Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 152309
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
709 PM EDT TUE APR 15 2014

.SYNOPSIS...
SHARP COLD FRONT PUSHING ACROSS NEW ENGLAND OVERNIGHT WILL BRING A
MIX OF STRONG GUSTY WINDS...HEAVY RAIN...AND EVEN A BRIEF CHANGE
TO A WINTRY MIX BEFORE ENDING EARLY ON WEDNESDAY. HIGH PRESSURE
IMMEDIATE FOLLOWING BRINGING DRY BUT UNSEASONABLE CONDITIONS FOR
WEDNESDAY INTO WEDNESDAY NIGHT. DRY WEATHER CONTINUES THURSDAY INTO
THE FIRST PART OF FRIDAY WITH MODERATING AFTERNOON TEMPS INLAND...
BUT REMAINING CHILLY ALONG THE COAST. LOW PRESSURE MAY BRING A
ROUND OR TWO OF RAIN SHOWERS SOMETIME FRIDAY NIGHT INTO SATURDAY
THEN DRY AND COOLER SUNDAY/MONDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...

7 PM UPDATE...

COLD FRONT NOW ENTERING THE CT RVR VLY WITH A SHARP WIND SHIFT TO
THE WEST ALONG WITH FALLING TEMPS. QUITE THE BAROCLINIC ZONE WITH
TEMP OF 61 AT ORE AND 37 AT PSF! WARM SECTOR REMAINS ACROSS
EASTERN MA/RI AND INTO EASTERN CT WITH TEMPS IN THE L60S AWAY FROM
THE SOUTH COAST. DEEP MOISTURE PLUME WITH PWATS UP TO 1.4 INCHES
CENTERED OVER RI AND EASTERN MA...SLOWLY MOVING EASTWARD. RAIN
SHIELD HAS BECOME MORE FRAGMENTED WITH TIME HOWEVER HEAVIER
ELEMENTS EMBEDDED IN LARGER RAIN SHIELD. HEAVIER RAIN THREAT WILL
BE FOCUSED ACROSS RI AND EASTERN MA UNTIL ABOUT 03Z...WITH DEEP
MOISTURE PLUME MOVING OFFSHORE BY THEN. HOWEVER STRONG Q/G FORCING
FROM UPPER LEVEL JET WILL BE MOVING FROM THE MID ATLC REGION
ACROSS SOUTHERN NEW ENGLAND AROUND 06Z. THIS WILL YIELD LIGHT TO
MODERATE PRECIP...HOWEVER THE HEAVIER PRECIP SHOULD BE MOVING
OFFSHORE AS LOW LEVEL JET EXITS AS WELL.

COLD AIR ARRIVES IN WESTERN CT/MA 03Z-06Z AND THEN 06Z-09Z EASTERN
MA AND RI. HOWEVER COLUMN DRIES OUT QUICKLY SO ANY SNOW/SLEET
SHOULD BE SHORT LIVED. NEVERTHELESS COULD HAVE SOME SLICK SPOTS
INLAND DURING THE PREDAWN HOURS. PREVIOUS FORECAST CAPTURES THIS
WELL SO NO MAJOR CHANGES WITH THIS FORECAST UPDATE. EARLIER
DISCUSSION BELOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

COLD FRONT NOW PUSHING INTO WESTERN NEW ENGLAND. WIDESPREAD RAIN
WITH EMBEDDED HEAVIER SHOWERS LENDING TO NUMEROUS OBSERVATIONS OF
SOUTHERLY WIND GUSTS IN EXCESS OF 40 MPH WITH ISOLATED GUSTS UP
TO AROUND 50 MPH. THE PROGRESSIVE NATURE OF THE RAIN IS LENDING TO
A QUARTER- TO HALF-INCH PER HOUR RAINFALL AMOUNTS...NOT SO MUCH AN
ISSUE TOWARDS FLASH FLOODING...BUT ENOUGH OVER THE COURSE OF TODAY
INTO THIS EVENING TO LEND TO RIVER AND URBAN/POOR DRAINAGE FLOODING.

THREATS AND ASSOCIATED IMPACTS ARE OUTLINED BELOW:

HEAVY RAIN/FLOODING...

