Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 211124 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 724 AM EDT TUE APR 21 2015 .SYNOPSIS... SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ALONG WITH MILD TEMPERATURES THIS MORNING...GIVES WAY TO A DRYING TREND THIS AFTERNOON. A COLD FRONT WILL BRING SCATTERED SHOWERS...AND PERHAPS EVEN AN ISOLATED THUNDERSTORM OR TWO...WEDNESDAY AFTERNOON AND EVENING. UNSEASONABLY COOL WEATHER FOLLOWS THURSDAY THROUGH THIS WEEKEND WITH JUST A SPOT SHOWER FROM TIME TO TIME. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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730 AM UPDATE... CLEARING TREND WILL CONTINUE ACROSS THE REGION. WATCHING SCT SHOWERS SOUTH OF RHODE ISLAND WILL CONTINUE THIS MORNING AND WILL MOVE ONSHORE IMPACTING NARRAGANSETT BAY AND SURROUNDING AREAS. EXPECT FOG/DRIZZLE/LIGHT SHOWERS TO CONTINUE EARLY THIS MORNING. BEFORE A LULL OCCURS LATE THIS MORNING AS SHORTWAVE MOVES OVER THE REGION. AS WE WARM SECTOR AND CLOUDS BEGIN BREAKING...TEMPS WILL REBOUND INTO THE MID 60S WITH THE LOW CHANCE OF 70S ACROSS SE MASS. APPEARS THAT DIURNAL CU AND SHOWERS WILL BE POSSIBLE THIS AFTERNOON AS LAPSE RATES STEEP AND MARGINAL MOISTURE. PREVIOUS DISCUSSION... EXPECTING RAPID CLEARING BEHIND A WARM FRONT LATER THIS MORNING WITH TEMPERATURES SOARING INTO THE UPPER 60S TO NEAR 70 MOST LOCATIONS. WESTERLY WINDS WILL ALLOW EVEN THE COASTAL LOCATIONS TO GET IN ON THE WARM TEMPERATURES...UNLIKE THIS PAST SATURDAY.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... A SHORTWAVE WILL BE APPROACHING FROM THE WEST...BRINGING A CHANCE FOR SOME SHOWERS TO PORTIONS OF WESTERN MA BY DAYBREAK WEDNESDAY. WITH A COLD FRONT HAVING ALREADY PASSED THROUGH OUR REGION LATE THIS AFTERNOON...MODELS DO NOT SHOW MUCH RAINFALL AS INSTABILITY IS RATHER LIMITED. MUCH OF TONIGHT SHOULD REMAIN DRY ACROSS SOUTHERN NEW ENGLAND WITH SEASONABLE MINIMUM TEMPERATURES. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... HIGHLIGHTS... * SCATTERED SHOWERS WED WITH A LOW RISK OF THUNDER/SMALL HAIL * SEASONABLY MILD TEMPERATURES WED * UNSEASONABLY COOL THU-SUN WITH A SPOT SHOWER OR TWO AT TIMES OVERVIEW... OVERALL THE 12Z GUIDANCE IS IN GOOD AGREEMENT WITHIN THE MEDIUM AND LONG RANGE. HOWEVER EXACT TIMING AND STRENGTH OF EACH SYSTEM STILL NEEDS TO BE WORKED OUT. UPPER LEVEL LOW WILL CONTINUE TO DOMINATE THE REGION THROUGH THE EXTENDED...PINWHEELING BETWEEN THE GREAT LAKES AND NEW ENGLAND. THIS SYSTEM WILL YIELD TO A MORE SHOWERY AND COOLER FORECAST FOR THE REST OF THE WEEK AND INTO THE WEEKEND. DETAILS... * WEDNESDAY AND WEDNESDAY NIGHT...MODERATE CONFIDENCE. STRONG SHORTWAVE WILL MOVE THROUGH THE FLOW ON WEDNESDAY DEVELOPING A SURFACE LOW ACROSS HUDSON RIVER VALLEY AND INTO SOUTHERN NEW ENGLAND. THIS LOW WILL BRING SCT RAIN SHOWERS AND ISOLATED THUNDER TO THE AREA BY THE AFTERNOON HOURS. APPEARS WE MAY TRY TO WARM SECTOR ALLOWING SURFACE TEMPS TO REACH INTO THE LOW TO MID 60S. THIS WILL STEEPEN THE LAPSE RATES TO AROUND 7-8 C/KM AS 500 MB TEMPS ARE -24C. MODEL GUIDANCE IS ALSO INDICATING THAT SOME SURFACE CAPE MAY DEVELOP WHICH WILL HELP IN THUNDERSTORM DEVELOPMENT. IN FACT WE COULD SEE SMALL HAIL/GRAUPEL AS FREEZING HEIGHTS WILL BE LOW THANKS TO THE COLD POOL. STILL A LOT OF DETAILS TO WORK OUT BUT SOMETHING TO WATCH IN THE COMING DAY. * THURSDAY INTO MONDAY...MODERATE CONFIDENCE. STRONG CUT OFF LOW WILL CONTINUE TO SPIN OVER THE NORTHEAST DURING THIS TIME PERIOD. NEW ENGLAND COULD SEE A SEVERAL WAVES DEVELOP AND PUSH THROUGH THE REGION. HOWEVER MAY SEE A LOT OF DIURNAL CU AND DIURNAL SHOWERS DEVELOPING RATHER THAN WIDESPREAD RAIN. THESE SHOWERS WILL BE DIURNALLY DRIVEN AS COLD POOL ALOFT WILL BE OVERHEAD STEEPENING THE LAPSE RATES. AREAS THAT HAVE THE BEST CHANCE FOR ANY PRECIP WILL BE NORTH OF THE PIKE...CLOSER TO THE LOW PRESSURE. LASTLY EXPECT TEMPS TO BE ABOUT 5-10 F BELOW AVERAGE FOR THE WEEK THANKS TO THE COOLER TEMPS ALOFT VIA THE COLD POOL. IN FACT SOME AREAS MAY NOT SEE THE 60S FOR THE REST OF THE WEEK AND INTO THE WEEKEND. && .AVIATION /11Z TUESDAY THROUGH SATURDAY/...
