Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 041516 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1016 AM EST WED MAR 4 2015 .SYNOPSIS... WEAK LOW PRESSURE WILL PUSH ALONG THE STALLED FRONT WITH ANOTHER ROUND OF SNOW TONIGHT INTO THURSDAY. HIGH PRESSURE WILL BUILD IN FOR FRIDAY THROUGH THIS WEEKEND...BRINGING DRY CONDITIONS WITH COLDER THAN NORMAL TEMPERATURES. A WEAKENING FRONT MAY BRING SOME LIGHT SNOW SHOWERS ON MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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ONE AREA OF LIGHT RAIN IS MOVING OFF CAPE COD WITH PATCHY SPRINKLES/DRIZZLE OVER SOUTHERN RI/CT. OKX AND DIX RADARS SHOW SOME MORE LIGHT RAIN MOVING EAST FROM EASTERN PA BUT MOST WILL STAY SOUTH OF THE COAST...THE REST STAYS SOUTH OF PROVIDENCE AND TAUNTON. SURFACE OBS SHOW THE COLD FRONT MOVING THROUGH CENTRAL MASS AND NORTHWEST CT. THIS WILL CONTINUE TO MOVE ACROSS SOUTHERN NEW ENGLAND THIS AFTERNOON/EVENING WHICH WOULD FORCE MOST OF THE PCPN SOUTH OF OUR AREA. THE FRONTAL ORIENTATION IS MORE EAST-WEST ACROSS PA AND NEAR-PARALLEL TO THE UPPER FLOW. THIS SIGNALS THE EVENTUAL STALLING OF THE FRONT THIS EVENING OR TONIGHT. WE MADE A FEW ADJUSTMENTS TO POPS /HIGHER ALONG THE SOUTH COAST INITIIALLY/ AND SKY COVER /100 PERCENT ALL AREAS THROUGH MIDDAY AND THROUGH THE AFTERNOON SOUTH OF THE PIKE/.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... SHORT RANGE MODELS IN GOOD AGREEMENT ON TIMING...THOUGH STILL SOME DIFFERENCES ON PLACEMENT OF THE STALLED FRONT S OF NEW ENGLAND. HIGH RES MODELS /HRRR...WRF AND RAP13/ AND AS WELL AS THE 00Z NAM AND ECMWF WERE IN GOOD AGREEMENT...WITH THE 00Z GFS A BIT FURTHER N THAN THE OTHER MODELS. USED A NON-GFS BLEND FOR THIS FORECAST. QUESTION REMAINS HOW FAR N WILL THE MOISTURE FROM THE APPROACHING SURFACE WAVE MOVING ALONG THE STALLED FRONT WILL GO. MODELS STILL SIGNALING A SHARP NORTH CUTOFF TO THE PRECIP AS IT MOVES E-NE OVERNIGHT...WITH THE HEAVIER PRECIP REMAINING ACROSS S COASTAL AREAS. KEPT CAT POPS GOING ACROSS S RI/S COASTAL MA AND THE ISLANDS...WITH LIKELY POPS ACROSS N CT/MOST OF RI INTO SE MA. DID KEEP CHANCE POPS GOING TO AROUND THE MASS PIKE THEN SHOULD BE LITTLE IF ANY PRECIP N OF THERE. GOOD SLUG OF PRECIP MOVES E ACROSS S COASTAL AREAS MAINLY AFTER MIDNIGHT THROUGH MIDDAY THU. ANOTHER QUESTION WILL BE HOW QUICKLY THE COLD AIR FILTERS IN. LOOKS LIKE TIMING IS SIMILAR TO PREVIOUS FORECAST...SO EXPECT TEMPS FALLING BELOW FREEZING AFTER MIDNIGHT. SO...RAIN WILL MIX WITH SOME SLEET BEFORE CHANGING OVER TO SNOW DURING TONIGHT. PLUS...WITH PERIODS OF MODERATE SNOW...WILL LIKELY SEE DYNAMIC COOLING LATE TONIGHT INTO THU MORNING ACROSS S COASTAL AREAS. EXPECT TOTAL QPF TONIGHT AND THU TO RANGE FROM