Area Forecast Discussion
Issued by NWS Boston, MA

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495
FXUS61 KBOX 252332
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
732 PM EDT MON APR 25 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. ANOTHER LOW PRESSURE
CENTER WILL QUICKLY PASS SOUTH OF NEW ENGLAND THURSDAY NIGHT INTO
EARLY FRIDAY. HIGH PRESSURE MOVES OUT OF CENTRAL CANADA LATE
FRIDAY...BRINGING DRY BUT COOL CONDITIONS THIS WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
7 PM UPDATE...
ALTHOUGH A FEW ECHOS CONTINUE TO MOVE ACROSS SRN NEW ENGLAND THIS
EVENING...DWPT DEPRESSIONS CONTINUE TO RANGE BETWEEN 10 AND 25F SO
LITTLE IF ANY HAS HIT THE GROUND. WITH LOW PRES STILL WELL
UPSTREAM IT WILL TAKE SOME TIME FOR CLOUDS TO LOWER AND DWPTS TO
RISE UNTIL ANY PRECIP CAN BE FELT. THEREFORE...SLOWED PROGRESSION
OF POPS MAINLY THROUGH THE EVENING HOURS. OTHERWISE...FORECAST ON
TRACK WITH LITTLE REASON TO MAKE ADJUSTMENTS BASED ON LATEST
GUIDANCE.

TONIGHT...

MID-LEVEL BOUNDARY WILL STRENGTHEN OVER THE REGION AS UPPER LEVEL
SHORTWAVE APPROACHES SOUTHERN NEW ENGLAND. SOUTHERLY FLOW AT THE
SURFACE WILL HELP INCREASE THE MOISTURE RESULTING IN SHOWERY WEATHER
OVERNIGHT. BELIEVE BEST CHANCE WILL BE WHERE THE MID-LEVEL BOUNDARY
SET-UP AND POINTS NORTHWARD. AS OF THIS FORECAST APPEARS THE
BOUNDARY WILL SET UP SOMEWHERE NEAR THE PIKE...SO LOCATIONS ACROSS
NORTHERN MASS HAVE THE BETTER SHOT OF SEEING SCT TO NUMEROUS
SHOWERS. BETWEEN 6-9Z...CHANCES INCREASE FOR THE REST OF THE REGION
AS BOUNDARY STRENGTHENS AND BEGINS TO PUSH SOUTHWARD.

TEMPREATURES OVERNIGHT WILL SLOWLY DROP AS CLOUD COVER WILL LIMIT
ANY RADIATIONAL COOLING.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
TOMORROW...

STALLED BOUNDARY WILL MOVE SOUTHWARD AS A COLD FRONT EARLY TOMORROW
MORNING AS SHORTWAVE PASSES THROUGH THE FLOW. STILL SOME PLACEMENT
ISSUES ON WHERE EXACTLY THIS FRONT WILL STALL...BUT AS OF THIS
FORECAST ANTICIPATE THE REGION TO BE MAINLY ON THE NORTHERN SIDE OF
THE BOUNDARY. 925 MB TEMPS WILL BE BELOW 0C NORTH OF THE PIKE AND
WITH NORTHEAST FLOW COMING OFF THE WATER...EXPECT A VERY CHILLY DAY.
SOME LOCATIONS ACROSS THE HIGHER TERRAIN WILL STRUGGLE TO REACH
ABOVE 40F.

PRECIPITATION WILL CONTINUE TOMORROW AND WILL BEGIN TO LET UP BY THE
LATE AFTERNOON/EARLY EVENING HOURS. DURING THE DAY...GUIDANCE
CONTINUES TO SHOW SOME ELEVATED INSTABILITY PARAMETERS WHICH SUPPORT
THE POTENTIAL FOR THUNDER. THE BEST CHANCE WILL BE ACROSS THE
SOUTHERN WATERS...WHICH WILL BE SOUTH OF THE BOUNDARY. CANT RULE OUT
THE POTENTIAL FOR A RUMBLE ACROSS THE IMMEDIATE SOUTH COAST.

