Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 041057 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 657 AM EDT WED MAY 4 2016 .SYNOPSIS... CLOUDY...DREARY AND COOL WEATHER CONTINUES THROUGH FRIDAY WITH PERIODS OF RAIN AS WEAK WAVES OF LOW PRESSURE PASS SOUTH AND EAST OF OUR REGION. SOME SHOWERS ARE STILL POSSIBLE AT TIMES THIS WEEKEND...BUT TEMPERATURES WILL BEGIN TO MODERATE. SIGNIFICANT IMPROVEMENT WILL LIKELY OCCUR EARLY TO MIDDLE OF NEXT WEEK AS HIGH PRESSURE BUILDS IN WITH MUCH MILDER TEMPERATURES. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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*** STEADY RAIN DEVELOPS AFTERNOON-EARLY EVENING TODAY *** 7 AM UPDATE... NO MAJOR CHANGES TO THE FORECAST OTHER THAN MINOR UPDATES TO BETTER ALIGN WITH PRESENT TRENDS. BRIEF GLIMPSES OF SUNSHINE BEING REPORTED THIS MORNING WHICH WILL BECOME OVERSHADOWED BY CLOUDS AND THE THREAT OF RAIN THROUGH TODAY INTO THIS EVENING AS MID-LEVEL ENERGY AS NOTED IN THE DISCUSSION BELOW ROTATES THROUGH THE BROADER CYCLONIC FLOW CAPTURING AND BACK-BUILDING THE MOIST TROPICAL-ORIGIN PLUME OFFSHORE. SUBSEQUENTLY LOOKING AT A POSSIBLE ISOLATED HEAVY DOWNPOUR / THUNDERSTORM THREAT OVER SE NEW ENGLAND DURING THE PM COMMUTE. PREVIOUS DISCUSSION... WATER VAPOR IMAGERY DEPICTS A NOTABLE SHORT WAVE TROUGH OVER TN AND KY EARLY THIS MORNING...MOVING NORTHEAST TOWARD THE MID ATLC STATES. WELL IN ADVANCE OF THIS SYSTEM THERE IS SOME WEAK SHORT WAVE RIDGING AND ASSOCIATED SUBSIDENCE ACROSS SOUTHERN NEW ENGLAND. THIS WILL YIELD MOSTLY DRY CONDITIONS THIS MORNING ACROSS THE AREA. HOWEVER BY AFTERNOON AND ESPECIALLY AFTER 5 PM THE SHORT WAVE CURRENTLY OVER TN/KY APPROACHES THE AREA AND INDUCES A COASTAL LOW OFF THE MID ATLC COAST. AS THE LOW TRACKS NORTHEAST THIS WILL RESULT IN AN INCREASE IN ONSHORE ENE WINDS YIELDING ANOTHER DAY OF COOL CONDITIONS. AS THIS SHORT WAVE APPROACHES IT BACKS THE MID LEVEL FLOW ALONG THE EASTERN SEABOARD AND CAPTURES A SUBTROPICAL PLUME OF MOISTURE JUST OFFSHORE WITH PWATS OVER 1 INCH. THIS WILL RESULT IN A SHIELD OF RAIN OVERSPREADING THE AREA BETWEEN 18Z AND 00Z. THERE IS SOME ELEVATED INSTABILITY OVER RI AND SOUTHEAST MA THAT MAY RESULT IN A FEW T-STORMS WITH LOCALLY HEAVY RAINFALL HERE.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
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TONIGHT ... WIDESPREAD RAIN LIKELY DURING THE EVENING BUT THEN SHOULD TRANSITION TO SPOTTY LIGHT RAIN/DRIZZLE LATE EVENING AND OVERNIGHT AS DRY SLOT OVERSPREADS THE AREA. HOWEVER DAMP/RAW NORTHEAST FLOW CONTINUES AND MAINTAINS COOL TEMPS. THURSDAY ... FORECAST UNCERTAINTY HINGES ON LOCATION OF WARM CONVEYOR BELT /WCB/ AND CORRESPONDING DRY SLOT. ALL NON NAM SOLUTIONS SUPPORT DEEP LAYER MOISTURE ASSOCIATED WITH WCB REMAINING JUST OFFSHORE AND ONLY CLIPPING EXTREME EASTERN MA. THUS GREATEST RISK FOR APPRECIABLE RAINFALL IS OVER EASTERN MA AND SOUTHEAST MA. ELSEWHERE ANOTHER DREARY DAY WITH MOIST AND COOL NORTHEAST WINDS AS NEXT FRONTAL WAVE APPROACHES FROM THE SOUTH.