AROUND 0.1 TO 0.2 INCHES CLOSE TO THE MASS PIKE UP TO 0.5 TO 0.8 INCHES ACROSS THE S COAST...CAPE COD AND THE ISLANDS. WITH THE COLDER AIR WORKING IN...WILL SEE A GOOD AMOUNT OF SNOWFALL...WITH THE BEST SHOT ACROSS THE ISLANDS. FEEL CONFIDENT THAT THE ISLANDS WILL RECEIVE THE HIGHEST SNOWFALL FROM THIS PASSING SYSTEM...SO WENT WITH A WINTER STORM WARNING FOR THOSE AREAS. KEPT A WATCH GOING ALONG THE S COAST FOR NOW AS THERE IS STILL A CHANCE THAT THEY WILL ALSO SEE 6+ INCHES OF SNOW BUT STILL ON THE FENCE ON THIS...MAY ALSO BE JUST BELOW WARNING CRITERIA. EXPECT STEADY PRECIP TO CONTINUE THROUGH A GOOD PORTION OF THU... THOUGH WILL START TO DIMINISH DURING THU AFTERNOON AS THE LOW PRES WAVE MOVES BY AND THE UPPER TROUGH APPROACHES. PRECIP SHOULD START TAPERING OFF FROM NW-SE...THOUGH WILL LINGER ACROSS E RI/SE MA THROUGH MOST OF THE DAY. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... * HIGH PRESSURE BUILDS IN THU NIGHT...PASSING S FRIDAY * MOISTURE STARVED COLD FRONT MOVES THROUGH THIS WEEKEND * UNCERTAIN FORECAST EARLY NEXT WEEK MODELS ARE IN FAIRLY GOOD AGREEMENT GOING INTO THE WEEKEND. THERE ARE SOME MINOR DISCREPANCIES IN TIMING OF A COLD FRONT THROUGH THE WEEKEND. THEN NEXT WEEK THEY DIVERGE A BIT...WITH ECMWF ATTEMPTING TO BRING A COASTAL LOW UP OVER THE BENCHMARK TUESDAY AND THE GFS BRINGING IN A STRONG HIGH PRESSURE JUST SOUTH OF SOUTHERN NEW ENGLAND. AT THIS POINT...WILL OPT FOR A BLEND OF AVAILABLE GUIDANCE FOR THE WEEKEND INTO EARLY NEXT WEEK TO TAKE CARE OF SOME OF THE TIMING ERRORS. HIGH PRESSURE BUILDS IN FROM THE MIDWEST THURSDAY NIGHT...BRINGING AN END TO THE SNOW. THEN FRIDAY...THE HIGH PRESSURE BECOMES SUPPRESSED TO THE SOUTH AS LOW PRESSURE MOVES INTO QUEBEC. THIS WILL KEEP CHILLY TEMPERATURES...WELL BELOW NORMAL FOR EARLY MARCH... IN PLACE FOR SOUTHERN NEW ENGLAND. THIS WEEKEND...A SHORTWAVE PUSHES LOW PRESSURE THROUGH QUEBEC... ALLOWING A COLD FRONT TO MOVE THROUGH SOUTHERN NEW ENGLAND. AT THIS POINT...THIS FRONTAL PASSAGE APPEARS TO BE FAIRLY MOISTURE STARVED SO LITTLE IF ANY PRECIP WILL ACCOMPANY THIS FRONT. TEMPERATURES MODERATE A BIT BUT REMAIN WELL BELOW NORMAL. EARLY NEXT WEEK MODELS DIVERGE WITH RADICALLY DIFFERENT SOLUTIONS FOR SOUTHERN NEW ENGLAND. GIVEN THE TIME FRAME...THIS IS NOT COMPLETELY UNUSUAL...SO WILL TAKE EITHER MODEL WITH A GRAIN OF SALT AT THIS TIME. REGARDLESS OF THE MODEL...IT DOES LOOK LIKE TEMPERATURES CONTINUE TO MODERATE INTO NEXT WEEK. && .AVIATION /15Z 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 THURSDAY/...MODERATE CONFIDENCE. THIS AFTERNOON...VFR. PATCHES OF MVFR CIGS IN WESTERN MASS. LINGERING IFR CIGS AND MVFR VSBYS IN LIGHT RAIN AND FOG ALONG THE SOUTH COAST WILL IMPROVE TO VFR DURING THE AFTERNOON. TONIGHT...N