Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 042010 AAA AFDBOX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TAUNTON MA 410 PM EDT WED MAY 4 2016 .SYNOPSIS...
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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.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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***A PERIOD OF STEADY RAIN IN MOST LOCATIONS THIS EVENING WILL TAPER TO SCATTERED SHOWERS/AREAS OF DRIZZLE AFTER MIDNIGHT*** CLOSED UPPER LEVEL LOW DROPPING SOUTH TOWARDS THE OHIO VALLEY WAS BACKING THE MID LEVEL FLOW. THIS WAS ALLOWING FOR A DEEPER PLUME OF MOISTURE TO ADVECT NORTHWARD INTO SOUTHERN NEW ENGLAND. AT THE SAME TIME...ANOTHER WAVE OF LOW PRESSURE WAS APPROACHING SOUTHERN NEW ENGLAND. THE RESULT WILL BE A PERIOD OF STEADY RAIN ACROSS MOST OF SOUTHERN NEW ENGLAND THIS EVENING...SOME OF WHICH MAY BE BRIEFLY HEAVY. THERE ALSO IS SOME MARGINAL ELEVATED INSTABILITY...SO A FEW EMBEDDED THUNDERSTORMS CAN NOT BE RULED OUT. THE HIGHEST RISK FOR THAT ACROSS SOUTHEAST NEW ENGLAND. THE SHORTWAVE LIFTS NORTHEAST OF THE REGION LATER THIS EVENING...TAKING THE STRONGER FORCING WITH IT. HOWEVER...AN ABUNDANCE OF LOW LEVEL MOISTURE REMAINING ALONG WITH NORTHEAST FLOW WILL RESULT IN SCATTERED SHOWERS...AREAS OF DRIZZLE AND PATCHY FOG PERSISTING. LOW TEMPS WILL BOTTOM OUT IN THE 40S.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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***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.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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*/ HIGHLIGHTS... - THRU THE WEEKEND AN UNSETTLED COOL PATTERN OF LOW CLOUDS/DRIZZLE - TWO BOUTS OF MORE APPRECIABLE WET WEATHER: FRIDAY AND SUNDAY - MODERATE WARMING DRY TREND THRU NEXT WEEK - NEXT SHOT OF UNSETTLED WEATHER POSSIBLE AT THE FOLLOWING FRIDAY OVERVIEW AND MODEL PREFERENCES... VERY AMPLIFIED TROF-RIDGE-TROF PATTERN CONTINUES ACROSS THE CONUS WITH HIGHLY POSITIVE PNA...BUT NEAR NEUTRAL NAO/AO/EPO. LITTLE CHANGE IS EXPECTED IN THIS PATTERN FRI AND SAT...HOWEVER BY SUN AN ARCTIC VORTEX FORMING NEAR HUDSON BAY WILL ACT AS A KICKER FORCING THE STAGNANT TROF ACROSS THE NORTHEAST TO FINAL SHIFT E. THIS BREAKS DOWN THE CENTRAL RIDGE AND ALLOWS PHASING WITH THE SRN STREAM. THE RESULT IS YET ANOTHER TROF EARLY NEXT WEEK