752  
FXUS61 KBOX 170721  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
321 AM EDT MON JUN 17 2024  
   
SYNOPSIS
 
 
INCREASING TEMPERATURES AND HUMIDITY TODAY ALONG WITH GUSTY  
SOUTH WINDS. DANGEROUS HEAT AND HUMIDITY ARRIVES ON TUESDAY AND  
PEAKS IN THE WEDNESDAY THROUGH FRIDAY TIME FRAME. NEAR TO  
RECORD BREAKING HIGH TEMPERATURES ARE POSSIBLE WITH AFTERNOON  
HEAT INDICES BETWEEN 98 AND 106 DEGREES AWAY FROM THE IMMEDIATE  
SOUTH COAST. THE MAIN THREAT FOR SCATTERED SHOWERS AND  
THUNDERSTORMS WILL BE FRIDAY INTO THE WEEKEND...BUT SPECIFIC  
TIMING REMAINS UNCERTAIN. WE DO EXPECT THE EXCESSIVE HEAT TO  
BREAK THIS WEEKEND, BUT IT WILL REMAIN HUMID.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
TODAY:  
 
UPPER LEVEL RIDGE CONTINUES TO BUILD OVER THE REGION WITH HIGH  
PRESSURE STILL OVERHEAD. 850MB TEMPS WILL BE ON THE RISE TO +15C  
AHEAD OF THE DANGEROUS HEAT AND HUMIDITY EXPECTED STARTING TUESDAY.  
WINDS AT THE SURFACE WILL ALSO CONTINUE TO INCREASE OUT OF THE SOUTH  
AT 10 TO 15 MPH, GUSTING 20-25 MPH. THIS WILL BRING HIGH  
TEMPERATURES BACK UP INTO THE LOW TO MID 80S WITH DEWPOINTS IN THE  
LOW 60S. WINDS SHOULD BE STRONG ENOUGH TO KEEP SEA BREEZES AT BAY  
EXCEPT NEAR THE SOUTH COAST WHERE SOUTHERLY WINDS WILL ENHANCE THE  
SEA BREEZE AND BRING COOLER DAYTIME TEMPS IN THE UPPER 70S TO  
SOUTHERN RI AND SE MA.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/
 
 
TONIGHT:  
 
CENTER OF THE 595 DM RIDGE ARRIVES OVERNIGHT. DEWPOINTS WILL  
CONTINUE TO RISE OVERNIGHT WITH SOUTHERLY FLOW. EVEN WITH MAINLY  
CLEAR SKIES AND DECREASING WINDS, OVERNIGHT LOWS WILL ONLY DROP INTO  
THE MID 60S REGION WIDE.  
 
TOMORROW:  
 
DANGEROUS HEAT AND HUMIDITY ARRIVES TUESDAY AS TEMPERATURES RISE INTO  
THE LOW TO MID 90S. WITH DEWPOINTS RISING NEAR 70F, THE HEAT INDEX  
WILL RISE INTO THE UPPER 90S TO LOW 100S. DUE TO THIS, A HEAT  
ADVISORY OR EXCESSIVE HEAT WATCH HAVE BEEN ISSUED FOR MUCH OF SNE.  
THE SOUTH COAST ALONG WITH THE CAPE AND ISLANDS WERE LEFT OUT DUE TO  
SOUTHERLY FLOW BRINGING COOLER TEMPERATURES OFF THE OCEAN. THE WPC  
EXPERIMENTAL HEAT RISK TOOL HIGHLIGHTS MUCH OF SNE IN A MODERATE  
RISK FOR HEAT RELATED IMPACTS. WHAT THIS MEANS IS THAT THOSE WHO ARE  
SENSITIVE TO HEAT, OR WITHOUT EFFECTIVE COOLING SYSTEMS COULD BE AT  
RISK. IF YOU DO HAVE TO SPEND TIME OUTDOORS STARTING TUESDAY,  
REMEMBER TO STAY HYDRATED AND TAKE BREAKS IN SHADED AREAS OR INDOORS  
WITH AIR CONDITIONING.  
 
