NOT THINKING STORMS RISE TO THE LEVEL OF
SEVERE WEATHER. OTHERWISE, WILL TURN A BIT MORE HUMID THAN IT'S BEEN
BUT NOT OPPRESSIVE, WITH LOWS IN THE MID TO UPPER 60S.
KEY MESSAGE 2...EARLY CLOUD COVER THURSDAY DISSIPATES, BUT ISOLATED
TO WIDELY SCATTERED SHOWERS/WEAKER STORMS DEVELOP ACROSS NORTHERN MA.
SHOWERS/EMBEDDED STORMS FROM OVERNIGHT SHOULD BE PEELING OFFSHORE
EARLY THURSDAY MORNING, WITH CONSIDERABLE CLOUDINESS AROUND DURING
THE MORNING HOURS. GRADUAL HEATING AND MIXING SHOULD ALLOW FOR CLOUD
COVER TO SCATTER OUT. WHILE MOST OF THE DAY SHOULD BE MORE-OR-LESS
DRY, THERE IS A RISK FOR MID-AFTERNOON SHOWERS OR WEAK THUNDERSTORMS
MAINLY NORTH OF THE MASS PIKE AS A STRONGER SHORTWAVE TROUGH ALOFT
MOVES FROM NORTHERN QUEBEC INTO ME/NH AND SWINGS A COLD FRONT
SOUTHWARD. I THINK THE COVERAGE AND STRENGTH OF SHOWERS OR WEAK
STORMS COULD BE LIMITED BY DRIER AIR ALOFT, TO GO ALONG WITH DELAYED
HEATING/DESTABILIZATION, SO HAVE CAPPED POPS TO NO MORE THAN 30%. SO
WHILE THURSDAY ENDS UP DRY, THERE SHOULD BE SOME SHOWERS OR WEAK
STORMS TO DODGE THURSDAY AFTERNOON THROUGH SUNDOWN, BUT NOTHING THAT
LOOKS HAZARDOUS. WILL BEGIN TO TURN LESS HUMID LATE UPON COLD
FRONTAL PASSAGE.
KEY MESSAGE 3...BECOMING COOLER AND LESS HUMID FRIDAY THROUGH
SATURDAY NIGHT. A PERIOD OF SHOWERS AND POSSIBLE THUNDERSTORMS
SUNDAY AFTERNOON INTO MONDAY NIGHT. DRY WEATHER SHOULD RETURN
TUESDAY AND WEDNESDAY.
GAINING SOME CLARITY THAT A COLD FRONT SHOULD BE OVER THE COASTAL
WATERS FRIDAY MORNING AND MOVING FARTHER OFFSHORE DURING THE DAY.
HIGH PRESSURE THEN SETTLES ACROSS SOUTHERN NEW ENGLAND FOR SATURDAY,
BEFORE IT TOO MOVES OFFSHORE SUNDAY. THE MAIN IMPACT WILL BE DRIER
AND COOLER CONDITIONS DURING THIS TIME.
ANTICIPATING A BRIEF CHANGE BACK TO MORE HUMID CONDITIONS LATE
SUNDAY INTO MONDAY NIGHT. THIS SHOULD BE WHEN A LOW PRESSURE PASSES
BY TO OUR NORTH, BUT DRAGS ITS ASSOCIATED FRONTS THROUGH SOUTHERN
NEW ENGLAND. THE COMBINATION OF THE INCREASED HUMIDITY AND THE LIFT
FROM SOME FRONT MEANS AT LEAST A PERIOD OF SHOWERS. NOT OVERLY
CONCERNED ABOUT THUNDERSTORMS JUST YET, BUT WILL NEED TO KEEP THIS
IN MIND WITH LATER FORECASTS. THIS SHOULD NOT BE A WASHOUT THIS
ENTIRE TIME, BUT THE GREATEST RISK FOR SHOWERS LOOKS TO BE SUNDAY
NIGHT.
