059
FXUS61 KBOX 222338
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
738 PM EDT TUE JUL 22 2025
SYNOPSIS
A WARM UP IS ON THE HORIZON AS TEMPERATURES AND HUMIDITY SLOWLY
START TO INCREASE STARTING WEDNESDAY. WARMING TREND PEAKS FRIDAY.
HEAT INDICES MAY REACH THE MID 100S FRIDAY AFTERNOON IN SOME
LOCATIONS IN SOUTHERN NEW ENGLAND DUE TO THE INCREASING HUMIDITY
AND HEAT. A COLD FRONT PASSES THROUGH SOMETIME LATE FRIDAY THAT
WILL LOWER TEMPERATURES A FEW DEGREES FOR THE WEEKEND. CHANCES
FOR SHOWERS AND STORMS WILL LINGER THROUGH THE WEEKEND INTO THE
START OF NEXT WEEK.
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/
KEY MESSAGE:
* MILD TEMPERATURES AGAIN TONIGHT UNDER CLEAR SKIES
DETAILS...
COMFORTABLE TEMPERATURES CONTINUE THIS EVENING AND OVERNIGHT AS HIGH
PRESSURE SITS OVER SOUTHERN ONTARIO. THE HIGH MOVES INTO
QUEBEC/NORTHERN NEW ENGLAND TONIGHT, AND THE WEAK PRESSURE GRADIENT
WILL ALLOW FOR CLEAR SKIES AND RADIATIONAL COOLING ACROSS SOUTHERN
NEW ENGLAND. OVERNIGHT TEMPS IN THE MID TO HIGH 50S FOR MOST OF THE
INTERIOR, BUT THE LOW 60S FOR URBAN AREAS AND THE CAPE.
SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/
KEY MESSAGES:
* DAYTIME TEMPERATURES START TO RISE, BEGINNING AN OVERALL WARMING
TREND.
DETAILS...
AS THE HIGH MOVES OFFSHORE, SURFACE WINDS SHIFT TO BE PREDOMINATELY
SOUTHERLY... ADVECTING MORE WARM, MOIST AIR OFF THE WATER AND
CAUSING DEWPOINTS TO JUMP BACK INTO THE 60S. THIS WILL MARK THE
BEGINNING OF AN UPWARD SHIFT IN TEMPERATURES AND HUMIDITY. 850MB
TEMPERATURES WARM A FEW DEGREES FROM TUESDAY BRINGING HIGHS BACK UP
TO NEAR NORMAL FOR THIS TIME OF YEAR, IN THE UPPER 70S-LOW 80S FOR
THE SOUTH COAST AND CAPE/ISLANDS AND LOW-MID 80S FOR THE REMAINING
AREAS. WHILE HUMIDITY IS EXPECTED TO SLOWLY RISE, THE AIRMASS IS
STILL DRY OVERALL, ALLOWING FOR "FEELS LIKE" TEMPERATURES TO REMAIN
AT OR JUST SLIGHTLY ABOVE THE ACTUAL TEMPERATURES.
LONG TERM /THURSDAY THROUGH TUESDAY/
KEY MESSAGES:
* WARMING TREND PEAKS FRIDAY WITH CONTINUED INCREASING HUMIDITY.
HEAT ADVISORY NOW IN EFFECT FROM 11 AM THURSDAY UNTIL 8 PM FRIDAY
FOR HEAT INDICES RANGING FROM 95-103F.
* DRY THURSDAY BEFORE FRONT ARRIVES FRIDAY, BRINGING CHANCES FOR
SHOWERS AND STORMS THAT COULD EXTEND INTO THE WEEKEND.
* ANOTHER DISTURBANCE FOLLOWING THE WEEKEND FRONT MAY BRING MORE
SHOWERS AND STORMS TO START NEXT WEEK.
DETAILS...
