317  
FXUS61 KBOX 221935  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
335 PM EDT SAT SEP 22 2018  
   
SYNOPSIS
 
 
CANADIAN HIGH PRESSURE WILL BRING DRY BUT UNSEASONABLY COOL  
TEMPERATURES THROUGH MONDAY. A WARM FRONT APPROACHING FROM THE  
SOUTH MAY BRING A SOAKING/HEAVY RAINFALL TO THE REGION TUESDAY.  
WARMER AND MUGGIER WEATHER ARRIVES WEDNESDAY WITH THE SCATTERED  
SHOWERS AND THUNDERSTORMS POSSIBLE AS A COLD FRONT APPROACHES.  
APPEARS DRIER AND MORE SEASONABLE WEATHER ARRIVES BY LATE NEXT  
WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
 
 
335 PM UPDATE...  
 
WITH THE COLD FRONT OFFSHORE AND HIGH PRESSURE BUILDING INTO THE  
AREA, MUCH DRIER AIR HAD ADVANCED THRU SOUTHERN NEW ENGLAND. IN SOME  
LOCALES SURFACE DEWPOINTS DROPPED 20+ DEGREES TODAY. HIGH PRESSURE  
BUILDS EASTWARD FROM THE GREAT LAKES REGION INTO NEW ENGLAND  
TONIGHT, CONTINUING TO KEEP OUR AREA DRY. WHILE MUCH OF THE COLUMN  
IS QUITE DRY, MODELS CONTINUE TO SHOW CONSIDERABLE AMOUNT OF UPPER  
LEVEL MOISTURE, IN THE GENERAL VICINITY OF AN ELONGATED SHORT WAVE  
AND ALSO UPPER LEVEL JET. CIRRUS SHIELD PERSISTS THRU THIS EVENING,  
THEN SHOULD DIMINISH IN COVERAGE OVERNIGHT.  
 
LOW TEMPS WOULD IMPACTED BY HIGH CLOUDS ESPECIALLY IF THEY HANG ON  
FOR THE OVERNIGHT. AT THIS TIME GOING WITH LOWS MAINLY IN THE 40S,  
EXCEPT UPPER 40S TO MID 50S IN URBAN CENTERS AND CLOSER TO THE  
SHORELINE. IF WE DO CLEAR OUT OR IF CLOUD COVER MOVES TO THE SOUTH,  
COULD SEE SOME LOCALES DIP INTO THE UPPER 30S ACROSS THE TYPICALLY  
COOLER SPOTS IN NORTHWEST MA.  
 

 
   
SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/
 
 
SUNDAY...HIGH PRESSURE BECOMES CENTERED OVER OUR AREA AND WEAKENS,  
KEEPING OUR AREA DRY AND KEEPING WINDS LIGHT. HIGH CLOUDS MAY LINGER  
INTO THE MORNING ACROSS A PORTION OF OUR AREA. OTHERWISE EXPECTING  
MOSTLY SUNNY SKIES. LOOKING AT HIGHS IN THE MID AND UPPER 60S,  
THOUGH A FEW SPOTS MAY REACH 70. COASTAL SEA BREEZES LIKELY.  
 
SUNDAY NIGHT...A STRONG AREA OF HIGH PRESSURE CENTERED OVER  
ONTARIO/QUEBEC PUSHES SOUTHEASTWARD IN OUR DIRECTION. MODELS SHOW A  
BACK DOOR COLD FRONT HEADED IN OUR DIRECTION, ASSOCIATED WITH THE  
LEADING EDGE OF THIS AIRMASS. MODELS NOT INDICATING PRECIPITATION  
WITH THIS FEATURE, BUT COULD SEE SOME CLOUDS AND NE WIND GUSTS 20-25  
MPH ALONG EAST COASTAL MA. OVERALL LOOKING AT ANOTHER NIGHT OF LOWS  
IN THE 40S FOR MUCH OF THE AREA, EXCEPT SOME LOW 50S IN URBAN  
CENTERS AND SOME LOCALES NEAR THE SHORELINE.  
 