OF MASS PIKE...MAINLY VFR CIGS THOUGH MAY LOWER TO MVFR ALONG THE PIKE AFTER MIDNIGHT. S OF THE MASS PIKE... CONDITIONS DETERIORATE TO MVFR BY 05Z IN MIXED PRECIP CHANGING OVER TO SNOW FROM N-S. WILL VSBYS LOWER TO IFR-LIFR ACROSS N CT/RI/SE MA IN PERIODS OF SN/+SN AFTER 05Z. THURSDAY...N OF THE MASS PIKE...VFR. S OF THE PIKE...GENERALLY MVFR-IFR CIGS/VSBYS IN -SN/SN WITH LOCAL LIFR ALONG THE S COAST...CAPE COD AND THE ISLANDS. WILL START TO SEE IMPROVING CIGS BUT IFR CIGS MAY LINGER IN -SN DURING THE AFTERNOON THOUGH WILL ALSO BEGIN TO IMPROVE LATE IN THE DAY. KBOS TAF...HIGH CONFIDENCE IN OVERALL TRENDS...LOWER CONFIDENCE IN EXACT TIMING. KBDL TAF...HIGH CONFIDENCE IN OVERALL TRENDS...LOWER CONFIDENCE IN EXACT TIMING. OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY... MODERATE CONFIDENCE. MAINLY VFR THROUGH THIS PERIOD. BRIEF MVFR CONDITIONS ARE POSSIBLE THURSDAY NIGHT AS SNOW COMES TO AN END.
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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 THURSDAY/...MODERATE CONFIDENCE. THIS AFTERNOON...SW WINDS GUSTING TO 20-25 KT WILL DIMINISH AS A COLD FRONT APPROACHES THE WATERS. EXPECT THE FRONT TO STALL ACROSS THE SOUTHERN OUTER WATERS OR POSSIBLY A BIT FURTHER S. SMALL CRAFT ADVISORIES MAY BE DROPPED ON THE NEAR SHORE WATERS AROUND MIDDAY OR EARLY AFTERNOON...BUT LOOK TO LINGER ON THE OUTER WATERS MAINLY FOR HIGH SEAS. TONIGHT AND THURSDAY...WINDS SHIFT TO NW. GUSTS UP TO 25 KT MAINLY ON THE OUTER WATERS TONIGHT. SEAS REMAIN AOA 5 FT ON THE OUTER WATERS AS WELL. OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY... HIGH CONFIDENCE. WINDS AND SEAS SLOWLY DIMINISH THURSDAY NIGHT AND FRIDAY AS HIGH PRESSURE BUILDS OVER THE WATERS. THEY THEN INCREASE BUT ONLY MODESTLY OVER THE WEEKEND AS A COLD FRONT APPROACHES THEN CROSSES THE WATERS. SMALL CRAFT ADVISORIES WILL LIKELY BE NECESSARY ON THE OUTER WATERS FOR A PORTION OF THIS TIME.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 7 PM EST THURSDAY FOR MAZ023-024. WINTER STORM WATCH FROM 7 PM EST THIS EVENING THROUGH THURSDAY EVENING FOR MAZ020>022. RI...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 7 PM EST THURSDAY FOR RIZ008. WINTER STORM WATCH FROM 7 PM EST THIS EVENING THROUGH THURSDAY EVENING FOR RIZ003>007. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EST TODAY FOR ANZ231>234. SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ235-237- 250-254>256. SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ANZ251.
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&& $$ SYNOPSIS...RLG/EVT NEAR TERM...WTB SHORT TERM...EVT LONG TERM...RLG AVIATION...WTB/RLG/EVT MARINE...RLG/EVT

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