277
FXUS61 KBOX 021750
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
150 PM EDT THU JUL 2 2026
WHAT HAS CHANGED
NO SIGNIFICANT CHANGES TO THE FORECAST.
KEY MESSAGES
- DANGEROUS PROLONGED HEATWAVE CONTINUES THROUGH SAT JULY 4TH.
AFTERNOON HEAT INDICES OF 100 TO 115 DEGREES TODAY & FRI BUT
STILL 95 TO 100+ ON SAT. LITTLE RELIEF AT NIGHT EITHER.
- LOW CONVECTIVE/SEVERE WEATHER PROBABILITY TODAY AND TONIGHT
GIVEN THE LACK OF FORCING...BUT IF ISOLATED STORMS ARE ABLE TO
DEVELOP THEY COULD BECOME SEVERE. THE THUNDERSTORM AND SEVERE WEATHER
POTENTIAL INCREASES LATE FRI AND/OR SAT AHEAD OF AN APPROACHING
COLD FRONT.
- RELIEF FROM THE HEAT WITH COOLER/SEASONABLE TEMPERATURES
RETURNING FOR THE FIRST HALF OF NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...DANGEROUS PROLONGED HEATWAVE CONTINUES THROUGH
SAT JULY 4TH. AFTERNOON HEAT INDICES OF 100 TO 115 DEGREES TODAY
AND FRI BUT STILL 95 TO 100+ ON SAT. LITTLE RELIEF AT NIGHT EITHER.
THE PEAK OF THIS DANGEROUS HEATWAVE WILL BE TODAY AND FRIDAY AND THE
MODEL GUIDANCE CONTINUES TO INDICATE SOME VERY IMPRESSIVE PARAMETERS
FOR EXTREME HEAT. 925T ARE INDICATED TO BE IN THE +28C TO +30C RANGE
TODAY AND FRIDAY. GIVEN WESTERLY FLOW THINKING THAT NEAR RECORD HIGH
TEMPERATURES IN THE 97 TO 103 DEGREE RANGE ARE REASONABLE TODAY WITH
PLENTY OF SUNSHINE AND A VERY WARM START. MORE IMPORTANTLY...VERY
HIGH DEWPOINTS WILL RESULT IN DANGEROUS HEAT INDICES OF 105 TO 115
DEGREES THIS AFTERNOON! NEAR RECORD HIGH TEMPERATURES ARE EXPECTED
AGAIN ON FRIDAY. PERHAPS A DEGREE OR TWO LOWER IN SOME SPOTS...BUT
GENERALLY IN THE 96 TO 102 DEGREE RANGE. HEAT INDICES WILL AGAIN BE
AT EXTREME/DANGEROUS LEVELS ON THE ORDER OF 100 TO 110 DEGREES.
WHILE SAT JULY 4TH SHOULD NOT BE AS EXTREME AS TODAY AND FRIDAY
GIVEN HEIGHT FALLS AND SOMEWHAT LOWER MID LEVEL TEMPERATURES...STILL
EXPECTING HIGH TEMPERATURES INTO THE 90S WITH HEAT INDICES OF 95-
100+ DEGREES WHEN MANY HAVE OUTDOOR ACTIVITIES PLANNED. SO IN A
NUTSHELL...THE DANGEROUS HEAT AND HUMIDITY WILL CONTINUE THROUGH
SAT JULY 4TH.
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, THE URBAN HEAT ISLAND OF BOSTON MAY STRUGGLE TO
DROP BELOW 80 TONIGHT AND FRIDAY NIGHT.
KEY MESSAGE 2...LOW CONVECTIVE/SEVERE WEATHER PROBABILITY TODAY AND
TONIGHT GIVEN THE LACK OF FORCING...BUT IF ISOLATED STORMS ARE ABLE
TO DEVELOP THEY COULD BECOME SEVERE. THE THUNDERSTORM AND SEVERE
WEATHER POTENTIAL INCREASES LATE FRI AND/OR SAT AHEAD OF AN
APPROACHING COLD FRONT.
MOST OF THE MODEL GUIDANCE HAS STRUGGLED IN CAPTURING THE CONVECTIVE
COMPLEXES THAT HAVE IMPACTED PARTS OF THE NORTHEAST THE LAST COUPLE
OF DAYS. THINKING THE RISK FOR TODAY AND TONIGHT IS SOMEWHAT LOWER
THAN THE LAST TWO DAYS...BUT AN ISOLATED THUNDERSTORM RISK STILL
EXISTS. THE UPPER LEVEL FORCING IS QUITE MEAGER TODAY AND THERE WILL
BE A MID LEVEL CAP IN PLACE. NONETHELESS...VERY HIGH INSTABILITY
WILL DEVELOP FOR SOUTHERN NEW ENGLAND STANDARDS COUPLED WITH A
REMNANT EML. SO IF WE ARE ABLE TO GET A FEW STORMS TO DEVELOP FROM
ELEVATED HEATING/LOCALIZED CONVERGENCE THEY COULD BECOME SEVERE IN
THIS ENVIRONMENT. HOWEVER...THINKING IF ANY DO DEVELOP THEY WILL BE
RATHER ISOLATED WITH A MUCH MORE LIMITED COVERAGE THAN THE PAST TWO
DAYS.
