Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 011054 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 654 AM EDT WED OCT 1 2014 .SYNOPSIS... COOL...DAMP CONDITIONS REMAIN IN PLACE INTO THURSDAY MORNING...WITH MORE WIDESPREAD RAINFALL EXPECTED TODAY. DRY WEATHER RETURNS LATER THURSDAY INTO FRIDAY AS HIGH PRESSURE BUILDS BACK ACROSS THE REGION. A COLD FRONT WILL MOVE ACROSS NEW ENGLAND LATER SATURDAY AFTERNOON AND EARLY SATURDAY NIGHT...FOLLOWED BY COOLER AND DRIER CONDITIONS FOR SUNDAY AND MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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7 AM UPDATE... UPPER LEVEL LOW PRESSURE MOVING TOWARD NEW ENGLAND WITH CORE MOVING OVERHEAD THIS AFTERNOON/EVENING. BANDS OF SHOWERS ROTATING AROUND THE CENTER OF THIS LOW ARE MOVING SE TO NW ACROSS SOUTHERN NEW ENGLAND. AS THE LOW SHIFTS FARTHER EAST TODAY THIS MOVEMENT SHOULD BECOME EAST TO WEST. WE HAVE EXPANDED THE AREA OF LIKELY POPS AND MADE A FEW ADJUSTMENTS TO TEMPS. OTHERWISE...CONTINUE THE WET FORECAST FOR SOUTHERN NEW ENGLAND. PREVIOUS DISCUSSION... AN UPPER LEVEL LOW OVER PENNSYLVANIA MOVES EASTWARD OVER SOUTHERN NEW ENGLAND TODAY. COMBINED WITH THE LOW PRESSURE SYSTEM WELL SOUTHEAST OF NANTUCKET...AN INVERTED TROUGH SHOULD DEVELOP JUST WEST OF SOUTHERN NEW ENGLAND. THIS WILL CREATE A DEEP LAYER OF LIFT THAT WILL ALLOW RAIN TO BECOME WIDESPREAD ACROSS THE REGION TODAY. PERSISTENT NORTHEASTERLY FLOW BRINGS IN PLENTY OF COOL MOIST AIR IN OFF THE OCEAN AND PWATS ARE 125 TO 175 PERCENT OF NORMAL FOR EARLY OCTOBER. THIS WILL ALLOW FOR A MUCH NEEDED STEADY RAINFALL ACROSS MOST OF THE AREA WITH ROUGHLY HALF AN INCH TO AN INCH OF RAIN EXPECTED IN MOST LOCATIONS. HIGHER AMOUNTS ARE POSSIBLE WHERE BANDS OF HEAVIER RAIN SET UP. WHILE WE CAN/T DETERMINE EXACTLY WHERE THESE BANDS WILL DEVELOP...THE BEST CHANCE FOR HIGHER RAINFALL AMOUNTS LOOKS TO BE ACROSS SOUTHEAST MASS WHERE RAIN WILL LAST THE LONGEST BEFORE THE LOW PULLS AWAY TO THE EAST. USED LOCALLY PRODUCED BIAS CORRECTED MOS FOR TEMPERATURES TODAY WHICH WILL REMAIN COOL AROUND 60 DEGREES FOR MOST LOCATIONS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... TONIGHT...STEADY RAIN WILL COME TO AN END SLOWLY FROM WEST TO EAST AS LOW PRESSURE PULLS FARTHER AWAY FROM THE REGION. RAIN IS LIKELY TO CONTINUE ACROSS EASTERN MA AND RI THROUGH MUCH OF THE NIGHT. CONTINUED EASTERLY FLOW WILL KEEP LOW LEVEL MOISTURE IN PLACE ALLOWING FOR LOW CLOUDS...DRIZZLE...AND FOG TO REMAIN ACROSS THE REGION. LOW TEMPERATURES SHOULD BE IN THE 50S. THURSDAY...WILL START TO SEE SOME DRYING...PARTICULARLY IN THE WEST AS HIGH PRESSURE STARTS TO BUILD IN. CAPE AND ISLANDS WILL BE LAST TO LOSE THE MOISTURE BUT CLOUDS SHOULD BEGIN BREAKING UP BY THE END OF THE DAY. BELOW NORMAL TEMPERATURES REMAIN WITH HIGHS AROUND 60...EXCEPT FOR THE CONNECTICUT VALLEY WHERE THEY MAY CLIMB INTO THE MID 60S. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... 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 MOVES OFF THROUGH THE MARITIMES THURSDAY AND FRIDAY. THE DAILIES... THURSDAY NIGHT-FRIDAY... HIGH PRESSURE BUILDS SOUTH OVER NEW ENGLAND. CROSS SECTIONS OF RH SHOW DRYING IN MOST LAYERS THURSDAY NIGHT BUT THEN AN INCREASING LAYER OF MOISTURE BELOW 800 MB BY FRIDAY AFTERNOON. THIS SUGGESTS CLEARING...BUT FOLLOWED BY INCREASING LOW CLOUDS AGAIN DURING FRIDAY. RH CHARTS FROM THE GFS AND ECMWF SHOW CLOUD MOISTURE BEING PUSHED WEST ACROSS THE GULF OF MAINE FROM THE DEPARTING COASTAL LOW...AND INTO SOUTHEAST NH/EASTERN MASS FRIDAY AFTERNOON. BY FRIDAY NIGHT THE SAME MODELS SHOW LIGHT PCPN OVER THIS AREA...SUGGESTING SPRINKLES OR DRIZZLE. WE WILL HAVE A DRY FORECAST DURING THURSDAY NIGHT AND FRIDAY...BUT WITH INCREASING CLOUDS FROM THE EAST FRIDAY NIGHT ALONG WITH FOG/DRIZZLE AND IN EAST COASTAL AREAS A CHANCE FOR MEASUREABLE PCPN. LIGHT EAST WINDS WILL LIMIT MIXING...AND TEMPS IN THIS SHALLOW LAYER WILL SUPPORT MAX TEMPS IN THE 60S...COOLEST NEAR THE EAST MASS COAST AND WARMEST IN THE CT VALLEY. SATURDAY... THE UPPER TROUGH MOVING ACROSS THE GREAT LAKES DEEPENS AS IT MOVES IT. THE TROUGH USES A 110 KNOT JET TO PUSH A COLD FRONT EAST TOWARD NEW ENGLAND. TEMPERATURE PROFILES SHOW A STRONG THERMAL GRADIANT ACROSS THE FRONT. THE DEEPENING OF THE TROUGH ALSO TURNS THE UPPER FLOW OVER NEW ENGLAND MORE FROM THE SOUTH-SOUTHWEST DRAWING MOISTURE NORTH...PRECIPITABLE WATER VALUES ARE FORECAST TO REACH 1.5 TO 1.6 INCHES. STABILITY PARAMETERS ARE LESS THAN MARGINAL...MID LEVEL LAPSE RATES ARE 5C/KM OR LESS AND TOTALS ARE LESS THAN 44. FORECAST WILL CONTINUE TO FEATURE LIKELY POPS BUT SLIGHTLY SLOWER THAN PREVIOUSLY. THIS SLOWER TIMING ALIGNS WITH SIMILAR TRENDS IN THE GFS AND ECMWF WITH WINDSHIFT IN THE CT VALLEY 2 PM TO 8 PM AND IN THE COASTAL PLAIN 8 PM TO MIDNIGHT. SUNDAY-MONDAY-TUESDAY...SHORTWAVE MOVES NORTH OF OUR AREA SUNDAY...BUT THE MAIN TROUGH AXIS REMAINS OVER THE GREAT LAKES. CONTOUR HEIGHTS AT 500 MB ARE BELOW NORMAL OVER THE WEEKEND BUT THEN MODERATE TO NEAR NORMAL DURING THE FIRST PART OF NEXT WEEK. SUNDAY AND MONDAY LOOK DRY WITH SEASONABLY COOL TEMPS. THE TROUGH AXIS EJECTS NORTHEAST BY TUESDAY AND MAY SUPPORT A CHANCE OF SHOWERS AT THAT TIME. && .AVIATION /12Z 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 THURSDAY...MODERATE CONFIDENCE. TODAY...IFR CIGS/VSBYS IN THE EAST AND MVFR IN THE CT VALLEY AND PARTS OF SOUTHERN NH. THIS MAY SLOWLY IMPROVE TO A MORE WIDESPREAD MVFR AT BEST...BUT SHOULD THEN LOWER TO IFR AGAIN WITH SUNSET. TONIGHT...IFR/LIFR CONDITIONS THE FIRST PART OF THE NIGHT. THIS MAY SHOW SOME SLOW IMPROVEMENT FROM WEST TO EAST LATER IN THE NIGHT WITH THE MOST IMPROVEMENT TOWARDS DAYBREAK THURSDAY. THURSDAY...AREAS OF IFR /MAINLY IN THE EAST/ WILL IMPROVE TO VFR. KBOS...