Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 250632 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 130 AM EST WED FEB 25 2015 .SYNOPSIS... FAST MOVING LOW PRESSURE WILL BRING A PLOWABLE SNOWFALL TO RHODE ISLAND AND EASTERN MASSACHUSETTS LATE TONIGHT INTO VERY EARLY WEDNESDAY MORNING. A REINFORCING SURGE OF COLD BUT DRY WEATHER RETURNS WEDNESDAY NIGHT THROUGH FRI NIGHT. TEMPS SLOWLY MODERATE SAT AS HIGH PRES BUILDS INTO THE REGION...THEN A FRONTAL SYSTEM MAY BRING SOME SNOW LATE SUN INTO MON. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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***MODERATE TO HEAVY SNOW AFFECTING THE BOSTON TO PROVIDENCE CORRIDOR WITH SHARP CUTOFF TO THE SNOW SHIELD AND DRY WEATHER JUST TO THE NORTHWEST*** 130 AM UPDATE... MODERATE TO BRIEFLY HEAVY SNOW FALLING ACROSS RHODE ISLAND AND SOUTHEAST MA IS WORKING INTO NORTHEAST MA...INCLUDING THE BOSTON METRO AREA. HOWEVER...THERE IS A VERY SHARP CUTOFF TO THE SNOW SHIELD WITH DRY WEATHER PREVAILING FROM WILLIMANTIC...TO WORCESTER TO JUST NORTHWEST OF LAWRENCE. WHERE IT IS SNOWING...EXCELLENT SNOWGROWTH WILL RESULT IN GOOD RATIOS WITH A GENERAL 2 TO 4 INCHES OF ACCUM EXPECTED. THE HEAVIEST SNOW WILL FALL FROM SOUTHERN RI INTO SOUTHEAST MA AND PROBABLY EASTERN ESSEX COUNTY. WOULD NOT BE SURPRISED TO SEE SOME LOCALIZED 5 INCH AMOUNTS...BUT ITS FAIRLY PROGRESSIVE SO IT WILL BE HARD TO GET MUCH MORE THAN THAT. THE INVERTED TROUGH FEATURE THAT IS CAUSING THE SNOW WILL LIFT NORTHEAST OVER THE NEXT FEW HOURS...SO THIS WILL BE A SHORT DURATION EVENT. EXPECT SNOW TO END IN MOST AREAS BY 5 OR 6 AM...PERHAPS LASTING AN HOUR OR SO LONGER ACROSS THE CAPE.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... WEDNESDAY... ANY SNOW AT SUNRISE WILL BE CONFINED TO EXTREME EASTERN MA AND WILL EXIT OFFSHORE BY 7 AM...PERHAPS 8 AM FOR OUTER CAPE COD AND CAPE ANN. BEHIND THE DEPARTING SHORT WAVE NW WINDS PICK UP TO 20-30 MPH BY MIDDAY AND CONTINUE INTO THE AFTERNOON. SO DESPITE TEMPS CLIMBING INTO THE U20S AND L30S...A GUSTY NW WIND WILL PROVIDE A BIT OF A WIND CHILL. ALTHOUGH NOT NEARLY AS COLD AS WE HAVE EXPERIENCED RECENTLY. SUNSHINE DEVELOPS BY MID TO LATE MORNING. WED NIGHT... A TRAILING SHORT WAVE TROUGH BRINGS A REINFORCING SURGE OF COLD AIR TO THE REGION...ALTHOUGH NOT NEARLY AS COLD AS RECENT DAYS. MIN TEMPS BY SUNRISE THU WILL BE IN THE SINGLE DIGITS INLAND...AROUND 10 BOSTON AND PROVIDENCE TO TEENS ALONG THE SOUTH COAST...CAPE COD AND ISLANDS. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... HIGHLIGHTS... * OCEAN EFFECT SNOW POSSIBLE ON THE CAPE THURSDAY * HIGH PRESSURE EXPECTED THROUGH THE WEEKEND * COLD FRONT BRINGS WINTRY PRECIP SUNDAY INTO MONDAY * ANOTHER STORM POSSIBLE TUESDAY MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE WEEKEND. THEN THEY DIVERGE A BIT...PARTICULARLY WITH A LOW PRESSURE SYSTEM EXPECTED TO IMPACT SOUTHERN NEW ENGLAND ON TUESDAY. HIGH PRESSURE BUILDS INTO SOUTHERN NEW ENGLAND FROM THE MIDWEST THROUGH SATURDAY. THEN THE HIGH PRESSURE MOVES OFFSHORE...ALLOWING LOW PRESSURE TO MOVE THROUGH QUEBEC AND BRING A COLD FRONT THROUGH SOUTHERN NEW ENGLAND LATE SUNDAY. THIS WILL BRING A PERIOD OF WINTRY WEATHER TO THE REGION. THEN HIGH PRESSURE BUILDS BACK IN BRIEFLY LATE MONDAY. THE MODELS DIFFER ON THE STRENGTH...DEVELOPMENT...AND TRACK OF A LOW PRESSURE SYSTEM EXPECTED TO AFFECT SOUTHERN NEW ENGLAND TUESDAY. THE ECMWF HAS THE MORE TYPICAL PATTERN OF A LOW MOVING THROUGH THE GREAT LAKES AND A SECONDARY LOW DEVELOPING OFF THE COAST OF NEW JERSEY AND TRACKING ACROSS THE 40/70 BENCHMARK. THE GFS KEEPS THE LOW PRESSURE AS AN INSIDE RUNNER...TRACKING UP THROUGH PENNSYLVANIA AND NEW YORK STATE. THESE TWO DIFFERENT SOLUTIONS WILL AFFECT EVERYTHING FROM TEMPERATURES TO PRECIPITATION TYPES. BUT THIS IS 7-8 DAYS OUT SO WE EXPECT THINGS TO CHANGE QUITE A BIT BETWEEN NOW AND THEN. THURSDAY AND FRIDAY...HIGH PRESSURE BUILDS INTO THE REGION. LOW PRESSURE SYSTEMS TRACKING WELL SOUTH OF SOUTHERN NEW ENGLAND MAY BRING SOME OCEAN EFFECT SNOW TO THE CAPE AND ISLANDS. SATURDAY...HIGH PRESSURE CENTERS OVER SOUTHERN NEW ENGLAND BRINGING DRY WEATHER AND MODERATING TEMPERATURES. SUNDAY AND MONDAY...HIGH PRESSURE MOVES OFFSHORE. LOW PRESSURE OVER HUDSON BAY WILL TRACK EASTWARD THROUGH QUEBEC BRINGING A COLD FRONT THROUGH SOUTHERN NEW ENGLAND. THIS WILL RESULT IN A PERIOD OF WINTRY PRECIP THROUGHOUT THE AREA. RIGHT NOW...THERMAL PROFILES INDICATE THAT THIS IS LIKELY TO BE IN THE FORM OF SNOW SHOWERS. A CHANGE IN THERMAL PROFILE COULD RESULT IN A WINTRY MIX OF PRECIP DURING THIS TIME. THE OTHER CONCERN DURING THIS TIME IS THE POTENTIAL FOR GUSTY WINDS. THE ECMWF INDICATES A RATHER STRONG LOW LEVEL JET DEVELOPING WHILE THE GFS KEEPS THE LOW LEVEL WINDS RATHER CALM. AT ANY RATE...EXPECT ADVISORY LEVEL WINDS WOULD BE THE MOST WE WOULD NEED TO BE CONCERNED ABOUT. WILL KEEP AN EYE ON THIS THROUGHOUT THE WEEK. TUESDAY...A COUPLE OF DIFFERENT SOLUTIONS FORECAST IN THE MODELS. THE ECMWF HAS A LOW PRESSURE SYSTEM MOVING THROUGH THE GREAT LAKES WITH A SECONDARY LOW FORMING OFF THE NEW JERSEY COAST AND PASSING JUST INSIDE THE 40/70 BENCHMARK. THE GFS HAS THE LOW TRACKING THROUGH PENNSYLVANIA AND NEW YORK BRINGING A WARM FRONT THROUGH SOUTHERN NEW ENGLAND. THESE TWO SOLUTIONS HAVE VASTLY DIFFERENT THERMAL PROFILES AND THIS WOULD AFFECT PRECIPITATION TYPES. WE HAVE AWHILE TO GO ON THIS STORM SO WILL ALLOW LATER RUNS TO BETTER