WITH LARGE AMOUNTS OF HEAT, COMES LARGE AMOUNTS OF INSTABILITY. HREF  
MEAN SBCAPE VALUES ARE ABOVE 1000 J/KG ON TUESDAY, HOWEVER, AN 875MB  
WARM NOSE WILL MAKE IT DIFFICULT FOR CONVECTION TO BREAK THE CAP.  
WITH ALMOST ZERO SHEAR AND VERY DRY UPPER LEVELS, ANY CONVECTION  
THAT DOES FIRE WILL HAVE A DIFFICULT TIME MAINTAINING ITSELF. MOST  
OF THE HI-RES GUIDANCE IS IN AGREEMENT WITH THIS SHOWING WEAK  
SHOWERS WITH THE EXCEPTION OF THE NSSL WRF WHICH SEEMS A BIT BULLISH  
ON CONVECTIVE COVERAGE AND INTENSITY. DID ADD SLIGHT CHANCE POPS TO  
INTERIOR NW MA TO MATCH THE HREF 4HR MAX UPDRAFT PROBS AT 10%.  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/
 
 
KEY POINTS...  
 
* DANGEROUS HEAT & HUMIDITY CONTINUES THROUGH FRI  
* NEAR RECORD HIGHS WITH HEAT INDICES FROM 98 TO 106 DEGREES  
* MAIN THREAT FOR SCATTERED SHOWERS/T-STORMS FRI INTO THE WEEKEND  
* EXCESSIVE HEAT BREAKS THIS WEEKEND...BUT IT STILL WILL BE HUMID  
 
DETAILS...  
 
AS HAS BEEN THE CASE FOR SEVERAL DAYS...THE MODELS CONTINUE TO BE IN  
EXCELLENT AGREEMENT THAT THE HEAT AND HUMIDITY WILL PEAK IN THE WED  
THROUGH FRI TIME FRAME. THE GUIDANCE INDICATES 500 MB HEIGHT FIELDS  
APPROACHING 600 DM...WHICH IS RARELY SEEN IN OUR REGION AND A STRONG  
SIGNAL FOR THE POTENTIAL OF RECORD HEAT. THIS IS ALSO SUPPORTED BY  
THE NAEFS & EPS SITUATIONAL AWARENESS TABLES...WHICH INDICATES  
SEVERAL PARAMETERS OUTSIDE THE MODELS CLIMATOLOGY.  
 
THE GUIDANCE SUPPORTS NEAR RECORD HIGHS WELL INTO THE 90S...PERHAPS  
TOUCHING 100 DEGREES IN SPOTS. RECORD HIGHS WILL BE CHALLENGED AND  
WE MAY APPROACH ALL TIME RECORD HIGHS FOR THE MONTH OF JUNE.  
REGARDLESS...AFTERNOON HEAT INDICES ARE LIKELY TO BE IN THE BALLPARK  
OF BETWEEN 98 AND 106 DEGREES AWAY FROM THE IMMEDIATE SOUTH COAST,  
CAPE AND ISLANDS. WE OPTED TO CONTINUE THE EXCESSIVE HEAT WATCH  
THROUGH FRI FOR THE LOWER ELEVATIONS OF WESTERN MA/CT AS WELL AS  
INTERIOR EAST/NORTHEAST MA. THIS IS WHERE THE GREATEST RISK IS FOR  
HEAT INDICES TO REACH OR JUST EXCEED 105 DEGREES. ACROSS THE REST OF  
THE REGION...OPTED TO ISSUE A HEAT ADVISORY AWAY FROM THE MARINE  
MODIFIED AIRMASS NEAR THE IMMEDIATE SOUTH COAST, CAPE AND ISLANDS.  
THERE WILL NOT BE MUCH RELIEF OVERNIGHT WITH HEAT INDICES ONLY  
DROPPING INTO THE 70S.  
 
