Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 051449 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1049 AM EDT THU MAY 5 2016 .SYNOPSIS... CLOUDY...DREARY AND COOL WEATHER CONTINUES THROUGH FRIDAY WITH PERIODS OF RAIN AS WAVES OF LOW PRESSURE TRACK NEAR SOUTHERN NEW ENGLAND. DESPITE SOME SHOWERS POSSIBLE THIS WEEKEND THERE WILL BE MANY HOURS OF DRY WEATHER ALONG WITH MODERATING TEMPERATURES. 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/... 1040 AM UPDATE... LOW PRESSURE WAS SLOWLY DEEPING OFF THE NORTH CAROLINA COAST... DOWN TO 997 MB AS OF 10 AM...ABOUT 1 MB DEEPER THAN THE MODELS. WE CONTINUE TO BE SOCKED IN WITH A MOIST NORTHEAST FLOW. MESOSCALE MODELS INDICATE THAT THE WESTERN EDGE OF THE RAIN SHIELD...WHICH HAS ALREADY OVERSPREAD EASTERN CAPE COD/EASTERN MARTHAS VINEYARD/ NANTUCKET...WILL CONTINUE TO SLOWLY EXPAND WESTWARD THIS AFTERNOON. AM EXPECTING IT TO GET AS FAR WEST AS I-495 IN MA AND THE RI/CT/MA BORDER LATE THIS AFTERNOON/EARLY EVENING BEFORE EXITING TO THE NORTHEAST TONIGHT. A FEW SHOWERS COULD BE LOCALLY HEAVY ESPECIALLY ON THE CAPE AND ISLANDS. HAVE INCREASED POPS IN EASTERN AREAS. SOUNDINGS INDICATE WINDS ALREADY 30-35 KT AT 2000 FT IN RI AND EASTERN MA. HAVE BEEN GETTING GOOD MIXING AND SURFACE GUSTS TO NEAR 30 KT IN THOSE AREAS LATE THIS MORNING. MODELS INDICATE WINDS INCREASING BY ANOTHER 5 KT OR SO THIS AFTERNOON/EVENING. THUS IT WILL BECOME WINDY WITH GUSTS TO 35 KT...OR AROUND 40 MPH POSSIBLE IN EASTERN MA AND RI. EXPECTING IT TO REMAIN BELOW WIND ADVISORY CRITERIA OF 46 MPH GUSTS. COASTAL SURGES RUNNING A TAD HIGHER THAN FORECAST. NO CHANGES TO THE COASTAL FLOOD ADVISORY BUT HAVE TWEAKED VALUES A BIT UPWARD FOR TONIGHT...SEE COASTAL DISCUSSION BELOW. NO CHANGE TO TEMPERATURE FORECASTS FOR THIS PERIOD. STILL FORECASTING HIGHS IN THE UPPER 40S TO MID 50S THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... TONIGHT... RAIN SHIELD ASSOCIATED WITH COASTAL LOW WILL PULL AWAY FROM CAPE COD AND THE ISLANDS AS DRY SLOT APPROACHES FROM THE SOUTH. THIS MAY RESULT IN AREAS OF DRIZZLE AND FOG FORMING WITH DRY AIR ALOFT AND MOIST NE LOW LEVEL FLOW ACROSS SOUTHERN NEW ENGLAND. FRIDAY... OTHER THAN SPOTTY LIGHT RAIN/DRIZZLE THE DAY SHOULD START OFF MAINLY DRY. IN FACT SOME OF THE MODEL GUID SUGGEST THERE COULD BE A FEW BREAKS OF SUNSHINE ACROSS CAPE COD AND NANTUCKET EARLY IN THE MORNING. ALTHOUGH THIS WILL BE SHORT LIVED AS VERTICALLY STACKED LOW TRACKS FROM THE MID ATLC TO THE NJ COAST. THIS ADVECTS DEEP LAYER MOISTURE IN THE FORM OF RAIN INTO CT AND WESTERN- CENTRAL MA FRI AFTN. PRECIP MAY NOT REACH EASTERN MA UNTIL AFTER DARK. IT WILL BECOME BREEZY ONCE AGAIN ACROSS EASTERN MA AS EAST WINDS INCREASE. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... */ HIGHLIGHTS... - DREARY WEATHER OF LIGHT RAIN / DRIZZLE FRIDAY NIGHT - SATURDAY - COLD FRONT AND BEST CHANCES OF RAIN ON SUNDAY - QUICK BLAST OF COLDER AIR MONDAY MORNING BEHIND THE FRONT...DRY - POSSIBLE PROLONGED PERIOD OF UNSETTLED WEATHER THRU THE WEEK */ DISCUSSION... TACKLING AN ENSEMBLE FORECAST APPROACH WITH A BROADER VIEW...BLOCKY FLOW PATTERN DEAMPLIFIES WHILE SEEMINGLY TO SUBTLY SHIFT E OVER THE COURSE OF NEXT WEEK. RIDGING PREVAILS ACROSS THE NE PACIFIC INTO THE GULF OF ALASKA WITH TROUGHING OVER THE N-CENTRAL CONUS. DOWNSTREAM RIDGING IS PREFERRED OVER THE NE CONUS WITH A FAVORABLE ENVIRONMENT FOR STORM DEVELOPMENT S OF GREENLAND. PERHAPS A CONSEQUENCE OF POOR FORECAST CONSENSUS OF THE PACIFIC NORTH AMERICA PATTERN...WHAT WAS JUST A DAY OR TWO AGO A FORECAST OF DRY WEATHER AND TEMPERATURES INTO THE 70S HAS BEEN COMPLETELY OBLITERATED INTO RENEWED PERIOD OF DREARY WET WEATHER. SO AN INITIAL WET AND DREARY PERIOD BENEATH A DYING LOW OCCLUSION FRIDAY NIGHT INTO SATURDAY. SHOWERS ERODING INTO POCKETS OF LIGHT RAIN / DRIZZLE AS DRIER AIR WRAPS INTO THE SYSTEM. TRICKY FORECAST THAT WARRANTS AT LEAST CHANCE POPS. OVERALL SATURDAY INTO SATURDAY NIGHT DOES NOT APPEAR TO BE A WASH-OUT...PERHAPS THE SALVAGEABLE DAY OF THE WEEKEND PRIOR TO THE DISMAL WEATHER CONCLUDING SUNDAY AS A N-STREAM DISTURBANCE AND ATTENDANT COLD FRONT SWEEPS NEW ENGLAND WITH THE BEST AND LIKELY CHANCES OF RAIN. BEHIND THIS FRONT WILL SEE A QUICK BLAST OF COLD AIR ADVECTION AND BREEZY W/NW FLOW. OVERALL TEMPERATURES THROUGHOUT THE AFOREMENTIONED FORECAST PERIOD REMAINING BELOW-AVERAGE. THEREAFTER A LOW CONFIDENCE FORECAST. FROM AN ENSEMBLE APPROACH IT WOULD APPEAR ENERGY OUT OF THE N-CENTRAL CONUS DEAMPLIFIES BENEATH A MID-UPPER LEVEL CONFLUENT FLOW PATTERN AND FAVORABLE RIDGING. BUT IN EVALUATING DETERMINISTIC GUIDANCE...VARIANCE IS EVIDENT IN HANDLING INDIVIDUAL WAVES THROUGH THE MID LEVEL FLOW WITH THE 05.0Z ECMWF HIGHLIGHTING A MORE ROBUST N STREAM WAVE AROUND MIDWEEK. LEANING ON AN ENSEMBLE-WEIGHTED FORECAST WILL LEAN TOWARDS A FORECAST OF WAVE ENERGY SWEEPING ALONG A STALLED W TO E FRONTAL BOUNDARY BETWEEN THE C-CONUS AND STORMS DEVELOPING S OF GREENLAND. NO CERTAINTY ON THE EXACT FRONTAL BOUNDARY / BAROCLINIC ZONE BUT A PROLONGED PERIOD LOOKS PLAUSIBLE OF NUISANCE LIGHT TO MODERATE RAIN UNDER BROKEN TO OVERCAST CONDITIONS WHICH WILL MAKE CONDITIONS COOLER THAN AVERAGE TOWARDS MID MAY. CAN NOT RULE OUT SOME BREAKS IN-BETWEEN AND SUN- SHINE...AND IF THE BOUNDARY LAYER IS ABLE TO MIX OUT AND H85 TEMPERATURES HOVER AROUND +10C WE COULD SEE SEASONABLE TEMPERATURES AROUND THE 60S. AGAIN...A LOW CONFIDENCE FORECAST FROM TUESDAY INTO THE FOLLOWING WEEKEND. &&7 AM UPDATE... .AVIATION /14Z THURSDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. 