FLOOD WARNINGS HAVE BEEN ISSUED FOR MULTIPLE POINTS ALONG THE
CONNECTICUT RIVER BASIN WITH THE EXPECTATION OF MINOR RIVER
FLOODING...PERHAPS MODERATE FLOODING AT MIDDLE HADDAM.

SUB-TROPICAL MOISTURE WITH ASSOCIATED PRECIPITABLE WATER VALUES IN
EXCESS OF 1.5-INCHES SURGING NORTH WITH THE AMPLIFYING LOW-LEVEL
FLOW /70-80 KTS PRESENTLY PER WSR-88D VERTICAL WIND PROFILERS/ IS
ANOMALOUSLY HIGH ON THE ORDER OF 3-4 STANDARD DEVIATIONS ABOVE
NORMAL.

CONVERGENT AHEAD OF THE FRONT AND ALONG THE NOSE OF THE LOW-
LEVEL-JET...MOISTURE IS UNDERGOING BOTH FRONTOGENETICAL LIFT AND
STRONG DEEP-LAYER ASCENT BENEATH AN AREA OF STRONG UPPER-LEVEL
DIVERGENCE PER RRQ. THIS IS LENDING TO WIDESPREAD RAIN WITH
EMBEDDED HEAVIER SHOWERS AND EVEN THE POSSIBILITY OF ISOLATED
THUNDERSTORMS /ESPECIALLY IMMEDIATELY AHEAD OF THE COLD FRONT OVER
NJ INTO THE LOWER HUDSON VALLEY TOWARDS THE BERKSHIRES/.

WHILE RAINFALL RATES HAVE BEEN ANYWHERE FROM A QUARTER TO HALF-
AN-INCH PER HOUR...THE CUMULATIVE RAINFALL AMOUNTS ARE EXPECTED TO
BE AROUND 2 INCHES WITH LOCALLY HIGHER AMOUNTS AROUND 3 INCHES IN
A TIME-FRAME ROUGHLY AROUND 6-HOURS. THUS THE FLOOD WATCH
CONTINUES.

THE BASIS FOR THE FLOOD WATCH CONTINUES TO BE A FOCUS UPON ALREADY
SWOLLEN RIVERS FROM UPSTREAM SNOWMELT TAKING ON ADDITIONAL WATER
GOING INTO MINOR FLOODING...POSSIBLY INTO MODERATE FLOOD FOR THE
CONNECTICUT RIVER AT MIDDLE HADDAM.

RIVER BASINS OF CONCERN INCLUDE CONNECTICUT/MERRIMACK/PAWCATUCK.
ALSO ANTICIPATE IMPACTS TO LOCAL STREAMS/CREEKS/TRIBUTARIES...
ESPECIALLY THOSE THAT ARE NARROWER AND FLASHIER. THOSE WITH
INTERESTS ALONG AREA RIVERS SHOULD PAY ATTENTION TO THE LATEST
FORECASTS AND CURRENT WATER LEVELS.

THE FLOOD WATCH ALSO INCLUDES URBAN AND POOR DRAINAGE ISSUES FOR
THE DRIVE-HOME COMMUTE PRESENTLY ONGOING FOR ALL ROADWAYS ACROSS
SOUTHERN NEW ENGLAND. PONDING OF WATER THE BIGGEST CONCERN.

PLEASE SEE THE COASTAL FLOODING SECTION BELOW FOR COASTAL FLOOD
THREATS.

WINDS...

SEVERAL LOCATIONS ACROSS CENTRAL/EASTERN NEW ENGLAND OBSERVING
WIND GUSTS IN EXCESS OF 40 KTS /46 MPH/. WSR-88D VERTICAL WIND
PROFILERS SHOWING WINDS AT H925 AMPLIFYING TO 70 KTS. INCREASING
AREAL COVERAGE OF RAIN WITH EMBEDDED HEAVIER SHOWERS AIDING IN THE
PRECIP-DRAG / MECHANICAL MIXING OF FASTER MOMENTUM ALOFT DOWN TO
THE SURFACE. SHOULD SEE THESE WINDS CONTINUE INTO THE EVENING
HOURS. WIND ADVISORIES CONTINUE ACCORDINGLY.

