Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 281549 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1049 AM EST FRI NOV 28 2014 .SYNOPSIS... DRY BUT COLDER WEATHER OVERSPREADS THE REGION THIS AFTERNOON THROUGH SATURDAY. A WARM FRONT CROSSES THE AREA SATURDAY NIGHT WITH A LIGHT WINTRY MIX OF PRECIPITATION POSSIBLE. BEHIND THE FRONT MUCH MILDER WEATHER IS ON TAP FOR SUNDAY AND MONDAY. A POLAR FRONT WILL THEN SWEEP ACROSS THE REGION LATER MON BRINGING A RETURN TO COLDER WEATHER TUE. A WARM FRONT MAY THEN BRING ANOTHER RISK OF WINTRY PRECIPITATION THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 11 AM UPDATE...EQUIPMENT PROBLEMS HAVE BEEN RESOLVED FOR THE TIME BEING. MADE SOME UPDATES TO THE POPS AND WEATHER BASED ON LATEST TRENDS. SNOW HAS MOVED OFFSHORE ALL AREAS EXCEPT CAPE COD AND EASTERN PLYMOUTH COUNTY AND POSSIBLY THE EASTERNMOST PART OF CAPE ANN. THEREFORE...HAVE CANCELLED THE WINTER WEATHER ADVISORY FOR ALL BUT CAPE COD AND EASTERN PLYMOUTH COUNTY. 10 AM UPDATE...DUE TO SOME EQUIPMENT PROBLEMS...WAS UNABLE TO COMPLETE THE MORNING UPDATE. WILL UPDATE AS SOON AS POSSIBLE. IN THE MEANTIME...THE FORECAST DOES LOOK ON TRACK. SNOW SHOWERS ARE SLOWLY DIMINISHING AND MOVING OFFSHORE AT THIS TIME. EXPECT THIS TREND TO CONTINUE. 7 AM UPDATE... WILDCARD WILL BE OVER THE OUTER CAPE WHERE MODELS SUGGEST HEAVIER QPF...WHICH MATCHES UP WITH LATEST RADAR TRENDS. HOWEVER WETBULB TEMPS HERE ARE ABOVE FREEZING. THUS DESPITE SEEING MODERATE TO HEAVY SNOW ON PROVINCETOWN WEB CAM SNOW WILL STRUGGLE TO ACCUMULATE ESPECIALLY ON PAVED SURFACES. HOWEVER RADAR LOOKS IMPRESSIVE ACROSS THIS AREA SO WILL HAVE TO MONITOR IF ADDITIONAL COOLING TAKES PLACE VIA DYNAMICAL AND DIABATIC COOLING PROCESSES. OTHERWISE ADDITIONAL ACCUMULATIONS SHOULD BE FOCUSED FROM THE UPPER CAPE NORTHWARD INTO PLYMOUTH COUNTY...BOSTON TO CAPE ANN. PREVIOUS FORECAST AND STATEMENTS /SPS AND WSW/ CAPTURES THIS WEATHER THEME SO NO MAJOR CHANGES PLANNED. EARLIER DISCUSSION BELOW. ----------------------------------------------------------------- INVERTED TROUGH STARTING TO RECENTER ACROSS E MA AT 10Z WITH A BRIEF BREAK...BUT NOTING LIGHT PRECIP FILLING IN AGAIN ACROSS E MA INTO N RI. ANOTHER HEAVIER BATCH OF PRECIP HAS ALSO DEVELOPED ACROSS MASS BAY AND LOOKS TO BE HEADING S TOWARD CAPE COD...WHICH SHORT RANGE MODELS HAVE SIGNALED THIS MORNING. SO FAR THIS MORNING...HAVE RECEIVED A FEW REPORTS INCLUDING BETWEEN 2.5 AND 3 INCHES OF NEW SNOW IN GLOUCESTER AND 1.7 INCHES IN MANCHESTER NH. ALSO HAVE LIGHT SNOW FALLING HERE AT KBOX AT 10Z. EXPECT PRECIP TO CONTINUE THROUGH THE MORNING ACROSS EASTERN AREAS AND...WITH