Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 292001 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 401 PM EDT FRI MAY 29 2015 .SYNOPSIS... HIGH PRESSURE WILL BRING DRY AND BEAUTIFUL WEATHER THIS AFTERNOON... EXCEPT ALONG PORTIONS OF THE VERY IMMEDIATE EASTERN MA COAST WHERE SOME LOW CLOUDS MAY AFFECT THE REGION. A COLD FRONT WILL SLOWLY MOVE ACROSS THE REGION THIS WEEKEND...THEN STALL SOUTH OF NEW ENGLAND DURING THE EARLY WEEK. THIS WILL BRING A CHANCE OF SHOWERS AND THUNDER SUNDAY...AND A CHANCE OF RAIN EARLY WEEK. HIGH PRESSURE BRINGS DRY WEATHER FOR THE LATTER PART OF THE WEEK.&& .NEAR TERM /UNTIL 6 PM THIS EVENING/... 205 PM UPDATE... PLENTY OF DIURNAL CUMULUS CLOUDS HAVE DEVELOPED ACROSS SOUTHERN NEW ENGLAND AT MID AFTERNOON...ESPECIALLY ACROSS CENTRAL MA/RI BUT THERE WAS STILL SOME PARTIAL SUNSHINE. WE ARE ALSO WATCHING AN AREA OF LOW CLOUDS TRYING TO WORK ONTO THE PLYMOUTH COAST AT MID AFTERNOON OFF THE OCEAN. THEY ARE BEING OFFSET SOME BY DIURNAL HEATING...BUT WILL HAVE TO WATCH CLOSELY BECAUSE THEY MAY AFFECT OTHER PORTIONS OF THE EASTERN MA COAST TOWARD EVENING. LOW CONFIDENCE IN THAT SO WILL CONTINUE TO MONITOR. OTHERWISE...AFTERNOON TEMPS SHOULD PEAK BETWEEN 80 AND 85 INLAND FROM THE COAST. ALONG THE COAST...SEA BREEZES AND SOME LOW CLOUDS WILL HOLD AFTERNOON TEMPS BETWEEN 65 AND 75. COOLEST READINGS ALONG THE THE PLYMOUTH COUNTY MA COAST...GIVEN LOWER CLOUDS. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... TONIGHT... HIGH PRESSURE WILL BEGIN TO SHIFT OFFSHORE AS SOUTHWESTERLY FLOW RETURNS TO THE REGION. THIS WILL ALLOW FOR ANOTHER MILD AND MUGGY NIGHT FOR SOUTHERN NEW ENGLAND. WAA WILL BE ON THE INCREASE WHICH WILL INCREASE CLOUD COVER...ESP FOR THE SOUTH COASTAL REGIONS. CANNOT RULE OUT ANOTHER ROUND OF MARINE FOG/STRATUS. OTHERWISE TEMPS WILL REMAIN IN THE UPPER 50S TO LOW 60S WITH DEWPOINTS ALSO IN THE MID TO UPPER 50S. TOMORROW... COLD FRONT WILL MOVE ACROSS THE GREAT LAKES REGION ON SATURDAY ALLOW FOR SHOWERS AND THUNDERSTORMS TO DEVELOP. BEST DYNAMICS AND FORCING WILL BE WELL TO THE WEST OF THE REGION...HOWEVER BECAUSE WE ARE IN A VERY WARM AND MOIST AIRMASS CANNOT RULE OUT A FEW POP-UP SHOWERS AND THUNDERSTORMS OUT AHEAD OF THIS FRONT LATE SATURDAY AFTERNOON/EVENING. OTHERWISE BULK OF THE DAY WILL BE DRY WITH TEMPS WARMING INTO THE LOW TO MID 80S...COOLER ALONG THE SOUTH COAST. && .LONG TERM /SUNDAY THROUGH FRIDAY/... BIG PICTURE... CHANGEABLE PATTERN THROUGH THE WEEK. UPPER RIDGE MOVES OFFSHORE SUNDAY. UPPER TROUGH SLOWLY CROSSES THE NORTHEAST USA EARLY WEEK. UPPER RIDGE FROM THE WESTERN USA THEN SHIFTS EAST OVER THE EASTERN USA LATE WEEK. DIFFERENCES AMONG THE MODELS REGARDING TIMING WITH THE UPPER TROUGH EARLY WEEK WITH THE GGEM THE FASTEST AND ECMWF SLOWEST. WE USED A MODEL CONSENSUS IN TIMING. THE DAILIES... SUNDAY THROUGH TUESDAY... COLD