THE AXIS OF A MID-LEVEL RIDGE CONTINUES TO SHIFT SOUTH AND EAST
THURSDAY HEADING INTO FRIDAY, LEADING TO MORE ZONAL FLOW ALOFT OVER
SOUTHERN NEW ENGLAND. ENSEMBLES AND DETERMINISTIC GUIDANCE CONTINUE
TO SHOW A STRONG SIGNAL FOR POSSIBLE DANGEROUS HEAT ON FRIDAY
ESPECIALLY. DETERMINISTIC MODELS AND ENSEMBLE MEANS ALL HAVE 925 MB
TEMPERATURES RANGING FROM 25-28C, MOSTLY STAYING JUST UNDER 30C
ACROSS THE REGION, AND ENSEMBLES HAVE CONTINUED TO SHOW ANOMALOUSLY
HIGH 850 MB TEMPERATURES AROUND 20C. GOOD MIXING WILL NOT ONLY MAKE
IT A BREEZY FRIDAY, BUT IT WILL ALSO HELP BRING DOWN THESE HIGHER
TEMPERATURES ALOFT. WITH INCREASED CONFIDENCE, WE'VE DECIDED TO
ISSUE A HEAT ADVISORY STARTING THURSDAY MORNING GOING THROUGH FRIDAY
EVENING. ALTHOUGH THURSDAY CURRENTLY LOOKS TO BE A MORE MARGINAL
DAY, HEAT INDICES IN THE MID 90S CANNOT BE RULED OUT ACROSS SOUTHERN
NEW ENGLAND. EXCEPTIONS TO THIS ARE THE IMMEDIATE SOUTH COAST AND
THE BERKSHIRES. SW WINDS OFF THE WATER WILL KEEP THE SOUTH COAST
INTO THE CAPE AND ISLANDS COOLER THAN THE REST OF THE REGION, WITH
HIGHS IN THE LOW 80S THURSDAY AND MID 80S FRIDAY. HIGHS OVER THE
REST OF SOUTHERN NEW ENGLAND ARE EXPECTED TO BE IN THE LOW 90S
THURSDAY WITH DEW POINTS APPROACHING 70F, AND HIGHS FRIDAY WILL
CLIMB INTO THE MID 90S WITH HEAT INDICES THAT COULD HIT THE MID 100S.
A FRONT ARRIVES SOMETIME FRIDAY NIGHT THAT WILL INCREASE THE CHANCE
FOR SOME SHOWERS AND STORMS OUT AHEAD OF IT. TIMING IS STILL NOT
COMPLETELY CERTAIN, BUT LATEST GUIDANCE HAS IT MOVING THROUGH
OVERNIGHT. NSSL ML PROBS AND CSU ML PROBS ARE AT 30 PERCENT FOR THE
CHANCE OF SEVERE WEATHER ON FRIDAY, WITH BOTH ENSEMBLES AND
DETERMINISTIC GUIDANCE HINTING AT SOME INSTABILITY THAT COULD FAVOR
SOME STORM DEVELOPMENT. HIGHS WILL DROP A FEW DEGREES IN THE WAKE OF
THIS FRONT, BUT THE HUMIDITY IS EXPECTED TO REMAIN THROUGH THE
WEEKEND. ANY RESIDUAL BOUNDARIES IN THE AREA WILL KEEP THE CHANCE
FOR SOME SHOWERS AND STORMS IN THE MIX THROUGH THE WEEKEND.
ANOTHER DISTURBANCE OR TWO MAY PASS THROUGH THE REGION HEADING INTO
THE START OF NEXT WEEK. ENSEMBLE MEAN PWAT VALUES ARE RANGING FROM
1.25-1.50" FOR MONDAY, AND THERE'S A LOW SIGNAL AT THIS TIME FOR
SOME INSTABILITY. SOME SHOWERS MAY LINGER INTO THE START OF NEXT
WEEK, BUT TIMING AND OTHER DETAILS ARE STILL UNCERTAIN AT THIS
TIME.
AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
00Z TAF UPDATE:
THROUGH TONIGHT...MODERATE CONFIDENCE.
VFR WITH A CHANCE AT MVFR OR EVEN IFR FOR PARTS OF THE CT VALLEY
AND THE CAPE AND ISLANDS DUE TO RADIATIONAL FOG. WINDS
APPROACHING OR BECOMING CALM ACROSS SOUTHERN NEW ENGLAND,
OTHERWISE PRIMARILY S TO SSW.
WEDNESDAY...HIGH CONFIDENCE.
