Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 220828 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 428 AM EDT WED OCT 22 2014 .SYNOPSIS...
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LOW CLOUDS...FOG AND SPOTTY LIGHT RAIN/DRIZZLE THIS MORNING WILL BE REPLACED BY A SOAKING WIND SWEPT RAIN LATER THIS AFTERNOON...TONIGHT INTO EARLY THURSDAY IN ASSOCIATION WITH AN INTENSIFYING COASTAL STORM. 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 PM THIS EVENING/...
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*** A WINDSWEPT SOAKING RAIN WITH POTENTIAL FLOODING BEGINS LATER TODAY AND CONTINUES TONIGHT INTO THURSDAY MORNING *** RELATIVELY QUIET THIS MORNING WITH ONLY PATCHY FOG AND SPOTTY LIGHT RAIN/DRIZZLE IMPACTING THE REGION. HOWEVER WATER VAPOR IMAGERY INDICATING IMPRESSIVE TROUGH AMPLIFICATION WITH A NEW WARM CONVEYOR BELT DEVELOPING OFF THE DELAWARE COAST AND THEN WRAPPING CYCLONICALLY BACK INTO NJ AND EASTERN PA...FORMING A TROWAL. THIS AREA OF STRONG ASCENT WILL OVERSPREAD SOUTHERN NEW ENGLAND FROM SOUTH OF NORTH BETWEEN 21Z AND 00Z. MEANWHILE THIS TROUGH AMPLIFICATION WILL RESULT IN A STRONG RESPONSE AT THE SURFACE WITH LOW PRES OFF THE DELAWARE COAST INTENSIFYING TODAY. AS A RESULT ONSHORE PGRAD WILL DEVELOP WITH A STRONG LOW LEVEL NORTHEAST JET EVOLVING OVER THE EASTERN MA WATERS INTO MUCH SOUTHERN NEW ENGLAND. THIS WILL RESULT IN A WINDSWEPT RAIN EVENT LATER TODAY ACROSS MUCH OF THE REGION ESPECIALLY EASTERN MA. THE ONSET OF THE HEAVY RAIN /21Z-00Z/ WILL LIKELY IMPACT THE 2ND HALF OF THE EVENING COMMUTE. AS FOR TEMPS...NOT AS WARM AS YESTERDAY AS N-NE FLOW IS WELL ENTRENCHED ACROSS THE REGION.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
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TONIGHT... STRONG SHORT WAVE TROUGH FORMING THE TROWAL MOVES ACROSS THE AREA YIELDING STRONG FORCING FOR ASCENT. IMPRESSIVE LOW LEVEL JET OF 50 TO 60 KT FROM THE GULF OF MAINE INTO EASTERN NEW ENGLAND PROVIDES STRONG LOW LEVEL WARM AIR ADVECTION. THIS LOW LEVEL WARM ANOMALY WILL COMBINE WITH COLD AIR ALOFT ASSOCIATED WITH THE UPPER LEVEL LOW TO YIELD A DEEP LAYER OF MOIST ADIABATIC LAPSE RATES. THIS WILL LIKELY BE SUFFICIENT FOR SOME CONVECTIVE ELEMENTS TO DEVELOP WITHIN THE TROWAL AND INCREASE THE RISK FOR FLOODING. GOOD MODEL AGREEMENT FOR A WIDESPREAD 1.5 TO 2.5 INCHES OF RAINFALL ACROSS THE REGION. HIGH RES MODELS SUCH AS THE W-ARW HAS UP TO 4" OF RAINFALL ACROSS EASTERN MA NORTHWEST-WARD INTO SOUTHERN NH. THESE HIGHER AMOUNTS ARE POSSIBLE GIVEN THE STRONG JET DYNAMICS AND INSTABILITY ALOFT. IN ADDITION WILL LIKELY SEE SOME RAINFALL ENHANCEMENT ACROSS THE UPSLOPE REGIONS OF THE WORCESTER HILLS AND MONADNOCKS. CONVERSELY MAY SEE SOME SHADOWING ON THE WEST SIDE OF THIS HIGHER TERRAIN. GIVEN GOOD MODEL AGREEMENT ON A WIDESPREAD RAINFALL OF 