126  
FXUS61 KBOX 171907  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
307 PM EDT THU JUL 17 2025  
   
SYNOPSIS  
 
DANGEROUS HEAT AND HUMIDITY CONTINUES TODAY. AN APPROACHING  
COLD FRONT MAY BRING HIT OR MISS SHOWERS AND THUNDERSTORMS  
TODAY, BUT MUCH OF THE DAY WILL BE DRY. THE COLD FRONT WILL ALSO  
BRING AN END TO THE HEAT AND HUMIDITY LATER TONIGHT WITH  
BEAUTIFUL DRY WEATHER FRIDAY AND SATURDAY. ANOTHER COLD FRONT  
WILL LIKELY BRING A ROUND OF SHOWERS AND EMBEDDED THUNDERSTORMS  
TO THE REGION POSSIBLY LATE SATURDAY NIGHT, BUT MORE LIKELY  
SUNDAY, ALONG WITH THE RETURN OF SOME HUMIDITY. THIS WILL BE  
SHORT-LIVED THOUGH AS A DRY AND VERY PLEASANT AIRMASS MOVES BACK  
IN TIME FOR THE START OF THE NEXT WORK WEEK.  
 
 
   
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/  
 
KEY MESSAGES...  
 
* HEAT & HUMIDITY CONTINUES THIS AFTERNOON WITH HEAT INDICES 95-100  
 
* ANY SEVERE WEATHER THREAT TODAY SHOULD BE ISOLATED/LOCALIZED  
 
DETAILS...  
 
TODAY & TONIGHT...  
 
A COLD FRONT IS SLOWLY MAKING IT'S WAY INTO SOUTHERN NEW  
ENGLAND AND BRINGING ANOTHER RISK FOR SOME SCATTERED CONVECTION  
LATE THIS AFTERNOON AND EVENING. STARTING TO SEE QUITE A BIT OF  
MID-LEVEL DRY AIR AS WELL, SO ANY SEVERE STORMS THAT FORM WILL  
LIKELY BE ISOLATED IN NATURE. MODEST INSTABILITY WILL QUICKLY  
DEVELOP WITH CAPE ON THE ORDER OF 1500 TO 2500+ J/KG ALONG WITH  
25 TO 30 KNOTS OF EFFECTIVE SHEAR. A FAIR AMOUNT OF 0-1 KM  
HELICITY WILL ALSO DEVELOP ON THE ORDER OF 100 TO 200+ UNITS.  
GIVEN THE AMOUNT OF DRY AIR ALOFT, IT'LL BE A STRUGGLE FOR  
STORMS TO FIRE THIS FAR SOUTH; HOWEVER, IF SOME MESOSCALE  
PROCESSES CAN COME INTO PLAY, THERE WILL BE AN  
ISOLATED/LOCALIZED SEVERE WIND THREAT AND BRIEF TORRENTIAL  
RAINFALL.  
 
OUTSIDE THE CONVECTIVE THREAT...THE MAJORITY OF THE DAY WILL  
FEATURE HEAT AND HUMIDITY. HIGH TEMPS WILL BE IN THE UPPER 80S  
TO LOWER 90S ALLOWING HEAT INDICES TO REACH INTO THE 95 TO 100  
DEGREE RANGE. HEAT ADVISORIES REMAIN IN PLACE THROUGH 7 PM THIS  
EVENING.  
 
 
   
SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/  
 
KEY MESSAGES...  
 
* COLD FRONT BRINGS RELIEF FROM HIGH HEAT AND HUMIDITY  
 
DETAILS...  
 
FRIDAY...  
 
ANY SHOWERS THAT SPRING UP THIS AFTERNOON AND EVENING WILL EXIT  
SOUTHERN NEW ENGLAND OVERNIGHT. A DRIER AIRMASS MOVES IN POST-  
FROPA, BRINGING MUCH NEEDED RELIEF FROM THE HIGH HEAT AND  
HUMIDITY HEADING INTO THE WEEKEND. MOSTLY SUNNY & BEAUTIFUL  
WEATHER FOR FRI WITH HIGHS MAINLY BETWEEN 80 AND 85 AND VERY  
COMFORTABLE HUMIDITY LEVELS.  
 
 
   
LONG TERM /SATURDAY THROUGH THURSDAY/  
 
KEY MESSAGES...  
 
* ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS LATE SAT NIGHT-SUN.  
 
* DRY WITH AVERAGE TEMPS MOST OF NEXT WEEK - WARMS UP AGAIN WED/THU.  
 
NORTHERN STREAM DOMINATES INTO NEXT WEEK WHICH SUPPRESSES  
SUBTROPICAL RIDGE AND KEEPS THE HEAT/HUMIDITY AWAY, THOUGH AS WE  
HEAD TOWARD THE END OF NEXT WEEK THERE ARE SIGNS THE RIDGE MAY  
RETURN AND BRING INCREASING HEAT AND HUMIDITY BY THU (ALTHOUGH  
PROBABLY NOT TO THE LEVELS WE SAW THIS WEEK).  
 
