988  
FXUS61 KBOX 170207  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
1007 PM EDT THU AUG 16 2018  
   
SYNOPSIS
 
 
SHOWERS AND THUNDERSTORMS WILL BE ON THE INCREASE FRIDAY INTO  
SATURDAY AS A COLD FRONT APPROACHES SOUTHERN NEW ENGLAND. THIS  
FRONT MOVES THROUGH LATE SATURDAY, FOLLOWED BY MAINLY DRY AND  
COOLER WEATHER SUNDAY INTO TUESDAY AS HIGH PRESSURE BUILDS IN  
FROM THE NORTH. THE HUMIDITY WILL RETURN BY WEDNESDAY LEADING TO  
THE RISK OF MORE SHOWERS AND THUNDERSTORMS.  
 

 
   
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
 
 
950 PM UPDATE...  
 
ANY PRECIP FROM EARLIER THIS EVENING HAS ENDED ACROSS THE  
REGION. NOTING ONLY A FEW SPOTTY CLOUDS IN THE W-NW FLOW ALOFT  
FROM SW NH SOUTHEASTWARD ACROSS PORTIONS OF N RI AND E MASS, AS  
SEEN ON LATEST GOES-EAST RGB NIGHTTIME MICROPHYSICS COMPOSITE.  
SHOULD SEE THESE CLOUDS DISSIPATE OR PUSH OFFSHORE THROUGH  
AROUND MIDNIGHT OR SO. MAY BE SEEING SOME PATCHY FOG DEVELOPING  
ALONG THE IMMEDIATE S COAST WHERE THE HIGHER DEWPOINTS REMAIN,  
BUT WILL BE SPOTTY AT BEST.  
 
OTHER THAN MINOR ADJUSTMENTS TO BRING CONDITIONS CURRENT, NOT  
MUCH CHANGE TO THE PREVIOUS FORECAST.  
 
PREVIOUS DISCUSSION...  
 
MOSTLY CLEAR SKIES EXPECTED THROUGH AROUND 2 AM OR SO BEFORE  
CLOUDS BEGIN TO APPROACH FROM WEST. LOWS WILL FALL BACK TO THE  
60S AND LOWER 70S.  
 

 
   
SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/
 
 
* POTENTIAL FOR STRONG/SEVERE STORMS LATER FRI INTO FRI EVENING  
* LOCALIZED WIND DAMAGE/FLASH FLOODING POSSIBLE  
* ISOLATED SHORT-LIVED TORNADO ALSO POSSIBLE  
 
SHOWERS AND THUNDERSTORMS BECOME MORE LIKELY FRIDAY, ESPECIALLY  
DURING AFTERNOON AND EVENING ACROSS INTERIOR, AS FRONT LIFTS  
BACK NORTH THRU SNE AS A WARM FRONT.  
 
MODELS SHOW GOOD INSTABILITY WITH MLCAPE UP TO 1500 J/KG BUT  
0-6KM SHEAR IS MINIMAL, HOWEVER IT DOES INCREASE LATER IN DAY  
AND ESPECIALLY FRIDAY EVENING. SETUP FAVORS POTENTIAL FOR A FEW  
STRONG/SEVERE STORMS WITH LOCALIZED WIND DAMAGE. ALSO HAVE  
POTENTIAL FOR LOCALIZED FLASH FLOODING AS PRECIPITABLE WATER  
VALUES CLIMB BACK TO 2 INCHES OR HIGHER. WE ALSO NEED TO BE  
CONCERNED WITH AN ISOLATED SHORT-LIVED TORNADO LATE FRIDAY  
AFTERNOON/FRIDAY EVENING GIVEN RATHER HIGH 0-500M HELICITY NEAR  
100, LOW LCLS, AND WARM FRONT NEARBY. LATER FRIDAY NIGHT,  
CONDITIONS BECOME LESS FAVORABLE FOR ORGANIZED STRONG/SEVERE  
STORMS AS WARM FRONT LIFTS INTO NORTHERN NEW ENGLAND BUT  
SHOWERS/STORMS SHOULD MAKE THEIR WAY TO COAST DUE TO APPROACH  
OF MID LEVEL SHORT WAVE.  
 
WARM AND HUMID CONDITIONS RETURN WITH HIGHS FRIDAY IN 80S AND  
LOWS FRIDAY NIGHT ONLY FALLING BACK INTO UPPER 60S TO MID 70S.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/
 
 
HIGHLIGHTS...  
 