ACROSS THE NE...BUT NOT AS DEEP AS THE FEATURE THAT INFLUENCED OUR WX THROUGH THIS WEEK. BLEND OF DETERMINISTIC GUIDANCE STILL SEEMS REASONABLE WITH THIS UPDATE...AS IT FEATURES THE TWO PRIMARY PERIODS OF RAINFALL EXPECTED THROUGH SUN..AND THEN A DRYING TREND THEREAFTER. DETAILS... FRI AND SAT... THE FINAL VORT MAX ASSOCIATED WITH THE STUBBORN CUTOFF LOW PRES WHICH HAS DEFINED OUR WX OF LATE WILL BE ROTATING ACROSS NEW ENGLAND FROM S-N LATE FRI INTO EARLY SAT. PWATS ARE NEAR NORMAL...WITH MUCH OF THE COLUMNS MOISTURE TRAPPED IN THE LOWEST 300MB...THEREFORE...EXPECT THIS TO BE MAINLY A BATCH OF WIDESPREAD SHRA/DRIZZLE WETTING THE GROUNDS ONCE AGAIN. FINAL TOTALS STILL REMAIN GENERALLY AT OR BELOW A QUARTER INCH. DRIER...BUT COOL CONDITIONS FOLLOW FOR THE AFTERNOON SAT. TEMPS REMAIN GENERALLY BELOW NORMAL UNDER MOSTLY CLOUDY SKIES AND LITTLE CHANGE IN AIRMASS. RAW MODEL 2M TEMPS ARE BETTER SUITED HERE...BUT STILL LIKELY A BIT TOO HIGH. SUN... ARCTIC VORTEX AND ATTENDANT SFC COLD FRONT SWEEP ACROSS NEW ENGLAND WITH A RENEWED RISK FOR WIDESPREAD SHRA AS THE FRONT MOVES THROUGH. NOTING A SLIGHT INCREASE IN PWATS IN THE RETURN FLOW AHEAD OF THIS FEATURE COMBINED WITH A CONDITIONALLY UNSTABLE LAYER BETWEEN H9 AND H7 WHICH COULD SUPPORT A FEW HEAVIER SHRA. WHILE FINAL QPF VALUES ARE EXPECTED TO REACH ONLY ABOUT 0.25 INCHES...IT WILL FALL OVER A SHORTER PERIOD OF TIME SUN AFTERNOON. COOLER AND DRIER TEMPERATURES FOLLOW THE FROPA...WITH CLEARING EXPECTED INTO THE OVERNIGHT HOURS. MON... REINFORCING ARCTIC FRONT MOVES THROUGH EARLY MON...BUT MAIN IMPACTS WILL BE INCREASED NW FLOW AND A SLIGHT COOL DOWN IN TEMPS. OVERALL COLUMN MOISTURE IS MUCH LOWER BY THE TIME OF THIS FROPA...SO LITTLE IF ANY PRECIPITATION IMPACTS ARE EXPECTED. IN SPITE OF THE SUN BREAKING THROUGH CLOUDS THROUGH THE DAY. HIGHS MAY ONCE AGAIN STRUGGLE TO REACH SEASONAL NORMALS AS H85 TEMPS AVERAGE ONLY ABOUT +3C. THIS WOULD YIELD HIGHS MAINLY IN THE UPPER 50S AND LOW 60S. TUE AND WED... SOME UNCERTAINTY IN WHERE WEAK BAROCLINIC ZONE WILL SET UP BUT AT THIS TIME...IT APPEARS IT WILL HOLD NEAR OR SLIGHTLY S OF THE REGION. THIS SUGGESTS THE PATTERN FOR MAINLY NEAR OR SLIGHTLY BELOW NORMAL WX TO CONTINUE INTO THE MIDDLE OF NEXT WEEK. MODELS ARE ALSO DRY THROUGH THE COLUMN FOR THE MOST PART...SUGGESTING THAT HIGH PRES WILL YIELD A LULL IN PRECIP ACTIVITY CONTINUING INTO AT LEAST WED.
