Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 301856 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 156 PM EST FRI JAN 30 2015 .SYNOPSIS...
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LOW PRESSURE DEVELOPING SOUTH OF NANTUCKET THIS AFTERNOON WILL INTENSIFY OVER THE GULF OF MAINE TONIGHT BRINGING PERIODS OF SNOW. BLUSTERY AND VERY COLD CONDITIONS ARE EXPECTED THIS WEEKEND. LOW PRESSURE WILL PASS SOUTH OF NEW ENGLAND SUNDAY NIGHT AND MONDAY... POSSIBLY BRINGING ANOTHER ACCUMULATING SNOWFALL. COLD CONDITIONS WILL CONTINUE THROUGH MOST OF NEXT WEEK. YET ANOTHER LOW MAY DEVELOP AROUND NEXT WED OR THU WITH A THREAT FOR SNOW...THOUGH LOW CONFIDENCE.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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145 PM UPDATE... *** WINTER STORM WARNING FOR ESSEX WILL BE DOWNGRADED TO A WINTER WEATHER ADVISORY *** SNOW SHIELD ASSOCIATED WITH INITIAL SHORT WAVE IS EXITING SOUTHERN NEW ENGLAND AS DRY SLOT IS NOW OVERSPREADING THE REGION FROM SOUTHWEST TO NORTHEAST. THUS STEADY SNOW HAS ENDED AND WILL BE REPLACED BY SCATTERED FLURRIES. AS MID LEVEL TROUGH TAKES ON A NEGATIVE TILT SECONDARY LOW/CYCLOGENESIS IS TAKING PLACE THIS AFTERNOON JUST SOUTHEAST OF NANTUCKET AND CAPE COD PER GOOD PRES FALLS OVER THIS AREA. SURFACE WINDS HAVE RESPONDED WITH MOST LOCATIONS NOW NORTHWEST. THUS BOUNDARY LAYER WILL BE COOLING THE REMAINDER OF THE DAY. AS FOR SNOW ACCUMULATIONS TONIGHT...LATEST 12Z GUID INCLUDING THE EC SUGGEST COMMA-HEAD SNOWS WILL BE TOO FAR EAST TO IMPACT MOST OF THE AREA. GREATEST RISK FOR ACCUMULATING SNOWS TONIGHT INTO SAT AM WILL BE OVER CAPE ANN AND CAPE COD. SNOW ACCUMULATIONS OF 2 TO 4 INCHES ARE POSSIBLE...HIGHEST AMOUNTS ACROSS THE OUTER CAPE... EAST OF HYANNIS. THUS WILL DOWNGRADE WINTER STORM WARNING FOR ESSEX TO AN ADVISORY. WILL CONTINUE ADVISORIES TO ESSEX AND CAPE COD. ELSEWHERE ACROSS EASTERN MA INCLUDING BOSTON SHOULD SEE SNOW ACCUMS TONIGHT INTO SAT AM OF A COATING TO 2 INCHES. FARTHER WEST INTO RI/CT/WESTERN-CENTRAL MA LITTLE IF ANY SNOWFALL.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
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TONIGHT INTO SATURDAY... NEG TILT TROF EVOLVES INTO A CLOSED MID LEVEL OVER SOUTHERN NEW ENGLAND THIS EVENING THEN IT JUMPS TO THE GULF OF MAINE LATER TONIGHT. THE SFC LOW DEEPENS RAPIDLY TONIGHT IN THE GULF OF MAINE BUT LIKELY REMAINS A BIT TOO FAR OFFSHORE TO ROTATE HEAVY SNOW BACK ACROSS SNE AS THE HEAVIER PRECIP WILL REMAIN TO THE NORTH OVER MAINE. HOWEVER...A ROBUST COMMA HEAD WILL