134
FXUS61 KBOX 011757
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
157 PM EDT WED JUL 1 2026
WHAT HAS CHANGED
NO SIGNIFICANT CHANGES TO THE FORECAST.
KEY MESSAGES
- DANGEROUS PROLONGED HEAT AND HUMIDITY WED THROUGH SAT WITH MAX
AFTERNOON HEAT INDICES IN THE 98 TO 112 DEGREE RANGE WITH
LITTLE RELIEF AT NIGHT. PEAK OF THE HEAT THU INTO FRI.
- A CLUSTER OF SHOWERS AND A FEW THUNDERSTORMS MAY IMPACT PARTS
OF OUR REGION VERY LATE TODAY INTO TONIGHT. ACTIVITY LIKELY
WEAKENING WITH MAIN SEVERE WEATHER RISK TO OUR NORTHWEST, BUT
CANNOT RULE OUT A LOW RISK ACROSS WESTERN MA/CT.
- W/NW FLOW ALOFT MAY BRING A LOW CONVECTIVE/SEVERE WEATHER RISK
WED-FRI. HOWEVER, LIMITED FORCING AND CAP MAY KEEP US MAINLY
DRY. GREATEST RISK FOR THUNDERSTORMS/SEVERE WEATHER POTENTIAL
MIGHT WAIT UNTIL INDEPENDENCE DAY WITH THE ACTUAL COLD FRONT.
DISCUSSION
KEY MESSAGE 1...DANGEROUS PROLONGED HEAT AND HUMIDITY WED
THROUGH SAT WITH MAX AFTERNOON HEAT INDICES IN THE 98 TO 112
DEGREE RANGE WITH LITTLE RELIEF AT NIGHT. PEAK OF THE HEAT THU
INTO FRI.
HIGH CONFIDENCE FORECAST IN DANGEROUS PROLONGED HEAT AND HUMIDITY
WED THROUGH SAT. FOCUSED THE HEADLINE MESSAGING ON THE PEAK
THREATS RATHER THAN TRYING TO SLICE THE BOLOGNA TOO THIN. THUS,
EXTREME HEAT WARNINGS FOR MOST OF SOUTHERN NEW ENGLAND. HEAT
ADVISORIES FOR THE CAPE AND VINEYARD. THE PEAK OF THIS HEAT
LOOKS TO BE IN THE THURSDAY-FRIDAY TIME FRAME.
HEAT INDICES WILL RISE TO BETWEEN 98 AND 108 DEGREES AWAY FROM
THE SOUTH COAST. THE WORST OF THE HEAT AND HUMIDITY WILL LIKELY
BE IN THE CT AND MERRIMACK RIVER VALLEYS. HIGH TEMPERATURES WILL
LIKELY REACH BETWEEN 97 AND 103 AWAY FROM THE SOUTH COAST AND
ANY VERY LOCALIZED SEA BREEZES. HEAT INDICES WILL REACH DANGEROUS
LEVELS IN THE 102 TO 113 DEGREE RANGE. IT WILL REMAIN HOT AND
HUMID FOR INDEPENDENCE DAY AS WELL. WHILE IT MAY BE A FEW DEGREES
LOWER THAN THU/FRI, DANGEROUS HEAT AND HUMIDITY MAY CONTINUE AND
WILL BE DETERMINED BY THE TIMING OF A COLD FRONT.
NOT ONLY WILL THIS BE A DANGEROUS PROLONGED PERIOD OF HEAT,
THERE WILL BE LITTLE RELIEF AT NIGHT. LOW TEMPERATURES WILL ONLY
DROP INTO THE MIDDLE 70S IN MOST LOCATIONS AND 75 TO 80 DEGREES
IN THE URBAN CENTERS. IN FACT, BOSTON MAY NOT DROP BELOW 80
DEGREES DURING THE PEAK OF THE HEAT AND HUMIDITY!