A LARGE HIGH PRESSURE OVER THE MIDWEST SHOULD START NUDGING INTO OUR
REGION TUESDAY AND BE MORE OF A FACTOR IN OUR WEATHER DURING THE
MIDDLE OF NEXT WEEK.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
18Z TAF UPDATE:
THROUGH 00Z THURSDAY: HIGH CONFIDENCE.
VFR. SHRA/ROGUE TS DEVELOPING IN VT/NH MAKES A CLOSE PASS ESE
BUT SHOULD END NORTH OF TAFS THROUGH 00Z. N/NE WINDS UNDER 10
KT, WITH SEABREEZES AT BOS.
TONIGHT: HIGH CONFIDENCE OVERALL BUT MODERATE CONFIDENCE ON
TIMING.
VFR INITIALLY, BUT SHRA/EMBEDDED WEAK TS COMING IN FROM THE NW
AFTER 03Z WILL DETERIORATE CONDITIONS INTO THE VFR/MVFR RANGE.
BKN/OVC VFR/MVFR CEILINGS WITH SHRA MORE LIKELY FOR BDL, BUT
HAVE LEFT AS PROB30S AFTER 06Z FOR BOS, PVD AND ORH AND THE CAPE
AIRPORTS. WINDS BECOME SW 5-10 KT.
THURSDAY: MODERATE CONFIDENCE.
LINGERING SHRA/PSBL TS MAINLY PVD AND CAPE AIRPORTS SHOULD MOVE
OFFSHORE BY 14Z. LEFTOVER SCT/BKN VFR/MVFR DECKS SHOULD BEGIN TO
SCATTER OUT BY 15-17Z, WHICH WILL INCREASE THE RISK FOR SHRA/TS
MAINLY FROM THE MASS PIKE NORTH AS SFC COLD FRONT MOVES THROUGH.
COVERAGE LOOKS TOO SPOTTY FOR A TAF MENTION BUT WILL NEED TO BE
CONSIDERED IN LATER TAF ISSUANCES. WINDS SW TO W UNDER 10 KT,
THEN SHIFT TO WNW/NW 5-10K KT AFTER 20Z.
THURSDAY NIGHT: HIGH CONFIDENCE.
SHRA DISSIPATES EARLY TO VFR. NW WINDS 5-10 KT.
KBOS TERMINAL...HIGH CONFIDENCE.
KBDL TERMINAL...HIGH CONFIDENCE.
OUTLOOK /THURSDAY NIGHT THROUGH MONDAY/...
FRIDAY THROUGH SATURDAY NIGHT: VFR.
SUNDAY: VFR. BREEZY. CHANCE SHRA.
SUNDAY NIGHT: VFR. BREEZY. CHANCE SHRA, SLIGHT CHANCE TSRA.
MONDAY: VFR. BREEZY. CHANCE SHRA.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
THROUGH THURSDAY NIGHT: HIGH CONFIDENCE.
SUB-SCA WINDS AND SEAS THROUGH THE PERIOD. N WINDS UNDER 10 KT
SHIFT TO SW EARLY TONIGHT AROUND 10-15 KT, THEN REMAIN SO UNTIL
FRONTAL PASSAGE LATE THURS/EARLY THURS NIGHT WITH WINDSHIFT TO
NW AROUND 10-15 KT. SEAS 3 FT OR LESS ALL WATERS. POSSIBLE
THUNDERSTORMS OVER MAINLY SOUTHERN WATERS OVERNIGHT TONIGHT,
THEN MORE ISOLATED SHRA THURS AFTERNOON OVER NORTHEAST WATERS.
OUTLOOK /THURSDAY NIGHT THROUGH MONDAY/...
FRIDAY THROUGH SATURDAY NIGHT: WINDS LESS THAN 25 KT.
SUNDAY: WINDS LESS THAN 25 KT. SLIGHT CHANCE OF RAIN SHOWERS.
SUNDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS.
CHANCE OF RAIN SHOWERS, SLIGHT CHANCE OF THUNDERSTORMS.
MONDAY: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS. CHANCE OF
RAIN SHOWERS.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...NONE.
DISCUSSION...BELK/LOCONTO
AVIATION...BELK/LOCONTO
MARINE...BELK/LOCONTO
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