1445Z UPDATE... SHORT TERM /THROUGH FRIDAY/... THIS AFTERNOON...WIDESPREAD IFR AND LOWER-END MVFR CIGS THIS AFTERNOON...WITH THE LOWEST CEILINGS NEAR THE COAST AND AT ORH. PATCHY FOG EASTERN HALF. RAIN...WITH LOCALLY HEAVY SHOWERS OVER THE CAPE AND ISLANDS. RAIN MAY SPREAD WEST TO THE I-495 BELT IN MA AND TO NEAR THE MA/CT/RI BORDER LATE THIS AFTERNOON/EARLY EVENING. NE WINDS GUSTING TO 25-35 JT ACROSS E MA AND RI TERMINALS THROUGH THIS EVENING. TONIGHT... TRENDS OF MVFR W AND IFR-LIFR E CONTINUE. -RA OVER E/SE NEW ENGLAND WITH 25 TO 35 KT NE WINDS CONTINUES DURING THE EVENING HOURS CONCLUDING TOWARDS MIDNIGHT. SOME IMPROVEMENT EXPECTED INTO THE MORNING HOURS. FRIDAY... GRADUAL IMPROVEMENT IF EVER BRIEFLY. MVFR LIKELY. -RA DEVELOPING LATE ALONG WITH NE WINDS. KBOS TERMINAL...MODERATE CONFIDENCE CONCERNING THE TAF. WILL BRING RAIN IN ON 20Z AND KEEP CONDITIONS LOW PRIOR TOWARDS IMPROVING CONDITIONS SHORTLY AFTER MIDNIGHT. KBDL TERMINAL...WILL KEEP -RA WEST. CONDITIONS IMPROVING LATER TODAY POTENTIALLY UP TO LOW END VFR. OUTLOOK /FRIDAY NIGHT - MONDAY NIGHT/...MODERATE CONFIDENCE. LOW END VFR TO LIFR MIX WITH LOW CIGS AND VSBY RESTRICTIONS PER SHRA/DZ/BR INITIALLY...IMPROVING THROUGH SATURDAY. E WINDS VEER S WHILE INCREASING AHEAD OF A COLD FRONT SWEEPING TERMINALS SUNDAY WITH GUSTS UP TO 25 KTS. POSSIBLE LLWS AND LIKELY -RA/RA IMPACTS PRIOR TO THE COLD FRONT...BEHIND WHICH WINDS BACK W/NW AND ARE IMMEDIATELY GUSTY WITH UP TO 30 KTS SUNDAY NIGHT INTO MONDAY MORNING. IMPROVING VFR WHILE WINDS W/NW WINDS DIMINISH MONDAY INTO MONDAY NIGHT. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. 1045 AM UPDATE... THIS AFTERNOON... GALE WARNING IS IN EFFECT. NE WINDS WILL HAVE FREQUENT GUSTS TO 30 TO 35 KT WITH A GUST TO 40 KT POSSIBLE OVER THE SE WATERS TOWARD EVENING. SHOWERS...LOCALLY HEAVY...WITH AREAS OF FOG WILL RESTRICT VISIBILITY TO 3 MILES OR LESS AT TIMES OVER THE WATERS. SEAS BUILDING TO 8 TO 12 FEET ON THE OUTER WATERS. TONIGHT... NE GALES CONTINUE DURING THE EVENING FOLLOWED BY WINDS DIMINISHING AFTER MIDNIGHT. VSBY MAY BE REDUCED IN AREAS OF FOG AND DRIZZLE AT TIMES. FRIDAY... LOW PRES MOVES UP THE COAST FROM THE MID ATLC TO NJ. THIS WILL RESULT IN EAST WINDS INCREASING AS THE DAY PROGRESSES ALONG WITH RAIN OVERSPREADING THE RI WATERS IN THE AFTERNOON. OUTLOOK /FRIDAY NIGHT - MONDAY