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Area Forecast Discussion
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000
FXUS61 KBOX 230609
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
209 AM EDT THU OCT 23 2014

.SYNOPSIS...
A POWERFUL EARLY SEASON COASTAL STORM WILL BRING STRONG TO DAMAGING
WINDS ALONG WITH LOCALLY VERY HEAVY RAINFALL IN SQUALLS AND
ISOLATED THUNDERSTORMS INTO THURSDAY MORNING...THEN LESSENING
THURSDAY AFTERNOON. SHOWERS WILL LINGER FRIDAY AS THE STORM
SLOWLY PULLS AWAY FROM NEW ENGLAND. SHOWERS POSSIBLE AGAIN
SATURDAY AS LOW PRES MOVES INTO SOUTHERN QUEBEC. DRY...SEASONABLE
WEATHER RETURNS EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TODAY/...

*** A POWERFUL EARLY SEASON COASTAL STORM WILL BRING STRONG TO
 DAMAGING WINDS AND LOCALLY HEAVY RAINFALL AND MINOR FLOODING INTO
 THU MORNING ***

2 AM UPDATE...

IMPRESSIVE EARLY SEASON COASTAL STORM SOUTH OF NEW ENGLAND
WITH ITS WARM CONVEYOR BELT/TROWAL RAINS AND EMBEDDED CONVECTION
PINWHEELING FROM GEORGES BANK NORTHWESTWARD INTO MASSACHUSETTS AND
SLOWLY PIVOTING NORTHWEST. HEAVY RAINFALL AND CONVECTION WITHIN
THIS WARM CONVEYOR BELT WILL CONTINUE THE THREAT FOR FLOODING
ACROSS EASTERN MA AND EVENTUALLY INTO SOUTHEAST NH. THUS WILL
CONTINUE WITH THE FLOOD WATCH.

OCCLUDED LOW SOUTH OF NEW ENGLAND AND STRONG HIGH PRES OVER QUEBEC
WILL CONTINUE TO FOCUS A STRONG LOW LEVEL NORTHEAST JET ACROSS
SOUTHEAST NH/NORTHEAST MA/RI AND NORTHEAST CT. THIS LOW LEVEL JET
WILL REMAIN STRONG THRU 12Z AND THEN SLOWLY WEAKENING THIS
AFTERNOON. THUS WIND HEADLINES WILL REMAIN IN PLACE.

PREVIOUS FORECAST CAPTURES THESE DETAILS NICELY SO NO MAJOR
CHANGES WITH THIS UPDATE.  EARLIER DISCUSSION BELOW.

=============================================================

POTENT CLOSED UPPER LEVEL LOW WILL CONTINUE TO AMPLIFY TONIGHT.
THIS WILL ALLOW SURFACE LOW PRESSURE TO INTENSIFY AS IT SLOWLY
LIFTS TO THE NORTHEAST PASSING NEAR THE BENCHMARK ON THURSDAY.
GIVEN THAT THIS SYSTEM HAS CLOSED MID LEVEL CIRCULATIONS...WERE
EXPECTING A BREAK DOWN IN PRECIPITATION FIELDS THAT WE OFTEN SEE
DURING WINTER STORMS.

1) HEAVY RAIN POTENTIAL:

IN A NUTSHELL...PERIODS OF HEAVY RAIN ARE EXPECTED TONIGHT ACROSS 
THE ENTIRE REGION.  THE BIGGEST UNCERTAINTY IS TRYING TO LOCATE 
WHERE THE HEAVIEST RAIN BANDS WILL SET UP.  THERE ARE A LOT OF 
MOVING PARTS TO THIS FORECAST...WHICH MAKES THIS A DIFFICULT TASK.  

WE EXPECT HEAVY RAIN TO INITIALLY OVERSPREAD SOUTHEAST NEW ENGLAND 
AND WORK NORTHWARD ACROSS THE REST OF THE REGION THIS EVENING.  
THE MID LEVEL DRY SLOT WILL THEN APPROACH SOUTHEAST NEW ENGLAND BY 
LATE EVENING.  THIS MAY RESULT IN THE PRECIPITATION FIELD MORE 
SCATTERED AT TIMES ACROSS SOUTHEAST SECTIONS OVERNIGHT...BUT ALSO 
MORE CONVECTIVE GIVEN SOME ELEVATED CAPE. SO WHILE WE MAY SEE SOME 
BREAKS IN THE PRECIPITATION SHIELD ACROSS SOUTHEAST 
SECTIONS...ISOLATED THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL WILL 
ALSO BE POSSIBLE.  IN ADDITION...WE PROBABLY WILL SEE A SUBTLE 
COASTAL FRONT SET UP ACROSS SOUTHEAST MA LATE TONIGHT INTO THURSDAY 
MORNING SO SOME ENHANCEMENT IS POSSIBLE.  

