Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 191808 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 208 PM EDT SUN OCT 19 2014 .SYNOPSIS... GUSTY NORTHWEST WINDS WILL BRING COLDER AIR TO SOUTHERN NEW ENGLAND TONIGHT. HIGH PRESSURE MOVES OVER THE REGION ON MONDAY. A DISTURBANCE DROPPING THROUGH THE GREAT LAKES WILL GENERATE A LONG DURATION COASTAL STORM TUESDAY THROUGH FRIDAY WITH PERIODS OF HEAVY RAIN. && .NEAR TERM /THROUGH TONIGHT/... REMAINDER OF THIS AFTERNOON... UPPER TROUGH OVERHEAD WILL MOVE OFF TO THE EAST BY THIS EVENING. TEMPERATURES AT 500 MB HAVE BEEN RUNNING AROUND -22C WHICH IS COLD ENOUGH TO DESTABILIZE THE AIRMASS...ESPECIALLY COMBINED WITH ANY SOLAR HEATING OF THE SURFACE. EXPECT PLENTY OF DIURNAL CLOUDS AND POSSIBLY A FEW LIGHT SHOWERS. OBSERVED WINDS ALOFT BELOW 850 MB ARE 25 KNOTS. MIXING WILL TAP THESE WINDS AND SUPPORT NORTHWEST GUSTS OF 25-30 MPH. TONIGHT... HIGH PRESSURE BUILDS OVER THE REGION WITH CLEARING SKIES AND DIMINISHING WIND. THE LIGHT WIND AND CLEAR SKIES WILL ALLOW FOR RADIATIONAL COOLING ESPECIALLY AWAY FROM THE COAST. OBSERVED AFTERNOON DEW POINTS ARE IN THE 30S WITH 20S UPSTREAM IN ONTARIO AND WESTERN NY. WITH THIS VALUES ADVECTING OVER NEW ENGLAND...EXPECT PLENTY OF ROOM FOR TEMPERATURES TO FALL BELOW FREEZING IN INTERIOR SOUTHERN NEW ENGLAND WHILE COASTAL AREAS FALL INTO THE 30S. EXPECTED VALUES ARE SIMILAR TO THE PREVIOUS TWO FORECASTS. WE WILL CONTINUE THE FREEZE WARNING FOR MUCH OF SOUTHERN NEW ENGLAND WITH FROST ADVISORY ALONG NARRAGANSETT BAY AND THE MASS EAST COAST. MODELS START TO BRING HIGH CLOUDS IN LATE AT NIGHT. WITH SUFFICIENT THICKNESS...THESE CLOUDS COULD SLOW THE COOLING AND KEEP SOME OF THE INTERIOR ABOVE FREEZING. BUT WE EXPECT THE INITIAL CLOUDS TO BE THIN ENOUGH TO HAVE LITTLE EFFECT. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... MONDAY... HIGH PRESSURE CRESTS OVER THE REGION. WINDS WILL SHIFT AROUND TO SOUTHWEST DURING THE AFTERNOON. EXPECT SOME INCREASE IN MID AND HIGH CLOUDS BUT OVERALL A FAIR WEATHER DAY. MIXING SHOULD REACH TO 925 MB...POSSIBLY A LITTLE HIGHER. TEMPS EQUIVILANT TO -1C/-3C AT 850 MB...SUPPORTS MAX TEMPS IN THE 50S. MONDAY NIGHT... RIDGE MOVES OFF TO THE EAST WHILE A TROUGH DIGS OVER THE GREAT LAKES. THIS TURNS OUR UPPER FLOW INTO A SOUTHWEST FLOW. WEAK HINTS IN THE MODEL DATA OF A 70-KNOT JET OVERHEAD OF THE NORTHEAST USA. THE RIGHT ENTRANCE REGION OF THIS POSSIBLE JET IS LOCATED SOUTH OF THE REGION SUGGESTING THE BEGINNING OF CYCLOGENESIS ALONG THE MID ATLANTIC COAST. MEANWHILE THE SOUTHWEST FLOW WILL BE TRANSPORTING MOISTURE UP THE COAST IN CLOUDS. EXPECT INCREASING AND THICKENING CLOUDS THROUGH THE NIGHT WITH POTENTIAL FOR INCREASING LIFT. THE MOISTURE AND LIFT WOULD LEAD TO A CHANCE OF RAIN LATE AT NIGHT. TEMPS WILL INITIALLY COOL IN THE EVENING WITH ENOUGH TIME TO DROP 10-15 DEGREES FROM DAYTIME HIGHS. WE USED A RANGE OF MIN TEMPS IN THE