1.5 TO 2.5 INCHES ALONG WITH RISK OF HIGHER AMOUNTS IN CONVECTION AND FFG ONLY AROUND 3 INCHES WE ISSUED A FLOOD WATCH FOR EASTERN MA AND SOUTHEAST NH. IT WILL BE WINDY TONIGHT WITH NE WINDS 15 TO 25 MPH WITH GUSTS UP TO 35 MPH...HIGHEST ACROSS NORTHEAST MA. THURSDAY... BANDS OF HEAVY RAIN WITHIN THE TROWAL WILL REMAIN OVER THE AREA DURING THE MORNING. HOWEVER DRY SLOT SHOULD OVERSPREAD THE REGION IN THE AFTERNOON WITH RAIN TRANSITIONING TO SCATTERED SHOWERS IN THE AFTERNOON.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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* LINGERING SHOWERS POSSIBLE ON FRI * MAINLY DRY AND SEASONABLE WEATHER THIS WEEKEND OVERVIEW AND MODEL PREFERENCES... 22.00Z MODEL GUIDANCE SUITE IS STARTING TO SHOW BETTER AGREEMENT WITH NOT ONLY THE EXIT OF THE UPPER LVL CUTOFF THROUGH THE END OF THE WEEK...BUT ALSO WITH THE SHORTWAVE THAT WILL ASSIST WITH THIS SHIFT FOR THE WEEKEND. THE PREVIOUS DIFFERENCE IN TILT OF THIS SECONDARY SHORTWAVE SEEMS TO HAVE BEEN RESOLVED SOMEWHAT. WITH OPERATIONAL RUNS NOW DISPLAYING A BIT OF A NEGATIVE TILT. THEREFORE...GIVEN THIS BETTER AGREEMENT A GENERAL BLEND OF OPERATIONAL GFS/ECMWF SHOULD PROVIDE A GOOD BASELINE FOR THIS LONG TERM UPDATE. DEFINING THE LONG TERM...WILL INITIALLY BE THE EXITING CUTOFF AND OCCLUSION. HOWEVER...AFTER BRIEF MESO-RIDGE YET ANOTHER ROBUST WAVE AND ATTENDANT COLD FRONT MOVE THROUGH OVER THE WEEKEND. THEREFORE...EXPECT AN UNSETTLED START TO THE LONG TERM...FOLLOWED BY GRADUAL DRYING BY EARLY NEXT WEEK. DETAILS... THU NIGHT INTO FRI... THE FIRST OF A SERIES OF SHORTWAVES WILL FINALLY FORCE THE STALLED UPPER LVL CUTOFF AND SFC LOW PRES TO BEGIN A SHIFT INTO THE MARITIMES DURING THIS PERIOD. THU NIGHT...CONTINUED -SHRA ACTIVITY IS EXPECTED AS THE REMNANT WARM CONVEYOR REMAINS JUST OFFSHORE. HOWEVER...DRIER AIR WILL BEGIN TO MOVE INTO THE REGION AS WINDS TAKE ON A MORE WESTERLY COMPONENT...SUCH THAT LESS WIDESPREAD SHOWERS ARE EXPECTED ON FRI...WITH EVEN A FEW MORE BREAKS OF SUN POSSIBLE. THEREFORE..EXPECT GRADUALLY DECREASING POPS THROUGH THE PERIOD. MINS STILL ON THE MILD SIDE AS DWPTS REMAIN ELEVATED THU NIGHT...BUT HIGHS ON FRI MAY BE A BIT WARMER THANKS TO DIMINISHING ONSHORE FLOW AND CLOUD COVER. MAINLY UPPER 50S AND LOW 60S. FRI NIGHT INTO SAT... POTENTIAL FOR A MAINLY DRY PERIOD HERE IS WEAK RIDGING BUILDS ACROSS THE AREA BETWEEN THE FIRST SHORTWAVE...AND A SLIGHTLY STRONGER WAVE DIVING OUT OF CENTRAL CANADA. MAINLY NW FLOW...WITH TEMPS CLOSER TO SEASONAL NORMALS...IF NOT A BIT WARMER THANKS TO H85 AVERAGING ABOUT +5C. MAY SEE SOME HIGHS IN THE MID 60S. SAT NIGHT THRU SUN... SECONDARY ROBUST BUT FAST MOVING SHORTWAVE WILL PUSH LOW PRES THROUGH QUEBEC...DRAGGING A COLD FRONT ACROSS THE REGION LATE SAT NIGHT INTO SUN. MODEL SOUNDINGS SHOW ENOUGH MOISTURE /EVEN UNDER NW FLOW/ FOR