 
   
LONG TERM /MONDAY THROUGH SATURDAY/
 
 
HIGHLIGHTS...  
 
* DRY/UNSEASONABLY COOL MON  
* SOAKING/HEAVY RAIN POSSIBLE TUE FOR PORTIONS OF SNE  
* WARM/MUGGY WED WITH SCATTERED SHOWERS/T-STORMS POSSIBLE  
* LOW CONFIDENCE...BUT FAVORING DRIER/SEASONABLE TEMPS LATE NEXT WEEK  
 
DETAILS...  
 
MONDAY...  
 
STRONG HIGH PRESSURE OVER EASTERN CANADA WILL RESULT IN DRY WEATHER  
BUT UNSEASONABLY COOL TEMPERATURES MONDAY. HIGHS MAINLY IN THE  
UPPER 50S TO THE MIDDLE 60S. ALSO, GIVEN THE POSITION OF THE HIGH  
PRESSURE SYSTEM...ENE WINDS WILL BE A BIT BREEZY ALONG THE COAST. IT  
DEFINITELY WILL FEEL LIKE FALL.  
 
TUESDAY...  
 
A WARM FRONT WILL BE LIFTING NORTHWARD ACROSS THE REGION ON TUE.  
PWATS/SOUTHERLY LLJ INCREASE TO 2+ STANDARD DEVIATIONS ABOVE NORMAL.  
THESE INGREDIENTS OVER RUNNING THE COOL DOME AT THE SURFACE WILL  
RESULT IN A PERIOD OF WIDESPREAD RAIN. GIVEN THE BOUNDARY AS A FOCUS  
COUPLED WITH THE DECENT PWAT PLUME AND LOW LEVEL JET...A  
SOAKING/HEAVY RAINFALL MIGHT BE IN STORE FOR THE REGION. STILL  
DIFFICULT TO PIN DOWN THE LOCATION...BUT A SWATH OF 1 TO 2.50  
INCHES OF RAIN IS CERTAINLY POSSIBLE FOR SOME LOCALES. MAY SEE  
SOME TYPICAL BRIEF NUISANCE POOR DRAINAGE STREET FLOODING  
ISSUES...BUT FLASH FLOODING UNLIKELY AT THIS TIME AS RAINFALL  
RATES WILL PROBABLY NOT BE SUFFICIENT. HIGH TEMPS PROBABLY  
REMAIN IN THE 60S IN MOST LOCATIONS GIVEN CLOUDS AND RAIN, AND  
MAY NOT EVEN BREAK 60 ACROSS THE INTERIOR HIGH TERRAIN.  
 
WEDNESDAY...  
 
APPEARS THAT SOUTHERN NEW ENGLAND WILL BE IN THE WARM SECTOR...SO WE  
PROBABLY WILL SEE A WARM AND A BIT MUGGY OF AN AFTERNOON. DEPENDING  
ON SOLAR INSOLATION...HIGHS SHOULD REACH WELL INTO THE 70S IF NOT  
BREAKING 80 IN SOME LOCATIONS. WHILE WED WILL PROBABLY NOT BE A  
WASHOUT...A COLD FRONT MAY BRING SOME SCATTERED SHOWERS AND  
THUNDERSTORMS WITH SOME INSTABILITY PROGGED.  
 
THU/FRI/SAT...  
 
LOW CONFIDENCE FORECAST...BUT APPEARS DRIER/SEASONABLE WEATHER WILL  
WORK INTO THE REGION BEHIND THE COLD FRONT.  
 

 
   
AVIATION /20Z SATURDAY THROUGH THURSDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH SUNDAY NIGHT/...  
 
THRU 00Z...HIGH CONFIDENCE. VFR. NW/N WINDS AROUND 10 KTS.  
 
