Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 290914 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 514 AM EDT MON SEP 29 2014 .SYNOPSIS...
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SUMMERLIKE WARMTH WILL COME TO AN END THIS AFTERNOON AS A FRONT MOVES SOUTH ACROSS THE REGION...DROPPING TEMPERATURES...BRING CLOUDS AND PATCHY DRIZZLE TO THE AREA TONIGHT. COOL TEMPERATURES WILL CONTINUE THROUGH MOST OF THIS WEEK AS PERSISTENT NORTHEAST WINDS REMAIN IN PLACE. ONE OR TWO WEAK WAVES OF LOW PRESSURE MAY BRING THE CHANCE OF SHOWERS FOR THE REGION. AN APPROACHING FRONT WITH ASSOCIATED LOW PRESSURE LOOKS TO AFFECT SOUTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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PREDAWN HOURS... PATCHY FOG ACROSS THE INTERIOR CT VALLEY THIS MORNING AND THE I-495 CORRIDOR OF EASTERN MA. THIS FOG WILL BURN OFF A FEW HOURS AFTER SUNRISE. ELSEWHERE QUIET AND MILD WEATHER PREVAILS AS DEW PTS IN THE U50S AND L60S ALONG WITH HIGH CLOUDS AND LIGHT W-SW WIND PRECLUDE COOLER TEMPS. AFTER SUNRISE... 1032 MB ANTICYCLONE OVER ONTARIO AND QUEBEC EARLY THIS MORNING BUILDS SOUTHEAST INTO ATLANTIC CANADA LATER TODAY. THIS SENDS A BACKDOOR COLD FRONT AND A MUCH COOLER AIRMASS ACROSS THE AREA THIS AFTERNOON OVER NORTHEAST MA AND SOUTHEAST NH...THEN ACROSS THE REMAINDER OF THE AREA THIS EVENING. BEFORE THE FRONTAL PASSAGE IT WILL ONCE AGAIN BE A WARM DAY GIVEN THE MILD START THIS MORNING. HOWEVER NOT QUITE AS WARM AS PREVIOUS DAYS WITH HIGHS TODAY 75 TO 80 BEFORE TEMPS DROP THIS AFTERNOON THRU THE 70S AND INTO THE 60S. THIS WILL BE A TYPICAL BACKDOOR FRONT WITH WINDS SHIFTING TO THE E-NE AND GUSTING UP TO 25 MPH OR SO. NOT QUITE AS STRONG AS A SPRING BACKDOOR FRONT AS WATER TEMPS IN THE GULF OF MAINE REMAIN IN THE L60S...COMPARED TO WATER TEMPS IN THE 40S AND 50S DURING THE SPRING. COULD BE A BRIEF PERIOD OF PATCHY DRIZZLE IMMEDIATELY BEHIND THE FRONT GIVEN LOW LEVEL MOISTURE PROFILES.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... TONIGHT... POST FRONTAL AIRMASS OVERSPREADS THE ENTIRE REGION ALONG WITH ONSHORE FLOW STRENGTHENING. THIS RESULTS IN INCREASING LOW LEVEL MOISTURE IN THE FORM OF LOW CLOUDS AND AREAS OF DRIZZLE POSSIBLE. COOLER WITH LOWS DIPPING INTO THE 50S. TUESDAY... LEAD SHORT WAVE TROUGH MOVES ACROSS THE REGION. WEAK MID LEVEL CYCLONIC FLOW COUPLED WITH MOIST ONSHORE FLOW SHOULD YIELD THE RISK OF A FEW LOW TOP SHOWERS AND/OR AREAS OF DRIZZLE...WITH HIGHEST RISK ACROSS RI AND EASTERN MA. CLOUDS AND ONSHORE FLOW WILL RESULT IN A MUCH COOLER AFTERNOON WITH HIGHS ONLY IN THE 60S. COULD TURN OUT TO BE COOLER AS 2 METER TEMPS FROM NAM/GFS AND SREF ALL INDICATE MAX TEMPS ONLY IN THE U50S OVER NORTHEAST MA AND SOUTHWEST NH. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
