Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 261423
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1023 AM EDT TUE APR 26 2016

.SYNOPSIS...
A WAVE OF LOW PRESSURE WILL TRACK JUST SOUTH OF NEW ENGLAND TUE
PROVIDING A WIDESPREAD APPRECIABLE RAINFALL TO THE REGION ALONG
WITH A CHILLY NORTHEAST WIND AND MUCH COOLER THAN NORMAL TEMPS.
HIGH PRESSURE BUILDS ACROSS THE REGION WEDNESDAY. A LOW PRESSURE
WILL TRACK WELL SOUTH OF NEW ENGLAND THURSDAY INTO FRIDAY AS HIGH
PRESSURE REMAINS IN CONTROL BRINGING MAINLY DRY WEATHER AND NEAR
SEASONABLE TEMPS INTO THE WEEKEND. AN APPROACHING FRONTAL SYSTEM
WILL BRING ANOTHER CHANCE OF RAIN NEXT MONDAY.

&&

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

1030 AM UPDATE...

IMPRESSIVE SHORT WAVE MOVING ACROSS LAKE ONTARIO AT 10 AM PER
LATEST WATER VAPOR IMAGERY. A MODEST MOISTURE PLUME AHEAD OF THIS
FEATURE WITH PWATS OF 1.O TO 1.2 INCHES ACROSS SOUTHERN NY STATE
INTO CT AND LONG ISLAND. MARGINAL INSTABILITY ALOFT WITH BOTH 12Z
OBSERVED SOUNDINGS FROM OKX AND ALY REPORTING MID LEVEL LAPSE
RATES OF 6-6.5C/KM. THUS THE COMBINATION OF GOOD SYNOPTIC SCALE
FORCING...MODEST DEEP LAYER MOISTURE AND MARGINAL ELEVATED
INSTABILITY WILL RESULT IN A PERIOD OF RAIN THRU 18Z - 21Z FROM
WEST TO EAST. ANY ELEVATED CONVECTION SHOULD BE CONFINED TO THE
SOUTH COAST OR REMAIN OFFSHORE. APPRECIABLE RAINFALL EXPECTED
WITH UPSTREAM HOURLY RAINFALL RATES UP TO 0.18 INCHES AT AQW THIS
PAST HOUR. STORM TOTAL AMOUNTS OF 0.25 TO 0.50 SEEM REASONABLE.
PREVIOUS FORECAST CAPTURES THESE DETAILS NICELY. ONLY ADJUST WITH
THIS UPDATE WAS TO MODIFY HOURLY POPS TO BETTER REFLECT LATEST
RADAR TRENDS.

AS MENTIONED ABOVE EXPECTING RAIN TO TAPER OFF 18Z-21Z FROM WEST
TO EAST ACROSS THE REGION. HOWEVER ACROSS EASTERN MA AND POSSIBLY
INTO RI MOIST NE FLOW BENEATH LOW LEVEL INVERSION MAY PROMOTE
SPOTTY DRIZZLE INTO THIS EVENING.

FRONTAL BOUNDARY SOUTH OF NEW ENGLAND SO COOL NORTHEAST FLOW WILL
LIMIT TEMPS TODAY TO THE 40S. HOWEVER GIVEN DEW PTS IN THE 30S
TEMPS WILL FALL ONCE RAIN COMMENCES WITH SOME HIGHER TERRAIN
LOCATIONS REMAINING IN THE U30S. FOR EXAMPLE ORE AND ORH CURRENTLY
AT 39 WITH LIGHT RAIN FALLING. IT WILL FEEL EVEN COOLER ACROSS
EASTERN MA WITH NE WINDS UP TO 25 MPH OFF THE CHILLY OCEAN WATERS.

AS FOR PTYPE...DESPITE CHILLY TEMPS PTYPE WILL BE ALL RAIN.
ALTHOUGH AS WARM LAYER CENTERED AROUND 850 MB SLOWLY ERODES THIS
AFTERNOON RAIN MAY MIX WITH SLEET FOR A TIME ACROSS NORTHERN MA
TO THE NH BORDER.


