Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 041735 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1235 PM 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/... 1235 PM UPDATE... PATCHES OF LIGHT RAIN WILL MOVE ALONG S COAST THROUGH LATE AFTERNOON...AHEAD OF COLD FRONT WHICH IS SLOWLY SAGGING S THROUGH REGION. SOME BREAKS OR THINNING IN CLOUD COVER HAS ALLOWED TEMPERATURES TO RECOVER INTO 30S AND LOWER 40S AS OF MIDDAY...AND READINGS MAY RISE ANOTHER DEGREE OR TWO. EARLY THOUGHTS FOR NEXT UPDATE... 12Z MODELS HAVE NUDGED THINGS A BIT FARTHER S FROM EARLIER RUNS... ESPECIALLY HIGH-RES MODELS WHICH SHOW SHARP CUTOFF TO NORTHERN EDGE OF PRECIPITATION SHIELD WHICH HAS TO BE TAKEN INTO CONSIDERATION. INITIAL PLAN IS TO CUT BACK ON SNOWFALL TOTALS ALONG AND N OF MASS PIKE...AND NUDGE AMOUNTS DOWN A TAD FARTHER TO S. WILL MAKE FINAL DECISION ON TOTALS/HEADLINES AFTER COORDINATION WITH WPC AND SURROUNDING OFFICES. THERE ARE SEVERAL RED FLAGS TO CONSIDER AGAINST GOING WITH OVERLY HIGH AMOUNTS INCLUDING BEING ABLE TO OVERCOME INITIALLY WARM LOW LEVEL TEMPERATURES /WHICH AFFECTS PRECIP TYPE AND ACCUMULATIONS/...CONTINUED SOUTHWARD NUDGE ON MODELS AND FACT THAT BEST LIFT IN MAX SNOW GROWTH ZONE IS LIMITED TO LATE TONIGHT AND EARLY THU MORNING NEAR S COAST. FACT THAT HIGH-RES MODELS SHOW LITTLE IF ANY SNOWFALL N OF MASS PIKE MAKES SENSE GIVEN WE EXPECT A SHARP GRADIENT ON NORTHERN EDGE OF SYSTEM. && .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 /18Z WEDNESDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH THURSDAY NIGHT/...MODERATE CONFIDENCE. MVFR/IFR PERSISTS ALONG S COAST...CAPE COD AND ISLANDS THROUGH THIS EVENING WITH ISOLATED LIGHT SHOWERS. CIGS MAY IMPROVE SLIGHTLY AFTER 00Z BUT OVERALL TREND IS TO MAINTAIN PERSISTENCE IN CONDITIONS. VFR CIGS ELSEWHERE. MVFR/IFR SPREADS N IN LIGHT SNOW TONIGHT...PROBABLY AS FAR N AS BDL-SFZ-BOS MAINLY DUE TO VSBY. LIGHT RAIN CHANGES TO SLEET AND SNOW CLOSER TO S COAST AFTER 06Z WHERE LIFR EXPECTED THROUGH DAYBREAK THU. VFR CIGS FARTHER N AND W. CONDITIONS SLOWLY IMPROVE THU FROM NW TO SE...WITH CAPE COD AND ISLANDS LAST TO IMPROVE 16Z-20Z. SNOW ACCUMULATIONS... BOS/BAF/BED/ORH...1 INCH BDL/PVD...2 INCHES FMH/HYA...3-4 INCHES ACK...5-7 INCHES KBOS TAF...HIGH CONFIDENCE. COORDINATED TAF WITH CWSU ZBW. KBDL TAF...HIGH CONFIDENCE. OUTLOOK...FRIDAY THROUGH SUNDAY... MODERATE CONFIDENCE. MAINLY VFR THROUGH THIS PERIOD. BRIEF MVFR CONDITIONS ARE POSSIBLE THURSDAY NIGHT AS SNOW COMES TO AN END. && .MARINE... 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 WILL BE DROPPED ON THE NEAR SHORE WATERS AROUND CAPE COD...BUT WILL LINGER THROUGH AFTERNOON ON IPSWICH BAY DUE TO 5 FOOT SEAS. ALSO SHOULD 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. && .BOX WATCHES/WARNINGS/ADVISORIES... 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 6 PM EST THURSDAY FOR ANZ235-237- 250-254>256. SMALL CRAFT ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR ANZ251. && $$ SYNOPSIS...RLG/EVT NEAR TERM...JWD SHORT TERM...EVT LONG TERM...RLG AVIATION...JWD MARINE...WTB/RLG/EVT

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