068
FXUS61 KBOX 091208
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
808 AM EDT THU JUL 9 2026
WHAT HAS CHANGED
NO CHANGES TO THE FORECAST FOR THIS UPDATE
CYCLE.
KEY MESSAGES
- WARM WITH HIGH HUMIDITY TODAY AND FRIDAY.
- HUMID WITH A CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY AFTERNOON
AND EVENING.
- DRY AND SEASONABLY COOL FOR THE WEEKEND INTO EARLY NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...WARM WITH HIGH HUMIDITY TODAY AND FRIDAY.
A WARMING TREND BEGINS IN EARNEST TODAY AS 925MB TEMPERATURES RISE
TO NEAR 20C WITH THE FULL JULY SUN ANGLE. HIGHS IN THE UPPER 80S TO
NEAR 90 ARE LIKELY ACROSS MOST OF SOUTHERN NEW ENGLAND BY THE
AFTERNOON. EXPECTING A VERY HUMID DAY WITH DEWPOINTS INCREASING TO
NEAR OR JUST ABOVE 70 (AT TIMES) THIS AFTERNOON. A WEAK COLD FRONT
BRINGS A CHANCE FOR WIDELY SCATTERED SHOWERS AND AN ISOLATED STORM
OR TWO. WEAK FORCING FROM A SUBTLE SHORTWAVE SHOULD PREVENT A MORE
WIDESPREAD THREAT FOR STRONG OR SEVERE STORMS. BEST CHANCE FOR
SHOWERS AND THUNDERSTORMS WILL BE ACROSS NORTHWEST MASSACHUSETTS.
ANY STORMS THAT DO FORM WILL HAVE THE POTENTIAL TO PRODUCE FREQUENT
LIGHTNING AND HEAVY RAIN AS PWAT VALUES CLIMB ABOVE 1.7 INCHES.
KEY MESSAGE 2... HUMID WITH A CHANCE OF SHOWERS AND THUNDERSTORMS
FRIDAY AFTERNOON AND EVENING.
WARM AND HUMID CONDITIONS CONTINUE FRIDAY ALTHOUGH IT WILL LIKELY BE
FEW DEGREES COOLER WITH 925MB TEMPS RUNNING ABOUT 3-4C COOLER THAN
THURSDAY. STILL, DEW POINT TEMPERATURES NEAR 70 WILL KEEP APPARENT
TEMPERATURES IN THE UPPER 80S TO LOW 90S. ATTENTION TURNS TO A COLD
COLD FRONT SAGGING SOUTHWARD FROM NORTHERN NEW ENGLAND DURING THE
EARLY AFTERNOON IN NORTHERN MA AND REACHING THE SOUTHERN CT-RI-MA
COASTLINE BY EARLY EVENING. THE ASSOCIATED FORCING WILL BE GREATER
THAN THURSDAY SO THERE WILL BE A GREATER CHANCE FOR MORE WIDESPREAD
SHOWER AND THUNDERSTORM ACTIVITY ON FRIDAY. LATEST GUIDANCE STILL
SHOWS SIGNIFICANT DIFFERENCES IN THE MAGNITUDE OF INSTABILITY AND
THUS THE EVENTUAL CONVECTIVE EVOLUTION FRIDAY AFTERNOON. THE 00Z
NAM'S CAPE VALUES, WHILE SOMEWHAT LOWER THAN PREVIOUS, ARE STILL
AROUND 1500-2500 J/KG DUE TO ITS HIGH-DEWPOINT BIAS. MEANWHILE,
THE GFS'S OVERMIXING BIAS SHOWS CONSIDERABLY LOWER VALUES AT
AROUND 500 J/KG OR LESS. THE ANSWER IS PROBABLY SOMEWHERE IN THE
MIDDLE WITH THE NBM WHICH HAS 800-1300 J/KG BY FRIDAY
AFTERNOON. IN ANY CASE, THE PRIMARY RISKS WITH ANY THUNDERSTORM
LOOKS TO BE LIGHTNING AND SLOW-MOVING HEAVY DOWNPOURS, WHICH
COULD LEAD TO INSTANCES OF STREET FLOODING IN AREAS THAT SEE
REPEATED THUNDERSTORMS. LATEST GUIDANCE INDICATES 700-500 MB
HEIGHTS WHICH BECOME INCREASINGLY PARALLEL TO THE SOUTHWARD-
SAGGING FRONTAL BOUNDARY, WHICH ADDS TO THE RISK FOR SLOWER-
MOVING STORMS AND ALSO CASTS SOME UNCERTAINTY WHEN WE CLEAR OUT,
WITH THE CANADIAN GUIDANCE SUGGESTING POST-FRONTAL LIGHT RAINS
LINGERING INTO PART OF SATURDAY ALONG THE SOUTH COAST.