WE DO THINK THE THUNDERSTORM AND SEVERE WEATHER POTENTIAL WILL
INCREASE LATE FRI AND/OR SAT WITH HEIGHT FALLS ASSOCIATED WITH A
COLD FRONT. THIS IS ALSO INDICATED BY THE MACHINE LEARNING
GUIDANCE...BUT WILL HAVE TO WAIT UNTIL WE GET MORE INSIDE THE HIGH
RESOLUTION MODEL WINDOW TO HAVE ANY MORE SPECIFICS. THE MACHINE
LEARNING GUIDANCE DOES INDICATE THAT IF WE DO GET SEVERE
WEATHER...GREATEST RISK WOULD BE STRAIGHT LINE WIND DAMAGE...BUT
HIGH PWATS ALSO WILL BRING A CONCERN FOR LOCALIZED TORRENTIAL
RAINFALL/STREET FLOODING AS WELL AS DANGEROUS CLOUD TO GROUND
LIGHTNING.
KEY MESSAGE 3...RELIEF FROM THE HEAT WITH COOLER/SEASONABLE
TEMPERATURES RETURNING FOR THE FIRST HALF OF NEXT WEEK.
LONG RANGE ENSEMBLE GUIDANCE IS IN GOOD AGREEMENT IN THE UPPER LEVEL
RIDGE BREAKING DOWN. THIS WILL BRING AND END TO THE EXTREME HEAT.
COOLER/SEASONABLE TEMPERATURES RETURN SUNDAY AND CONTINUE INTO NEXT
WEEK!
AVIATION /18Z THURSDAY THROUGH TUESDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
18Z TAF UPDATE...
TODAY THROUGH FRIDAY...HIGH CONFIDENCE.
MAINLY VFR CONDITIONS INTO FRIDAY EVENING. FEW TO SCT CUMULUS AT
7000-8000 FT HAS DEVELOPED, BUT THE DECKS HAVE REMAINED SHALLOW.
CAPPING HAS KEPT CONVECTION FROM INITIATING, AND THAT SHOULD
CONTINUE THROUGH MUCH OF THIS AFTERNOON AND EVENING. FOG/STRATUS
DEVELOPMENT AGAIN LIKELY LATE THIS EVENING AND OVERNIGHT FOR
TERMINALS ACROSS THE CAPE AND ISLANDS. GREATER RISK FOR SOME
THUNDERSTORMS IN STORE FOR SATURDAY.
WESTERLY WINDS MAY GUST TO 20-25 KNOTS THIS AFTERNOON WITH SOME
SW WIND GUSTS AROUND 25 KNOTS TOWARDS THE CAPE AND ISLANDS.
ANOTHER ROUND OF WESTERLY 20+ KNOT GUSTS WILL DEVELOP AGAIN
DURING THE DAY FRIDAY.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. THINKING GRADIENT REMAINS
STRONG ENOUGH TODAY TO PREVENT A SEA BREEZE.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK /FRIDAY NIGHT THROUGH TUESDAY/...
INDEPENDENCE DAY: VFR. BREEZY. SCATTERED SHRA, SCATTERED TSRA.
SATURDAY NIGHT: VFR. BREEZY. ISOLATED SHRA, ISOLATED TSRA.
SUNDAY: VFR. SLIGHT CHANCE SHRA, SLIGHT CHANCE TSRA.
SUNDAY NIGHT: VFR. CHANCE SHRA.
MONDAY: VFR. CHANCE SHRA, SLIGHT CHANCE TSRA.
MONDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. CHANCE
SHRA.
TUESDAY: VFR. BREEZY. SLIGHT CHANCE SHRA.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TODAY THROUGH FRIDAY...HIGH CONFIDENCE.
SW WINDS WILL GUST TO 25 KNOTS AT TIMES TODAY AND LONG FETCH WILL
RESULT IN 3 TO 5 FOOT ACROSS OUR SOUTHERN WATERS. THEREFORE...WE
HAVE CONTINUED SMALL CRAFT HEADLINES FOR OUR SOUTHERN WATERS TODAY.
WINDS SHOULD DIMINISH A TAD AND TURN TO MORE OF A WESTERLY COMPONENT
TONIGHT INTO FRIDAY...ALLOWING US TO DROP THE SMALL CRAFT HEADLINES
BY THAT TIME.
OUTLOOK /FRIDAY NIGHT THROUGH TUESDAY/...
INDEPENDENCE DAY THROUGH SATURDAY NIGHT: WINDS LESS THAN 25 KT.
SCATTERED RAIN SHOWERS, SCATTERED THUNDERSTORMS.
SUNDAY: WINDS LESS THAN 25 KT.
SUNDAY NIGHT: WINDS LESS THAN 25 KT. CHANCE OF RAIN SHOWERS.
MONDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.
CHANCE OF RAIN SHOWERS, SLIGHT CHANCE OF THUNDERSTORMS.
MONDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT. CHANCE OF RAIN SHOWERS.
TUESDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING 5 FT.
SLIGHT CHANCE OF RAIN SHOWERS.
CLIMATE
RECORD HIGH TEMPERATURES:
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 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.
MA...EXTREME HEAT WARNING UNTIL 8 PM EDT SATURDAY FOR MAZ002>021-
026.
AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR MAZ006-007-
013>024.
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 THIS EVENING FOR
ANZ231>235-237.
SMALL CRAFT ADVISORY UNTIL 1 AM EDT FRIDAY FOR ANZ254>256.
DISCUSSION...FRANK
AVIATION...BOATMAN
MARINE...FRANK
CLIMATE...FT
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