005
FXUS61 KBOX 122354
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
754 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 /00Z THURSDAY THROUGH MONDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TONIGHT: HIGH CONFIDENCE IN TRENDS, BUT MODERATE CONFIDENCE IN
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/POSSIBLE 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 /FRIDAY 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 /FRIDAY 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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