WILL ALSO HAVE TO WATCH FOR A SECOND AREA OF HEAVIER PRECIPITATION 
IN ASSOCIATION WITH THE MID LEVEL DEFORMATION ZONE/BACK BENT WARM 
FRONT.  LOCATION OF THIS IS TRICKY BUT PERHAPS FURTHER BACK INTO 
THE INTERIOR ACROSS  SOUTHERN NH AND EAST SLOPES OF BERKSHIRES?  

FINALLY IN BETWEEN THE TWO BANDS OF HEAVIEST RAIN THERE WILL LIKELY 
BE A MINIMUM.  SO BASICALLY...A WIDESPREAD 1 TO 2.50 INCHES OF RAIN 
IS EXPECTED FOR MUCH OF THE REGION...BUT LOCALIZED 4+ INCH AMOUNTS 
ARE CERTAINLY POSSIBLE ACROSS A PORTION OF THE REGION.  WILL JUST 
HAVE TO CONTINUE TO MONITOR RADAR/SATELLITE TRENDS OVERNIGHT AND 
FINE TUNE OUR QPF FORECAST.  THE FLOOD WATCH IS IN EFFECT ACROSS 
EASTERN NEW ENGLAND FOR THE POTENTIAL FOR LOCALIZED FLOODING IF THE 
HIGHER AMOUNTS ARE REALIZED.

2) TIMING:

HEAVY RAIN OVER SPREADS THE REGION FROM SOUTHEAST TO NORTHWEST THIS 
EVENING.  PERIODS OF HEAVY RAIN WILL OCCUR TONIGHT INTO THURSDAY 
MORNING...WHICH WILL LIKELY IMPACT THE MORNING RUSH HOUR.  ISOLATED 
THUNDERSTORMS ARE POSSIBLE TONIGHT INTO THURSDAY MORNING ACROSS 
SOUTHEAST NEW ENGLAND NEAR THE DRY SLOT.  THE STEADIEST 
RAIN SHOULD BE OVER BY THURSDAY AFTERNOON...BUT SCATTERED SHOWERS 
WILL CONTINUE.

3) STRONG WIND POTENTIAL:

NORTHEAST LOW LEVEL JET OVER 50 KNOTS WILL IMPINGE ON EASTERN NEW 
ENGLAND THROUGH EARLY THURSDAY MORNING.  IN FACT...BUFKIT SOUNDINGS 
SHOWING SOME PRETTY IMPRESSIVE WIND FIELDS BELOW 1000 FEET.  THE 
UNCERTAINTY IS THAT AN INVERSION WILL ATTEMPT TO KEEP THE STRONGEST 
WINDS JUST OFF THE DECK.  HOWEVER...HEAVY RAIN BANDS MAY BE ABLE TO 
PULL BRIEF STRONG WIND GUSTS TO THE GROUND.  THE WIND ADVISORY 
CONTINUES FOR NORTHEAST MA INTO COASTAL PLYMOUTH COUNTY.  PROBLEMS 
MAY BE EXACERBATED GIVEN THE MANY FULLY LEAFED TREES...RESULTING IN 
SOME DOWNED TREE LIMBS AND EVEN ISOLATED POWER OUTAGES.  THERE 
IS THE CHANCE THAT THE WIND ADVISORY MAY NEED TO BE EXPANDED FURTHER 
NORTHWEST...BUT AGAIN ITS UNCERTAIN HOW MUCH WIND WILL MIX DOWN.  
THE WINDS SHOULD DIMINISH BY MID MORNING ON THURSDAY AS THE LOW 
LEVEL JET WEAKENS.

&&


.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
* LINGERING SHOWERS POSSIBLE ON FRIDAY
* SHOWERS POSSIBLE AGAIN SATURDAY AS LOW PRES MOVES INTO QUEBEC
* MAINLY DRY AND SEASONABLE WEATHER EARLY NEXT WEEK

OVERALL THE 12Z MODEL SUITE IS IN FAIRLY GOOD AGREEMENT THROUGH THE 
LONG TERM. THERE ARE SOME DISCREPANCIES IN THE MESOSCALE DETAILS BUT 
OTHERWISE THEY ARE IN GOOD AGREEMENT.  AFTER THE COASTAL STORM 
CURRENTLY AFFECTING THE REGION MOVES AWAY FROM SOUTHERN NEW 
ENGLAND...THE WEATHER STARTS TO DRY OUT AND BECOME MORE SEASONABLE. 
THERE ARE A COUPLE OF COLD FRONTS EXPECTED TO MOVE THROUGH THE 
REGION AND EACH OF THESE MAY BRING SOME SHOWERS WITH THEM.

