Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 301047 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 647 AM EDT TUE SEP 30 2014 .SYNOPSIS... COOL TEMPERATURES EXPECTED THROUGH MOST OF THIS WEEK AS PERSISTENT NORTHEAST WINDS REMAIN IN PLACE. ONE OR TWO WEAK WAVES OF LOW PRESSURE MAY BRING A CHANCE OF SHOWERS FOR THE REGION. AN APPROACHING FRONT WITH ASSOCIATED LOW PRESSURE LOOKS TO AFFECT SOUTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 7 AM UPDATE...NO SIGNIFICANT CHANGES MADE AT THIS TIME. COOL NORTHEAST FLOW CONTINUES. ADJUSTMENTS BASED ON OBSERVED CONDITIONS BUT GENERAL FLOW OF THE FORECAST REMAINS THE SAME. PREVIOUS DISCUSSION... NORTHEASTERLY FLOW CONTINUES ALLOWING FOR AREAS OF LOW CLOUDS... FOG...AND DRIZZLE THROUGH THE MORNING HOURS. AS THE BOUNDARY LAYER STARTS TO MIX A BIT THOUGH...DRIZZLE SHOULD COME TO AN END. A FEW STEADIER SHOWERS ARE POSSIBLE ACROSS RHODE ISLAND AND SOUTHEASTERN MASSACHUSETTS LATER TODAY AS A WEAK SHORTWAVE MOVES ACROSS SOUTHERN NEW ENGLAND. EXPECT TEMPERATURES TO BE ABOUT 5 DEGREES BELOW NORMAL. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... TONIGHT...EXPECTING ANOTHER NIGHT MUCH LIKE THE LAST WITH LOW PRESSURE WELL SOUTHEAST OF NANTUCKET. AREAS OF LOW CLOUDS... FOG...AND DRIZZLE ARE LIKELY ONCE AGAIN WITH VERY MOIST AIR IN THE LOW LEVELS. MORE WIDESPREAD SHOWERS ARE POSSIBLE ACROSS RHODE ISLAND AND SOUTHEASTERN MASSACHUSETTS AS THE MID LEVEL LOW PUSHES INTO SOUTHERN NEW ENGLAND. OVERNIGHT LOWS WILL BE FAIRLY MILD THANKS TO THE LOW LEVEL HUMIDITY WITH MOST LOCATIONS REMAINING IN THE 50S. WEDNESDAY...BEST SHOT OF SHOWERS AS MID LEVEL LOW MOVES OVER SOUTHERN NEW ENGLAND. THESE WILL LIKELY BE LIMITED MAINLY TO SOUTHEASTERN MASSACHUSETTS AND RHODE ISLAND WHERE THE BEST LIFT EXISTS. OTHERWISE...MORE OF THE SAME LOW CLOUDS...DRIZZLE...AND FOG. OVERCAST SKIES AND WET WEATHER WILL KEEP TEMPERATURES IN THE LOW TO MID 60S. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... BIG PICTURE... ALASKA SHORTWAVE DIGS OVER THE WESTERN USA/CANADA AND KICKS THE ESTABLISHED UPPER TROUGH EAST TO THE GREAT LAKES. THIS BRINGS A BROAD CYCLONIC FLOW OVER THE EASTERN USA WITH BELOW NORMAL HEIGHTS WHILE AN UPPER RIDGE BUILDS OVER THE WESTERN USA. EMBEDDED IN THIS FLOW...A CLOSED LOW OVER NEW ENGLAND WEDNESDAY NIGHT MOVES OFF THROUGH THE MARITIMES THURSDAY AND FRIDAY. THE DAILIES... WEDNESDAY NIGHT-THURSDAY... UPPER LOW OVER SOUTHERN NEW ENGLAND MOVES OFF TO THE EAST. LINGERING INSTABILITY UNDER THE COLD CORE SHOULD SUPPORT LINGERING SHOWERS WEDNESDAY NIGHT TAPERING OFF THURSDAY MORNING. CROSS SECTIONS SHOW PLENTY OF MOISTURE BELOW 600 MB THROUGH THURSDAY MIDDAY FOLLOWED BY A DRYING TREND IN THE AFTERNOON. TEMPS AT THE TOP OF THE MIXED LAYER ARE EQUIV TO 850 MB TEMPS OF 2-5C...SUPPORTING MAX TEMPS IN THE LOW TO MID 60S. MOIST GROUND AND COOLING TEMPS THURSDAY NIGHT WILL ALLOW PATCHY FOG TO FORM ESPECIALLY OVER THE INTERIOR. FRIDAY... HIGH PRESSURE BUILDS SOUTH OVER NEW ENGLAND. CROSS SECTIONS OF RH SHOW INCREASING CIRRUS-LEVEL MOISTURE BUT DRY THROUGH MOST OF THE COLUMN...INCREASING LOW LEVEL MOISTURE TOWARD EVENING. OVERALL...EXPECT A FAIR WEATHER DAY WITH LIGHT EAST TO SOUTHEAST WIND. TEMPS AT THE TOP OF THE MIXED LAYER WOULD SUPPORT MAX TEMPS IN THE MID AND UPPER 60S. THE EAST FLOW MAY KEEP COOLER TEMPS NEAR THE EAST MASS COAST. FRIDAY NIGHT-SATURDAY... SHORTWAVE DRIVING AROUND THE DEEPENING EASTERN TROUGH PUSHES A COLD FRONT ACROSS THE MID ATLANTIC STATES FRIDAY NIGHT AND ACROSS NEW ENGLAND ON SATURDAY. THE SHORTWAVE AND THE SUPPORTING JET ENERGY SHOW SIGNS OF LIFTING