Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 252016 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 416 PM EDT MON APR 25 2016 .SYNOPSIS...
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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.
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&& .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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4 PM UPDATE... A PLEASANT SPRING DAY WAS IN STORE FOR SOUTHERN NEW ENGLAND AS TEMPS WARMED INTO THE LOW TO MID 60S. SEA BREEZES ON BOTH COASTLINES KEPT CONDITIONS COOLER THAN NORMAL. CLOUDS COVER IS BEGINNING TO INCREASE THIS AFTERNOON/EVENING THANKS TO AN INCREASE IN MID-LEVEL MOISTURE. LATEST SPC ANALYSIS DOES SHOW THAT FRONTOGENESIS IS DEVELOPING ACROSS UPSTATE NEW YORK AND WILL CONTINUE INTO SOUTHERN NEW ENGLAND AS UPPER LEVEL WAVE APPROACHES THE REGION. THIS DEVELOPING STATIONARY FRONT WILL BE THE MAIN FOCUS FOR WEATHER OVER THE NEXT 24 HOURS. STILL CANNOT RULE OUT A FEW ISO SHOWERS EARLY THIS EVENING...BUT SOUNDINGS CONTINUE TO INDICATE A DRY AIRMASS IN THE LOW LEVELS. THEREFORE COULD SEE EITHER VIRGA OR SPRINKLES ESP ACROSS WESTERN ZONES INTO THE EVENING COMMUTE. 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.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
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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.
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&& .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
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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.
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&& .AVIATION /20Z MONDAY THROUGH SATURDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY/...HIGH CONFIDENCE. BEFORE 00Z...VFR. A FEW SPRINKLES POSSIBLE. TONIGHT...VFR TO START BUT LOWERING TO MVFR TOWARD MORNING WITH RAIN /MAINLY LIGHT/ BECOMING WIDESPREAD AFTER 06Z. 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 /WEDNESDAY 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.
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&& .MARINE...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH MONDAY NIGHT/...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 /WED THROUGH SAT/... 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.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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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.
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&& $$ SYNOPSIS...DOODY/DUNTEN NEAR TERM...DUNTEN SHORT TERM...DUNTEN LONG TERM...DOODY AVIATION...DOODY/DUNTEN MARINE...DOODY/DUNTEN

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