FRONT EITHER OVER OR JUST NORTH OF NORTHERN MASS SUNDAY MORNING WILL MOVE SOUTH ACROSS THE REGION DURING THE DAY. PRECIPITABLE WATER VALUES ALONG AND AHEAD OF THE FRONT WILL BE 1.50 TO 1.75 INCHES WHICH IS AROUND 2 STD DEV ABOVE NORMAL. TOTALS OF 47-49 AND SHOWALTERS OF 0 TO -2. ALL OF THIS SUGGESTS SUFFICIENT MOISTURE FOR SHOWERS AND ENOUGH INSTABILITY OVER THE LOW LEVEL CONVERGENCE TO SUPPORT A FEW THUNDERSTORMS. DIFFERENCES AMONG THE MODELS ON TIMING THE FROPA BUT ALL MOVE IT SOUTH OF THE COAST BY SUNDAY EVENING. THE FRONT IS THEN ALIGNED WITH THE UPPER FLOW AND STALLS. SHORTWAVE MOVING THROUGH THE GREAT LAKES IS FORECAST TO GENERATE A WAVE ALONG THE FRONT WHICH CROSSES THE APPALACHIANS MONDAY AND PASSES SOUTH OF NEW ENGLAND TUESDAY. THIS ALONG WITH HIGH PRESSURE IN EASTERN CANADA SHOULD BRING A COOL NORTHEAST FLOW TO THE REGION MONDAY AND TUESDAY. MEANWHILE A SOUTHWEST FLOW CONTINUES ABOVE 5OOO FEET AGL AND SUPPIES LIFT AND MOISTURE OVER THE TOP. WE WILL MAINTAIN LIKELY POPS MONDAY DIMINISHING TO CHANCE POPS DURING THE DAY TUESDAY AS THE LOW MOVES EAST. WEDNESDAY THROUGH FRIDAY... HIGH PRESSURE BUILDS SURFACE AND ALOFT BRINGING DRY WEATHER TO SOUTHERN NEW ENGLAND. WITH THE DEMISE OF THE NORTHEAST MARINE FLOW...MIXING SHOULD RETURN WITH HEIGHTS REACHING AT LEAST 875 MB WEDNESDAY AND AT LEAST 850 MB THURSDAY AND FRIDAY. TEMPERATURES AT THE TOP OF THE MIXED LAYER EACH DAY SUGGEST MAX SFC TEMPS IN THE MID 60S TO LOW 70S WEDNESDAY...70S TO NEAR 80 THURSDAY...AND 75-85 FRIDAY. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. REST OF THIS AFTERNOON...HIGH CONFIDENCE EXCEPT LOW CONFIDENCE ON EASTERN MA COAST. MAINLY VFR...BUT WE ARE WATCHING AN AREA OF LOW CLOUDS JUST EAST OF BOSTON HARBOR AND ONTO THE PLYMOUTH COUNTY COAST. LOW CONFIDENCE...BUT A PERIOD OF IFR CIGS MAY DEVELOP TOWARD EVENING ON THE NORTH SHORE AND INTO BOSTON HARBOR. TONIGHT...LOW CONFIDENCE. WINDS ALONG EASTERN MA COAST TURN SOUTHWEST SO THAT SHOULD LIMIT LOW CLOUDS COMING IN FROM THE EAST. IN FACT...IF THEY DO GET IN FOR A TIME THIS EVENING THEY MAY SCOUR OUT. BIGGER CONCERN THEN TURNS TO LOW CLOUDS/FOG PATCHES THAT MAY DEVELOP ALONG THE SOUTH COAST AND ESPECIALLY CAPE/ISLANDS. AGAIN...CONFIDENCE IS LOW SO WILL HAVE TO MONITOR CLOSELY. SATURDAY...MODERATE CONFIDENCE. ANY LOW CLOUDS/FOG PATCHES SOUTH OF PIKE PROBABLY SCOUR OUT BY LATE MORNING/EARLY AFTERNOON...EXCEPT CAPE/ISLANDS WHERE THEY MAY LINGER INTO THE AFTERNOON. DRY WEATHER EXPECTED...ALTHOUGH THERE IS A LOW RISK OF A SPOT SHOWER/THUNDERSTORM ACROSS NORTHWEST MA LATE IN THE AFTERNOON/EARLY EVENING. SATURDAY NIGHT...MODERATE CONFIDENCE. MAINLY VFR TO MARGINAL MVFR CIGS EXCEPT FAR SOUTHEAST NEW ENGLAND COAST WHERE IFR CIGS/VSBYS ARE POSSIBLE. SCATTERED SHOWERS AND PERHAPS A THUNDERSTORM OR TWO WILL BE POSSIBLE MAINLY ACROSS THE INTERIOR WITH THE