Area Forecast Discussion
Issued by NWS Boston, MA

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062 FXUS61 KBOX 050736 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 336 AM EDT THU MAY 5 2016 .SYNOPSIS...
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* UPDATES TO LONG TERM PORTION OF THE FORECAST... 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.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/... DRY SLOT HAS OVERSPREAD THE REGION BRINGING AN END TO THE STEADY RAINS FROM LAST EVENING. HOWEVER MOIST LOW LEVEL NE JET PROVIDING LOW CLOUDS ALONG WITH AREAS OF DRIZZLE AND FOG. NE WINDS OFF THE CHILLY OCEAN WATERS WILL KEEP TEMPS IN THE LOW TO MID 40S WITH UPPER 30S ACROSS THE HIGHER TERRAIN SUCH AS WORCESTER. THESE CONDITIONS WILL PERSIST INTO DAYBREAK. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... *** UNSEASONABLY COOL/DREARY WEATHER CONTINUES THURSDAY/THURSDAY NIGHT WITH A PERIOD OF STEADY RAIN LIKELY LATE IN THE AFTERNOON AND EVENING ACROSS EASTERN NEW ENGLAND *** THURSDAY AND THURSDAY NIGHT... ANOTHER WAVE OF LOW PRESSURE WILL BE TRACKING SOUTHEAST OF SOUTHERN NEW ENGLAND THURSDAY INTO THURSDAY EVENING. THIS COMBINED WITH HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RESULT IN ANOTHER DREARY/UNSEASONABLY COOL DAY ACROSS THE REGION. THIS NEXT WAVE OF LOW PRESSURE WILL BE A BIT STRONGER THAN THE PAST FEW...SO NORTHEAST WIND GUSTS OF 20 TO 30 MPH ARE EXPECTED ACROSS THE EASTERN HALF OF SOUTHERN NEW ENGLAND WITH PERHAPS A FEW GUSTS TO 35 MPH. HIGH TEMPS ON THURSDAY WILL ONLY BE IN THE UPPER 40S TO AROUND 50 IN MOST LOCATIONS. GUSTY WINDS ALONG THE COASTAL PLAIN WILL RESULT IN WIND CHILLS IN THE UPPER 30S TO THE LOWER 40S IN THIS REGION! AS FOR PRECIPITATION...GIVEN MOIST ONSHORE FLOW...LOW CLOUDS ALONG WITH SCATTERED SHOWERS/AREAS OF DRIZZLE AND PATCHY FOG ARE EXPECTED THU INTO THU NIGHT. A PERIOD OF STEADIER RAINFALL WILL PROBABLY OCCUR LATE THURSDAY AFTERNOON AND EVENING ACROSS EASTERN NEW ENGLAND. THIS WILL DEPEND ON EXACTLY HOW CLOSE INTENSIFYING LOW PRESSURE AND ITS ASSOCIATED DEEPER MOISTURE/FORCING TRACK IN REGARDS TO THE SOUTHERN NEW ENGLAND COAST. ECMWF/NAM ARE THE MOST ROBUST SHOWING 40 TO 50 KNOTS OF NORTHEAST WINDS AT 925 MB...WHILE THE GFS IS WEAKER. EITHER WAY...GIVEN THAT TYPE OF NORTHEAST LOW LEVEL FLOW THERE SHOULD BE A PERIOD OF STEADIER RAIN AT LEAST ALONG THE EASTERN MA COAST. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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*/ 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.
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&& .AVIATION /08Z THURSDAY THROUGH MONDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. 10 PM UPDATE ... SHORT TERM /THROUGH FRIDAY/ ... HIGH CONFIDENCE ON TRENDS BUT LOWER ON EXACT DETAILS. THRU 12Z ... PERSISTENCE A GOOD SHORT TERM FORECAST IN THIS REGIME. THUS EXPECT MVFR ACROSS CT RVR VLY WITH IFR ELSEWHERE. MAINLY DRY BUT AREAS OF DRIZZLE POSSIBLE. GUSTY NE WINDS UP TO 25 KT WITH STRONGEST WINDS ALONG THE IMMEDIATE COAST. AFTER 12Z ... MVFR ACROSS CT RVR VLY SPREADS EASTWARD INTO RI AND CENTRAL MA HOWEVER IFR LIKELY LINGERS ACROSS EASTERN MA. NE WINDS INCREASE TO 30-35 KT LATE IN THE DAY OVER EASTERN MA. RAIN REDEVELOPS ACROSS EASTERN MA AROUND 21Z AND THEREAFTER. TONIGHT ... MVFR EXCEPT IFR EASTERN MA IN STEADY RAIN BUT THEN A DRYING TREND AFTER MIDNIGHT ALONG WITH IFR CONFINED TO ONLY SOUTHEAST MA. GUSTY NE WINDS 30-35 KT ACROSS EASTERN MA SLOWLY EASE LATE. FRI ... MVFR LIKELY WITH RAIN REDEVELOPING LATE IN THE DAY ACROSS CT. NE WINDS FAIRLY LIGHT EARLY BUT THEN BEGINNING TO INCREASE LATE IN THE DAY. KBOS TERMINAL ... UNCERTAINTY IN TAF CENTERED ON POTENTIAL STEADY/HEAVY RAIN 21Z TODAY THRU 03Z THIS EVENING. HEAVIEST RAIN MAY REMAIN OFFSHORE. OTHERWISE ANY RAIN TODAY WILL BE LIGHT AND SPOTTY. KBDL TERMINAL ... HIGH CONFIDENCE IN TAF. 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.