SLIGHT TO CHANCE POPS WITH THIS FROPA. NOT EXPECTING WIDESPREAD OR PARTICULARLY HEAVY SHOWERS GIVEN THE DRY NW FLOW. IN FACT...SRN PORTIONS OF THE FORECAST AREA MAY REMAIN MOSTLY DRY THANKS TO ENHANCED DOWNSLOPE COMPONENT TOWARD THE S COAST. SLIGHTLY COOLER AIRMASS MOVES IN WITH THIS COLD FROPA...SO WILL LEAN TEMPS TOWARD A COOLER THAN NORMAL HIGHS AND NEAR NORMAL LOWS. MON AND TUE... GUIDANCE IN FAIRLY GOOD AGREEMENT THAT HIGH PRES FINALLY IS ABLE TO NOSE ACROSS THE AREA FROM THE S. THIS ALLOWS GRADUAL WARMING THROUGH THE COLUMN AND DRY CONDITIONS. THE WARMING MAY YIELD H85 TEMPS NEAR +14C BY TUE EVENING. THEREFORE...WILL LIKELY SEE ENOUGH WARMING TO YIELD TEMPERATURES ABOVE NORMAL...POSSIBLY THE UPPER 60S TO NEAR 70 BY TUE. WED... GUIDANCE DIFFERS HERE ON THE TIMING OF A COLD FRONTAL PASSAGE. YIELDING SOLUTIONS OF A PASSAGE DURING THE DAY ON WED...TO DURING THE DAY ON THU. THEREFORE...MAY AT LEAST HAVE SOME SLIGHT CHANCE POPS FOR A SHOWER WITH THIS FROPA.
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&& .AVIATION /08Z 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 /THROUGH THU/... FORECAST CONFIDENCE IS HIGH ON OVERALL TRENDS BUT LOWER ON EXACT DETAILS INCLUDING TIMING. TODAY...IFR CONDITIONS IN LOW CLOUDS/FOG AND SPOTTY DRIZZLE THIS MORNING SHOULD LIFT TO MVFR AS A STEADY RAIN MOVES ONSHORE AFTER 18Z. ALSO NE WINDS WILL INCREASE TODAY WITH STRONGEST WINDS OVER NORTHEAST MA INTO SOUTHEAST NH WHERE GUSTS UP TO 35 KT ARE POSSIBLE ESPECIALLY DURING PERIODS OF HEAVY RAIN. LLWS LIKELY AS LOW LEVEL NORTHEAST JET DEVELOPS OVER SOUTHERN NH AND NORTHEAST MA. CHANCE OF ISOLATED THUNDER OVER RI AND SOUTHEAST MA AFTER 21Z. TONIGHT...IFR/LIFR IN PERIODS OF HEAVY RAIN WITH EMBEDDED THUNDER. LLWS ACROSS EASTERN AND CENTRAL MA AND SOUTHERN NH. GUSTY NE WINDS ESPECIALLY IN THE HEAVIER RAIN BANDS. THU...IFR/LIFR IN PERIODS OF HEAVY RAIN DURING THE MORNING THEN TRENDING TOWARD MVFR LATER IN THE AFTERNOON AS HEAVY RAIN TAPERS OF SCATTERED SHOWERS. LLWS POSSIBLE IN THE MORNING OVER SOUTHERN NH AND CENTRAL-EASTERN MA. KBOS...MODERATE CONFIDENCE IN TAF BUT LOW CONFIDENCE ON EXACT DETAILS. LLWS LIKELY AFTER 18Z AS STRONG NE LOW LEVEL JET DEVELOPS AND PERSIST INTO THU AM. KBDL...MODERATE CONFIDENCE IN TAF BUT LOW CONFIDENCE ON EXACT DETAILS. LOW PROB OF LLWS TONIGHT INTO THU AM AS STRONG LOW LEVEL NE JET DEVELOPS. OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY... THURSDAY NIGHT...MODERATE CONFIDENCE. MAINLY MVFR/IFR CONDITIONS CONTINUE AS WIDESPREAD SHOWERS/FOG ARE EXPECTED. FRIDAY INTO SATURDAY...HIGH CONFIDENCE. GRADUAL IMPROVEMENT. MAINLY VFR AS WINDS SHIFT TO THE NORTHWEST. SAT NIGHT INTO SUN...MODERATE CONFIDENCE. ALTHOUGH CONDITIONS ARE LIKELY TO BE PREDOMINANTLY VFR. A PERIOD OF MVFR OR LOWER CONDITIONS ARE POSSIBLE IN ISOLATED SHOWERS. CONDITIONS IMPROVE LATE DAY SUN.