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN TIMING. KBDL...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN TIMING. OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY...MODERATE CONFIDENCE. THURSDAY NIGHT-FRIDAY...VFR. AREAS OF IFR CIGS/VSBYS IN PATCHY FOG EARLY FRIDAY MORNING. AREAS OF IFR CIGS MOVE WEST OFF THE OCEAN INTO EAST COASTAL MASSACHUSETTS INCLUDING THE CAPE AND ISLANDS LATE FRIDAY AND MORE LIKELY FRIDAY NIGHT. SATURDAY...IFR CIGS FROM THE WORCESTER HILLS EAST DURING THE MORNING. VFR FARTHER WEST TO START THE DAY BUT LOWERING TO MVFR AND SCATTERED IFR AS A COLD FRONT APPROACHES LATE IN THE DAY AND BRINGS SHOWERS. WIND SHIFTS FROM SOUTH DURING THE DAY TO WEST BEHIND THE COLD FRONT LATE IN THE DAY AND EARLY AT NIGHT. SUNDAY...VFR WITH GUSTY WEST WINDS. HIGH PRESSURE BUILDS OVER THE REGION WITH FAIR WEATHER.
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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...TODAY THROUGH THURSDAY...HIGH CONFIDENCE PERSISTENT NORTHEASTERLY WINDS INCREASE THROUGH THE DAY GUSTING TO AROUND 25 KTS BY ABOUT MIDDAY TODAY. SEAS CONTINUE TO INCREASE...PARTICULARLY ON THE NORTHEASTERN WATERS AND INTO BOSTON HARBOR AND CAPE COD BAY. ADDED ALL THE WATERS EXCEPT FOR NARRAGANSETT BAY TO THE SMALL CRAFT ADVISORY FOR BOTH WINDS AND SEAS AND ALL SMALL CRAFT ADVISORIES HAVE BEEN EXTENDED THROUGH THURSDAY. OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY...MODERATE CONFIDENCE. THURSDAY NIGHT-FRIDAY...NORTHEAST WINDS GUSTING 20 TO 25 KNOTS WILL MAINTAIN 5 TO 9 FOOT SEAS ON THE OUTER WATERS AND EXPOSED EASTERN WATERS SUCH AS MASSACHUSETTS BAY. SMALL CRAFT ADVISORY WILL BE NEEDED. FOG AND LOW CLOUDS MOVING IN FROM THE GULF OF MAINE MAY CREATE POOR VSBYS FRIDAY NIGHT. SATURDAY... LINGERING POOR VSBYS SATURDAY MORNING IN FOG AND LOW CLOUDS. THESE CONDITIONS WILL IMPROVE LATER IN THE DAY AS A COLD FRONT APPROACHES WITH SHOWERS. SOUTH WINDS WILL GUST 25 TO 30 KNOTS DURING THE DAY AND EVENING...SHIFTING TO WEST AFTER THE COLD FRONT MOVES THROUGH SATURDAY NIGHT. SEAS WILL CONTINUE AT 5 TO 8 FEET ON THE OUTER WATERS AND OTHER EXPOSED WATERS. SMALL CRAFT ADVISORY IS LIKELY. SUNDAY...WINDS AND SEAS DIMINISH A LITTLE BUT STILL ROUGH. SEAS WILL LINGER AT 5 TO 7 FEET ON THE OUTER WATERS. WEST TO SOUTHWEST WINDS WILL GUST TO 25 KNOTS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 PM EDT THURSDAY FOR ANZ232. SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 5 PM EDT THURSDAY FOR ANZ233-234. SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 8 PM EDT THURSDAY FOR ANZ230. SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 8 PM EDT THURSDAY FOR ANZ231. SMALL CRAFT ADVISORY UNTIL 8 PM EDT THURSDAY FOR ANZ235-237- 250-251-254>256. && $$ SYNOPSIS...WTB/RLG NEAR TERM...WTB/RLG SHORT TERM...RLG LONG TERM...WTB AVIATION...WTB/RLG MARINE...WTB/RLG

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