* SHOWERS/THUNDERSTORMS LIKELY SATURDAY ACROSS A GOOD PORTION OF  
SOUTHERN NEW ENGLAND  
* LOCALLY HEAVY RAINFALL POSSIBLE, ALONG WITH THE POTENTIAL FOR  
A FEW STRONG TO SEVERE STORMS SATURDAY  
* MILD TO WARM DAYS AND COOL NIGHTS SUN/MON/TUE  
* MORE HUMID WITH INCREASING RISK OF SHOWERS/THUNDERSTORMS TUE  
NIGHT/WED  
 
16/12Z GUIDANCE REMAIN IN DECENT OVERALL AGREEMENT, WITH THE  
TYPICAL DETAIL DIFFERENCES TOWARDS THE END OF NEXT WEEK. IN  
GENERAL, EXPECTING THE CURRENT HEAT AND HIGH HUMIDITY PATTERN  
TO BREAK FOR A TIME, ABOUT SUNDAY INTO TUESDAY. EXPECTING THE  
BERMUDA HIGH TO MOVE BACK OUT TO SEA, WHICH WILL ALLOW A MID  
LEVEL TROUGH TO SETTLE OVER NEW ENGLAND. THIS SHOULD MEAN DEW  
POINTS IN THE 60S (AND PERHAPS UPPER 50S ACROSS THE HIGHER  
TERRAIN), WITH HIGH TEMPERATURES IN THE 70S. UNFORTUNATELY, THIS  
MID LEVEL TROUGH WILL STILL MEAN AT LEAST A RISK FOR PERIODIC  
SHOWERS AND THUNDERSTORMS. NO SINGLE DAY WOULD BE A COMPLETE  
WASHOUT.  
 
THERE REMAINS A LOW RISK FOR STRONGER THUNDERSTORMS SATURDAY,  
MAINLY SOUTH OF THE MA PIKE, WHICH WOULD BE CLOSER TO THE  
GREATER INSTABILITY. NOT A CERTAINTY, THOUGH.  
 
WILL CONTINUE TO FAVOR A CONSENSUS APPROACH TO SMOOTH OVER THE  
LESS PREDICTABLE DETAILS.  
 

 
   
AVIATION /02Z FRIDAY THROUGH TUESDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH FRIDAY/...  
 
HIGH CONFIDENCE.  
 
OVERNIGHT...VFR. EXPECT DRY CONDITIONS. MAY SEE BRIEF SPOTTY MVFR  
VSBYS IN PATCHY FOG ACROSS N CENTRAL AND W MASS AFTER 08Z.  
 
FRIDAY AND FRIDAY NIGHT...SCATTERED SHOWERS/STORMS DEVELOP IN  
WESTERN NEW ENGLAND FRIDAY MORNING AND HEAD EAST, REACHING COAST  
FRIDAY EVENING AND CONTINUING FRIDAY NIGHT. VFR CONDITIONS  
EXPECTED MOST OF THE TIME BUT AREAS MVFR/IFR IN SHOWERS/STORMS.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.  
 
OUTLOOK /FRIDAY NIGHT THROUGH TUESDAY/...  
 
FRIDAY NIGHT: MAINLY VFR, WITH AREAS MVFR POSSIBLE. CHANCE  
SHRA, CHANCE TSRA, PATCHY FG.  
 
SATURDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. CHANCE SHRA,  
SLIGHT CHANCE TSRA.  
 
SATURDAY NIGHT: MAINLY VFR, WITH AREAS MVFR POSSIBLE. CHANCE  
SHRA.  
 
SUNDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY. SLIGHT  
CHANCE SHRA.  
 
SUNDAY NIGHT THROUGH MONDAY: VFR. SLIGHT CHANCE SHRA.  
 
MONDAY NIGHT: VFR.  
 
TUESDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. SLIGHT CHANCE  
SHRA.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH FRIDAY/...HIGH CONFIDENCE.  
 
WEAK COLD FRONT STALLS NEAR OR JUST S OF CAPE COD OVERNIGHT,  
WITH WINDS BECOMING LIGHT/VARIABLE BEFORE VEERING TO S-SE  
FRIDAY. SEAS 3 FT OR LESS. INCREASING S WINDS EXPECTED FRIDAY  
NIGHT WITH GUSTS UP TO 20 KT ON SOUTH COASTAL WATERS, WHICH MAY  
BRING SEAS UP TO 5 FT OFFSHORE.  
 
OUTLOOK /FRIDAY NIGHT THROUGH TUESDAY/...  
 
FRIDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING  
5 FT. CHANCE OF RAIN SHOWERS, CHANCE OF THUNDERSTORMS, PATCHY  
FOG. LOCAL VISIBILITY 1 TO 3 NM.  
 
SATURDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING  
5 FT. CHANCE OF RAIN SHOWERS, SLIGHT CHANCE OF THUNDERSTORMS,  
PATCHY FOG.  
 
SATURDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS  
APPROACHING 5 FT. CHANCE OF RAIN SHOWERS, ISOLATED  
THUNDERSTORMS, PATCHY FOG.  
 
SUNDAY THROUGH SUNDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO  
5 FT. CHANCE OF RAIN SHOWERS.  
 
MONDAY: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. SLIGHT CHANCE  
OF RAIN SHOWERS.  
 
MONDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING  
5 FT.  
 
TUESDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING 5 FT.  
SLIGHT CHANCE OF RAIN SHOWERS.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR MAZ020-  
022>024.  
RI...AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR RIZ006>008.  
MARINE...NONE.  
 

 
 

 
SYNOPSIS...BELK/JWD  
NEAR TERM...BELK/EVT  
SHORT TERM...JWD  
LONG TERM...BELK  
AVIATION...BELK/EVT/JWD  
MARINE...BELK/EVT/JWD  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab MA Page
The Nexlab RI Page
The Nexlab NH Page
The Nexlab CT Page Main Text Page