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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 LIKELY TODAY AND TONIGHT ACROSS EASTERN MASSACHUSETTS *** TODAY...NE GALES DEVELOP AROUND 15Z ACROSS THE CAPE ANN WATERS AND CONTINUING THE REMINDER OF THE DAY. ELSEWHERE NE WINDS SHOULD REMAIN IN THE 20-25KT RANGE. HEAVY RAIN AND TSTMS ENTER THE SOUTHERN WATERS THIS EVENING AND THE REMAINDER OF THE WATERS OVERNIGHT. TONIGHT...NE GALES LIKELY ACROSS CAPE ANN WATERS. SCA ELSEWHERE. HEAVY RAIN WITH EMBEDDED TSTM ALL WATERS. THU...HEAVY RAIN AND SCT TSTMS EXIT THE WATERS BY MIDDAY. NE WINDS OVER THE CAPE ANN WATERS SHOULD EASE DURING THE MORNING. OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY... THURSDAY NIGHT INTO FRIDAY NIGHT...HIGH CONFIDENCE. SMALL CRAFT ADVISORY CONDITIONS CONTINUE ACROSS ALL WATERS BUT GRADUALLY DIMINISH FRI INTO FRI NIGHT. NW WINDS WITH GUSTS AROUND 25 KT POSSIBLE THROUGH THE DAY FRI...WITH SEAS RANGING 5-9FT /HIGHEST AROUND CAPE ANN/ AND GRADUALLY DIMINISHING BY FRI NIGHT. SATURDAY...MODERATE CONFIDENCE. MAINLY QUIET BOATING WEATHER. ALTHOUGH WIND GUSTS AROUND 20 KT POSSIBLE ESPECIALLY OVER SRN WATERS OUT OF THE NW. SUNDAY...MODERATE CONFIDENCE. WINDS AND SEAS ONCE AGAIN INCREASE WITH SEAS REACHING 5-7 FT ON S AND SE WATERS WITH WIND GUSTS AROUND 25 KT OUT OF THE NW. SMALL CRAFT ADVISORIES ARE LIKELY TO BE NEEDED AGAIN.
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&& .TIDES/COASTAL FLOODING...
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FORTUNATELY ASTRONOMICAL HIGH TIDES ARE RATHER LOW THIS WEEK. THIS WILL LOWER THE RISK OF COASTAL FLOODING. HOWEVER NORTHEAST GALES OVER THE CAPE ANN WATERS ALONG WITH THE DURATION OF ONSHORE WINDS WILL YIELD A LOW RISK OF MINOR COASTAL FLOODING. ALTHOUGH GIVEN THE LOWER WATER LEVELS EROSION IS MORE LIKELY GIVEN THE PERSISTENT ONSHORE WINDS AND WAVES BATTERING THE COASTLINE. AGAIN GREATEST RISK FOR EROSION IS ACROSS SALISBURY AND PLUM ISLAND.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...FLOOD WATCH FROM THIS AFTERNOON THROUGH THURSDAY MORNING FOR MAZ005>007-013>019-026. NH...FLOOD WATCH FROM THIS AFTERNOON THROUGH THURSDAY MORNING FOR NHZ012-015. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 8 AM EDT THURSDAY FOR ANZ231>235-237. SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THURSDAY FOR ANZ230-236. GALE WARNING FROM 11 AM THIS MORNING TO 6 PM EDT THURSDAY FOR ANZ250-251. SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR ANZ254>256.
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&& $$ SYNOPSIS...NOCERA/DOODY NEAR TERM...NOCERA SHORT TERM...NOCERA LONG TERM...DOODY AVIATION...NOCERA/DOODY MARINE...NOCERA/DOODY TIDES/COASTAL FLOODING...

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