KEY MESSAGE 3...DRY AND SEASONABLY COOL FOR THE WEEKEND INTO EARLY
NEXT WEEK.
TRENDING MUCH DRIER BEHIND FRIDAY'S COLD FRONT BY SATURDAY WITH ANY
LINGERING MOISTURE PULLING AWAY FROM THE REGION SATURDAY MORNING.
THE 500 MB PATTERN THEN TRANSITIONS TO ONE OF CYCLONIC
FLOW/TROUGHING IN THE MEAN, WHICH FAVORS COOLER TEMPERATURES (LOW TO
MID 80S) AND LOWER HUMIDITY LEVELS THAN EXPERIENCED FOR LATE IN THE
WEEK. WEEKEND APPEARS FAVORABLE FOR OUTDOOR PLANS WITH NICE SUMMER
WEATHER. WE'LL BE ON THE FAR WESTERN PERIPHERY OF A PRETTY
IMPRESSIVE UPPER LEVEL RIDGE WHICH LATEST GUIDANCE STILL SHOWS
REACHING TO NEARLY 600 DM BUILDING OVER THE NORTHERN/CENTRAL PLAINS
AND UPPER MIDWEST. WE STILL MIGHT NEED TO KEEP AN EYE ON POSSIBLE
STORMINESS PIVOTING AROUND THE RIDGE BUT IT LOOKS AS THOUGH THE
WEEKEND INTO EARLY NEXT WEEK ENDS UP DRIER THAN NOT.
AVIATION /12Z THURSDAY THROUGH MONDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TODAY...MODERATE CONFIDENCE.
VFR. AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE AFTER 20Z
ACROSS THE WESTERN TERMINALS.
TONIGHT...MODERATE CONFIDENCE. LOWERING CLOUDS MOVING IN WITH
AREAS OF MVFR AND POSSIBLY IFR.
FRIDAY...MODERATE CONFIDENCE.
MVFR/IFR TOWARDS THE SOUTH COAST EARLY. OTHERWISE, VFR. RISK FOR
AFTERNOON SHOWERS AND THUNDERSTORMS.
KBOS TERMINAL...HIGH CONFIDENCE.
KBDL TERMINAL...HIGH CONFIDENCE.
OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/...
FRIDAY NIGHT: VFR. SLIGHT CHANCE SHRA.
SATURDAY THROUGH MONDAY: VFR.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
THROUGH FRIDAY MORNING...HIGH CONFIDENCE.
MOSTLY TRANQUIL CONDITIONS TODAY AS HIGH PRESSURE BUILDS OVER
THE REGION. A WEAK FRONT APPROACHES THE REGION LATER THIS
AFTERNOON INTO THE EVENING WITH SHOWERS AND THUNDERSTORMS
POSSIBLE OVER THE SOUTHERN WATERS. ANOTHER TRANQUIL START TO THE
DAY FRIDAY WITH SHOWERS AND THUNDERSTORMS DEVELOPING BY THE
AFTERNOON.
OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/...
FRIDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING
5 FT. SLIGHT CHANCE OF RAIN SHOWERS.
SATURDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT.
SATURDAY NIGHT THROUGH SUNDAY: WINDS LESS THAN 25 KT. SEAS
LOCALLY APPROACHING 5 FT.
SUNDAY NIGHT THROUGH MONDAY: WINDS LESS THAN 25 KT.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...NONE.
DISCUSSION...FT
AVIATION...BELK/FT
MARINE...FT
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