THE CHILLY TEMPS ACROSS THE REGION...WILL SEE MORE LIGHT SNOW EXCEPT A MIX OF LIGHT SNOW AND/OR RAIN ACROSS S COASTAL PLYMOUTH COUNTY AND ON CAPE COD. HOWEVER...WE NOTED THAT TEMPS WERE COOLER ON THE UPPER CAPE AROUND THE FALMOUTH AREA WHERE LIGHT SNOW FELL OFF AND ON OVERNIGHT. WITH NEW AREA OF HEAVIER PRECIP NOTED ON LATEST RADAR IMAGERY THAT IS TRENDING TOWARD THE CAPE OFF MASS BAY...THIS WILL BRING STEADIER AND HEAVIER PRECIP. THIS WILL BRING DOWN COOLER TEMPS...SO WILL SEE SOME MORE SNOW. THIS WILL LIKELY CAUSE DYNAMIC COOLING /COLDER AIR MIXING DOWN FROM ALOFT/ THAT WILL POSSIBLY BRING AN INCH OR TWO POSSIBLE BEFORE ENDING EARLY THIS AFTERNOON. THIS COULD COVER THE GROUND AND...CONSIDERING THAT THERE WILL BE QUITE A FEW TRAVELERS AND SHOPPERS ON THE ROADWAYS TODAY...WE DECIDED TO ISSUE A WINTER WEATHER ADVISORY CONCENTRATING THE UPPER CAPE THROUGH 3 PM. WE ALSO INCLUDED WESTERN ESSEX...SOUTHEAST MIDDLESEX AND WESTERN PLYMOUTH COUNTIES IN THE ADVISORY AS THERE WILL BE SOME OFF AND ON BANDS OF STEADIER SNOW FALLING THROUGH THE MORNING THERE THAT COULD CAUSE SNOW COVERED PRIMARY AND SECONDARY ROADS THROUGH MIDDAY. AS THE STRENGTHENING LOW MOVES NE WELL OFFSHORE TODAY...EXPECT IMPROVING CONDITIONS ACROSS CENTRAL AND WESTERN AREAS THAT WILL SHIFT E DURING THIS AFTERNOON. COLDER AIR WILL CONTINUE TO FILTER ACROSS THE REGION. TEMPS WILL ONLY RISE TO THE UPPER 20S TO AROUND 30 ACROSS THE HIGHER TERRAIN OF S NH/N CENTRAL MA AS WELL AS THE E SLOPES OF THE BERKSHIRES...RANGING TO THE MID 30S TO AROUND 40 ALONG THE IMMEDIATE COAST. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... TONIGHT... ANY LEFTOVER PRECIP ON THE OUTER CAPE WILL EXIT THE COAST BY 02Z...THEN SKIES WILL BECOME MOSTLY CLEAR. W-NW WINDS WILL REMAIN A BIT GUSTY EARLY TONIGHT ALONG THE COAST...BUT WINDS ACROSS THE REGION WILL DIMINISH AS HIGH PRES RIDGE BUILDS E. CORE OF COLDEST H85 TEMPS REMAINS ACROSS NORTHERN NEW ENGLAND...BUT WILL DROP TO -10C TO -13C OVERNIGHT. WITH LIGHT WINDS...PARTLY CLOUDY SKIES AND A NEW SNOWPACK ACROSS S NH/N CENTRAL AND W MA...WILL SEE TEMPS FALL TO THE SINGLE DIGITS TO LOWER TEENS THERE...WHILE MID TO UPPER TEENS WILL BE SEEN ACROSS MOST OTHER AREAS OVERNIGHT. READINGS WILL HOLD IN THE 20S ALONG THE IMMEDIATE COAST. && .LONG TERM /SATURDAY THROUGH THURSDAY/... UPDATED 340 AM HIGHLIGHTS... * CHILLY BUT DRY SATURDAY * MUCH MILDER SUNDAY AND MONDAY * RETURN TO CHILLY WEATHER TUESDAY SYNOPTIC OVERVIEW AND MODEL GUIDANCE EVALUATION... 