Area Forecast Discussion
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FXUS61 KBOX 031048
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
648 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/...

7 AM UPDATE...

NOT MANY CHANGES TO THE GOING FORECAST ONLY TO REFLECT THE ONGOING
TRENDS. AS NOTED IN THE DISCUSSION BELOW...AN OVER-RUNNING SETUP
PRESENTLY THAT EVOLVES INTO A POTENTIAL HEAVY RAIN EVENT ALONG THE
S COAST AS LOW TO MID LEVEL FORCING EVOLVES AS A MODEST POCKET OF
FRONTOGENESIS BENEATH THE RIGHT-REAR QUADRANT OF THE UPPER LEVEL
JET. STRONG LIFT WITH POTENTIAL INSTABILITY...CAN NOT DISAGREE
WITH THE PRIOR FORECAST OF HEAVY RAIN POTENTIAL ALONG THE S COAST
WHICH WOULD LIKELY BRING ABOUT VISIBILITY RESTRICTIONS AND PERHAPS
SOME NUISANCE FLOODING ISSUES. FOCUS THIS MORNING INTO MIDDAY WITH
RAIN TAPERING OFF THEREAFTER.

*/ HIGHLIGHTS...

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

*/ DISCUSSION...

FRONTAL WAVE OVER THE MID ATLC REGION THIS MORNING WILL TRACK ENE
TODAY IN THE DEEP SW FLOW ALOFT ALONG THE E SEABOARD. WITHIN THIS
AIRSTREAM COPIOUS AMOUNTS OF MOISTURE AVAILABLE AS PWATS OF UP TO
1.5 INCHES CURRENTLY STREAMING NE ACROSS DE INTO S NJ. THIS DEEP
LAYER MOISTURE WILL BE OVERSPREADING A FAIRLY BAROCLINIC ENVIRONMENT
WITH GOOD THERMAL PACKING ACROSS S NEW ENGLAND. THIS WILL RESULT
IN A LARGE RAIN SHIELD CONTINUING TO OVERSPREAD THE REGION THIS
MORNING.

AS FRONTAL WAVE TRACKS S OF NEW ENGLAND LATER THIS MORNING MODELS
SUGGEST INCREASING LOW LEVEL FRONTOGENESIS ACROSS THE S 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 S COAST OF MA AND RI 09Z TO 15Z FROM W TO E. 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 W TO E. 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 /12Z TUESDAY THROUGH SATURDAY/...

FORECASTER CONFIDENCE LEVELS...

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

12Z UPDATE...

SHORT TERM /THROUGH WEDNESDAY/...MODERATE CONFIDENCE.

TODAY...

TOUGH FORECAST. -RA OVERALL...WITH POSSIBLE RA/+RA ALONG THE S
COAST THIS MORNING TOWARDS MIDDAY. A WOBBLING OF CONDITIONS
RANGING FROM LOW-END VFR DOWN TO LIFR. EVALUATING UPSTREAM AND
CONSIDERING FORECAST TRENDS...LOW CONDITIONS OVER ALL S NEW
ENGLAND TERMINALS THIS MORNING. GRADUAL IMPROVING TREND NW TO SE
BUT IT IS LIKELY THAT THE S TERMINALS ESPECIALLY CLOSE TO THE
COAST WILL BE SOCKED IN WITH LOW CLOUDS MUCH OF TODAY. -DZ / BR
LINGERING FOR THOSE LOCALES.

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.

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

7 AM UPDATE...NO MAJOR CHANGES TO THE FORECAST.

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


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