THURSDAY NIGHT AND FRIDAY...LOW PRESSURE SLOWLY MOVES INTO THE GULF 
OF MAINE AND THEN THE MARITIMES FRIDAY.  WHILE THE BULK OF THE RAIN 
WILL BE ENDING BY THURSDAY NIGHT...COULD SEE SOME LINGERING SHOWERS. 
HOWEVER...WINDS SHIFT TO THE NORTHWEST EARLY FRIDAY BRINGING 
SOMEWHAT DRIER AIR INTO THE REGION.  OVERALL EXPECT DRIER WEATHER 
AND A GRADUAL IMPROVEMENT AS WE MOVE INTO FRIDAY AFTERNOON.

SATURDAY...ANOTHER UPPER LEVEL TROUGH MOVES OVER THE NORTHEAST WITH 
LOW PRESSURE MOVING THROUGH SOUTHERN QUEBEC AND INTO THE MARITIMES.  
THE MODELS DON/T SHOW A WHOLE LOT OF MOISTURE OR A BIG WIND SHIFT 
WITH THIS FRONT BUT WE COULD SEE SOME SHOWERS. THE GFS HAS A 
STRONGER LOW LEVEL JET THAN THE ECMWF WHICH COULD ENHANCE THE AMOUNT 
OF RAINFALL BUT THERE IS STILL MUCH TO BE SEEN WITH THIS SYSTEM.

SUNDAY THROUGH TUESDAY...HIGH PRESSURE STARTS TO BUILD INTO SOUTHERN 
NEW ENGLAND BRINGING DRY AND SEASONABLE WEATHER.  TEMPERATURES BEGIN 
TO CLIMB AND MAY WARM TO WELL ABOVE NORMAL BY TUESDAY.

WEDNESDAY...LOW PRESSURE MOVING THROUGH THE GREAT LAKES AND INTO 
QUEBEC MAY BRING A COLD FRONT THROUGH SOUTHERN NEW ENGLAND.  ANOTHER 
CHANCE OF SOME SHOWERS POSSIBLE WITH THIS FRONT BUT PLENTY OF 
UNCERTAINTY.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT. 
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

SHORT TERM /THROUGH THU/...

THRU 12Z...

BAND OF HEAVY SHOWERS WITH EMBEDDED T-STORMS OVER CAPE COD
NORTHWEST INTO WESTERN MA WILL CONTINUE TO SLOWLY PIVOT NORTHWARD
WITH TIME. STRONG NE WINDS CONTINUE WITH HIGHEST GUSTS OVER
NORTHEAST MA. IFR PERSIST ALONG THE COAST WITH MVFR ELSEWHERE.

AFTER 12Z...

BAND OF HEAVY RAIN WITH EMBEDDED T-STORMS SHOULD BE ACROSS
NORTHERN MA INTO SOUTHERN NH AND SLOWLY LIFTING NORTHWARD.
MARGINAL IFR/MVFR CONDITIONS CONTINUE. GUSTY NE WINDS CONTINUE
WITH STRONGEST WINDS FOCUSED ACROSS NORTHEAST MA.

TONIGHT...

IFR EASTERN MA WITH MVFR ELSEWHERE. SLOW IMPROVEMENT WITH SHOWERS
BECOMING LESS NUMEROUS AND WINDS SLOWLY EASING.

FRIDAY...

MVFR BUT TRENDING TOWARD VFR LATE. SCATTERED SHOWERS BECOMING LESS
NUMEROUS AS THE DAY PROGRESSES. NNW WINDS 10-20 KT.

KBOS...HIGH CONFIDENCE IN TAF ON TRENDS BUT LOWER CONFIDENCE ON
EXACT TIMING OF DETAILS.

KBDL...HIGH CONFIDENCE IN TAF ON TRENDS BUT LOWER CONFIDENCE ON
EXACT TIMING OF DETAILS.

OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...

SATURDAY THROUGH MONDAY...MODERATE CONFIDENCE. VFR.  LOW PROBABILITY 
OF SCATTERED SHOWERS SATURDAY.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT. 
MODERATE...30 TO 60 PERCENT. 
HIGH...GREATER THAN 60 PERCENT.