TONIGHT AND SUNDAY...HIGH CONFIDENCE. VFR. LIGHT WINDS WITH COASTAL  
SEA BREEZES DEVELOPING ON SUNDAY.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. LOW PROB OF A SEA BREEZE  
PRIOR TO 23Z THIS EVE. SEA BREEZE LIKELY FOR SUNDAY.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.  
 
OUTLOOK /MONDAY THROUGH THURSDAY/...  
 
MONDAY: VFR. BREEZY.  
 
MONDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY.  
 
TUESDAY: MVFR/IFR CONDITIONS POSSIBLE. BREEZY. RA.  
 
TUESDAY NIGHT: MAINLY MVFR, WITH AREAS IFR POSSIBLE. BREEZY.  
SHRA LIKELY.  
 
WEDNESDAY: MAINLY MVFR, WITH LOCAL IFR POSSIBLE. WINDY WITH  
GUSTS TO 30 KT. CHANCE SHRA, ISOLATED TSRA.  
 
WEDNESDAY NIGHT: MAINLY MVFR, WITH AREAS VFR POSSIBLE. CHANCE  
SHRA, ISOLATED TSRA.  
 
THURSDAY: MAINLY VFR, WITH AREAS MVFR POSSIBLE.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH SUNDAY NIGHT/...HIGH CONFIDENCE.  
 
EARLY THIS EVENING...NW WINDS GUSTING TO AROUND 20 KT CONTINUE TO  
GRADUALLY DIMINISH. SEAS OF 3 TO 5 FEET ON THE OUTER COASTAL WATERS  
WILL ALSO GRADUALLY SUBSIDE...SCA HEADLINES CONTINUE IN THAT AREA  
UNTIL 7 PM.  
 
TONIGHT AND SUNDAY...LIGHT WINDS AND SEAS WITH HIGH PRESSURE  
BUILDING OVER THE WATERS. SEA BREEZE DEVELOPMENT LIKELY DURING  
SUNDAY.  
 
SUNDAY NIGHT...WINDS BECOME NE AND STRENGTHEN OVERNIGHT AS A BACK  
DOOR COLD FRONT APPROACHES. SCA HEADLINES MAY BE NEEDED FOR LATE  
SUNDAY NIGHT FOR THE NORTHERN COASTAL WATERS, POSSIBLY INCLUDING  
BOSTON HARBOR FOR GUSTS UP TO 25 KTS.  
 
OUTLOOK /MONDAY THROUGH THURSDAY/...  
 
MONDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS  
UP TO 30 KT. AREAS OF ROUGH SEAS.  
 
MONDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH  
GUSTS UP TO 25 KT. SEAS UP TO 5 FT.  
 
TUESDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH  
GUSTS UP TO 30 KT. SEAS UP TO 5 FT. RAIN LIKELY. LOCAL  
VISIBILITY 1 TO 3 NM.  
 
TUESDAY NIGHT: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS  
WITH LOCAL GUSTS UP TO 30 KT. AREAS OF ROUGH SEAS. RAIN SHOWERS  
LIKELY.  
 
WEDNESDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH  
GUSTS UP TO 30 KT. ROUGH SEAS UP TO 8 FT. CHANCE OF RAIN  
SHOWERS, ISOLATED THUNDERSTORMS.  
 
WEDNESDAY NIGHT: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS  
WITH AREAS OF GUSTS UP TO 30 KT. AREAS OF ROUGH SEAS. CHANCE OF  
RAIN SHOWERS, ISOLATED THUNDERSTORMS.  
 
THURSDAY: WINDS LESS THAN 25 KT. LOCAL ROUGH SEAS.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...NONE.  
RI...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR  
ANZ254>256.  
 

 
 

 
SYNOPSIS...NMB/FRANK  
NEAR TERM...NMB  
SHORT TERM...NMB  
LONG TERM...FRANK  
AVIATION...NMB/FRANK  
MARINE...NMB/FRANK  
 
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