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... */ HIGHLIGHTS... - THRU THE WEEKEND AN UNSETTLED COOL PATTERN OF LOW CLOUDS/DRIZZLE - TWO BOUTS OF MORE APPRECIABLE WET WEATHER: FRIDAY AND SUNDAY - FROST/FREEZE HEADLINES POSSIBLE MONDAY MORNING ESP OVER N/W MASS - MODERATE WARMING DRY TREND THRU NEXT WEEK - NEXT SHOT OF UNSETTLED WEATHER POSSIBLE AT THE FOLLOWING FRIDAY */ OVERVIEW... COOL UNSETTLED WEATHER PATTERN CONTINUES THROUGH AT LEAST SATURDAY. DREARY AND DRIZZLY SOCKED IN WITH LOW CLOUDS AND MIST WITH POSSIBLE FOG RESULTING IN TEMPERATURES RUNNING BELOW-AVERAGE...ATYPICAL FOR EARLY MAY. IN-BETWEEN TWO PERIODS OF MORE APPRECIABLE RAIN UPWARDS OF A FEW TENTHS FORECAST. THE FIRST AROUND FRIDAY WITH THE BLOCKY CONUS PATTERN TRAPPING A CLOSED CUT-OFF LOW AND COLD POOL AROUND THE DELMARVA PENINSULA. DEEP LAYER FORCING THRU A CONDITIONALLY UNSTABLE ENVIRONMENT...ANTICIPATE WIDESPREAD RAIN THOUGH CONVECTIVELY DRIVEN MODERATE TO HEAVY SHOWERS ARE POSSIBLE. CHOKING OFF SATURDAY WITH DRIER AIR WRAPPING IN AND A WEAK RIDGE BUILDING AHEAD OF THE N- STREAM KICKER CONDITIONS MAY BRIEFLY IMPROVE PRIOR TO A SECOND BOUT OF WET WEATHER SUNDAY ALONG A SWEEPING COLD FRONT. IN WAKE OF THE COLD FRONT DREARY WEATHER IS PUSHED OUT...COOLER AIR MOVES IN. A MODERATE RISK OF FREEZING TEMPERATURES AND FROST/FREEZE HEADLINES FOR MONDAY MORNING ESPECIALLY OVER N/W MASS. A COOLER AIRMASS IN PLACE BENEATH CYCLONIC FLOW AND MID LEVEL FORCING ALOFT YIELDS CONVECTIVELY FORCED SHOWERS MONDAY. THIS ALL BEFORE A WARMING TREND THROUGH THE FOLLOWING WEEK MORE TYPICAL FOR EARLY MAY. ENSEMBLE MEAN H85 TEMPERATURES WARMING TO +10C SUGGEST SURFACE HIGHS IN THE 70S BY WEDNESDAY INTO THURSDAY WHEN WINDS BEGIN TO TURN MORE S/W. DRY FORECAST WITH HIGH PRESSURE. THE NEXT SHOT OF UNSETTLED WEATHER IS POSSIBLE BY THE END OF THE WEEK. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. 12Z UPDATE... SHORT TERM /THROUGH THURSDAY/...MODERATE CONFIDENCE. TODAY... LOW-END VFR TO MVFR LOWERING DOWN TO LIFR TOWARDS THIS AFTERNOON INTO EVENING WITH THE THREAT OF -RA. NE WINDS INCREASING 15-20 KTS WITH GUSTS UP TO 25 KTS OVER E MASS. TONIGHT... WIDESPREAD IFR-LIFR. -RA THIS EVENING TAPERING OVERNIGHT. MODEST NE WINDS 15-20 KTS WITH GUSTS UP TO 25 KTS OVER E MASS. THURSDAY ... GREATEST RISK FOR STEADY RAIN WILL BE OVER EXTREME EASTERN MA. OTHERWISE NUISANCE TYPE SPOTTY LIGHT RAIN/DRIZZLE YIELDING LIFR AND IFR TRENDING TOWARD MFR IN THE AFTERNOON. KBOS TERMINAL...LOWERING TREND TOWARDS LATE AFTERNOON INTO EVENING. CONFIDENT ON THE TREND BUT NOT ON THE SPECIFIC TIMING. SCT IFR CIGS MAY FILTER IN AS EARLY AS 15Z. KBDL TERMINAL...CIGS MAY LOWER EARLIER THEN PRESENT TAF SUGGESTS. CONFIDENT ON THE TREND BUT NOT SO MUCH ON THE SPECIFIC TIMING. OUTLOOK /THURSDAY NIGHT - SUNDAY NIGHT/...MODERATE CONFIDENCE. LOW END VFR TO LIFR MIX WITH LOW CIGS AND -DZ THOUGH SUNDAY. PARENT VSBY IMPACTS WITH BR AND POSSIBLE FOG. TWO PERIODS OF -RA FRIDAY AND AGAIN SUNDAY. E/NE FLOW SHIFTS OUT OF THE S SUNDAY BEFORE BACKING N/W BY SUNDAY NIGHT WITH PASSAGE OF A COLD FRONT. STRONGEST WINDS WITH GUSTS UP TO 25 KTS WITH THE WIND SHIFT. CONDITIONS IMPROVE TO VFR INTO MONDAY MORNING.