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HEADLINES... * EXPECT NORTHEAST WINDS TO BRING COOLER THAN NORMAL TEMPS THROUGH MOST OF THE WEEK * CHANCE FOR SHOWERS LOOK OCCUR FROM WED INTO THU * UNCERTAINTY IN FORECAST CONTINUES LATE THIS WEEK INTO THE WEEKEND OVERVIEW... MODELS CONTINUE TO SHOW RATHER WIDE SOLUTION SPREAD THROUGH MOST OF THIS FORECAST PERIOD...THOUGH GENERAL TRENDS HAVE BEEN SIGNALED FOR THE LAST FEW DAYS AT LEAST THROUGH MID WEEK. THERE WILL BE A PERSISTENT NORTHEAST FLOW IN PLACE THANKS TO HIGH PRESSURE OVER THE MARITIMES AND EASTERN QUEBEC WITH A STALLED FRONT SOUTH OF THE REGION TO BEGIN THIS PERIOD. MODELS AND ENSEMBLES SHOWING SOME AGREEMENT AT LEAST WITH THE UPPER PATTERN AS H5 TROUGH DIGS OUT OF THE GREAT LAKES TOWARD NEW ENGLAND TO THE MID ATLC COAST. BROAD CUTOFF LOW LOOKS TO DEVELOP AROUND MID WEEK...BUT TENDS TO BE SLOWLY PROGRESSIVE INTO EARLY THIS WEEKEND. HOWEVER...THIS KEEPS A COOL...MOIST FLOW IN PLACE INTO THE WEEKEND. SOME QUESTION AS TO WHETHER WEAK WAVES OF LOW PRES DEVELOP TO THE SOUTH AND MOVE CLOSE TO THE REGION IN THE ONSHORE FLOW. THIS ALSO LEAVES QUESTIONS ABOUT HOW MUCH MEASURABLE RAIN WILL FALL AND WHERE IT WILL OCCUR. AT THIS POINT...HAVE CARRIED ONLY LIGHT QPF...AS IT LOOKS LIKE NOT TOO MUCH ENERGY OR LIFT WILL BE IN PLACE. MOST OF PRECIP LOOKS TO BE SOME FORCING WITH ONSHORE FLOW ALONG WITH DIURNAL INFLUENCES. OVERALL CONFIDENCE REMAINS BELOW AVERAGE...BUT SOMEWHAT HIGHER CONFIDENCE FOR WED INTO THU WITH SCT SHOWERS ACROSS CENTRAL AND EASTERN AREAS. DEPENDING UPON MOVEMENT OF THE BROAD CUTOFF UPPER LOW...MAY SEE ANOTHER FRONT WITH ASSOCIATED LOW PRESSURE APPROACH FROM THE W LATE THIS WEEK OR INTO THE WEEKEND. TIMING IS IN QUESTION THOUGH. DETAILS... TUESDAY NIGHT...NE WINDS WILL BECOME ESTABLISHED...BRINGING IN LOW LEVEL MOISTURE ACROSS THE REGION. BEST LIFT SHOULD BE OFFSHORE BY THIS TIME...BUT CAN NOT RULE OUT ISOLD SHOWERS TO OCCUR WITH ONLY LIGHT RAINFALL. WILL ALSO SEE LATE NIGHT/EARLY MORNING PATCHY FOG. LOWS WILL BE MAINLY IN THE LOWER-MID 50S. WEDNESDAY-THURSDAY...UPPER LEVEL ENERGY FROM DEVELOPING BROAD CUTOFF LOW MOVES INTO THE REGION AROUND THIS TIMEFRAME. THIS LOOKS TO COMBINE WITH THE ONSHORE FLOW TO BRING SOME LIGHT PRECIP...MAINLY SCT SHOWERS ACROSS CENTRAL AND EASTERN AREAS. SOME DAYTIME HEATING WILL ALSO HELP TO DEVELOP THE SHOWERS. CURRENT THINKING ON QPF IS GENERALLY LESS THAN 0.25 INCHES FOR MOST AREAS...THOUGH WITH THE ONSHORE FLOW MAY SEE A BIT MORE OVER CAPE COD AND THE ISLANDS DURING THIS TIMEFRAME. BLUSTERY NE WINDS WILL BE IN PLACE THOUGH... ESPECIALLY FROM ABOUT PLYMOUTH SOUTH TO CAPE COD AND THE S COAST. HIGH TEMPS WILL RUN CLOSE TO OR SLIGHTLY BELOW SEASONAL NORMS BOTH DAYS...THOUGH