INTERESTING THERMAL PROFILES HAVE SET UP ACROSS THE REGION TOMORROW.
DESPITE SUB FREEZING 925 MB AND 850 TEMPS NORTH OF THE PIKE ON
TUESDAY...THE WARM LAYER ABOVE 800 MB WILL YIELD A COLD RAIN FOR THE
REGION. HOWEVER THIS WARM LAYER BEGINS TO ERODE IN THE AFTERNOON
WHICH CAN SUPPORT A MIX OF SLEET AND/OR SNOW WITH THE RAIN BEFORE
ENDING ACROSS NORTHERN MA. ANY BRIEF CHANGEOVER TO SLEET AND/OR SNOW
WILL HINGE ON PRECIP INTENSITY AND ASSOCIATED DIABATIC
COOLING/MELTING. HAVE PUT IN A MENTION OF SLEET IN THE FORECAST ESP
IN LOCATIONS NORTH OF ROUTE 2...BUT IF THE WARM LAYER ERODES
QUICKER...THEN THE WINTERY MIX COLD MAKE IT AS FAR SOUTH AS THE
PIKE. NOT ANTICIPATE ACCUMULATIONS AT THIS TIME ESP SINCE SURFACE
TEMPS WILL BE VERY WARM.

OVERALL...ANTICIPATE A COLD RAW DAY THANKS TO WELL BELOW AVERAGE
TEMPS AND CONTINUOUS RAIN ACROSS SOUTHERN NEW ENGLAND.

TOMORROW NIGHT...

COLD FRONT WILL BE SOUTH OF THE REGION BY TOMORROW NIGHT. ANY
LINGERING SHOWERS OVER THE CAPE AND ISLANDS WILL COME TO AN END.
SKIES WILL BE CLEARING AS NORTHERLY DRY AIR WORKS ITS WAY INTO
SOUTHERN NEW ENGLAND. THIS COULD HELP AID IN DROPPING SURFACE TEMPS
INTO THE LOW TO MID 30S. APPEARS THAT FROST/FREEZE HEADLINES WILL BE
NEEDED WHERE THE GROWING SEASON HAS BEGUN.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
HIGHLIGHTS...

 * DRY AND COOLER WED AND THU.
 * SOME RAIN DEPENDING ON LOW PRES TRACK FRI.
 * COOL AND MAINLY DRY FOR THE WEEKEND.

OVERVIEW AND MODEL PREFERENCES...
VERY AMPLIFIED FLOW PATTERN ACROSS THE CONUS THIS PERIOD WITH
SPLIT FLOW REGIMES PHASING ALONG THE NORTHEAST AND MID ATLANTIC. N
OF THESE PHASED STREAMS IS A FAIRLY POTENT VORTEX WHICH WILL MAKE
LITTLE E PROGRESSION EXCEPT TO SLIDE FROM QUEBEC INTO LABRADOR .
ACROSS THE CENTRAL CONUS AN AMPLIFIED TROF/RIDGE COUPLET WILL BE
ALSO BE SLOW TO WORK E. THE PHASING STREAMS WILL CULMINATE IN A
SLOW MOVING FRONTAL BOUNDARY S OF THE REGION AFTER INITIAL FRONTAL
WAVE MOVES THROUGH TOMORROW INTO TOMORROW NIGHT. THIS WILL BE THE
FOCAL POINT FOR ANOTHER LATE WEEK WAVE BUT GIVEN THE VERY
AMPLIFIED/WEAK PATTERN ACROSS THE CONUS...EXACTLY HOW FAR N THIS
FRONTAL WAVE REACHES IS STILL SOMEWHAT IN QUESTION. ENSEMBLES
PROVIDE A GOOD MIDDLE GROUND AT THIS TIME AS THEY COVER BOTH THE
SRN AND NRN EXTREMES OF THE ENVELOPE. WILL CONTINUE TO USE THIS
ENSEMBLE BLEND THROUGH THE REST OF THE PERIOD..AS IT WILL ALSO
WORK FOR PERIODS WHERE THERE IS BETTER AGREEMENT BETWEEN
DETERMINISTIC MODELS.

DETAILS...