THE STRONG UPPER LEVEL RIDGE WILL TEND TO RESULT IN MAINLY DRY  
WEATHER WED & THU...BUT CAN NOT RULE OUT AN ISOLATED CONVECTIVE  
THREAT GIVEN THE ANOMALOUS AIRMASS IN PLACE.  
 
THE MAIN THREAT THOUGH FOR SCATTERED SHOWERS/T-STORMS WILL BE FRI  
AND INTO THE WEEKEND AS THE UPPER LEVEL RIDGE BEGINS TO GET  
SUPPRESSED SOUTH. THIS WILL ALLOW SHORTWAVE ENERGY TO IMPACT US AT  
TIMES ON WEST TO NORTHWEST FLOW ALOFT. TIMING IS DIFFICULT AT THIS  
POINT...BUT SCATTERED SHOWERS & T-STORMS WILL BE POSSIBLE FRI INTO  
THE WEEKEND. AS THE UPPER LEVEL RIDGE IS SUPPRESSED TO OUR  
SOUTH...WE DO EXPECT THE EXCESSIVE HEAT TO BREAK BUT IT STILL WILL  
BE HUMID.  
 

 
   
AVIATION /07Z MONDAY THROUGH FRIDAY/
 
 
FORECAST CONFIDENCE LEVELS:  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
TODAY: HIGH CONFIDENCE  
 
VFR. INCREASING SOUTH WINDS TODAY GUSTING 15 TO 20 KNOTS.  
 
TONIGHT: HIGH CONFIDENCE  
 
VFR. DECREASING SOUTHERLY WINDS.  
 
TOMORROW:  
 
VFR. LOW CHANCE FOR AN ISOLATED SHOWER OR THUNDERSTORMS ACROSS  
NW INTERIOR MA.  
 
KBOS TAF...HIGH CONFIDENCE IN TAF.  
 
VFR. INCREASING SSW WINDS TODAY GUSTING 20 KNOTS  
 
KBDL TAF...HIGH CONFIDENCE IN TAF.  
 
VFR. INCREASING S WINDS TODAY GUSTING 20 KNOTS  
 
OUTLOOK /TUESDAY NIGHT THROUGH FRIDAY/...  
 
TUESDAY NIGHT: VFR. BREEZY.  
 
JUNETEENTH: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY.  
SLIGHT CHANCE SHRA, SLIGHT CHANCE TSRA.  
 
WEDNESDAY NIGHT: VFR. BREEZY.  
 
THURSDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY. SLIGHT  
CHANCE SHRA, SLIGHT CHANCE TSRA.  
 
THURSDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY.  
 
FRIDAY: MAINLY VFR, WITH AREAS MVFR POSSIBLE. CHANCE SHRA,  
CHANCE TSRA.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS:  
 
LOW - LESS THAN 30 PERCENT.  
MEDIUM - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
TODAY:  
 
CONTINUED CLEAR CONDITIONS WITH INCREASING SOUTHERLY WINDS AT  
10-15 KNOTS, GUSTING 20-25 KNOTS. SEAS 2-4 FT  
 
TONIGHT:  
 
CLEAR CONDITIONS WITH SLOWLY DECREASING SOUTHWEST  
WINDS 10-15 KTS. SEAS 2-4 FT.  
 
TOMORROW:  
 
CLEAR CONDITIONS WITH INCREASING SOUTHERLY WINDS GUSTING 20-25  
KNOTS ONCE AGAIN. SEAS 2-4 FT  
 
OUTLOOK /TUESDAY NIGHT THROUGH FRIDAY/...  
 
TUESDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING  
5 FT.  
 
JUNETEENTH: WINDS LESS THAN 25 KT.  
 
WEDNESDAY NIGHT THROUGH THURSDAY: WINDS LESS THAN 25 KT. SEAS  
LOCALLY APPROACHING 5 FT.  
 
THURSDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING  
5 FT. SLIGHT CHANCE OF RAIN SHOWERS, SLIGHT CHANCE OF  
THUNDERSTORMS.  
 
FRIDAY: WINDS LESS THAN 25 KT. CHANCE OF RAIN SHOWERS, CHANCE  
OF THUNDERSTORMS.  
 

 
   
CLIMATE
 
 
ALL TIME JUNE HIGH TEMPERATURE RECORD (DAILY)  
 
BOS - 100 F (06/06/1925, 06/26/1952 AND 06/30/2021)  
BDL - 100 F (06/26/1952, 06/30/1964)  
PVD - 98 F (06/25/1943, 06/15/1945 AND 06/30/1945)  
ORH - 98 F (06/26/1952)  
 
MOST RECENT DAY OF 100 F (OR GREATER)  
 
BOS - 100 F (07/24/2022)  
BDL - 100 F (07/21/2019)  
PVD - 100 F (07/28/2020)  
ORH - 102 F (07/04/1911)*  
 
* FOR ORH THIS IS THE ONLY 100+ DEGREE DAY IN ITS PERIOD OF RECORD.  
 
DAILY HIGH TEMPERATURE RECORDS...  
 
JUNE 18TH  
 
BOS - 94 F (1907 AND 1929)  
BDL - 95 F (1957 AND 1994)  
PVD - 94 F (1929)  
ORH - 93 F (1907 AND 1929)  
 
JUNE 19TH  
 
BOS - 96 F (1923)  
BDL - 95 F (1995)  
PVD - 94 F (1923)  
ORH - 93 F (1923)  
 
JUNE 20TH  
 
BOS - 98 F (1953)  
BDL - 97 F (2012)  
PVD - 95 F (1941)  
ORH - 93 F (1953)  
 
JUNE 21ST  
 
BOS - 96 F (2012)  
BDL - 96 F (1953 AND 2012)  
PVD - 96 F (1941)  
ORH - 91 F (MULTI-YEARS)  
 
DAILY WARMEST LOW TEMPERATURES RECORDS...  
 
JUNE 18TH  
 
BOS - 72 F (1929)  
BDL - 70 F (1905)  
PVD - 72 F (1929)  
ORH - 69 F (1905 AND 1994)  
 
JUNE 19TH  
 
BOS - 73 F (1995)  
BDL - 72 F (1929)  
PVD - 70 F (1995)  
ORH - 72 F (1929)  
 
JUNE 20TH  
 
BOS - 78 F (1931)  
BDL - 74 F (1931)  
PVD - 74 F (1931)  
ORH - 72 F (1931)  
 
JUNE 21ST  
 
BOS - 80 F (2012)  
BDL - 73 F (1923 AND 2012)  
PVD - 75 F (2012)  
ORH - 74 F (1923 AND 2012)  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...EXCESSIVE HEAT WATCH FROM TUESDAY AFTERNOON THROUGH FRIDAY  
EVENING FOR CTZ002-003.  
HEAT ADVISORY FROM NOON TUESDAY TO 7 PM EDT FRIDAY FOR CTZ004.  
MA...EXCESSIVE HEAT WATCH FROM TUESDAY AFTERNOON THROUGH FRIDAY  
EVENING FOR MAZ003-005-006-010-011-013-014.  
HEAT ADVISORY FROM NOON TUESDAY TO 7 PM EDT FRIDAY FOR MAZ002-  
004-007>009-012-015>019-026.  
RI...HEAT ADVISORY FROM NOON TUESDAY TO 7 PM EDT FRIDAY FOR  
RIZ001>005.  
MARINE...NONE.  
 

 
 

 
 
SYNOPSIS...FRANK/KP  
NEAR TERM...KP  
SHORT TERM...KP  
LONG TERM...FRANK  
AVIATION...FRANK/KP  
MARINE...FRANK/KP  
CLIMATE...BL  
 
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