NIGHT/...MODERATE CONFIDENCE. WET WEATHER CONTINUES FRIDAY NIGHT UNDER E/NE FLOW WITH POTENTIAL VISIBILITY RESTRICTIONS. CONDITIONS IMPROVE SATURDAY INTO SATURDAY NIGHT AS E WINDS VEER S ALLOWING WAVE ACTION TO DIMINISH. BUT SHORT LIVED AS S WINDS INCREASE AHEAD OF A COLD FRONT SWEEPING THE WATERS LATE SUNDAY. GUSTS TO 25 KTS AHEAD OF THE FRONT WITH WAVES BUILDING 5 TO 7 FEET...BACKING W/NW WITH GUSTS TO 30 KTS IMMEDIATELY BEHIND THE FRONT DIMINISHING MONDAY INTO MONDAY NIGHT ALLOWING WAVES TO DIMINISH BELOW 5 FEET BY THE END OF PERIOD. && .TIDES/COASTAL FLOODING... 930 AM UPDATE... PRIOR FORECAST AND ADVISORY LOCATION LOOKS GOOD. HAVE ADJUSTED SURGE AND SEAS UP A LITTLE BASED ON LATEST TRENDS AND HIGH RESOLUTION WIND GUIDANCE. SURGE IS PRESENTLY RUNNING A LITTLE OVER A FOOT AT BOSTON...CHATHAM AND NANTUCKET HARBOR OR ABOUT A HALF FOOT ABOVE BOTH THE ESTOFS AND ETSS GUIDANCE. WOULD ANTICIPATE THE PERSISTENT NE FLOW WHICH MAY STRENGTHEN A TAD THIS EVENING TO RESULT IN A MODEST AND GRADUAL INCREASE IN SURGE. IT IS NOT OUT OF THE QUESTION THAT A FEW SPOTS...SUCH AS SCITUATE AND NANTUCKET HARBOR...MAY APPROACH THE HIGH END OF MINOR IMPACTS FOR THIS EVENING/S HIGH TIDE. HAVE KEPT THE ESSEX COUNTY COASTLINE OUT OF THE ADVISORY AREA FOR NOW BUT WILL REEVALUATE LATER TODAY. AT LEAST POCKETS OF MINOR COASTAL FLOODING POSSIBLE AGAIN FRI EVENING DUE TO HIGH ASTRO TIDE AND PROBABLE SLOWNESS FOR THE SURGE TO EVACUATE...BUT WE DO NOT THINK THIS WARRANTS A DOUBLE HEADLINE AT THIS TIME. COASTAL FLOOD ADVISORY HAS BEEN POSTED FOR THIS EVENING/S HIGH TIDE. ASTRO TIDE AT BOSTON IS 11.95 FT AT 10:55 PM. NE WINDS OF 25 TO 35 KT THIS AFTERNOON AND EVENING WILL RESULT IN A STORM SURGE AROUND 1 FT. THIS COMBINED WITH SOME WAVE ACTION ONTOP OF THE SURGE WILL BE SUFFICIENT TO PRODUCE MINOR COASTAL FLOODING ALONG THE EASTERN MA COASTLINE FROM BOSTON SOUTHWARD THRU PLYMOUTH COUNTY...CAPE COD BAY AND NANTUCKET. RISK IS LOWER NORTH OF BOSTON BUT LATER SHIFTS WILL HAVE TO EVALUATE FOR POTENTIAL HEADLINES. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...COASTAL FLOOD ADVISORY FROM 9 PM THIS EVENING TO 1 AM EDT FRIDAY FOR MAZ015-016-019-022-024. RI...NONE. MARINE...GALE WARNING UNTIL 2 AM EDT FRIDAY FOR ANZ231>235-237. GALE WARNING UNTIL 10 PM EDT THIS EVENING FOR ANZ230-236. GALE WARNING UNTIL 2 AM EDT SATURDAY FOR ANZ250-251-254>256. && $$ SYNOPSIS...NOCERA/SIPPRELL/FIELD NEAR TERM...NOCERA/FIELD SHORT TERM...NOCERA LONG TERM...SIPPRELL AVIATION...NOCERA/SIPPRELL/FIELD MARINE...NOCERA/SIPPRELL/FIELD TIDES/COASTAL FLOODING...THOMPSON/STAFF

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