THOSE TRAVELING OVER BRIDGES /THINKING THE SAGAMORE AND BOURNE/
SHOULD BE AWARE OF FIERCE CROSSWINDS. GUSTS IN EXCESS OF 50 MPH
WILL BE POSSIBLE. ALREADY RECEIVING NUMEROUS REPORTS OF TREES AND
WIRES DOWN...BLOWN TRANSFORMERS AND POWER OUTAGES. THESE IMPACTS
AND THREATS WILL CONTINUE OVER THE NEXT SEVERAL HOURS AHEAD OF THE
COLD FRONT SWEEPING THROUGH THE REGION.

WINTRY MIX/FLASH FREEZE POTENTIAL...

TEMPERATURES QUICKLY FALLING IMMEDIATELY BEHIND THE COLD FRONT AS
WINDS BACK OUT OF THE WEST. ALREADY TEMPERATURES IN THE 30S ARE
ENCROACHING INTO THE HUDSON RIVER VALLEY REGION. EXPECTING THIS
COLD AIR TO SURGE INTO THE REGION DURING THE OVERNIGHT HOURS...
MAINLY AROUND AND AFTER MIDNIGHT.

CONSIDERING THE STRONG DYNAMICS AND LIFT TO THE REAR OF THE COLD
FRONT...THERE IS THE POTENTIAL FOR LINGERING PRECIPITATION WITHIN
THE SHALLOW COLD-AIR MASS IN THE FORM OF A WINTRY MIX.

THUS A BRIEF CHANGEOVER TO A SNOW/SLEET MIX IS POSSIBLE...MAINLY
ACROSS INTERIOR PORTIONS OF NEW ENGLAND AND ESPECIALLY NORTH OF
THE ROUTE-2 CORRIDOR INCORPORATING NORTHERN MASSACHUSETTS AND
SOUTHERN NEW HAMPSHIRE. LIKELY TO SEE AN INCREASE IN LIKELIHOOD
ALONG WESTERN SLOPES OF HIGHER TERRAIN. ANY ACCUMULATIONS WILL BE
LIGHT AROUND A TRACE TO PERHAPS A TENTH OR TWO...ENOUGH TO MAKE
FOR SLIPPERY CONDITIONS.

DRIER AIR WILL WORK INTO THE REAR OF THE STORM RESULTING IN THE
BACK EDGE OF PRECIP TO DISSIPATE. THIS DRIER AIR CAN BE SEEN
WITHIN THE MID-LEVELS PER WATER-VAPOR IMAGERY...BUT SHOULD ALSO
SEE THIS DRY AIR AT THE SURFACE. THUS IT IS A QUESTION AS TO
WHETHER WET SURFACES WILL FREEZE AHEAD OF EVAPORATING. EITHER
WHICH WAY...THERE IS THE POTENTIAL FOR BLACK-ICE AND SLIPPERY
CONDITIONS THAT MAY EXIST FOR THE WEDNESDAY MORNING COMMUTE.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
WEDNESDAY...

AN UNSEASONABLY CHILLY AIRMASS WILL CONTINUE TO WORK INTO THE REGION
AS HIGH PRESSURE BUILDS IN FROM THE WEST. ANY LEFT OVER PRECIP
SHOULD EXIT THE CAPE/ISLANDS BY MID-MORNING AT THE LASTEST AS THE
COLD FRONT WILL BE WELL OFFSHORE.

WESTERLY WINDS CONTINUE TO GUST BETWEEN 30 AND 40 MPH DURING THE
MORNING...BUT WILL DIMINISH DURING THE AFTERNOON. THIS AIDED BY
ANOMALOUSLY COLD H85 TEMPS FOR THIS TIME OF YEAR BETWEEN -6C AND
-10C ALLOWING FOR EFFECTIVE BOUNDARY LAYER MIXING.

THOUGH WITH RESPECT TO TEMPERATURES...PLENTY OF STRONG APRIL
SUNSHINE WILL OFFSET COLDER AIR ALOFT TO SOME DEGREE. ALL IN
ALL...MUCH OF THE REGION SHOULD SEE HIGHS RECOVER WELL INTO THE
40S DURING THE AFTERNOON.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...

HIGHLIGHTS...