OVERALL, DRY WEATHER SHOULD DOMINATE WITH THE EXCEPTION OF LATE  
SAT NIGHT INTO SUN, WHEN LOW PRESSURE TRACKING TO OUR NW BRINGS  
A ROUND OF SHOWERS/STORMS. ML GUIDANCE SHOWS A LOW RISK OF  
SEVERE STORMS WITH ENVIRONMENT FEATURING DECENT INSTABILITY WITH  
SURFACE CAPE UP TO 2000 J/KG ACROSS INTERIOR AND STRONG 0-6KM  
SHEAR OF 35-45KT, BUT AS USUAL MID LEVEL LAPSE RATES LOOK FAIRLY  
WEAK. MOISTURE CONVERGENCE LOOKS IMPRESSIVE, HOWEVER, WITH A  
DECENT THETA-E RIDGE OVER SNE AND PWATS CLIMBING TO AROUND 2",  
SO ANY STORMS COULD PRODUCE LOCALIZED DOWNPOURS AND STREET  
FLOODING, BUT NOT SEEING MUCH OF A SIGNAL FOR FLASH FLOODING  
RIGHT NOW (EVEN IN ML GUIDANCE).  
 
 
   
AVIATION /19Z 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...MODERATE CONFIDENCE.  
 
MAINLY VFR, EXCEPT MVFR FOR THE SOUTH COAST & CAPE TERMINALS.  
IFR ACROSS THE ISLANDS. SOME LIGHT SHOWERS AND POSSIBLY A RUMBLE  
OF THUNDER OVER THE ISLANDS EARLY THIS AFTERNOON. OTHERWISE...  
BRIEF SHOWERS & T- STORMS POSSIBLE ACROSS THE REGION THIS  
AFTERNOON AND EARLY EVENING. THE EASTWARD EXTENT OF STORM  
ACTIVITY IS UNCERTAIN, WITH GREATEST CHANCES FOR TSRA WEST OF  
ORH. SW WINDS MAY GUST TO BETWEEN 20 AND 25 KNOTS BY AFTERNOON.  
 
TONIGHT...HIGH CONFIDENCE.  
 
ANY ISOLATED SHOWER & T-STORM ACTIVITY SHOULD COME TO AN END  
THIS EVENING. OTHERWISE...VFR CONDITIONS AS A DRY NW FLOW OF AIR  
TAKES OVER LATER TONIGHT INTO FRIDAY. NW WINDS MAY GUST BETWEEN  
20 AND 25 KNOTS BEHIND THE COLD FROPA OVERNIGHT INTO THE FIRST  
HALF OF FRIDAY BEFORE DIMINISHING.  
 
FRIDAY... HIGH CONFIDENCE.  
 
VFR. GUSTS DIMINISHING MID-MORNING. PREDOMINANTLY NNE WINDS,  
THOUGH THE ISLANDS WILL LIKELY TURN SSE BY FRIDAY EVENING.  
 
KBOS TERMINAL...MODERATE CONFIDENCE IN TAF.  
 
KBDL TERMINAL...MODERATE CONFIDENCE IN TAF.  
 
OUTLOOK /SATURDAY THROUGH TUESDAY/...  
 
SATURDAY: VFR. BREEZY.  
 
SATURDAY NIGHT: MAINLY VFR, WITH AREAS MVFR POSSIBLE. BREEZY.  
SHRA LIKELY, CHANCE TSRA.  
 
SUNDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY. SLIGHT  
CHANCE SHRA, SLIGHT CHANCE TSRA.  
 
SUNDAY NIGHT THROUGH MONDAY NIGHT: VFR.  
 
TUESDAY: VFR.  
 
 
   
MARINE  
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MEDIUM - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
TODAY THROUGH FRIDAY...HIGH CONFIDENCE.  
 
GUSTY SOUTHWEST WINDS NEAR 25 KNOTS DEVELOP ACROSS OUR NEAR  
SHORE SOUTHERN WATERS THIS AFTERNOON GIVEN GOOD MIXING AHEAD OF  
AN APPROACHING COLD FRONT. WE OPTED TO ISSUE A SMALL CRAFT  
ADVISORY FOR THOSE NEAR SHORE SOUTHERN WATERS GIVEN IT IS PEAK  
BOATING SEASON. WE ALSO EXPECT MARGINAL SCA SEAS TO DEVELOP WITH  
LONG SOUTHERLY FETCH ACROSS THE SOUTHERN OUTER-WATERS BY THIS  
EVENING INTO FRIDAY SO WE HAVE HEADLINES FOR THAT TOO.  
LASTLY...BEHIND THE COLD EXPECT A ROUND OF NW WIND GUSTS OF 25  
KNOTS OVERNIGHT INTO FRI MORNING ACROSS OUR NORTHERN  
WATERS...WHERE WE WILL HAVE ADDITIONAL SMALL CRAFT HEADLINES.  
 
OUTLOOK /SATURDAY THROUGH TUESDAY/...  
 
SATURDAY: WINDS LESS THAN 25 KT.  
 
SATURDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH  
GUSTS UP TO 25 KT. SEAS LOCALLY APPROACHING 5 FT. CHANCE OF  
RAIN SHOWERS, SLIGHT CHANCE OF THUNDERSTORMS.  
 
SUNDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.  
CHANCE OF RAIN SHOWERS, SLIGHT CHANCE OF THUNDERSTORMS.  
 
SUNDAY NIGHT THROUGH TUESDAY: WINDS LESS THAN 25 KT.  
 
 
   
BOX WATCHES/WARNINGS/ADVISORIES  
 
CT...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR CTZ002>004.  
MA...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR MAZ003>007-  
010>021-026.  
RI...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR RIZ001>007.  
MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT FRIDAY  
FOR ANZ230-250-251.  
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR  
ANZ231>237.  
SMALL CRAFT ADVISORY UNTIL 2 PM EDT FRIDAY FOR ANZ254>256.  
 
 
 
 
 
SYNOPSIS...MCMINN/JWD  
NEAR TERM...MCMINN  
SHORT TERM...MCMINN  
LONG TERM...JWD  
AVIATION...MCMINN/FT  
MARINE...JWD  
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