IT WILL PROBABLY FEEL COOLER DUE TO THE WINDS. THURSDAY NIGHT-FRIDAY...LOOKS TO BE A BRIEF DRY PERIOD BETWEEN SYSTEMS...AT LEAST FOR NOW. SOME DRIER AIR WORKS SW OUT OF QUEBEC AS WEAK HIGH PRES RIDGING APPEARS TO WORK DOWN THE COAST. HIGHS ON FRIDAY LOOK TO REBOUND A BIT...TOPPING OFF IN THE MID 60S TO AROUND 70...THOUGH A BIT COOLER ALONG THE COAST. FRIDAY NIGHT-SATURDAY...DIGGING H5 TROUGH WORKS OUT OF THE GREAT LAKES...THOUGH PROGRESSES SLOWLY ACROSS NY STATE FRI NIGHT. ASSOCIATED COLD FRONT ALONG WITH POSSIBLE WAVE ON THIS FRONT MAY APPROACH FRI NIGHT...WITH BEST SHOT OF PRECIP DURING SAT. WINDS SHIFT AROUND TO S-SW AHEAD OF THIS APPROACHING SYSTEM...THOUGH CLOUDS WILL ALSO BE MOVING IN. STILL RATHER LOW CONFIDENCE ON TIMING THIS SYSTEM WITH WIDE MODEL SOLUTION VARIANCE ON TIMING. LOOKS LIKE A SWATH OF DECENT QPF...BUT QUESTIONS ON THIS AS WELL DUE TO TIMING AND PLACEMENT OF HEAVIEST PRECIP. SATURDAY NIGHT-SUNDAY...TIMING OF THE FRONT ACROSS THE REGION VERY MUCH IN QUESTION. FOR NOW...HAVE FRONT MOVING OFFSHORE DURING SAT NIGHT WITH DRIER BUT COOLER CONDITIONS FOR SUNDAY. LOW CONFIDENCE.
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&& .AVIATION /09Z MONDAY THROUGH FRIDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...HIGH CONFIDENCE ON TRENDS BUT LOWER CONFIDENCE ON EXACT TIMING. THRU 12Z... LOCALIZED IFR/LIFR IN PATCHY FOG DURING THE PREDAWN HOURS WILL BURN OFF A FEW HOURS AFTER SUNRISE. ELSEWHERE VFR WILL PREVAIL. TODAY AND TONIGHT...A BACKDOOR COLD FRONT DROPS S ACROSS REGION SHIFTING THE WINDS TO THE N/NE THIS AFTERNOON. VFR CIGS AHEAD OF FRONT BUT EXPECT CIGS TO LOWER TO MVFR BEHIND IT...CLOSER TO 00Z. POST FRONTAL MOISTURE IS SHALLOW SO EXPECT MORE DRIZZLE TONIGHT RATHER THAN SHOWERS. EASTERLY/ONSHORE FLOW WILL INCREASE TONIGHT WHICH WILL ALLOW FOR MOISTURE TO INCREASE AND DROP CIGS TO MVFR WITH ISOLATED IFR. E-NE WINDS WILL ALSO GUST BETWEEN 15-25 KTS OVERNIGHT ESP ACROSS THE MERRIMACK VALLEY. TUE...NOT MUCH CHANGE WITH ONSHORE FLOW. IFR IN THE MORNING WILL TREND UP TOWARD MVFR. SPOTTY LIGHT RAIN/DRIZZLE POSSIBLE. KBOS TERMINAL...HIGH CONFIDENCE IN TAF TRENDS BUT LOWER CONFIDENCE ON EXACT TIMING. KBDL TERMINAL...HIGH CONFIDENCE IN TAF TRENDS BUT LOWER CONFIDENCE ON EXACT DETAILS. OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY... LOW TO MODERATE CONFIDENCE TUESDAY NIGHT AND WEDNESDAY...THEN MODERATE CONFIDENCE THURSDAY AND FRIDAY. TUESDAY NIGHT AND WEDNESDAY...SHOULD SEE WIDESPREAD MVFR CIGS AND AREAS OF MVFR VSBYS IN SHOWERS. PATCHY IFR CIGS/VSBYS POSSIBLE ACROSS EAST COASTAL SECTIONS TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. THURSDAY AND FRIDAY...MAY SEE LEFTOVER MVFR CIG/VSBYS EARLY THU ALONG THE E COAST...OTHERWISE LOW END VFR CONDITIONS EXPECTED.