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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 THURSDAY/...HIGH CONFIDENCE. 7 AM UPDATE...NO MAJOR CHANGES TO THE FORECAST. TONIGHT AND WEDNESDAY...PERSISTENT NE FLOW WILL BUILD SEAS TO BETWEEN 3 AND 5 FEET ACROSS OUR SOUTHERN OUTER-WATERS. SO WHILE WIND SPEEDS WILL GENERALLY NOT EXCEED 20 KNOTS THROUGH MIDDAY WEDNESDAY...WILL STILL NEED SMALL CRAFT HEADLINES FOR SOME 5 FOOT SEAS. PATCHY FOG POSSIBLE AT TIMES AS WELL. WEDNESDAY NIGHT...PRESSURE GRADIENT INCREASES AS WAVE OF LOW PRESSURE APPROACHES FROM THE SOUTH AND COMBINES WITH HIGH PRESSURE OVER THE CANADIAN MARITIMES. NORTHEAST WIND GUSTS TO 25 KNOTS MAY DEVELOP ACROSS A GOOD CHUNK OF OUR WATERS ALONG WITH SEAS BUILDING TO BETWEEN 4 AND 7 FEET. ADDITIONAL SCA HEADLINES WILL LIKELY BE NEEDED...BUT SINCE ITS 3RD PERIOD WILL WAIT UNTIL THE NEXT SHIFT GETS A LOOK AT IT. OUTLOOK /THURSDAY NIGHT - SUNDAY NIGHT/...MODERATE CONFIDENCE. DREARY AND DRIZZLY CONDITIONS WITH PERSISTENT E/NE FLOW INTO SUNDAY MORNING WITH GUSTS UP TO 25 KTS. WAVES IN EXCESS OF 5 FEET ON THE OUTER WATERS. EXPECT RESTRICTIONS IN VISIBILITY ESPECIALLY WITH RAIN FRIDAY. WINDS VEER S AHEAD OF A COLD FRONT WITH ADDITIONAL RAIN FOR SUNDAY. GUSTS UPWARDS OF 25 KTS AROUND COLD FRONTAL PASSAGE AS WINDS SHIFT OUT OF THE N/W. WAVES BUILDING 5 TO 7 FEET ON THE OUTER WATERS THROUGH MONDAY MORNING.
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&& .TIDES/COASTAL FLOODING... 325 AM UPDATE ... HIGH ASTRONOMICAL TIDES ARE EXPECTED...WITH PRIME CONCERN ON THE HIGHER OF THE TWO HIGH TIDE CYCLES THURSDAY NIGHT AND FRIDAY NIGHT. ASTRO HEIGHTS ARE PROJECTED JUST BELOW 12 FEET AT BOSTON BOTH NIGHTS. ASTRO HEIGHTS NEAR PROVIDENCE ARE PROJECTED AT 6 FEET THURSDAY NIGHT AND 6.5 FEET FRIDAY NIGHT. IT WILL NOT TAKE MUCH OF A SURGE ON TOP OF THOSE ASTRO HEIGHTS TO CAUSE SOME SPLASHOVER OR EVEN POSSIBLY SOME MINOR COASTAL FLOODING. PERSISTENT NORTHEAST WINDS AGAINST THE EAST MASSACHUSETTS COAST WILL ADD TO POTENTIAL FOR SURGE ALONG THAT COASTLINE. THUS THE MOST LIKELY AREA TO EXPERIENCE MINOR COASTAL FLOODING/INUNDATION IS ACROSS EASTERN MA COASTLINE FROM SCITUATE...HULL AND IN BOSTON/DORCESTER SUCH AS MORISSEY BLVD. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EDT THURSDAY FOR ANZ230>237-250-251. SMALL CRAFT ADVISORY UNTIL 7 PM EDT THURSDAY FOR ANZ254>256.
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&& $$ SYNOPSIS...NOCERA/SIPPRELL NEAR TERM...NOCERA/SIPPRELL SHORT TERM...NOCERA LONG TERM...SIPPRELL AVIATION...NOCERA/SIPPRELL MARINE...NOCERA/SIPPRELL TIDES/COASTAL FLOODING...WFO BOX STAFF

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