THROUGH EASTERN NY AND VERMONT...BUT WITH POTENTIAL TO DIRECTLY AFFECT SOUTHERN NEW ENGLAND. ANOTHER CONCERN WOULD BE THE DRY PATTERN WE HAVE BEEN IN FOR SEVERAL WEEKS...THESE PATTERNS TEND TO MAINTAIN THEMSELVES EVEN WHEN FORECAST DATA SAYS OTHERWISE. AND A DAY 5 FORECAST IS RATHER FAR OUT TO SHOW GREAT CERTAINTY. WE WILL MAINTAINING CONTINUITY WITH POPS FROM THE PREVIOUS FORECAST AND WITH ADJOINING OFFICES...BUT OUR ACTUAL CONFIDENCE IS 15-20 PERCENT LOWER. SUNDAY-MONDAY... HIGH PRESSURE BUILDS UP FROM THE SOUTH AND SHOULD PROVIDE DRY WEATHER MUCH OF THIS PERIOD. THE UPPER TROUGH CENTERED TO OUR WEST WILL BRING LOWER HEIGHTS OVER THE GREAT LAKES WHICH WILL MEAN COOLER TEMPS. TEMPERATURES HERE IN NEW ENGLAND SHOULD BE A LITTLE COOLER THAN NORMAL BUT EXPECT THE COLDEST TEMPS TO REMAIN WEST OF NEW ENGLAND WITH THE AXIS OF THE TROUGH. A SHORTWAVE MOVES THROUGH THE TROUGH ON MONDAY AND SOUTHERLY WINDS AHEAD OF THE SHORTWAVE WILL BRING HIGHER MOISTURE AIR OUR WAY...GENERATING SOME CLOUDS AND POSSIBLY SHOWERS. THESE CLOUDS/SHOWERS SHOULD HOLD UNTIL THE SHORTWAVE GETS CLOSER...PROBABLY MONDAY NIGHT. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... 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 IN TIMING. TODAY...IFR CONDITIONS SLOWLY IMPROVE FROM WEST TO EAST. SHOWERS ARE POSSIBLE PARTICULARLY ACROSS EASTERN MA/RI WHERE MVFR/IFR CONDITIONS ARE LIKELY TO CONTINUE THROUGHOUT THE DAY. TONIGHT...MORE OF THE SAME WITH IFR CONDITIONS LIKELY IN LOW CLOUDS...FOG...AND DRIZZLE. WEDNESDAY...CONDITIONS IMPROVE ONCE AGAIN AT LEAST TEMPORARILY IN THE WEST. SHOWERS ARE POSSIBLE PARTICULARLY ACROSS EASTERN MA/RI. KBOS...HIGH CONFIDENCE ON TRENDS...LOWER CONFIDENCE ON TIMING. KBDL...HIGH CONFIDENCE ON TRENDS...LOWER CONFIDENCE ON TIMING. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY... WEDNESDAY NIGHT-THURSDAY...CIGS/VSBYS AT MVFR/IFR IN LINGERING LOW CLOUDS AND FOG WEDNESDAY NIGHT AND THURSDAY MORNING. CONDITIONS SHOULD IMPROVE TO VFR THURSDAY AFTERNOON. PATCHY IFR CIGS/VSBYS IN FOG AFTER MIDNIGHT THURSDAY NIGHT. FRIDAY...VFR. SATURDAY...CONDITIONS DIMINISHING TO MVFR IN SHOWERS AS A COLD FRONT MOVES THROUGH. SOUTH WINDS LEAD THE COLD FRONT...WITH WINDS SHIFTING TO WEST AFTER THE FRONT MOVES THROUGH. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...HIGH CONFIDENCE THROUGH WED. PERSISTENT NORTHEASTERLY FLOW WILL RESULT IN BUILDING SEAS THROUGH THE PERIOD. INCREASED WAVE WATCH GUIDANCE BY 20 PERCENT TO ACCOUNT FOR A GENERAL LOW BIAS IN THIS TYPE OF SCENARIO. SCA CONTINUES FOR THE NORTHEASTERN WATERS THROUGH THIS MORNING. ALSO ISSUED SCA FOR SEAS ACROSS THE SOUTHERN AND SOUTHEASTERN OUTER WATERS FOR TONIGHT AND WEDNESDAY. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...MODERATE CONFIDENCE. NORTHEAST WINDS WEDNESDAY NIGHT THROUGH FRIDAY WITH GUSTS NEAR 20 KNOTS. WINDS SHIFT TO SOUTH SATURDAY AHEAD OF THE COLD FRONT...THEN SHIFT WEST AFTER THE COLD FRONT MOVES THROUGH. WIND GUSTS 20 TO 25 KNOTS POSSIBLE ON SATURDAY. SEAS OF 5 TO 8 FEET LINGER ON THE EXPOSED WATERS THROUGH MUCH OF THE PERIOD. EXPECT SMALL CRAFT ADVISORY ON AT LEAST THE EXPOSED WATERS FOR MUCH OF THE PERIOD. MAY EXPERIENCE A STORM SURGE OF 1 TO 1.5 FEET DURING MIDWEEK BUT THE ASTRONOMICAL TIDES ARE NOT ALL THAT HIGH. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR ANZ250- 251. SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 8 PM EDT WEDNESDAY FOR ANZ254>256. && $$ SYNOPSIS...WTB/RLG NEAR TERM...WTB/RLG SHORT TERM...RLG LONG TERM...WTB AVIATION...WTB/RLG MARINE...WTB/RLG

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