HIGHER RISK DURING THE OVERNIGHT HOURS. KBOS TERMINAL...LOW CONFIDENCE IN TAF. IFR CIGS SITTING JUST OFF BOSTON HARBOR AT MID AFTERNOON. THEY MAY WORK INTO BOSTON HARBOR FOR A TIME LATE THIS AFTERNOON/EVENING...BUT LOW CONFIDENCE. IF THEY DO...PROBABLY SCOUR OUT LATER IN THE EVENING AS WINDS TURN SOUTHWEST. KBDL TERMINAL...LOW TO MODERATE CONFIDENCE IN TAF. OUTLOOK...SUNDAY THROUGH WEDNESDAY...MODERATE CONFIDENCE. SUNDAY... COLD FRONT MOVES ACROSS SOUTHERN NEW ENGLAND FROM NORTH TO SOUTH. VFR CIGS/VSBYS WITH AREAS OF MVFR IN SHOWERS/THUNDERSTORMS. SOUTHWEST WINDS TO START...BECOMING NORTHEAST BY EVENING. WINDS AT 2000-3000 FEET AGL START SOUTHWEST 25-35 KNOTS AND BECOME NORTHEAST 25 TO 30 KNOTS BY EVENING. SOUTHWEST WINDS LINGER THROUGH THE DAY AT OR ABOVE 5000 FEET. THIS MAY CREATE SOME LOW LEVEL WIND SHEAR AT TIMES...DIRECTIONAL SHEAR IN THE VERTICAL IS LIKELY AND SPEED SHEAR POSSIBLY. MONDAY THROUGH TUESDAY... MVFR/IFR CIGS AND VSBYS WITH BEST CHANCE OVER THE COASTAL PLAIN AND EASTERN SLOPES OF THE WORCESTER HILLS. SHOWERS POSSIBLE THROUGH BOTH DAYS. WEDNESDAY... VFR WITH A NORTH-NORTHWEST WIND. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... TODAY AND TONIGHT...HIGH CONFIDENCE. HIGH PRES BUILDS OVER THE WATERS. MAINLY QUIET BOATING WEATHER EXPECTED ALTHOUGH SOME STRATUS/FOG IS POSSIBLE MAINLY ON THE SRN WATERS TONIGHT. SATURDAY...HIGH CONFIDENCE. HIGH PRESSURE WILL PUSH EAST OF THE WATERS AS COLD FRONT APPROACHES NEW ENGLAND. SW WINDS MAY GUST NEAR 25-30 KTS. MAY NEED NEAR SHORE SCA. OTHERWISE SEAS WILL BE CLOSE TO 5FT AS SOUTHERLY SWELL INCREASES. OUTLOOK...SUNDAY THROUGH WEDNESDAY...MODERATE CONFIDENCE. SUNDAY...SMALL CRAFT ADVISORY MAY BE NEEDED ON SOME OF THE WATERS. A COLD FRONT CROSSES THE EASTERN WATERS DURING THE DAY. THE FRONT CROSSES THE SOUTHERN WATERS SUNDAY EVENING. SHOWERS AND POSSIBLE THUNDERSTORMS ALONG AND AHEAD OF THE FRONT. EXPECTING SOUTHWEST GUSTS TO 20 KNOTS AHEAD OF THE FRONT. WINDS THEN SHIFT TO NORTHEAST AND EAST BEHIND THE FRONT WITH GUSTS TO 20 KNOTS FROM THAT DIRECTION. SEAS LINGER AROUND 5 FEET ON THE OUTER WATERS. MONDAY-TUESDAY...SMALL CRAFT ADVISORY MAY BE NEEDED ESPECIALLY ON THE EASTERN WATERS. NORTHEAST WINDS GUSTING 20 TO 25 KNOTS EACH DAY. SEAS 5 TO 8 FEET ON THE EASTERN MASS WATERS...AND 3 TO 5 FEET ON THE SOUTHERN WATERS. WEDNESDAY...A SMALL CRAFT ADVISORY MAY BE NEEDED...MAINLY ON THE EASTERN WATERS. DIMINISHING NORTHEAST TO NORTH WINDS. SEAS OF 5 FEET MAY LINGER ON THE EASTERN WATERS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON TO 10 PM EDT SATURDAY FOR ANZ230>237-251. SMALL CRAFT ADVISORY FROM 2 PM SATURDAY TO 8 AM EDT SUNDAY FOR ANZ250-254>256. && $$ SYNOPSIS...WTB/DUNTEN NEAR TERM...FRANK SHORT TERM...DUNTEN LONG TERM...WTB AVIATION...WTB/FRANK MARINE...WTB/DUNTEN

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