WED AND THU...
CANADIAN HIGH PRES WILL SLIDE INTO NEW ENGLAND ATTENDANT TO
RIDGING JUST W OF THE GREAT LAKES. THE CONDUIT OF COOLER AIR FROM
THIS FEATURE WILL YIELD A DRY...BUT GENERALLY COOLER THAN NORMAL
FORECAST AS H85 DROP TO NEAR OR EVEN SLIGHTLY BELOW 0C WHILE H92
TEMPS HOLD CLOSER TO +2C. COULD NEED ANOTHER ROUND OF FROST
HEADLINES FOR THOSE AREAS ACTIVATED...AS OVERNIGHT MINS WITH
RADIATIONAL COOLING COULD FALL BACK TO NEAR OR JUST BELOW FREEZING
FOR SOME AREAS.

THU NIGHT AND FRI...
FORECAST A BIT MORE UNCERTAIN HERE AS SHORTWAVE WILL BE ROTATING
OUT OF CANADA ON THE BACK SIDE OF THE SLOW MOVING LABRADOR VORTEX.
IT/S INTERACTION WITH WEAK FLOW REGIME AND RIDGING STALLED ACROSS
THE GREAT LAKES NOT WELL RESOLVED. WHILE THE GENERATION OF A
ANOTHER FRONTAL WAVE IS EXPECTED TO THE S...WHETHER OR NOT IT WILL
HAVE HAVE ENOUGH CURVATURE TO PULL IT FAR ENOUGH N TO IMPACT SRN
NEW ENGLAND IS THE PRIMARY ISSUE. AS MENTIONED ABOVE...WITH SOME
MOISTURE INCREASE AND ENSEMBLES SHOWING BOTH A MISS AND A
HIT...LOW END POPS ARE WARRANTED WITH THIS UPDATE...BUT GIVEN MORE
TIME AND BETTER TRACKING OF THE RIDGE AND SECONDARY
TROUGH...CONFIDENCE WILL INCREASE ON WHETHER ANOTHER WET 24 HOUR
PERIOD IS EXPECTED.

SAT...
REINFORCING COLD SHORTWAVE MOVES ACROSS THE REGION SAT. NOTING
ENOUGH LOW-MID LVL DESTABILIZATION TO SUPPORT A FEW SHOWERS
SPAWNING ESPECIALLY DURING PEAK AFTERNOON HEATING. IT/S NOT OUT OF
THE QUESTION GIVEN CURRENT PROGGED LOW LVL TEMPS...A FEW FLAKES
COULD FLY IN SOME OF THE HEAVIER SHOWERS THAT DEVELOP.

SUN AND MON...
RETURN OF HIGH PRES TO THE REGION AS THE CANADIAN HIGH FINALLY
DRIFTS E INTO EARLY NEXT WEEK. THE PERIOD OF MAINLY DRY BUT
COOLER WX IS EXPECTED TO CONTINUE.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH TUESDAY/...HIGH CONFIDENCE.

TONIGHT...
VFR THROUGH 06Z...WITH GRADUAL LOWERING TO MVFR DUE TO LOW CIGS
AND LOWERING VSBYS IN FOG/RAIN BETWEEN 06Z-12Z FROM W-E.

TUESDAY...MVFR BECOMING WIDESPREAD WITH IFR POSSIBLE OVER EASTERN
MA. STEADY RAIN WITH EMBEDDED MODERATE TO HEAVY RAIN AT TIMES. NE
WINDS INCREASING TO 15 TO 20 KT ACROSS EASTERN MA WITH GUSTS UP TO
25 KT POSSIBLE. LOW POSSIBILITY FOR THUNDER ACROSS THE ISLANDS.

TUESDAY NIGHT...MVFR/IFR TO START WITH CONDITIONS IMPROVING
THROUGH THE NIGHT TO VFR.

KBOS TAF...HIGH CONFIDENCE FOR VFR AND DRY WEATHER. LIGHT S-SW
WIND WILL BECOME E-SE EARLY THIS AFTERNOON.

KBDL TAF...HIGH CONFIDENCE FOR VFR AND DRY WEATHER. LOW RISK OF
SOME VERY LIGHT RAIN/SPRINKLES AFTER 21Z WITH STEADIER RAIN
ARRIVING AROUND 06Z TONIGHT.

