Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 212031 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 431 PM EDT TUE OCT 21 2014 .SYNOPSIS...
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SCATTERED SHOWERS TONIGHT INTO THE FIRST PART OF WEDNESDAY WILL TURN INTO A SOAKING RAIN LATER WEDNESDAY INTO EARLY THURSDAY IN ASSOCIATION WITH A COASTAL LOW PRESSURE SYSTEM. SHOWERS WILL LINGER FRIDAY AS THE STORM SLOWLY PULLS AWAY FROM NEW ENGLAND. MAINLY DRY WEATHER EXPECTED THIS WEEKEND WITH SEASONABLE TEMPERATURES.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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A FEW SHOWERS WERE AFFECTING SOUTHERN NH AND NORTHEAST MA AS OF LATE AFTERNOON...WHILE THE REST OF THE REGION WAS GENERALLY DRY. WE ACTUALLY HAVE SEEN SOME PARTIAL SUNSHINE BREAK OUT ACROSS A GOOD PORTION OF THE REGION...BUT THIS WILL BE TEMPORARY. OVERALL...JUST A FEW SHOWERS ARE EXPECTED THIS EVENING WITH THE BULK OF THE FORCING TO OUR NORTH. AS THE NIGHT WEARS ON...SURFACE WINDS WILL SWITCH TO THE NORTHEAST AS THE COASTAL LOW PRESSURE SYSTEM BEGINS TO MOVE NORTHEAST OFF THE MID ATLANTIC COAST. THIS WILL PROBABLY ALLOW AREAS OF LIGHT RAIN... SHOWERS AND EVEN SOME DRIZZLE TO EXPAND ACROSS OUR NORTHERN ZONES...WHILE JUST A FEW SPOT SHOWERS ARE POSSIBLE IN THE SOUTH. LOW TEMPS WILL MAINLY BE IN THE UPPER 40S TO MIDDLE 50S. WE MAY ALSO SEE SOME PATCHY FOG DEVELOP LATE.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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***A SOAKING RAIN LATE WEDNESDAY INTO EARLY THURSDAY WITH THE HEAVIEST AMOUNTS EXPECTED ACROSS NORTHEAST MASSACHUSETTS*** WEDNESDAY AND WEDNESDAY NIGHT... AREAS OF LIGHT RAIN AND SHOWERS WILL CONTINUE TO EXPAND FROM NORTH TO SOUTH THROUGH MID AFTERNOON WEDNESDAY...AS MOIST ONSHORE NORTHEAST FLOW INCREASES. THE WIDESPREAD SOAKING RAIN WILL WAIT UNTIL LATER WEDNESDAY AFTERNOON AND PARTICULARLY WEDNESDAY NIGHT. THE SOAKING RAIN WILL DEVELOP AS LOW PRESSURE AND ITS ASSOCIATED CLOSED MID LEVEL CENTERS LIFTS NORTHEAST. A STRONG EASTERLY LOW LEVEL JET OF 30 TO 40 KNOTS WILL PROVIDE PLENTY OF MOISTURE AND STRONG LIFT FOR A WIDESPREAD HEAVY RAIN EVENT. THE CORE OF THE STRONGEST LOW LEVEL JET WILL SETUP ACROSS OUR NORTHEAST ZONES...WHICH IS WHERE WE EXPECT THE HEAVIEST RAIN. OVERALL... EXPECT A WIDESPREAD 1 TO 2 INCHES OF RAIN ACROSS MOST OF OUR REGION THROUGH EARLY THURSDAY. THE EXCEPTION MIGHT BE OUR FAR NORTHEAST ZONES...WHERE 2 TO 3 INCH RAINFALL AMOUNTS SEEM