KEY MESSAGE 2...A CLUSTER OF SHOWERS AND A FEW THUNDERSTORMS MAY
IMPACT PARTS OF OUR REGION VERY LATE TODAY INTO TONIGHT. ACTIVITY
LIKELY WEAKENING WITH MAIN SEVERE WEATHER RISK TO OUR NORTHWEST,
BUT CANNOT RULE OUT A LOW RISK ACROSS WESTERN MA/CT.
THE OTHER CONCERN FOR LATE TODAY AND ESPECIALLY TONIGHT IS A
SHORTWAVE THAT WILL BE DROPPING SOUTHEAST IN NORTHWEST FLOW ALOFT
AROUND THE DEVELOPING RING OF FIRE. EFFECTIVE SHEAR OF 30-40 KNOTS
IS FAVORABLE FOR THIS ACTIVITY TO WORK INTO OUR REGION...BUT
INSTABILITY WILL BE RATHER MARGINAL. SO EXPECT A CLUSTER OF
WEAKENING SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS TO
IMPACT PORTIONS OF OUR REGION. THE GREATEST RISK IS ACROSS WESTERN
MA/CT. THE OVERALL SEVERE WEATHER THREAT IS LOW GIVEN THE LIMITED
INSTABILITY IN OUR REGION...BUT GIVEN NORTHWEST FLOW ALOFT AND
LINGERING MOMENTUM CAN NOT RULE OUT A LOW PROBABILITY FOR SOME
SEVERE WEATHER IN WESTERN MA/CT. HOWEVER...CURRENTLY THINKING
GREATEST RISK IS NORTHWEST OF OUR REGION.
KEY MESSAGE 3...W/NW FLOW ALOFT MAY BRING A LOW CONVECTIVE/SEVERE
WEATHER RISK WED-FRI. HOWEVER, LIMITED FORCING AND CAP MAY KEEP
US MAINLY DRY. GREATEST RISK FOR THUNDERSTORMS/SEVERE WEATHER
POTENTIAL MIGHT WAIT UNTIL INDEPENDENCE DAY WITH THE ACTUAL
COLD FRONT.
ANOMALOUS HEAT AND HUMIDITY WILL RESULT IN RATHER HIGH INSTABILITY
ACROSS OUR REGION WED THROUGH FRI. IN ADDITION, A REMNANT EML
IN NORTHWEST FLOW ALOFT IS PRESENT. IF SOMEHOW A FEW THUNDERSTORMS
DO DEVELOP, THEY COULD QUICKLY BECOME SEVERE, EVEN DURING THE
OVERNIGHT/MORNING HOURS. HOWEVER, A LACK OF OVERALL SYNOPTIC
FORCING AND A MID LEVEL CAP SHOULD KEEP THIS RISK LOW. THIS
POTENTIAL WILL STILL NEED TO WATCHED. GREATEST RISK FOR
CONVECTION AND POTENTIALLY SOME SEVERE WEATHER MAY WAIT UNTIL
INDEPENDENCE DAY WHEN A COLD FRONT AND STRONGER FORCING ARRIVES.
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...
TODAY THROUGH THURSDAY...HIGH CONFIDENCE OUTSIDE OF DURATION OF
THE SEABREEZE AT KBOS THROUGH THIS EVENING, IN ADDITION TO FOG
OVER EASTERN MA AND THE CAPE AFTER 06Z TONIGHT.
VFR CONDITIONS WILL DOMINATE THIS AFTERNOON THROUGH THURSDAY.
SW WINDS WILL GENERALLY GUST 15 TO 20 KNOTS LATER TODAY AND
AGAIN THU...WHILE PARTS OF THE CAPE/ISLANDS GUST TO 25 KNOTS AND
PERHAPS BRIEFLY AROUND 30 KNOTS IN THE TYPICALLY PRONE SPOTS.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF BUT WILL NEED TO WATCH
FOR THE DURATION OF THE SEABREEZE THIS AFTERNOON. CURRENT
THINKING IS THAT THE WINDS SHOULD TRANSITION BACK TO THE SW BY
21-22Z.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK /THURSDAY NIGHT THROUGH MONDAY/...