RESOLVE THIS PARTICULAR STORM. && .AVIATION /06Z WEDNESDAY 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 /TODAY THROUGH WEDNESDAY/... THROUGH 12Z THIS MORNING...MODERATE TO HIGH CONFIDENCE. IFR TO LIFR CONDITIONS IN MODERATE TO BRIEFLY HEAVY SNOW WERE AFFECTING THE BOSTON TO PROVIDENCE CORRIDOR. SHARP CUTOFF IN SNOW WITH NOTHING FROM WILLIMANTIC...TO WORCESTER TO NORTHWEST OF LAWRENCE ALTHOUGH THERE WERE MVFR CIGS. SNOW SHOULD EXIT MOST AREAS BETWEEN 9Z AND 11Z...ALTHOUGH COULD LAST AN HOUR OR SO LONGER ON THE CAPE/ISLANDS. AFTER 12Z TODAY AND INTO TONIGHT...HIGH CONFIDENCE. LINGERING MVFR CIGS ON CAPE/ISALNDS SHOULD IMPROVE BY 14Z. OTHERWISE...VFR CONDITIONS WITH WESTERLY WIND GUSTS OF 20 TO 25 KNOTS DEVELOPING BY AFTERNOON. WINDS THEN WILL DIMINISH EARLY THIS EVENING. KBOS TAF...MODERATE TO HIGH CONFIDENCE. IFR CONDITIONS IN SNOW EARLY THIS MORNING WITH 2 TO 4 INCHES EXPECTED. SNOW EXITS THE TERMINAL BETWEEN 9 AND 11Z WITH VFR CONDITIONS EXPECTED AFTER 12Z. KBDL TAF...HIGH CONFIDENCE. MVFR CIGS IMROVE TO VFR BY 9 OR 10Z. OUTLOOK...THURSDAY THROUGH SUNDAY... THURSDAY THROUGH FRIDAY...HIGH CONFIDENCE. VFR. LOW PROBABILITY OF MVFR/IFR CONDITIONS ON THE OUTER CAPE AND NANTUCKET IN OCEAN EFFECT SNOW SHOWERS. SATURDAY...HIGH CONFIDENCE. VFR. SUNDAY...MODERATE CONFIDENCE. MVFR/IFR CONDITIONS LIKELY IN SNOW SHOWERS.
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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 /TONIGHT THROUGH WEDNESDAY NIGHT/... TONIGHT...MODEST SOUTH WINDS BECOME NW TOWARD SUNRISE. SNOW LIMITS VSBY TO LESS THAN A MILE ROUGHLY 11 PM TO 5 AM. WED...NW WINDS 20-30 KT BEGINNING MID MORNING. ANY SNOW MOVES WELL OFFSHORE BY 8-9AM. WED NIGHT...NW WINDS DIMINISH AND BECOME NORTHERLY.OUTLOOK...THURSDAY THROUGH SUNDAY... OUTLOOK...THURSDAY THROUGH SUNDAY... MODERATE CONFIDENCE. SMALL CRAFT SEAS LINGER ON THE OUTER WATERS THURSDAY AND FRIDAY. HIGH PRESSURE STARTS BUILDING OVER THE WATERS THROUGH THE WEEKEND...KEEPING WINDS AND SEAS BELOW SMALL CRAFT CRITERIA. PERIODS OF OCEAN EFFECT SNOW THURSDAY AND FRIDAY NEAR THE CAPE AND ISLANDS MAY REDUCE VISIBILITIES AND MORE WIDESPREAD SNOW/RAIN WILL BE POSSIBLE LATE SUNDAY AS A COLD FRONT APPROACHES THE WATERS. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR MAZ006- 007-013>024. RI...WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR RIZ002- 004>008. MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 1 AM EST THURSDAY FOR ANZ230>237-250-251-254>256.
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&& $$ SYNOPSIS...NOCERA/RLG NEAR TERM...FRANK SHORT TERM...NOCERA LONG TERM...RLG AVIATION...FRANK/RLG MARINE...NOCERA/RLG

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