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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. 10 PM UPDATE ... ISOLATED T-STORM CAPE COD AND NANTUCKET WATERS TIL MIDNIGHT. OTHERWISE STEADY RAIN TAPERS OFF TO LIGHT RAIN/DRIZZLE OVERNIGHT. GUSTY NE WINDS OF 20-30 KT CONTINUES OVERNIGHT YIELDING ROUGH OCEAN WATERS. EARLIER DISCUSSION BELOW. ======================================================================== SHORT TERM /THROUGH FRIDAY/...HIGH CONFIDENCE. A COUPLE WAVES OF LOW PRESSURE COMBINED WITH A HIGH OVER THE CANADIAN MARITIMES WILL RESULT IN PERSISTENT NORTHEAST WIND GUSTS OF 20 TO 30 KNOTS THROUGH THURSDAY EVENING...BEFORE GRADUALLY DIMINISHING. THE STRONGEST OF THOSE WINDS ARE EXPECTED LATE THURSDAY MORNING INTO THE AFTERNOON...WHERE THERE IS A LOW RISK FOR A FEW LOCATIONS TO BRIEFLY TOUCH 35 KNOTS. SCA HEADLINES ARE POSTED FOR ALL WATERS. OTHER CONCERNS FOR MARINERS WILL BE A FEW EMBEDDED THUNDERSTORMS THIS EVENING...MAINLY ACROSS OUR SOUTHERN WATERS. PATCHY FOG MAY ALSO AFFECT THE REGION AT TIMES THROUGH THURSDAY NIGHT. 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.
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&& .TIDES/COASTAL FLOODING... HIGH ASTRONOMICAL TIDES OCCUR LATE THURSDAY EVENING THROUGH THE WEEKEND. FORTUNATELY...SEAS/WINDS WILL BE BELOW THRESHOLDS FOR A SIGNIFICANT COASTAL FLOOD EVENT. HOWEVER...THE POTENTIAL FOR POCKETS OF MINOR SPLASH OVER/MINOR COASTAL FLOODING EXIST ALONG THE EASTERN MA COAST DURING THE LATE THURSDAY EVENING AND LATE FRIDAY EVENING HIGH TIDES. THE ASTRONOMICAL HIGH TIDE LATE THURSDAY EVENING IS 12.0 FEET AT BOSTON AND THE LATE FRIDAY EVENING IS 12.3 FEET. THE WINDS WILL BE A BIT STRONGER THURSDAY EVENING...ESPECIALLY A FEW HOURS BEFORE ASTRO HIGH TIDE...BUT THE LATE FRIDAY EVENING HIGH TIDE IS A TAD HIGHER. ALL IN ALL...POCKETS OF SPLASH OVER/MINOR COASTAL FLOODING ARE A DECENT POSSIBILITY IN THE TYPICALLY VULNERABLE AREAS. A COASTAL FLOOD ADVISORY MAY EVENTUALLY BE NEEDED FOR BOTH THESE HIGH TIDE CYCLES. && .BOX WATCHES/WARNINGS/ADVISORIES...
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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 FROM NOON TODAY TO 2 AM EDT FRIDAY FOR ANZ231>235- 237. GALE WARNING FROM NOON TODAY TO 10 PM EDT THIS EVENING FOR ANZ230-236. GALE WARNING FROM NOON TODAY TO 2 AM EDT SATURDAY FOR ANZ250- 251-254>256.
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&& $$ SYNOPSIS...FRANK/SIPPRELL NEAR TERM...NOCERA SHORT TERM...FRANK LONG TERM...SIPPRELL AVIATION...NOCERA/SIPPRELL MARINE...NOCERA/SIPPRELL TIDES/COASTAL FLOODING...WFO BOX STAFF

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