00Z GEFS AND ECENS ENSEMBLES IN GOOD AGREEMENT ON THE LARGE SCALE FLOW ACROSS NORTH AMERICA THIS PERIOD OFFERING A TYPICAL LATE FALL WEATHER PATTERN...AN AMPLIFIED BUT PROGRESSIVE NORTHERN STREAM. THIS RESULTS IN LARGE DAILY TEMPERATURE VARIATIONS ACROSS SOUTHERN NEW ENGLAND THIS PERIOD. AS FOR THE DETERMINISTIC RUNS OF THE 00Z GFS AND ECMWF...OTHER THAN TYPICAL TIMING /GFS FASTER WITH FROPA MON/ AND AMPLITUDE DIFFERENCES AT THIS TIME RANGE THESE MODELS ARE IN GOOD AGREEMENT WITH THEIR ENSEMBLE COUNTERPARTS. THUS WILL USE A MODEL BLEND AS A BASELINE FOR THIS PORTION OF THE FORECAST. DAILY SENSIBLE WEATHER DETAILS... SATURDAY...COLD START TO THE DAY AFTER GOOD RADIATIONAL COOLING TONIGHT. HIGHS ONLY EXPECTED IN THE MU30S...WITH U20S AND L30S ACROSS THE HIGHER TERRAIN. THESE TEMPS ARE 10-15 DEGS COLDER THAN NORMAL. HOWEVER PARTLY SUNNY CONDITIONS ALONG WITH LIGHT WINDS WILL TAKE SOME OF THE EDGE OFF THE CHILLY TEMPS. SATURDAY NIGHT...WARM FRONT APPROACHES THE REGION. THUS INCREASING CLOUDS WITH THE CHANCE OF SOME SPOTTY LIGHT PRECIP. MODEL SOUNDINGS SUGGEST ANY LIGHT PRECIP WOULD BEGIN AS LIGHT SNOW OR FLURRIES THEN TRANSITIONING TO SLEET...FREEZING RAIN BEFORE ALL RAIN. COLUMN STRUGGLES TO SATURATE SO ANY PRECIP SHOULD LIGHT AND SPOTTY. HENCE NOT A HIGH IMPACT EVENT. SUNDAY AND MONDAY... SUBTROPICAL RIDGE BRIEFLY BUILDS ACROSS THE SOUTHEAST STATES AND THIS YIELDS MILDER AIR STREAMING NORTHWARD UP THE EASTERN SEABOARD INTO NEW ENGLAND WITH HIGHS INTO THE 50S ACROSS RI AND EASTERN MA BOTH DAYS. POLAR COLD FRONT MAY YIELD THE RISK FOR A FEW RAIN SHOWERS /POSSIBLE ENDING AS SNOW SHOWERS/ LATE MON/MON NIGHT. AS MENTIONED ABOVE ECMWF SLOWER WITH FROPA THAN GFS. GIVEN TIME RANGE WILL FOLLOW A MODEL BLEND. TUESDAY...1042 MB HIGH AND ITS ASSOCIATED POLAR AIRMASS SETTLE OVER NEW ENGLAND TUE WITH TEMPS NEARLY 20 DEGS COLDER THAN MON! HIGHS ONLY IN THE 30S...MU20S HIGHER TERRAIN. WEDNESDAY...OVERRUNNING PRECIP POSSIBLE WITH A WINTRY MIX GIVEN COLD AIR WILL INITIALLY BE SLOW TO DISLODGE. THURSDAY...TREND IS FOR DRIER BUT A RETURN TO COLDER WEATHER. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. .SHORT TERM /THROUGH TONIGHT/...MODERATE CONFIDENCE. 7 AM UPDATE... MVFR AND IFR CONDITIONS IN SNOW WILL BE CONFINED TO EASTERN MA THRU 14Z EXCEPT 18Z CAPE COD. OTHERWISE VFR CONDITIONS OVERSPREAD ALL TERMINALS THIS MORNING AND AFTERNOON. EARLIER DISCUSSION BELOW. ------------------------------------------------------------- TODAY...AREA OF LIGHT SNOW...SOME WHICH MAY FALL MODERATELY AT TIMES...ACROSS S CENTRAL NH/E MA INTO E RI. VSBYS MAY BRIEFLY LOWER TO LIFR IN PERIODS OF MOD-HVY SNOW. WILL SEE MIXED RAIN/SNOW ALONG COAST S OF BOSTON TO CAPE COD AND ISLANDS. CONDITIONS SHOULD BEGIN TO IMPROVE FROM W-E AROUND 16Z-19Z AS TROUGH