* DRY BUT UNSEASONABLY CHILLY WED NIGHT
* DRY WEATHER CONTINUES INTO FRI AND BECOMING MILDER INLAND
* A PERIOD OF SHOWERS POSSIBLE FRI NIGHT INTO SAT BUT LOW CONFIDENCE

AN ACTIVE AND SURPRESSED NORTHERN STREAM JET THIS PERIOD WILL RESULT
IN TEMPERATURES AT OR COOLER THAN NORMAL ALONG WITH A FEW CHANCES OF
SHOWERS. VERY TYPICAL PATTERN FOR MID APRIL.

DAILY DETAILS...

WEDNESDAY NIGHT...

CHILLY AIRMASS OVER THE REGION ALONG WITH MAINLY CLEAR SKIES AND
DIMINISHING WINDS. THIS WILL RESULT IN COLD TEMPS OUTSIDE OF THE
URBAN AREAS WITH MOST LOCATIONS IN THE 20S!

THURSDAY AND FRIDAY...

STRONG /1044 MB!/ HIGH PRESSURE ADVECTS INTO THE CANADIAN MARITIMES.
THIS WILL EVOLVE INTO A COOL MARITIME AIRMASS FOR SOUTHERN NEW
ENGLAND WITH LARGE TEMP DIFFERENCES FROM THE COAST TO INLAND. ACROSS
EASTERN MA THE VERY CHILLY OCEAN WATERS WITH SSTS IN THE L40S WILL
ACT LIKE A SNOWCOVER AND ENHANCE THIS COOL MARITIME AIRMASS. CHILLY
ONSHORE WINDS WILL ADVECT THIS VERY COOL AND SHALLOW MARITIME
AIRMASS INTO THE COASTAL PLAIN. THEREFORE ONLY EXPECTING HIGHS IN
THE 40S OVER EASTERN MA...MEANWHILE STRONG APRIL SUN HEATS UP THE
INTERIOR INTO THE 50S. AIRMASS CONTINUES TO MODIFY FRI WITH HIGHS 45-
50 EASTERN MA AND 55-60 WELL INLAND.

FRIDAY NIGHT AND SATURDAY...

MODELS CONTINUE TO STRUGGLE ON AMPLITUDE AND INTERACTION OF NORTHERN
AND SOUTHERN STREAM WAVES. 12Z GFS REMAINS MORE ROBUST AND PHASING
THAN THE 12Z ECMWF. THUS THE GFS IS THE WETTER SOLUTION OF THE TWO.
ENSEMBLES INDICATE MORE STREAM SEPARATION AND ARE SLOWER PHASING THE
STREAMS BUT THIS IS SOMEWHAT TYPICAL GIVEN THE LOWER RESOLUTION OF
THE ENSEMBLES.

TEMPS LIKELY REMAIN NEAR NORMAL...HIGHS IN THE 50S.

SUNDAY/MONDAY/TUESDAY...

AS EXPECTED LOTS OF TIMING ISSUES HERE GIVEN THE FAST FLOW ACROSS
THE NORTHERN STATES. GIVEN THIS FLOW REGIME AND TIME RANGE HERE WILL
FOLLOW A MODEL BLEND WHICH YIELDS TEMPS NEAR NORMAL AND A RISK OF
SHOWERS IN THE MON NIGHT/TUE TIME FRAME.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...

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

7 PM UPDATE...

NOT MUCH CHANGE FROM PREVIOUS TAFS. COLD FRONT INTO CT RVR VLY AT
7 PM AND CONTINUING TO MAKE STEADY EASTWARD PROGRESS. EARLIER
DISCUSSION BELOW.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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

IFR-LIFR CIGS/VSBYS WITH +RA CONTINUING THROUGH THE EVENING.
STRONG S WINDS CONTINUING WITH GUSTS IN EXCESS OF 40 KTS WITH A
FEW LOCATIONS UP TO AROUND 50 KTS /ESPECIALLY FOR E-S MA AND RI/.
LLWS IMPACTS OVER ALL TERMINALS WITH 60-70 KT 2 KFT AGL.

COLD FRONT PUSHES THROUGH THE TERMINALS AROUND MIDNIGHT. WILL SEE
WINDS BACK WEST REMAINING GUSTY UP TO 40 KTS. CONDITIONS QUICKLY
IMPROVING TO VFR. MAY SEE RAIN TRANSITION TO SNOW/SLEET BRIEFLY
WITH MINOR ACCUMS. BEST CHANCES OVER NW MA INTO S NH. PRECIP
COMING TO AN END AS WINDS DIMINISH THROUGH THE DAY WEDNESDAY.