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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...HIGH CONFIDENCE THROUGH TUE. TODAY...BACKDOOR FRONT MOVES ACROSS THE NORTHERN MA WATERS FROM LATE MORNING INTO THE AFTERNOON HOURS. ELSEWHERE FRONT WILL WAIT UNTIL LATE IN THE DAY OR THIS EVENING. EXPECT A WIND SHIFT TO THE NE ALONG WITH A BRIEF BURST OF 20-25 KT IMMEDIATELY BEHIND THE FRONT. GREATEST RISK OF 25 KT ACROSS THE CAPE ANN WATERS. THUS SMALL CRAFT ADVISORY POSTED FOR THOSE WATERS. TONIGHT...VSBY MAY LOWER IN AREAS OF DRIZZLE IN THE POST FRONTAL AIRMASS. NE WINDS SLACKEN AS THE NIGHT PROGRESSES. LARGEST SEAS ACROSS THE CAPE ANN WATERS NORTHWARD TOWARD MAINE COASTAL WATERS. TUESDAY...MODEST E-NE WINDS. VSBY MAY BE LIMITED IN AREAS OF DRIZZLE AND FOG. OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY... PERSISTENT NORTHEAST WINDS WILL BE IN PLACE ACROSS THE WATERS THROUGH MOST OF THIS FORECAST PERIOD. TUESDAY NIGHT...MAY SEE GUSTS UP TO 20 KT...BUT SEAS WILL BEGIN TO INCREASE. SHOULD REMAIN MAINLY BELOW SMALL CRAFT MOST OF THE NIGHT...THEN SOME 5 FT SEAS MAY DEVELOP ON THE EASTERN OUTER WATERS TOWARD DAYBREAK. WEDNESDAY AND WEDNESDAY NIGHT...MAY SEE NE WIND GUSTS UP TO 25 KT AT TIMES DURING THIS TIMEFRAME. E-NE SWELLS CONTINUE TO BUILD...UP TO 6 FT ON THE EASTERN OUTER WATERS. THURSDAY-FRIDAY...GUSTS MAY CONTINUE FOR A TIME DURING THU UP TO 25 KT. NE FETCH CONTINUES...WITH SWELLS CONTINUING TO BUILD. MAY REACH 8 FT ON THE EASTERN OUTER WATERS OR EVEN HIGHER BY LATE THU OR FRI. MAY EXPERIENCE A STORM SURGE OF 1 TO 1.5 FEET DURING MIDWEEK BUT THE ASTRONOMICAL TIDES ARE NOT ALL THAT HIGH.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 11 AM EDT TUESDAY FOR ANZ250-251. && $$ SYNOPSIS...NOCERA/EVT NEAR TERM...NOCERA SHORT TERM...NOCERA LONG TERM...EVT AVIATION...NOCERA/EVT MARINE...NOCERA/EVT

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