Area Forecast Discussion
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000
FXUS61 KBOX 030730
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
330 AM EDT TUE MAY 3 2016

.SYNOPSIS...

RAIN RE-DEVELOPS EARLY THIS MORNING AS LOW PRESSURE TRACKS SOUTH
OF NEW ENGLAND. RAIN TAPERS OFF THIS AFTERNOON FROM WEST TO EAST
BUT IT WILL REMAIN RATHER CLOUDY AND COOL. AN UNSETTLED AND COOL
PATTERN CONTINUES THROUGH THE REMAINDER OF THE WEEK BENEATH A
CLOSED LOW...CLEARING OUT OVER THE WEEKEND AS A COLD FRONT SWEEPS
THE REGION. DRY AND MILD WEATHER MAY RETURN INTO NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

300 AM UPDATE ...

*** A PERIOD OF STEADY RAIN THIS MORNING POSSIBLY HEAVY AT TIMES
 ALONG THE SOUTH COAST ***

FRONTAL WAVE OVER THE MID ATLC REGION EARLY THIS MORNING WILL
TRACK ENE TODAY IN THE DEEP SW FLOW ALOFT ALONG THE EASTERN
SEABOARD. WITHIN THIS AIRSTREAM COPIOUS AMOUNTS OF MOISTURE
AVAILABLE AS PWATS OF UP TO 1.5 INCHES CURRENTLY STREAMING NE
ACROSS DE INTO SOUTHERN NJ. THIS DEEP LAYER MOISTURE WILL BE
OVERSPREADING A FAIRLY BAROCLINIC ENVIRONMENT WITH GOOD THERMAL
PACKING ACROSS SOUTHERN NEW ENGLAND. THIS WILL RESULT IN A LARGE
RAIN SHIELD OVERSPREADING THE REGION EARLY THIS MORNING. AT 06Z
RAIN ALREADY INTO PSF AND DXR...AND SHOULD BE IN THE BOSTON-
PROVIDENCE CORRIDOR AROUND 4-6 AM AND THEN ACROSS CAPE COD AND
NANTUCKET BY 8 AM.

AS FRONTAL WAVE TRACKS SOUTH OF NEW ENGLAND LATER THIS MORNING
MODELS SUGGEST INCREASING LOW LEVEL FRONTOGENESIS ACROSS THE SOUTH
COAST OF MA AND RI. NOT VERY MAY-ISH BUT MORE LIKE A LATE
WINTER/EARLY SPRING SYSTEM. SOME ELEVATED INSTABILITY TOO SO
ISOLATED THUNDER POSSIBLE BUT THE GREATER IMPACT WILL BE THIS
INSTABILITY TO ENHANCE THE RISK FOR BANDS OF MODERATE TO HEAVY
RAIN ESPECIALLY ALONG THE SOUTH COAST OF MA AND RI 09Z TO 15Z FROM
WEST TO EAST. MAIN IMPACTS HERE WOULD BE CONFINED TO MINOR LOCAL
URBAN/POOR DRAINAGE FLOODING. ELSEWHERE EXPECTING LESS RAINFALL
NORTH OF THE MASS PIKE TOWARD THE MA/NH BORDER.

OTHERWISE SYSTEM IS FAIRLY PROGRESSIVE WITH RAIN TAPERING OFF THIS
AFTERNOON FROM WEST TO EAST. LOW CLOUDS LIKELY PERSIST GIVEN WEAK
RIDGING BUILDS DOWN FROM THE NORTHEAST. THIS SUBSIDENCE INVERSION
COMBINED WITH LOW MOISTURE TRAPPED MAY YIELD SPOTTY LIGHT DRIZZLE
LATER IN THE DAY.

ANOTHER COOL DAY AHEAD GIVEN THE RAIN AND LIGHT ONSHORE WINDS.
THIS WILL ONLY YIELD HIGHS IN THE U40S TO L50S...ABOUT 10-15 DEGS
COOLER THAN NORMAL. THE COOLER 2 METER TEMPS SEEM MORE REASONABLE
COMPARED TO THE MILDER MOS HIGHS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...