REASONABLE. THERE IS A LOW PROBABILITY OF SOME 4 INCH RAINFALL AMOUNTS IN OUR FAR NORTHEAST ZONES...MAINLY IN ESSEX COUNTY. IF THIS WERE TO MATERIALIZE...WE MIGHT HAVE SOME FLOODING ISSUES DEPENDING ON HOW FAST IT FALLS. HOWEVER...SINCE ITS A LOW PROBABILITY AND A 3RD AND 4TH PERIOD EVENT DID NOT ISSUE ANY FLOOD HEADLINES AT THIS TIME. WILL NEED TO MONITOR THINGS CLOSELY...ESPECIALLY IF MODEL TRENDS SLIDE THE AXIS OF HEAVY RAIN A BIT FURTHER SOUTH THAN CURRENTLY INDICATED. REGARDLESS...EXPECT TYPICAL NUISANCE POOR DRAINAGE STREET FLOODING ISSUES. FINALLY...WE DID NOTE SOME ELEVATED INSTABILITY LATE WED INTO WED NIGHT. INCLUDED A SLIGHT CHANCE OF THUNDER IN THE FORECAST...BUT DO NOT EXPECT ANYTHING WIDESPREAD.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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* LONG DURATION COASTAL STORM WILL BRING RAIN THU * LINGERING SHOWERS POSSIBLE ON FRI * MAINLY DRY AND SEASONABLE WEATHER THIS WEEKEND OVERALL MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE LONG TERM. THERE ARE SOME DISCREPANCIES WITH A COUPLE OF FEATURES AS WELL AS SOME DIFFERENCES IN THE MESOSCALE DETAILS BUT THOSE ARE TO BE EXPECTED. THE MAIN WEATHER STORY WILL BE THE LONG DURATION COASTAL STORM EARLY IN THE PERIOD. AFTER THE COASTAL STORM MOVES AWAY FROM SOUTHERN NEW ENGLAND...THE WEATHER DRIES OUT AND BECOMES MORE SEASONABLE. UPPER LEVEL FLOW FLATTENS OUT LATE IN THE WEEKEND INTO EARLY NEXT WEEK WITH MORE ZONAL FLOW EXPECTED. THURSDAY...EXPECT WIDESPREAD RAIN TO CONTINUE AS A COASTAL LOW PRESSURE SYSTEM SLOWLY MOVES UP THE COAST TO MAINE. AN ADDITIONAL HALF TO INCH AND A HALF OF RAIN IS EXPECTED ACROSS THE MAJORITY OF THE AREA THURSDAY. AS THE LOW PRESSURE MOVES INTO THE GULF OF MAINE AND THEN THE MARITIMES...EXPECT HIGHEST AMOUNTS TO OCCUR ALONG THE IMMEDIATE EAST COAST OF MASSACHUSETTS...PARTICULARLY ON CAPE COD AND CAPE ANN WHERE RAIN WILL LAST THE LONGEST. WITH THE HIGHER PWATS AND LOW LEVEL JET STRONGEST ACROSS NORTHERN NEW ENGLAND...EXPECT THE HEAVIEST RAIN AND THE STRONGEST WINDS TO OCCUR THERE. THE ONE EXCEPTION COULD BE ALONG CAPE ANN WHERE THERE MAY BE SOME STRONG NORTHEASTERLY WINDS OFF THE OCEAN. COOL...ONSHORE FLOW AND OVERCAST SKIES WILL KEEP TEMPERATURES IN THE 50S TO LOW 60S DURING THE DAY AND IN THE 50S OVERNIGHT. FRIDAY...COULD SEE SOME LINGERING SHOWERS AS LOW PRESSURE MOVES UP INTO THE MARITIMES BUT WINDS SHIFT TO THE NORTHWEST BRINGING SOMEWHAT DRIER AIR INTO THE REGION. OVERALL EXPECT DRIER WEATHER AND A GRADUAL