MOVES OFFSHORE. FURTHER INLAND...EXPECT MAINLY VFR. TONIGHT...MAY SEE LEFTOVER MVFR CONDITIONS ALONG E COAST WHICH SHOULD IMPROVE BY 02Z-03Z...OTHERWISE VFR. KBOS TERMINAL...MODERATE CONFIDENCE MAINLY FOR TIMING OF MVFR-IFR CONDITIONS THROUGH MIDDAY...THEN WHEN IMPROVING CONDITIONS MOVE IN. HIGH CONFIDENCE TONIGHT. KBDL TERMINAL...HIGH CONFIDENCE. OUTLOOK...SATURDAY THROUGH TUESDAY...MODERATE CONFIDENCE. UPDATED 340 AM SATURDAY...VFR. INCREASING SKY COVER SATURDAY. NORTHWEST WINDS BECOME SOUTHWEST BUT REMAIN LIGHT. SATURDAY NIGHT-SUNDAY...LOWERING CLOUDS SATURDAY NIGHT WITH POTENTIAL FOR MVFR CIGS/VSBYS IN WIDELY SCATTERED PCPN LATE AT NIGHT AND SUNDAY MORNING. LOW LEVEL WINDS...AROUND 2000 FEET...WILL INCREASE OVERNIGHT AND SUNDAY TO 40-45 KNOTS AND MAY CREATE LOW LEVEL WIND SHEAR. MONDAY...VFR WITH SCATTERED SHOWERS LATE OR AT NIGHT AS A COLD FRONT MOVES THROUGH. SOUTHWEST WINDS AHEAD OF THE COLD FRONT WILL SWITCH TO NORTHWEST AFTER THE FRONT MOVES THROUGH. TUESDAY...VFR WITH NORTH TO NORTHEAST WINDS. TUESDAY...VFR WITH NORTH TO NORTHEAST WINDS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. .SHORT TERM /THROUGH TONIGHT/...HIGH CONFIDENCE. TODAY...N-NW WINDS WILL INCREASE DURING THE MORNING WITH GUSTS UP TO 25 KT MAINLY ACROSS EASTERN AREAS. SEAS WILL ALSO BUILD AGAIN UP TO 5-6 FT MAINLY OVER THE OPEN WATERS. WINDS WILL BRIEFLY GUST TO 25 FT ACROSS CAPE COD BAY AND NANTUCKET SOUND AROUND MIDDAY SO HAVE PUT UP SMALL CRAFT THERE. WINDS WILL BEGIN TO DIMINISH LATE IN THE DAY. TONIGHT...W-NW WINDS WILL DIMINISH EARLY TONIGHT BUT SEAS WILL REMAIN AOA 5 FT ON THE OUTER WATERS AFTER MIDNIGHT BEFORE FINALLY SUBSIDING. OUTLOOK...SATURDAY THROUGH TUESDAY...MODERATE CONFIDENCE. SATURDAY...HIGH PRES OVER THE WATERS EARLY THEN SLIDES OFFSHORE SAT NIGHT. THUS FAIRLY LIGHT WINDS ALONG WITH DRY WEATHER DURING THE DAY. RISK OF A FEW SHOWERS OF RAIN AND SNOW AT NIGHT. SUNDAY...WARM FRONT LIFTS NORTH THRU THE REGION. MODEST SW WIND DEVELOPS BUT MAINLY DRY WEATHER. MONDAY...COLD FRONT REMAINS WEST OF NEW ENGLAND SO MODEST SW WINDS CONTINUE. TUE...COLD HIGH PRES DRIFTS ACROSS SOUTHERN QUEBEC. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR MAZ019. WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR MAZ022. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ231- 232-251. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250- 256. SMALL CRAFT ADVISORY UNTIL 3 AM EST SATURDAY FOR ANZ254-255. && $$ SYNOPSIS...NOCERA/EVT NEAR TERM...NOCERA/RLG/EVT SHORT TERM...EVT LONG TERM...NOCERA AVIATION...NOCERA/EVT MARINE...NOCERA/EVT

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