UPDATED 330 AM ...

TONIGHT ...

COLUMN BEGINS TO DRY FROM TOP DOWN AS SUBSIDENCE INCREASES BEHIND
DEPARTING FRONTAL WAVE. HOWEVER NOT EXPECTING SKIES TO CLEAR MUCH
IF ANY GIVEN LOTS OF LOW LEVEL MOISTURE TRAPPED BENEATH
SUBSIDENCE INVERSION. IN FACT THIS MAY YIELD PATCHY DRIZZLE/MIST
OVERNIGHT.

WEDNESDAY ...

LONG WAVE TROUGH SHARPENS AS NORTHERN STREAM JET ENERGY DIVING
SOUTHWARD FROM ONTARIO THRU THE GREAT LAKES FORMS A CLOSED LOW
OVER THE OH VALLEY LATE IN THE DAY. THIS BACKS THE UPPER LEVEL
FLOW ALONG THE EASTERN SEABOARD WITH A NEW FRONTAL WAVE AND PLUME
OF MOISTURE SURGING NORTHWARD INTO SOUTHERN NEW ENGLAND BY DAYS
END. SO THE WEATHER THEME FOR WED WILL BE A MAINLY DRY START
/OTHER THAN MORNING MIST-DRIZZLE/ FOLLOWED BY INCREASING THREAT
FOR RAIN ESPECIALLY LATE IN THE DAY FROM SOUTH TO NORTH.

ANOTHER COOLER THAN NORMAL DAY WITH SURFACE RIDGE WEDGED FROM THE
MARITIMES INTO NEW ENGLAND ALONG WITH CLOUDY SKIES AND LIGHT
ONSHORE WINDS.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...

*/ HIGHLIGHTS...

 - AN UNSETTLED AND COOL PATTERN THROUGH WEEKS END
 - POTENTIALLY CLEARING OUT OVER THE WEEKEND IN WAKE OF A COLD FRONT
 - THE POTENTIAL NEXT WEEK FOR A MORE TYPICAL PATTERN FOR MAY

*/ DISCUSSION...

A COOL UNSETTLED WEATHER PATTERN SETTING UP THROUGH EARLY NEXT WEEK
GIVEN THE BLOCKY PATTERN. ENSEMBLE FORECAST APPROACH PREFERRED GIVEN
ANOMALOUS SETUP OF 3 TO 4 STANDARD DEVIATIONS BELOW-AVERAGE ATYPICAL
FOR MAY. THIS PARENT WITH A DEEP TROUGH W EVOLVING INTO A CLOSED CUT-
OFF LOW BY WEEKS END PRIOR TO N-STREAM KICKER OVER THE WEEKEND. LOTS
OF ENERGY WITHIN THE OVERALL PATTERN DRAWING AND FORCING MOISTURE N
AS COOLER AIR IS ISENTROPICALLY DRAWN S. DAMP AND DREARY GIVEN THE
LIKELIHOOD A MAJORITY OF THE FORECAST PERIOD WILL BE SOCKED IN BY
CLOUDS AND POSSIBLY FOG/DRIZZLE GIVEN DOMINANT N/NE ONSHORE FLOW.
MAYBE A BRIEF BREAK PRIOR TO THE N-STREAM KICKER AND ATTENDANT COLD
FRONT CENTERED AROUND SUNDAY. CHANCE TO LIKELY POPS THROUGHOUT. FOR
NEXT WEEK A MORE AVERAGE AND DRIER WEATHER PATTERN POSSIBLY SETS UP
WITH DOMINANT W/SW FLOW MORE TYPICAL FOR THE MONTH OF MAY.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...

FORECASTER CONFIDENCE LEVELS...

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

UPDATED 300 AM ...

SHORT TERM /THROUGH WEDNESDAY/...

BEFORE 12Z ...

