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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