OUTLOOK /TUESDAY NIGHT THROUGH SATURDAY/...

WED AND THU...HIGH CONFIDENCE.
MAINLY VFR WITH HIGH PRES OVER THE REGION.

FRI...MODERATE CONFIDENCE.
DEPENDENT ON TRACK OF LOW PRES TO THE S. IF IT TRACKS CLOSER OR
OVER NEW ENGLAND...EXPECT WIDESPREAD MVFR/IFR CONDITIONS. IF IT
REMAINS OFFSHORE...MAINLY VFR CONDITIONS ARE EXPECTED.

SAT...HIGH CONFIDENCE.
MAINLY VFR WITH HIGH PRES RETURNING. A FEW SHOWERS POSSIBLE.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH TUESDAY/...MODERATE CONFIDENCE.

TONIGHT ... WINDS BECOMING ENE LATE AS LOW PRES APPROACHES NEW
ENGLAND. RAIN OVERSPREADS EASTERN WATERS AFTER MIDNIGHT.

TUE ... LOW PRES TRACKS JUST SOUTH OF NEW ENGLAND. THIS WILL YIELD
AN INCREASE IN ENE WINDS OF 15 TO 20 KT WITH LOW RISK OF A FEW 25-
30KT GUSTS VICINITY OF CAPE COD AND NANTUCKET WATERS EASTWARD
TOWARDS WESTERN GEORGES BANK. WIDESPREAD RAIN AND AREAS OF FOG LIMIT
VSBY. SCA HAS BEEN ISSUED FOR WIND GUSTS AND BUILDING SEAS OVER 5
FT.

TUE NIGHT...COLD FRONT WILL SWING THROUGH THE SOUTHERN WATERS
KEEPING THE NORTHEAST FLOW. SEAS ACROSS THE OUTER WATERS WILL REMAIN
AOA 5 FEET SO SCA WILL NEED TO BE EXTENDED. PRECIP AND FOG WILL COME
TO AN DURING THE OVERNIGHT HOURS.

OUTLOOK /TUESDAY NIGHT THROUGH SATURDAY/...

WED INTO THU...HIGH CONFIDENCE.
ANY LINGERING 5-6 FT SEAS ON THE SE WATERS SHOULD DISSIPATE BY
EARLY WED AS HIGH PRES MOVES OVER THE WATERS. THIS HIGH WILL YIELD
A PERIOD OF MAINLY QUIET BOATING WEATHER WITH WINDS SHIFTING FROM
W TO NW ON BY THU.

THU NIGHT INTO FRI NIGHT...MODERATE CONFIDENCE.
DEPENDENT ON HOW CLOSE A LOW PRESSURE TRACKS TO NEW ENGLAND FROM
THE SOUTH. IF IT MAKES A CLOSE PASS...EXPECT SMALL CRAFT
CONDITIONS ALONG WITH RAIN. IF IT STAYS FURTHER OFFSHORE...THERE
IS A LOWER RISK FOR SMALL CRAFT ADVISORY CONDITIONS.

SAT...MODERATE CONFIDENCE.
ANY REMAINING SMALL CRAFT CONDITIONS RECEDE YIELDING A SHORT
PERIOD OF QUIET BOATING WEATHER WITH HIGH PRES.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 5 AM TO 8 PM EDT TUESDAY FOR ANZ231-
     232.
     SMALL CRAFT ADVISORY FROM 2 AM TO 8 PM EDT TUESDAY FOR ANZ250-
     251.
     SMALL CRAFT ADVISORY FROM 5 AM TUESDAY TO 8 AM EDT WEDNESDAY
     FOR ANZ254.
     SMALL CRAFT ADVISORY FROM 8 AM TUESDAY TO 8 AM EDT WEDNESDAY
     FOR ANZ255-256.

&&

$$
SYNOPSIS...DOODY/DUNTEN
NEAR TERM...DOODY/DUNTEN
SHORT TERM...DUNTEN
LONG TERM...DOODY
AVIATION...DOODY/DUNTEN
MARINE...DOODY/DUNTEN



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