IMPROVEMENT AS THE DAY GOES ON. SATURDAY THROUGH MONDAY...ANOTHER UPPER LEVEL TROUGH MOVES OVER THE NORTHEAST BUT HERE IS WHERE WE SEE SOME DISCREPANCIES BETWEEN THE ECMWF AND THE GFS. THE ECMWF HAS A STRONG NEGATIVELY TILTED UPPER TROUGH OVER SOUTHERN NEW ENGLAND WHILE THE GFS HAS A MORE NEUTRAL UPPER TROUGH. IN BOTH MODELS LOW PRESSURE IN QUEBEC WILL PULL A COLD FRONT THROUGH AT LEAST A PORTION OF SOUTHERN NEW ENGLAND. THE GFS IS MORE AGGRESSIVE WITH THE FRONT AND HAS MORE MOISTURE ASSOCIATED WITH IT...RESULTING IN A GREATER CHANCE OF SHOWERS WITH THE FRONT. EXPECTING DRY SEASONABLE WEATHER SUNDAY AND MONDAY AS HIGH PRESSURE BUILDS ALONG THE EASTERN SEABOARD AND THEN SLIDES SOUTH OF SOUTHERN NEW ENGLAND. TUESDAY...LOW PRESSURE MOVING THROUGH THE GREAT LAKES AND INTO QUEBEC MAY BRING A COLD FRONT THROUGH SOUTHERN NEW ENGLAND LATE TUESDAY AND TUESDAY NIGHT. ANOTHER CHANCE OF SOME SHOWERS POSSIBLE WITH THIS FRONT BUT PLENTY OF UNCERTAINTY.
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&& .AVIATION /20Z TUESDAY THROUGH SUNDAY/...
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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 WEDNESDAY NIGHT/... TONIGHT...MODERATE CONFIDENCE. CONDITIONS GRADUALLY WILL LOWER TO MVFR FROM EAST TO WEST TONIGHT. WE THEN EXPECT FURTHER LOWERING TO MAINLY IFR BY DAYBREAK WEDNESDAY...BUT TIMING REMAINS UNCERTAIN. AREAS OF LIGHT RAIN AND DRIZZLE WILL EXPAND OVERNIGHT IN AREAS NORTH OF THE MA TURNPIKE...BUT A FEW SHOWERS ARE POSSIBLE JUST ABOUT ANYWHERE. PATCHY FOG MAY ALSO DEVELOP. WEDNESDAY AND WEDNESDAY NIGHT...MODERATE TO HIGH CONFIDENCE. LOW END MVFR TO IFR CONDITIONS EXPECTED. AREAS OF LIGHT RAIN...SHOWERS AND DRIZZLE WILL BE COMMON FOR THE FIRST PART OF WEDNESDAY ACROSS THE NORTHERN ZONES AND GRADUALLY EXPAND SOUTH. WIDESPREAD MODERATE TO HEAVY RAIN EXPECTED LATER WED INTO WED NIGHT. NORTHEAST WIND GUSTS OF 20 TO 25 KNOTS DEVELOP ON THE COAST WED NIGHT...BUT NEAR 30 KNOT GUSTS ARE POSSIBLE ACROSS NORTHEAST MA COAST. KBOS...MODERATE CONFIDENCE IN TAF BUT LOW CONFIDENCE IN TRENDS. KBDL...MODERATE CONFIDENCE IN TAF BUT LOW CONFIDENCE IN TRENDS. OUTLOOK...THURSDAY THROUGH SUNDAY... THURSDAY...HIGH CONFIDENCE. MVFR/IFR CONDITIONS LIKELY IN RAIN AND POSSIBLY SOME ISOLATED THUNDER. NE WINDS GUSTING UP TO 20 TO 25 KTS ACROSS S NH AND NE MA. FRIDAY...HIGH CONFIDENCE. SLOW IMPROVEMENT TO VFR EXPECTED IN CLEARING SKIES. SATURDAY AND SUNDAY...MODERATE CONFIDENCE. VFR. LOW PROBABILITY OF SCATTERED SHOWERS SATURDAY.