KBOS TERMINAL...MODERATE CONFIDENCE.

KBDL TERMINAL...MODERATE CONFIDENCE.

OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...

WEDNESDAY NIGHT THRU FRIDAY...VFR VSBYS LIKELY WITH MVFR CIGS
POSSIBLE...HIGHEST PROBABILITY ACROSS RI AND EASTERN MA.

FRIDAY NIGHT INTO SATURDAY...MVFR IN SCATTERED SHOWERS POSSIBLE BUT
CONFIDENCE IS VERY LOW.

SUNDAY...IMPROVING TREND WITH VFR LIKELY ALONG WITH INCREASING NW
WINDS.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

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

S WINDS OVER THE WATERS GUSTING IN EXCESS OF GALE FORCE THROUGH
THE EVENING WITH WAVES OF 10 TO 12 FEET ON THE OUTER WATERS. RAIN
AND FOG AHEAD OF THE FRONT WILL NET VISIBILITY ISSUES OVER THE
WATERS DOWN TO A MILE OR TWO AT TIMES. THERE IS THE POSSIBILITY OF
ISOLATED THUNDERSTORMS OVER THE SOUTH WATERS.

COLD FRONT SWEEPS THE WATERS AROUND MIDNIGHT BEHIND WHICH WINDS
WILL BACK OUT OF THE WEST REMAINING GUSTY UP TO 40 KTS. CONDITIONS
CLEARING QUICKLY AS WINDS DIMINISH THROUGH THE DAY WEDNESDAY. WAVE
ENERGY WILL SLOWLY DIMINISH...SO WHILE GALES CONCLUDE...SMALL
CRAFT ADVISORIES WILL LIKELY BE NECESSARY.

OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...

WED NIGHT THRU FRI...TREND HERE WILL BE DECREASING SOUTHERLY SWELLS
WITH INCREASING ENE WIND WAVES. MAINLY DRY WITH MARITIME AIRMASS
OVER THE WATERS COURTSEY OF 1040 MB HIGH ACROSS NEWFOUNDLAND.

FRI NIGHT AND SAT...LOW CONFIDENCE FORECAST WITH LOW PRES
APPROACHING FROM THE SOUTH AND ANOTHER FROM THE GREAT LAKES. DILEMMA
WILL BE HOW MUCH SEPARATION BETWEEN THESE SYSTEMS OR IF LOWS WILL
MERGE INTO ONE STRONGER SYSTEM. STILL TOO EARLY TO SAY.

SUNDAY...IMPROVING TRENDS WITH LOW PRES STRENGTHENING WELL EAST OF
NEW ENGLAND FOLLOWED BY A MODEST NW WIND.

&&

.TIDES/COASTAL FLOODING...
STRONG SOUTHERLY WINDS OVER THE WATERS GUSTING 30 TO 40 MPH WILL
YIELD AN AVERAGE 1.5 FOOT SURGE ALONG THE SOUTH COAST. COMBINED
WITH HIGH TIDE AROUND 9-10 PM /NOT ASTRONOMICALLY HIGH/...THERE
IS THE POSSIBILITY OF SPLASHOVER ALONG LOW-LYING AREAS. A COASTAL
FLOOD STATEMENT HAS BEEN ISSUED ACCORDINGLY TO ACCOUNT FOR THE
THREAT AND IMPACTS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR CTZ002>004.
MA...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR MAZ002>021-026.
     WIND ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR MAZ004>007-
     012>024-026.
NH...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR NHZ011-012-015.
RI...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR RIZ001>007.
     WIND ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR RIZ001>008.
MARINE...GALE WARNING UNTIL NOON EDT WEDNESDAY FOR ANZ230>234-236-250-
     251.
     GALE WARNING UNTIL 10 AM EDT WEDNESDAY FOR ANZ235-237-256.
     GALE WARNING UNTIL 2 PM EDT WEDNESDAY FOR ANZ254-255.

&&

$$
SYNOPSIS...NOCERA/SIPPRELL
NEAR TERM...NOCERA/SIPPRELL
SHORT TERM...SIPPRELL
LONG TERM...NOCERA
AVIATION...NOCERA/SIPPRELL
MARINE...NOCERA/SIPPRELL
TIDES/COASTAL FLOODING...RMT



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