VFR. WINDS PRIMARILY S TO SW AT 5-10 KTS.
WEDNESDAY NIGHT...HIGH CONFIDENCE.
VFR. WINDS BECOMING MORE SW AT 6-12 KTS. GUSTIER WINDS START
KICKING UP AROUND SUNRISE.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.
KBDL TERMINAL...MODERATE CONFIDENCE IN TAF.
POSSIBLE MVFR/IFR TONIGHT DUE TO RADIATIONAL FOG, BUT CONFIDENCE
NOT HIGH ENOUGH TO INCLUDE IN TAF AT THIS TIME.
OUTLOOK /THURSDAY THROUGH SUNDAY/...
THURSDAY: VFR. BREEZY.
THURSDAY NIGHT: MAINLY VFR, WITH LOCAL IFR POSSIBLE. BREEZY.
FRIDAY: VFR. BREEZY. SLIGHT CHANCE SHRA, SLIGHT CHANCE TSRA.
FRIDAY NIGHT: MAINLY VFR, WITH AREAS IFR POSSIBLE. BREEZY.
SLIGHT CHANCE SHRA, SLIGHT CHANCE TSRA, PATCHY BR.
SATURDAY: MAINLY VFR, WITH LOCAL IFR POSSIBLE. SLIGHT CHANCE
SHRA, SLIGHT CHANCE TSRA.
SATURDAY NIGHT: MAINLY VFR, WITH AREAS IFR POSSIBLE. CHANCE
SHRA, SLIGHT CHANCE TSRA, PATCHY BR.
SUNDAY: CHANCE SHRA, SLIGHT CHANCE TSRA, PATCHY BR.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
THROUGH WEDNESDAY NIGHT: HIGH CONFIDENCE.
S/SE WINDS TUESDAY AT 6-12 KTS. SEAS LESS THAN 3 FT. BREEZY
S/SSW WINDS ON WEDNESDAY AT 10-15 KTS. SEAS LESS THAN 3 FT.
WINDS BECOME GUSTIER NEAR 25 KTS AND SEAS BEGIN TO BUILD TO 3-4
FT ALONG THE FAR NORTHERN WATERS WEDNESDAY NIGHT. SCA MAY BE
NEEDED.
OUTLOOK /THURSDAY THROUGH SUNDAY/...
THURSDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS UP
TO 30 KT.
THURSDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH
GUSTS UP TO 30 KT. SEAS LOCALLY APPROACHING 5 FT. PATCHY FOG.
AREAS OF VISIBILITY 1 TO 3 NM.
FRIDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS
UP TO 25 KT. AREAS OF SEAS APPROACHING 5 FT. PATCHY FOG.
VISIBILITY 1 TO 3 NM.
FRIDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING
5 FT. SLIGHT CHANCE OF RAIN SHOWERS, SLIGHT CHANCE OF
THUNDERSTORMS, PATCHY FOG. VISIBILITY 1 TO 3 NM.
SATURDAY: WINDS LESS THAN 25 KT. SLIGHT CHANCE OF RAIN SHOWERS,
PATCHY FOG. VISIBILITY 1 TO 3 NM.
SATURDAY NIGHT THROUGH SUNDAY: WINDS LESS THAN 25 KT. CHANCE OF
RAIN SHOWERS, PATCHY FOG. VISIBILITY 1 TO 3 NM.
BOX WATCHES/WARNINGS/ADVISORIES
CT...HEAT ADVISORY FROM 11 AM THURSDAY TO 8 PM EDT FRIDAY FOR
CTZ002>004.
MA...HEAT ADVISORY FROM 11 AM THURSDAY TO 8 PM EDT FRIDAY FOR
MAZ003>007-010>019-026.
RI...HEAT ADVISORY FROM 11 AM THURSDAY TO 8 PM EDT FRIDAY FOR
RIZ001>004.
MARINE...NONE.
SYNOPSIS...HRENCECIN/MCMINN
NEAR TERM...MCMINN
SHORT TERM...MCMINN
LONG TERM...HRENCECIN
AVIATION...HRENCECIN/MCMINN
MARINE...HRENCECIN/MCMINN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page