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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 WEDNESDAY NIGHT/... ***HIGH SEAS AND GALE FORCE NORTHEAST WIND GUSTS POSSIBLE WEDNESDAY NIGHT ACROSS OUR NORTHEAST ATLANTIC WATERS*** TONIGHT...MODERATE TO HIGH CONFIDENCE. EAST TO SOUTHEAST WINDS WILL SHIFT TO THE NORTHEAST LATER TONIGHT AS LOW PRESSURE LIFTS NORTHEAST OFF THE MID ATLANTIC COAST. WINDS ACROSS MOST OF THE WATERS WILL REMAIN BELOW SCA THRESHOLDS...EXCEPT FOR THE NORTHEAST WATERS WHERE GUSTS TO 25 KNOTS POSSIBLE TOWARD DAYBREAK. WEDNESDAY AND WEDNESDAY NIGHT...MODERATE TO HIGH CONFIDENCE. LOW PRESSURE WILL LIFT NORTHEAST AS AN INTENSIFYING EASTERLY LOW LEVEL JET DEVELOPS. AT THE SURFACE...SHOULD SEE NORTHEAST SCA WIND GUSTS OVERSPREAD MOST OF OUR WATERS DURING THE DAY WEDNESDAY. THE CORE OF THE STRONGEST JET WILL BE NORTH OUR WATERS WEDNESDAY NIGHT. STILL THE POTENTIAL FOR A PERIOD OF NORTHEAST 35 KNOT WIND GUSTS ACROSS OUT FAR NORTHEAST WATERS. THEREFORE...HAVE ISSUED A GALE WATCH FOR THIS LOCATION. ALSO...SEAS MAY BUILD TO AROUND 15 FEET IN OUR EXTREME NORTHEAST ATLANTIC WATERS. OUTLOOK...THURSDAY THROUGH SUNDAY... THURSDAY...HIGH CONFIDENCE. 10 TO 15 FOOT SEAS ON THE NORTHEASTERN WATERS WILL SLOWLY DIMINISH THROUGH THE MORNING AND INTO THE EARLY AFTERNOON...5 TO 10 FOOT SEAS ELSEWHERE WILL DO THE SAME. NORTHEASTERLY WINDS 20 TO 25 KTS WILL SLOWLY DIMINISH THROUGH THE DAY AS WELL. SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED FOR MOST WATERS FOR AT LEAST A PORTION OF THE DAY. FRIDAY AND SATURDAY...HIGH CONFIDENCE. MAINLY QUIET BOATING WEATHER. WINDS AND SEAS INCREASE SLOWLY LATE SATURDAY NIGHT. SUNDAY...MODERATE CONFIDENCE. SEAS AND WINDS INCREASE GRADUALLY ON THE SOUTHERN WATERS...BRIEFLY REACHING SMALL CRAFT CRITERIA.
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&& .TIDES/COASTAL FLOODING...
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FORTUNATELY ASTRONOMICAL HIGH TIDES ARE RATHER LOW OVER THE NEXT 48 HOURS AND THE CORE OF THE STRONGEST WINDS WILL BE TO OUR NORTH. THEREFORE...THE RISK OF EVEN MINOR COASTAL FLOODING IS QUITE LOW. HOWEVER...THERE IS THE POTENTIAL FOR SOME MINOR BEACH EROSION ALONG THE SALISBURY AND PLUM ISLAND COASTS DURING THE HIGH TIDES WEDNESDAY NIGHT AND THURSDAY. NO COASTAL FLOOD HEADLINES ARE ANTICIPATED THOUGH FOR THIS UPCOMING EVENT.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON WEDNESDAY TO 8 AM EDT THURSDAY FOR ANZ231>235-237. GALE WATCH FROM WEDNESDAY EVENING THROUGH LATE WEDNESDAY NIGHT FOR ANZ250. SMALL CRAFT ADVISORY UNTIL 8 PM EDT WEDNESDAY FOR ANZ250. SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR ANZ251- 254>256.
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&& $$ SYNOPSIS...FRANK/RLG NEAR TERM...FRANK SHORT TERM...FRANK LONG TERM...RLG AVIATION...FRANK/RLG MARINE...FRANK/RLG TIDES/COASTAL FLOODING...FRANK

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