DEVELOP TO THE WEST OF THE MID LEVEL LOW TONIGHT AND EXTEND ACROSS EASTERN NEW ENG WHICH WILL LIKELY BRING BANDS OF SNOW TO THE REGION. THE WESTWARD EXTENT OF THE SNOW TONIGHT WILL LIKELY BE ACROSS CENTRAL MA AND RI WITH THE MAIN FOCUS ACROSS E MA INCLUDING THE CAPE/ISLANDS. MAINLY DRY WEATHER EXPECTED IN THE CT VALLEY. MODELS BACKED OFF A BIT ON THE QPF SO WE HAVE LOWERED SNOW ACCUM A TAD...BUT HAVE TO WATCH NE MA AND CAPE COD WHICH WILL BE CLOSEST TO THE BEST FORCING. SNOW LINGERS ACROSS E MA INTO SAT MORNING...BEFORE GRADUALLY MOVING OUT. THE OUTER CAPE WILL BE LAST TO DRY OUT AROUND MIDDAY. OTHERWISE...CLEARING SKIES WILL DEVELOP FROM WEST TO EAST LATE MORNING THROUGH THE AFTERNOON BUT WINDY AND VERY COLD SATURDAY WITH HIGHS MOSTLY IN THE TEENS. IN ADDITION TO THE SNOWFALL TONIGHT...NORTHWEST WINDS WILL INCREASE LATE TONIGHT INTO SAT WITH GUSTS TO 40 TO 45 MPH AS LOW INTENSIFIES EAST OF MA. LOW PROB WIND GUSTS COULD REACH 50 MPH NEAR THE S COAST AND WIND ADVISORIES MAY EVENTUALLY BE NEEDED. VERY COLD AIR MOVES IN TONIGHT INTO SATURDAY COMBINED WITH GUSTY NW WINDS WILL RESULT IN DANGEROUSLY COLD WIND CHILLS OF 10 TO 20 BELOW ZERO IN CENTRAL AND WESTERN MA AND PORTIONS OF N CT WHERE WIND CHILL ADVISORIES HAVE BEEN ISSUED. WIND CHILLS 5 TO 10 BELOW IN THE COASTAL PLAIN.
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&& .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... HEADLINES... * COLD CONDITIONS THROUGH SUNDAY AS WINDS DIMINISH * LOW PRESSURE LOOKS TO PASS S OF NEW ENGLAND SUNDAY NIGHT AND MONDAY WITH ACCUMULATING SNOW POSSIBLE * COLD CONDITIONS CONTINUE THROUGH MOST OF NEXT WEEK * ANOTHER LOW IS POSSIBLE AROUND WED OR THU...LOW CONFIDENCE OVERVIEW... OVERALL...NOTING A RATHER PROGRESSIVE UPPER LEVEL PATTERN ACROSS THE LOWER 48 WHICH WILL KEEP WEATHER SYSTEMS MOVING...BUT THERE IS ALSO THE POTENTIAL FOR A COUPLE MORE SNOW EVENTS ON THE HORIZON. DETAILS... SATURDAY NIGHT-SUNDAY...HIGH PRES MOVES OFF THE MID ATLC COAST AS A RIDGE POKES N INTO THE REGION. NW WINDS WILL REMAIN BLUSTERY EARLY SAT NIGHT...THEN WILL DIMINISH. A DRY COLD FRONT WILL PUSH ACROSS THE REGION SUNDAY MORNING...BRINGING LARGE HIGH PRES OUT OF SOUTH CENTRAL CANADA INTO THE NORTHERN GREAT LAKES. NOTING A DIGGING H5 SHORT WAVE WORKING E OUT OF THE MID MISSISSIPPI VALLEY AS SURFACE LOW DEVELOPS. WILL LIKELY SEE CLOUDS PUSHING IN DURING SUNDAY. SUNDAY NIGHT-MONDAY...BIG QUESTIONS WITH LOW PRES PASSING S OF NEW ENGLAND. FIRST...MORE COLD ARCTIC AIR WORKS ACROSS THE REGION...SO TEMPS WILL BE RATHER COLD. HOWEVER...MOST