UPPER 30S AND 40S. && .LONG TERM /TUESDAY THROUGH SUNDAY/... HIGHLIGHTS... * TRANQUIL WEATHER MON WITH COOL TEMPS/SUNSHINE AND LIGHT WINDS * A LONG DURATION COASTAL STORM WILL IMPACT NEW ENGLAND FROM TUE THROUGH FRI. OCCASIONAL HEAVY RAIN APPEARS TO BE THE PRIMARY THREAT AS THE AXIS OF STRONGEST WINDS MAY BE FOCUSED ACROSS NORTHERN NEW ENG OVERVIEW... DETERMINISTIC AND ENSEMBLE GUIDANCE REMAIN IN GOOD AGREEMENT ON THE EVOLUTION OF THE MID/LATE WEEK CLOSED LOW...DEVELOPING OVER THE MID ATLC REGION LATE TUE/TUE NIGHT AND SLOWING TRACKING NE OFF THE MID ATL COAST TO SE NEW ENG BY FRI. THERE REMAINS SOME DIFFERENCES IN THE TRACK OF THE SFC LOW BUT THE OVERALL TREND IS FURTHER N WHICH KEEPS THE AXIS OF THE EASTERLY LOW LEVEL JET TO THE N ACROSS MAINE. AS A RESULT...THE THREAT OF STRONG WIND AND COASTAL FLOODING HAS LESSENED SOMEWHAT. OCCASIONAL HEAVY RAIN IS THE PRIMARY THREAT...BUT TIMING AND LOCATION OF HEAVIEST RAINFALL REMAINS UNCERTAIN. IT MUST BE EMPHASIZED THAT THERE IS STILL INHERENT UNCERTAINTY IN THE STORM TRACK AT THIS TIME RANGE AND A SOUTHWARD SHIFT IS STILL POSSIBLE WHICH WOULD INCREASE THE OVERALL IMPACT TO SNE. DAILIES... TUESDAY... PRIMARY LOW OVER THE GT LAKES WILL GRADUALLY FILL WITH SECONDARY LOW DEVELOPING ALONG THE MID ATLC COAST AS NORTHERN STREAM TROF AMPLIFIES AND EVOLVES INTO A CLOSED MID LEVEL CIRCULATION. LIGHT RAIN AHEAD OF THE PRIMARY LOW WILL EXPAND ACROSS SNE DURING TUE AS WARM ADVECTION INCREASES IN RESPONSE TO DEVELOPING SECONDARY LOW OFF THE MID ATLC COAST. WITH SOUTHERLY FLOW TO START THE DAY ON TUE IT WILL BE A MILD DAY WITH TEMPS REACHING WELL INTO 60S IN THE COASTAL PLAIN...COOLER INTERIOR. TUESDAY NIGHT THROUGH FRIDAY... EXACT STORM DETAILS REMAIN UNCERTAIN AND DUE TO VARIABLE NATURE OF INDIVIDUAL DETERMINISTIC GUIDANCE SOURCES...WE FOLLOWED A SUPERBLEND OF ALL MODEL SOLUTIONS WITH PREV FORECAST AS A BASIS FOR THE CURRENT FORECAST. PERIODS OF RAIN OF VARYING INTENSITY EXPECTED BUT TIMING OF HEAVIEST RAINFALL REMAINS UNCERTAIN. A BLEND OF MODEL QPF YIELDS STORM TOTAL RAINFALL OVER THE 3-4 DAY PERIOD OF 1-2 INCHES SOUTH OF THE MASS PIKE INCREASING TO 2-4 INCHES TO THE NORTH. TREND WILL BE FOR RAIN TO TRANSITION TO MORE SCT SHOWERY PRECIP BY FRI AS LOW PRES MOVES E OF CAPE COD. IT APPEARS STRONG WIND THREAT HAS DIMINISHED AS MAIN CORE OF LOW LEVEL JET IS FORECAST TO THE NORTH. IN FACT 00Z GEFS INDICATES STRONGEST EASTERLY WIND ANOMALIES /3-4SD/ FOCUSED ACROSS NORTHERN NEW ENG. THE COASTAL FLOODING THREAT HAS ALSO DIMINISHED SOMEWHAT AS STRONGEST EASTERLY WINDS AND HIGHEST SEAS ARE EXPECTED TO SET UP TO THE NORTH ACROSS MAINE...AND ASTRONOMICAL TIDES ARE SOMEWHAT LOW DURING THIS PERIOD. HOWEVER AT THIS TIME RANGE IT IS STILL POSSIBLE FOR THIS RISK AREA TO SHIFT SOUTHWARD. THE RISK OF COASTAL EROSION APPEARS GREATER THAN INUNDATION GIVEN WAVE ACTION OVER SEVERAL HIGH TIDE CYCLES FOR CONSECUTIVE DAYS. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH MONDAY/...HIGH CONFIDENCE. THROUGH 00Z/8 PM... VFR WITH CLOUD BASES AROUND 4500 FEET. NORTHWEST WINDS GUSTING 25-30 KNOTS...DIMINISHING IN THE EVENING. TONIGHT AND MONDAY...VFR. CLEARING SKIES WITH LIGHT WINDS. MONDAY NIGHT...VFR MOST OF THE NIGHT. PATCHES OF MVFR CIGS IN LIGHT RAIN POSSIBLE LATE AT NIGHT. KBOS...HIGH CONFIDENCE IN TAF. KBDL...HIGH CONFIDENCE IN TAF. OUTLOOK...TUESDAY THROUGH THURSDAY... TUESDAY THROUGH THU...HIGH CONFIDENCE ON OVERALL THEME...WITH CONDITIONS LOWERING TO MVFR/IFR IN DEVELOPING RAIN BUT LOW CONFIDENCE ON EXACT TIMING OF DETAILS. STRONGEST WINDS EXPECTED TO THE NORTH OF THE REGION. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TODAY THROUGH MONDAY/...HIGH CONFIDENCE. TODAY...NORTHWEST WINDS OVER THE WATERS WILL BRING GUSTS OF 25 TO 30 KNOTS TO THE SURFACE. SOUTHEAST SWELL WILL CONTINUE ALTHOUGH DIMINISHED A LITTLE FROM YESTERDAY. SMALL CRAFT ADVISORY IS IN PLACE FOR ALL WATERS. TONIGHT...HIGH PRESSURE APPROACHES FROM THE WEST. NORTHWEST WINDS GUSTS WILL DROP FROM 30 KTS TO 15 KTS OVERNIGHT AS THE HIGH GETS CLOSER. IN FACT SOUTHEAST SWELL FROM GONZALO WILL DIMINISH OVERNIGHT. HOWEVER SEAS WILL STAY UP...AROUND 8 FEET ACROSS THE OUTER WATERS. SMALL CRAFTS WILL END ON THE NEARSHORE WATERS BUT LINGER ON THE OUTER WATERS. TOMORROW...HIGH PRESSURE WILL SLIDE SOUTH OF THE WATERS. WESTERLY WINDS GUSTS UP TO 20 KTS ARE STILL POSSIBLE. SEAS WILL BEGIN TO DIMINISH ESPECIALLY IN THE AFTERNOON. SCA HAS BEEN EXTENDED FOR THE OUTER WATERS. OUTLOOK...MONDAY NIGHT THROUGH THURSDAY... MON NIGHT AND TUE...HIGH CONFIDENCE. SOUTHERLY WINDS MON NIGHT INTO TUE GRADUALLY BECOMING EAST BY LATE TUE...BUT SPEEDS AND SEAS BELOW SCA. TUE NIGHT THROUGH THU...MODERATE CONFIDENCE. EXPECT STRONGEST E/NE GALE FORCE WINDS TO REMAIN NORTH OF THE WATERS. STRONGEST WIND GUSTS TO 30 KT WITH LOW PROB OF GALES AND HIGHEST SEAS UP TO 10+ FT EXPECTED ACROSS NE MA COASTAL WATERS LATE TUE NIGHT INTO WED WITH LESS WIND AND SEAS OVER SOUTH COASTAL WATERS. WINDS AND SEAS EXPECTED TO SUBSIDE WED NIGHT INTO THU. PERIODS OF HEAVY RAIN WILL REDUCE VSBY. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR CTZ002>004. MA...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR MAZ007-015-016-019-022-023. FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR MAZ005-006-009>014-017-018-020-021. NH...NONE. RI...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR RIZ002-004-005-007. FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR RIZ001-003-006. MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT MONDAY FOR ANZ230>237-251. SMALL CRAFT ADVISORY UNTIL 2 PM EDT MONDAY FOR ANZ250-254-255. SMALL CRAFT ADVISORY UNTIL 8 AM EDT MONDAY FOR ANZ256. && $$ SYNOPSIS...WTB/KJC NEAR TERM...WTB/KJC SHORT TERM...WTB LONG TERM...KJC AVIATION...WTB/KJC MARINE...KJC/DUNTEN

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