&&

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

TONIGHT...ANY LINGERING SHOWERS WILL COME TO AN END QUICKLY THIS
EVENING.  CLEAR SKIES ARE EXPECTED IN THE DRIER AIR MOVING DOWN FROM
THE NORTH.  WINDS MAY BE JUST HIGH ENOUGH TO PRECLUDE OPTIMAL
RADIATIONAL COOLING.  HOWEVER...TEMPERATURES SHOULD FALL INTO THE
LOW TO MID 30S FOR MUCH OF THE AREA.  FROST/FREEZE HEADLINES WILL
LIKELY BE NECESSARY WHERE THE GROWING SEASON HAS BEGUN.

WEDNESDAY...HIGH PRESSURE BUILDS INTO SOUTHERN NEW ENGLAND AND
TEMPERATURES REBOUND A BIT FROM THE COLD OF TODAY.  STILL A FEW
DEGREES BELOW NORMAL FOR LATE APRIL BUT A WELCOME DIFFERENCE AFTER
THE 40S TODAY.

&&

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

HIGHLIGHTS...

* MAINLY DRY WEATHER WITH TEMPS MODERATING TO NEAR SEASONABLE
  NORMALS DURING THE WEEKEND
* RAIN POSSIBLE NEXT MONDAY

OVERVIEW...
STRONG HIGH LATITUDE BLOCK OVER GREENLAND WILL WEAKEN LATE IN THE
WEEK INTO THE WEEKEND RESULTING IN ANOMALOUS VORTEX OVER EASTERN
CANADA LIFTING NORTHWARD...WITH GRADUAL MODERATION IN TEMPS TO NEAR
SEASONABLE LEVELS.  00Z GUIDANCE INCLUDING MAJORITY OF GEFS MEMBERS
HAVE TRENDED SOUTH WITH LOW PRES MOVING OFF MID ATLC COAST THU-FRI
AS INFLUENCE FROM E CANADIAN VORTEX AND UPPER LEVEL CONFLUENCE WILL
LIKELY LEAD TO A MORE SUPPRESSED SHORTWAVE. MAINLY DRY WEATHER
EXPECTED INTO THE WEEKEND WITH NEXT CHANCE OF RAIN COMING SUN NIGHT
OR MON AS FRONTAL SYSTEM APPROACHES...BUT TIMING IS UNCERTAIN AS
ECMWF IS ABOUT 24 HOURS SLOWER THAN GFS.

DETAILS...

WED NIGHT...
SFC RIDGING FROM HIGH PRES NORTH OF THE LAKES WILL BUILD INTO NEW
ENG WITH MAINLY CLEAR SKIES AND LIGHT NORTHERLY FLOW DEVELOPING.
GOOD RADIATIONAL COOLING WILL LEAD TO A COLD NIGHT WITH MINS
DROPPING INTO THE UPPER 20S TO MID 30S ACROSS MUCH OF THE REGION.
FROST/FREEZE HEADLINES WILL LIKELY BE NEEDED FOR THOSE AREAS
ACTIVATED.

THU INTO FRI...
LOW PRES MOVING OFF MID ATLC COAST WITH MODEL CONSENSUS FAVORING A
MORE SUPPRESSED SOLUTION WITH HIGH PRES REMAINING IN CONTROL. WE
LOWERED POPS AND HAVE A MAINLY DRY FORECAST...WITH JUST A VERY LOW
PROB FOR A FEW SHOWERS NEAR THE S COAST. TEMPS WILL BE MOSTLY IN THE
50S...TO AROUND 60 DEGREES IN THE CT VALLEY. COASTAL SEABREEZES
LIKELY BOTH DAYS.

SAT INTO SUN...
HIGH PRES REMAINS IN CONTROL WITH MAINLY DRY WEATHER...ALTHOUGH
NORTHERN STREAM SHORTWAVE MOVING THROUGH IN NW FLOW ALOFT MAY
TOUCH OFF A FEW SHOWERS DURING SUNDAY. MODERATING TEMPS TO NEAR
SEASONABLE NORMS.

MON...
LOW CONFIDENCE FORECAST REGARDING TIMING OF MOISTURE WITH NEXT
FRONTAL SYSTEM. ECMWF IS SLOWER AND MAINTAINS RIDGING AND DRY
WEATHER...WHILE GFS AND MAJORITY OF GEFS MEMBERS ARE WET.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
FORECASTER CONFIDENCE LEVELS...