MODELS AND SEVERAL ENSEMBLES SIGNALING LOW PRES WILL PASS CLOSE TO JUST S OF 40N LATITUDE...POSSIBLY PASSING NEAR THE 40N/70W BENCHMARK. NOTING THE 00Z GFS AND ECMWF WERE MORE IN LINE THIS MORNING IN SPREADING A SWATH OF QPF ACROSS THE REGION WHILE HIGH PRES EXTENDS INTO QUEBEC. LOOKS LIKE A SET UP FOR MORE ACCUMULATING SNOWFALL. CURRENT FORECAST SUGGESTS AROUND 0.3 TO 0.5 INCHES QPF AND...WITH THE COLD AIR IN PLACE...COULD SEE SNOW TO LIQUID RATIOS OF AROUND 15:1. EXACT TIMING IS STILL IN QUESTION THOUGH AS THE PATTERN REMAINS PROGRESSIVE...BUT WILL BE MONITORING THIS DEVELOPMENT VERY CLOSELY. TUESDAY...ANOTHER HIGH CROSSES THE REGION DURING TUESDAY WITH MORE COLD AIR WORKING IN. WEDNESDAY-THURSDAY...MODELS AND ENSEMBLES CONTINUE TO SIGNAL LOW PRES AND COLD FRONT MOVING OUT OF THE GREAT LAKES WED NIGHT...THEN MOVING OFFSHORE THU MORNING. LOW PRES MAY DEVELOP ALONG THIS FRONT...POSSIBLY BRINGING MORE SOUTHERN STREAM MOISTURE UP THE COAST. WAY TOO EARLY TO TELL HOW THE NORTHERN AND SOUTHERN STREAMS WILL INTERACT...LOW CONFIDENCE. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
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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 SATURDAY NIGHT/...MODERATE CONFIDENCE. 145 PM UPDATE... THRU 00Z...MVFR AND IFR ACROSS EASTERN MA WITH MVFR TO MVFR ELSEWHERE. ANY LIGHT SNOW AT EARLY AFTERNOON WILL TAPER OFF TO FLURRIES. LIGHT NW WINDS WILL SLOWLY INCREASE THRU THE DAY. AFTER 00Z...STRONG NW WINDS DEVELOP WITH GUSTS UP TO 40 KT...HIGHEST ALONG THE COAST. MAINLY VFR TONIGHT HOWEVER MVFR ACROSS RI AND EASTERN MA IN PERIODS OF LIGHT SNOW AND A LOW RISK OF IFR OVER CAPE ANN AND CAPE COD IN BANDS OF MODERATE SNOW. SATURDAY...ANY MVFR-IFR IN SNOW BANDS OVER EXTREME EASTERN MA IN THE MORNING WILL IMPROVE TO VFR BY AFTERNOON. ELSEWHERE VFR PREVAILS. STRONG NW WINDS WITH GUST UP TO 45 KT OVER CAPE COD...25-35 KT ELSEWHERE. SAT NIGHT...VFR ALONG WITH DIMINISHING WINDS. KBOS TAF...MODERATE CONFIDENCE. LOWER CONFIDENCE ON HOW CLOSE SNOW SHIELD GETS TO LOGAN 06Z-12Z. SHOULD REMAIN OFFSHORE. KBDL TAF...HIGH CONFIDENCE. OUTLOOK /SUNDAY THROUGH TUESDAY/... SUNDAY...HIGH CONFIDENCE. VFR. NW WINDS GUSTING TO 25-35 KNOTS SATURDAY...HIGHEST ALONG THE COAST. LIGHTER WINDS SUNDAY. SUNDAY NIGHT-MONDAY...LOW CONFIDENCE. DEVELOPING LOW PRES LOOKS TO PASS S OF NEW ENGLAND WITH ACCUMULATING SNOW POSSIBLE. COULD SEE IFR CONDITIONS FOR A TIME...ESPECIALLY S OF THE MASS PIKE. CONDITIONS MAY IMPROVE EARLY MON NIGHT TUESDAY...MODERATE CONFIDENCE. MAINLY VFR. MAY SEE GUSTY NW WINDS EARLY.