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&& .AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
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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 NIGHT/...MODERATE TO HIGH CONFIDENCE. REST OF THIS AFTERNOON...MAINLY MVFR CONDITIONS WITH SHOWERS INCREASING IN AREAL COVERAGE THROUGH EARLY EVENING. NE WIND GUSTS OF 20 TO 25 KNOTS ALONG THE SOUTHEAST NEW ENGLAND COAST. TONIGHT...A PERIOD OF STEADY RAIN THIS EVENING WITH CONDITIONS GRADUALLY LOWERING TO IFR LEVELS IN MOST LOCATIONS. A FEW EMBEDDED THUNDERSTORMS CAN NOT BE RULED OUT THIS EVENING WITH THE HIGHEST RISK IN SOUTHEAST NEW ENGLAND. THE BULK OF THE STEADY/HEAVIEST RAIN WILL BE OVER BY AROUND MIDNIGHT...BUT SCATTERED SHOWERS ALONG WITH AREAS OF DRIZZLE AND PATCHY FOG WILL CONTINUE THROUGH DAYBREAK. THURSDAY AND THURSDAY NIGHT...IFR TO LOW END MVFR CONDITIONS EXPECTED TO CONTINUE IN SCATTERED SHOWERS/LOW CLOUDS AND AREAS OF DRIZZLE/FOG PATCHES. A PERIOD OF STEADY RAIN WILL LIKELY OCCUR LATE THU AFTERNOON/EVENING MAINLY ACROSS EASTERN NEW ENGLAND. NE WIND GUSTS OF 20 TO 30 KNOTS ARE EXPECTED ALONG THE COASTAL PLAIN THU INTO EARLY THU EVENING BEFORE DIMINISHING. KBOS TERMINAL...MODERATE TO HIGH CONFIDENCE IN TAF. MVFR CONDITIONS SHOULD DETERIORATE TO IFR THRESHOLDS SOMETIME THIS EVENING. KBDL TERMINAL...MODERATE TO HIGH CONFIDENCE IN TAF. MVFR CONDITIONS SHOULD DETERIORATE TO IFR THRESHOLDS SOMETIME TONIGHT. OUTLOOK /FRIDAY THROUGH MONDAY/... FRI AND SAT...MODERATE CONFIDENCE. CONTINUED BKN-OVC CONDITIONS WITH OCCASIONAL SHOWERS AND DRIZZLE. THIS SUGGESTS PERIODS OF MVFR/IFR INTERMIXED WITH EVEN A FEW LOW VFR PERIODS THROUGH THE TWO DAY STRETCH. SUN...MODERATE CONFIDENCE. COLD FRONT SWEEPS THROUGH WITH VFR FIRST GIVING AWAY TO BRIEF MVFR WITH SHRA...THEN RAPID IMPROVEMENT BACK TO VFR IN THE AFTERNOON/EVENING. MON...MODERATE CONFIDENCE. MAINLY VFR.
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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 NIGHT/...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 /FRI THROUGH MON/... GRAY CONDITIONS WITH OCCASIONAL SHOWERS AND DRIZZLE WILL CONTINUE INTO SUN. THROUGH THIS PERIOD EVEN AS WINDS SHIFT FROM THE E...THE N-NE AND THEN FINALLY S BY SAT NIGHT INTO SUN...GUSTS SHOULD REMAIN GENERALLY BELOW 25 KT. HOWEVER...A LINGERING SWELL WILL PERSIST...ESPECIALLY ACROSS THE OCEAN WATERS...NEAR 5-6 FT. THEREFORE...SMALL CRAFT CONDITIONS MAY CONTINUE DUE TO THESE SEAS RIGHT INTO SUN. MON...CONDITIONS IMPROVE WITH MORE PEAKS OF SUN AND NW FLOW. WIND GUSTS MAY REACH 25 KT AT TIMES.
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&& .TIDES/COASTAL FLOODING...
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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.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT THURSDAY NIGHT FOR ANZ232>234. SMALL CRAFT ADVISORY FROM 6 AM TO 7 PM EDT THURSDAY FOR ANZ230- 236. SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO MIDNIGHT EDT THURSDAY NIGHT FOR ANZ231. SMALL CRAFT ADVISORY UNTIL 8 PM EDT FRIDAY FOR ANZ235-237- 254>256. SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 8 AM EDT FRIDAY FOR ANZ250-251.
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&& $$ SYNOPSIS...FRANK/DOODY NEAR TERM...FRANK SHORT TERM...FRANK LONG TERM...DOODY AVIATION...FRANK/DOODY MARINE...FRANK/DOODY TIDES/COASTAL FLOODING...

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