WIDE RANGE OF CONDITIONS EARLY THIS MORNING HOWEVER TREND WILL BE
DOWN TOWARD IFR/LIFR AS RAIN OVERSPREADS ALL TERMINALS FROM WEST
TO EAST. BANDS OF HEAVY RAIN WILL LIKELY EXIT NYC AREA AND COASTAL
CT AND APPROACHING SOUTHERN RI AND MA TOWARD 12Z. HEAVY CONFIDENCE
ON TRENDS BUT LOWER ON PRECISE DETAILS.

AFTER 12Z ...

RAIN OVER MOST OF THE AREA WITH BANDS OF MODERATE TO HEAVY RAIN
ALONG THE SOUTH COAST OF MA AND RI. IFR AND MVFR PREVAIL. RAIN BEGINS TO
PULL OUT OF THE REGION THIS AFTERNOON FROM WEST TO EAST. FORECAST
CONFIDENCE HIGH ON TRENDS BUT LOWER ON EXACT DETAILS.

TONIGHT ...

IFR AND MVFR WITH IFR LIKELY OVER SOUTHEAST MA AND THE HIGHER
TERRAIN. MVFR ELSEWHERE. SPOTTY DRIZZLE/MIST POSSIBLE IN IFR
AREAS. OTHERWISE MAINLY DRY. FORECAST CONFIDENCE HIGH ON TRENDS
BUT LOWER ON EXACT DETAILS.

WEDNESDAY ...

IFR LIKELY SOUTHEAST MA WITH MVFR ELSEWHERE. MAINLY DRY EARLY WITH
JUST SPOTTY MIST/DRIZZLE. RAIN REDEVELOPS LATE IN THE DAY FROM
SOUTH TO NORTH. LIGHT ENE WINDS.  FORECAST CONFIDENCE HIGH ON
TRENDS BUT LOWER ON EXACT DETAILS.

KBOS TERMINAL ... MODERATE TO HIGH CONFIDENCE IN TAF. BULK OF
HEAVY RAIN TODAY SHOULD SLIDE SOUTH OF LOGAN.

KBDL TERMINAL ... MODERATE TO HIGH CONFIDENCE IN TAF. HEAVIEST
RAIN TODAY IS FROM 09Z TO 15Z THEN TAPERING OFF.

OUTLOOK /WEDNESDAY NIGHT - SATURDAY NIGHT/...MODERATE CONFIDENCE.

MVFR TO LIFR MIX ESPECIALLY WITH -RA. WORST CONDITIONS POISED E/S
ALONG THE COASTS. DOMINANT E/NE FLOW.

&&

.MARINE...

FORECASTER CONFIDENCE LEVELS...

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

3 AM UPDATE ...

SHORT TERM /THROUGH WEDNESDAY/ ... HIGH CONFIDENCE.

LIGHT TO MODEST ENE WINDS TODAY THRU WED. PERIOD OF STEADY RAIN
THIS MORNING...HEAVY AT TIMES THEN TAPERING OFF THIS AFTERNOON.
MIST/DRIZZLE AND FOG TONIGHT INTO WED MORNING. THEN ANOTHER WEAK
FRONTAL WAVE SOUTH OF NEW ENGLAND BRINGS ANOTHER ROUND OF RAIN
LATE WED.

OUTLOOK /WEDNESDAY NIGHT - SATURDAY NIGHT/...MODERATE CONFIDENCE.

PERSISTENT E/NE FLOW THOUGH REMAINING BELOW 20 KTS WITH AREAS OF LOW
PRESSURE DEVELOPING NE ACROSS THE WATERS AT THE BEGINNING OF THE
PERIOD AND AGAIN FRIDAY INTO FRIDAY NIGHT. WAVES BUILDING 5 TO 7
FEET REQUIRING SMALL CRAFTS FOR HAZARDOUS SEAS. CONFIDENCE ON THE
OUTER WATERS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...

CT...NONE.
MA...NONE.
RI...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...NOCERA/SIPPRELL
NEAR TERM...NOCERA
SHORT TERM...NOCERA
LONG TERM...SIPPRELL
AVIATION...NOCERA/SIPPRELL
MARINE...NOCERA/SIPPRELL



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