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

1030 AM UPDATE ... NOT MUCH CHANGE FROM 12Z TAFS. BULK OF PRECIP
OCCURS NOW THRU 18Z WEST...21Z EAST. CIGS SLOWLY LOWER FROM VFR TO
MVFR TODAY. RAIN INTENSITY WILL MAINLY BE LIGHT TO MODERATE AT
TIMES. ANY ELEVATED T-STORMS SHOULD BE CONFINED TO THE SOUTH COAST
OR OFFSHORE. EARLIER DISCUSSION BELOW.

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

SHORT TERM /THROUGH WEDNESDAY/...

TODAY...HIGH CONFIDENCE. DETERIORATING CONDITIONS TO MVFR AS
ANOTHER BATCH OF RAIN MOVES INTO THE REGION FROM THE WEST. AREAS
OF IFR POSSIBLE THIS AFTERNOON. SOME SLEET MAY MIX IN WITH THE
RAIN IN N MA. NE WINDS GUSTING TO 15 TO 20 KTS ESPECIALLY ALONG
THE EAST COAST. LOW PROBABILITY OF THUNDER ALONG THE SOUTH COAST
AND ISLANDS.

TONIGHT...HIGH CONFIDENCE.  MVFR/IFR CONDITIONS IMPROVE QUICKLY TO
VFR.

WEDNESDAY...HIGH CONFIDENCE. VFR.

KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN
EXACT TIMING.

KBDL TERMINAL...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN
EXACT TIMING.

OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...

HIGH CONFIDENCE. MAINLY VFR THROUGH THE PERIOD.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

1030 AM UPDATE ... ONLY CHANGE FROM PREVIOUS FORECAST WAS TO SPEED
UP ARRIVAL OF SCA WINDS TO LATE THIS MORNING ACROSS SOUTH COASTAL
WATERS AND CONTINUING AT LEAST INTO THIS AFTERNOON. EARLIER
DISCUSSION BELOW.

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

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

TODAY...LOW PRESSURE TRACKS ALONG STALLED FRONT OVER THE SOUTHERN
WATERS.  EXPECT INCREASING SEAS AND GUSTY NORTHEASTERLY WINDS. WIND
GUSTS ARE EXPECTED TO BE JUST UNDER SMALL CRAFT CRITERIA BUT WILL BE
CLOSE ENOUGH THAT AM NOT COMFORTABLE TAKING IT DOWN AT THIS POINT.
WIDESPREAD RAIN AND AREAS OF FOG WILL LIMIT VISIBILITIES.  THERE IS
ALSO A LOW PROBABILITY OF THUNDER OCCURRING ON THE SOUTHERN WATERS.

TONIGHT...COLD FRONT MOVES SOUTH OUT OF THE COASTAL WATERS.
NORTHEASTERLY WINDS CONTINUE BUT GRADUALLY DIMINISH.  SEAS REMAIN
AOA 5 FEET SO WILL CONTINUE SMALL CRAFT ADVISORIES.

WEDNESDAY...HIGH PRESSURE BUILDS OVER THE WATERS.  WINDS AND SEAS
CONTINUE TO DIMINISH.

OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...

HIGH CONFIDENCE. QUIET BOATING WEATHER WITH WINDS AND SEAS REMAINING
BELOW SCA THRESHOLDS. WINDS BECOMING LOCALLY ONSHORE THU AFTERNOON
AS SEABREEZES DEVELOPS. MAINLY E/NE WINDS FRI/SAT.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ231-
     232.
     SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM EDT
     WEDNESDAY FOR ANZ235-237.
     SMALL CRAFT ADVISORY UNTIL 3 AM EDT WEDNESDAY FOR ANZ250-251.
     SMALL CRAFT ADVISORY UNTIL 6 PM EDT WEDNESDAY FOR ANZ254.
     SMALL CRAFT ADVISORY UNTIL 3 PM EDT WEDNESDAY FOR ANZ255-256.

&&

$$
SYNOPSIS...KJC/RLG
NEAR TERM...KJC/NOCERA/RLG
SHORT TERM...RLG
LONG TERM...KJC
AVIATION...KJC/NOCERA/RLG
MARINE...KJC/NOCERA/RLG


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