SHORT TERM /THROUGH THURSDAY/...

***20 FOOT SEAS AND STORM FORCE NORTHEAST WIND GUSTS CONTINUE
 INTO THURSDAY ACROSS THE EASTERN MASSACHUSETTS WATERS***

LOW LEVEL JET WILL CONTINUE TO RESULT IN NORTHEAST WIND GUSTS OF
40 TO 50 KNOTS ACROSS THE NORTHERN MASSACHUSETTS WATERS INCLUDING
BOSTON HARBOR THROUGH THURSDAY MORNING BEFORE GRADUALLY
DIMINISHING. STRONG WINDS AND LONG NORTHEAST FETCH WILL RESULT IN
20 FOOT SEAS ACROSS PORTIONS OF OUR NORTHERN MASSACHUSETTS WATERS.
GALE FORCE NORTHEAST WIND GUSTS WILL CONTINUE ACROSS THE SOUTHERN
WATERS THROUGH THURSDAY MORNING.

OUTLOOK...THURSDAY NIGHT THROUGH MONDAY...

THURSDAY NIGHT AND FRIDAY...HIGH CONFIDENCE.  8 TO 11 FOOT SEAS WILL 
SLOWLY DIMINISH AS LOW PRESSURE MOVES INTO THE MARITIMES.  NORTHEAST 
WINDS GUSTING TO NEAR 30 KTS WILL DIMINISH AND SHIFT TO THE 
NORTHWEST.  VISIBILITIES MAY BE REDUCED IN SCATTERED SHOWERS.

SATURDAY AND SUNDAY...MODERATE CONFIDENCE. AFTER A BRIEF LULL...SEAS 
AND WINDS WILL INCREASE AHEAD OF A COLD FRONT.  SMALL CRAFT 
ADVISORIES WILL LIKELY BE NEEDED FOR AT LEAST A PORTION OF THE 
WATERS.

MONDAY...MODERATE CONFIDENCE.  WINDS AND SEAS DIMINISH AS HIGH 
PRESSURE BUILDS OVER THE WATERS.

&&

.TIDES/COASTAL FLOODING...
DESPITE RATHER LOW ASTRONOMICAL HIGH TIDE CYCLES LATE TONIGHT AND
AGAIN MIDDAY THURSDAY...OPTED TO ISSUE A COASTAL FLOOD ADVISORY
FOR A PORTION OF THE EASTERN MA COAST. THIS IS MAINLY FOR THE AREA
NORTH OF CAPE ANN AND THE SCITUATE AREA. A LONG DURATION OF
NORTHEAST WINDS COMBINED WITH 15 TO 20 FOOT SEAS ACROSS OUR
NORTHERN MA WATERS MAY YIELD POCKETS OF SPLASH OVER AND POCKETS OF
MINOR COASTAL FLOODING. CERTAINLY NOT EXPECTING A SIGNIFICANT
COASTAL FLOOD EVENT...BUT FELT IT WAS WORTH AN ADVISORY. 

IN ADDITION...THERE IS POTENTIAL FOR SIGNIFICANT BEACH EROSION ALONG
THE EXPOSED BEACHES FROM SALISBURY TO PLUM ISLAND.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY UNTIL 8 AM EDT THIS MORNING FOR CTZ004.
MA...HIGH WIND WARNING UNTIL 8 AM EDT THIS MORNING FOR MAZ007-
     014>016-019.
     FLOOD WATCH UNTIL 11 AM EDT THIS MORNING FOR MAZ005>007-
     013>022-026.
     COASTAL FLOOD ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR 
     MAZ007-019.
     WIND ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MAZ005-006-012-
     013-017-018-020-021.
NH...FLOOD WATCH UNTIL 11 AM EDT THIS MORNING FOR NHZ012-015.
     WIND ADVISORY UNTIL 8 AM EDT THIS MORNING FOR NHZ012.
RI...WIND ADVISORY UNTIL 8 AM EDT THIS MORNING FOR RIZ001>007.
MARINE...GALE WARNING UNTIL 5 AM EDT EARLY THIS MORNING FOR ANZ231>237-
     254>256.
     STORM WARNING UNTIL 5 AM EDT EARLY THIS MORNING FOR ANZ230.
     STORM WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ250-251.

&&

$$
SYNOPSIS...NOCERA
NEAR TERM...FRANK/RLG
SHORT TERM...FRANK/NOCERA
LONG TERM...RLG
AVIATION...NOCERA/RLG
MARINE...FRANK/RLG
TIDES/COASTAL FLOODING...



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