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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 /THROUGH SATURDAY/...HIGH CONFIDENCE. TODAY...SOUTHERLY WINDS WILL SHIFT TO W THEN NW DURING FRI AFTERNOON...WITH GUSTS TO 25 KT DEVELOPING ACROSS RI COASTAL WATERS BY LATE AFTERNOON. TONIGHT AND SATURDAY...AS LOW PRES INTENSIFIES OVER WESTERN GULF OF MAINE...GALE FORCE NW WINDS WILL DEVELOP. GUSTS TO 40-45 KT EXPECTED LATE TONIGHT INTO SAT. THE GUSTY WINDS AND ROUGH SEAS COMBINED WITH ARCTIC AIR MOVING INTO THE REGION WILL RESULT IN AREAS OF MODERATE FREEZING SPRAY OVER THE NEARSHORE WATERS SO FREEZING SPRAY ADVISORIES WERE ISSUED. SNOW REDUCES VSBY OVER EASTERN WATERS TONIGHT INTO SAT MORNING. OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/...MODERATE CONFIDENCE THROUGH SUNDAY...THEN LOW CONFIDENCE SUN NIGHT-TUESDAY. SATURDAY NIGHT...NW WINDS GUSTING TO 35-40 KT EARLY...THEN SHOULD START TO DIMINISH AROUND OR AFTER MIDNIGHT. SEAS UP TO 10-14 FT ON THE OUTER WATERS EARLY...THEN SLOWLY SUBSIDING BUT REMAINING WELL ABOVE 5 FT. LIGHT TO MODERATE FREEZING SPRAY. SUNDAY...EXPECT WINDS AND SEAS REMAIN AT SMALL CRAFT LEVELS. LIGHT FREEZING SPRAY LIKELY. SUNDAY NIGHT-TUESDAY...HIGHLY DEPENDENT ON STRENGTH AND TRACK OF DEVELOPING LOW PRESSURE SOUTH OF THE REGION. WORSE CONDITIONS WOULD BE MONDAY WITH SLOW IMPROVEMENT ON TUESDAY. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...WIND CHILL ADVISORY FROM 1 AM TO 9 AM EST SATURDAY FOR CTZ002- 003. MA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MAZ004- 005-012>016-018-019-026. WIND CHILL ADVISORY FROM 1 AM TO 9 AM EST SATURDAY FOR MAZ003- 004-010-011. WIND CHILL ADVISORY FROM 11 PM THIS EVENING TO 11 AM EST SATURDAY FOR MAZ002-008-009. WINTER WEATHER ADVISORY FROM 6 PM TO 7 PM EST THIS EVENING FOR MAZ022. WINTER WEATHER ADVISORY FROM 11 PM THIS EVENING TO 10 AM EST SATURDAY FOR MAZ006-007-022. RI...NONE. MARINE...FREEZING SPRAY ADVISORY FROM 11 PM THIS EVENING TO 6 PM EST SATURDAY FOR ANZ231>235-237-250-251. GALE WARNING FROM 11 PM THIS EVENING TO 6 PM EST SATURDAY FOR ANZ232-250-254-255. GALE WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST SATURDAY FOR ANZ230-231-233-234-251. GALE WARNING FROM 1 AM TO 1 PM EST SATURDAY FOR ANZ236. GALE WARNING FROM 9 PM THIS EVENING TO 6 PM EST SATURDAY FOR ANZ235-237. GALE WARNING FROM 7 PM THIS EVENING TO 6 PM EST SATURDAY FOR ANZ256.
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&& $$ SYNOPSIS...KJC/EVT NEAR TERM...NOCERA SHORT TERM...KJC LONG TERM...EVT AVIATION...NOCERA/EVT MARINE...KJC/EVT

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