THURSDAY NIGHT THROUGH FRIDAY: VFR. BREEZY.
FRIDAY NIGHT: VFR.
INDEPENDENCE DAY THROUGH SUNDAY: VFR. SLIGHT CHANCE SHRA,
SLIGHT CHANCE TSRA.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TODAY THROUGH THURSDAY...HIGH CONFIDENCE.
BERMUDA HIGH PRESSURE WILL RESULT IN A PERSISTENT SW FLOW ACROSS OUR
WATERS. SW WINDS WILL GUST TO 25 KNOTS AT TIMES TODAY THROUGH
THURSDAY AND LONG FETCH WILL RESULT IN SEAS BUILDING TO 3 TO 6 FEET
ACROSS OUR SOUTHERN WATERS. THEREFORE...WE HAVE CONTINUED SMALL
CRAFT HEADLINES FOR OUR SOUTHERN WATERS INTO THURSDAY.
OUTLOOK /THURSDAY NIGHT THROUGH MONDAY/...
THURSDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH
GUSTS UP TO 25 KT. SEAS UP TO 5 FT.
FRIDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING 5 FT.
FRIDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING
5 FT.
INDEPENDENCE DAY: WINDS LESS THAN 25 KT.
SATURDAY NIGHT: WINDS LESS THAN 25 KT. SLIGHT CHANCE OF RAIN
SHOWERS, SLIGHT CHANCE OF THUNDERSTORMS.
SUNDAY: WINDS LESS THAN 25 KT. SLIGHT CHANCE OF RAIN SHOWERS.
CLIMATE
RECORD HIGH TEMPERATURES:
JULY 1:
KBOS: 98/1872
KBDL: 101/1964
KPVD: 97/1964
KORH: 94/1913
JULY 2:
KBOS: 98/1963
KBDL: 99/1966
KPVD: 98/1941
KORH: 97/1901
JULY 3:
KBOS: 102/1911
KBDL: 102/1966
KPVD: 98/2002
KORH: 96/1911
JULY 4:
KBOS: 104/1911
KBDL: 99/1911
KPVD: 99/1919
KORH: 102/1911
RECORD HIGH MINIMUM TEMPERATURES:
JULY 1:
KBOS: 73/1958
KBDL: 73/1968
KPVD: 71/1968
KORH: 72/2018
JULY 2:
KBOS: 76/2002
KBDL: 73/2018
KPVD: 75/1941
KORH: 73/1963
JULY 3:
KBOS: 80/2002
KBDL: 73/2018
KPVD: 78/2002
KORH: 72/2002
JULY 4:
KBOS: 77/2002
KBDL: 74/2018
KPVD: 77/2002
KORH: 73/2018
JULY 5:
KBOS: 81/1999
KBDL: 77/1999
KPVD: 78/1999
KORH: 73/1999
BOX WATCHES/WARNINGS/ADVISORIES
CT...EXTREME HEAT WARNING UNTIL 8 PM EDT SATURDAY FOR CTZ002>004.
AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR CTZ002>004.
MA...EXTREME HEAT WARNING UNTIL 8 PM EDT SATURDAY FOR MAZ002>021-
026.
AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR MAZ004>024-
026.
HEAT ADVISORY UNTIL 8 PM EDT SATURDAY FOR MAZ022-023.
RI...EXTREME HEAT WARNING UNTIL 8 PM EDT SATURDAY FOR RIZ001>007.
AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR RIZ001>008.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THURSDAY FOR ANZ231>235-
237.
SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ236.
SMALL CRAFT ADVISORY UNTIL 1 AM EDT FRIDAY FOR ANZ254>256.
DISCUSSION...FRANK
AVIATION...BOATMAN
MARINE...FRANK
CLIMATE...FT
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