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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 TUESDAY/... TODAY...CONDITIONS IMPROVING TO VFR BY MIDDAY. COLD FRONT MOVES THROUGH WITH WINDS SHIFTING W/SW THIS AFTERNOON. TONIGHT...HIGH CONFIDENCE IN MAINLY VFR CONDITIONS DESPITE THE RISK FOR A SPOT SHOWER OR TWO. KBOS TAF...HIGH CONFIDENCE IN TRENDS. MODERATE CONFIDENCE IN TIMING. MORNING PUSH LIKELY TO BE AFFECTED. KBDL TAF...HIGH CONFIDENCE IN TRENDS. MODERATE CONFIDENCE IN TIMING. A POP-UP SHOWER IS POSSIBLE. OUTLOOK...WEDNESDAY THROUGH SATURDAY... WED...MODERATE CONFIDENCE. A COLD FRONT WILL BRING A ROUND OF SCATTERED SHOWERS MAINLY WED AFTERNOON/EARLY EVENING. LOW RISK FOR EVEN A FEW RUMBLES OF THUNDER AND PERHAPS SMALL HAIL/GRAUPEL WITH THE HEAVIEST SHOWERS. THU/FRI/SAT...HIGH CONFIDENCE. MAINLY VFR. CONDITIONS COULD LOWER TO MVFR QUICKLY IN A BRIEF DIURNALLY DRIVEN SHOWER OR TWO.
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&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TONIGHT/... WILL LIKELY BE ABLE TO CONVERT THE REST OF THE GALE WARNINGS FOR THE OUTER SOUTHERN NEW ENGLAND WATERS TO SMALL CRAFT ADVISORIES. STILL NEED TO WATCH FOR THUNDERSTORMS THIS MORNING...SOME OF WHICH COULD PRODUCE BRIEF GUSTS UP TO 35 KT. VISIBILITY IMPROVES LATER TODAY WITH WINDS AND SEAS CONTINUING TO DIMINISH TONIGHT. VISIBILITIES MAY BE LIMITED AT TIMES. OUTLOOK...WEDNESDAY THROUGH SATURDAY... WEDNESDAY...HIGH CONFIDENCE. MODEST WEST TO SOUTHWEST FLOW EXPECTED AHEAD OF A COLD FRONT...BUT SPEEDS WILL BE NEAR SCA ESP ACROSS THE NEAR SHORE WATERS. A FEW SHOWERS WED AFTERNOON AND EVENING WITH A LOW RISK OF AN ISOLATED THUNDERSTORM WITH SMALL HAIL. THURSDAY THROUGH SATURDAY...HIGH CONFIDENCE. MODEST WESTERLY FLOW AS A RESULT OF CLOSED LOW PRESSURE ACROSS QUEBEC. ENOUGH COLD ADVECTION OVER THE WATERS WILL BE PRESENT TO GENERATE PERIODS OF 25 KNOT WIND GUSTS. MARGINAL SCA SEAS EXPECTED ACROSS THE OUTER-WATERS AT TIMES...BUT WITH GOOD VISIBILITY. && .TIDES/COASTAL FLOODING... EAST TO SOUTHEAST WINDS WILL INCREASE THROUGH TONIGHT. GUIDANCE CONTINUES TO TRACK STRONGEST WINDS ACROSS NEW ENGLAND EARLY THIS EVENING...BEFORE HIGH TIDE OCCURS ALONG THE SOUTH COAST /AROUND 03Z/ AND EAST COAST /ABOUT 06Z/. THIS RESULTS IN WINDS BEGINNING TO SLACKEN AS HIGH TIDE APPROACHES. ALSO SYSTEM IS FAIRLY PROGRESSIVE SO DURATION OF ONSHORE WINDS IS LIMITED. ESTOFS CONTINUES TO BE MORE ROBUST AND REALISTIC THAN ETSS WITH SURGE VALUES 1.0-1.5 FT AT THE TIME OF HIGH TIDE. SEAS ALSO BUILDING TO 10-15 FT JUST OFFSHORE. THIS SHOULD BE SUFFICIENT TO GENERATE AREAS OF MINOR COASTAL FLOODING AND SPLASH OVER. THUS WILL CONTINUE WITH A COASTAL FLOOD ADVISORY FOR THESE LOCATIONS DURING THIS EVENING AND EARLY TUE MORNING HIGH TIDES. WINDS DO NOT LOOK STRONG ENOUGH AT THE TIME OF HIGH TIDE FOR A MODERATE COASTAL FLOOD EVENT. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT WEDNESDAY FOR ANZ235-237- 250-254>256. SMALL CRAFT ADVISORY UNTIL NOON EDT WEDNESDAY FOR ANZ251. && $$ SYNOPSIS...BELK/DUNTEN NEAR TERM...BELK/DUNTEN SHORT TERM...BELK LONG TERM...DUNTEN AVIATION...BELK/DUNTEN MARINE...BELK/DUNTEN TIDES/COASTAL FLOODING...

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