Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 272331 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 631 PM EST FRI FEB 27 2015 .SYNOPSIS... HIGH PRESSURE SLOWLY BUILDING IN FROM THE WEST WILL BRING DRY BUT UNSEASONABLY COLD WEATHER INTO SUNDAY MORNING. A LOW PRESSURE SYSTEM WILL BRING A PLOWABLE SNOW LATE SUNDAY AND SUNDAY NIGHT. ANOTHER STORM IS LIKELY TUESDAY NIGHT INTO WEDNESDAY...WITH SNOW AND MIXED PRECIPITATION LIKELY CHANGING TO RAIN. COLD AND DRY CONDITIONS RETURN FOR THE END OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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630 PM UPDATE... SKIES ARE CLEAR ACROSS THE REGION. UPDATED T/TD GRIDS FOR CURRENT TRENDS OTHERWISE FORECAST ON TRACK. PREVIOUS DISCUSSION... HIGH PRESSURE CONTINUES TO BUILD IN PROVIDING EXCELLENT RADIATIONAL COOLING CONDITIONS ACROSS SOUTHERN NEW ENGLAND. LOW TEMPERATURES WERE A BLEND OF THE NAM AND GFS 2 METER TEMPS... RESULTING IN LOWS BETWEEN 5 AND 15 BELOW ZERO IN THE WESTERN LOCATIONS AND 0 TO 10 DEGREES ACROSS THE EASTERN ZONES.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... SATURDAY AND SATURDAY NIGHT...HIGH PRESSURE REMAINS IN CONTROL OF THE REGION. DESPITE A FRIGID START TO THE DAY...TEMPERATURES WILL REBOUND INTO THE MID TO UPPER 20S SATURDAY AFTERNOON. LIGHT WINDS AND THE HIGHER SUN ANGLE WILL AID IN IT FEELING A BIT MORE TOLERABLE DESPITE TEMPS REMAINING WELL BELOW NORMAL. ANOTHER COLD NIGHT IS EXPECTED SATURDAY NIGHT WITH EXCELLENT RADIATIONAL COOLING. && .LONG TERM /SUNDAY THROUGH FRIDAY/... HIGHLIGHTS... * PLOWABLE SNOW LIKELY LATE SUN/SUN NIGHT...CLEARING MONDAY * ANOTHER STORM POSSIBLE TUE NIGHT INTO WED...WITH SNOW OR MIXED PRECIP LIKELY CHANGING TO RAIN * COLD AND DRY TOWARD THE END OF THE WEEK SUNDAY... HIGH PRES MOVES OFF THE COAST DURING THE AFTERNOON WITH DEVELOPING WARM ADVECTION PATTERN RESULTING IN SUNSHINE QUICKLY GIVING WAY TO INCREASING CLOUDS. SOME UNCERTAINTY ON TIMING OF LEADING EDGE OF SNOW AND HOW QUICKLY THE COLUMN MOISTENS. SOME LIGHT SNOW MAY DEVELOP BY LATE AFTERNOON. MAX TEMPS UPPER 20S TO LOWER 30S. SUNDAY NIGHT... MODELS SIMILAR WITH LOW PRES TRACKING ACROSS CENTRAL NEW ENG LATE SUN NIGHT...WITH SOME HINT OF A WEAK LOW LEVEL CIRCULATION DEVELOPING SOUTH OF THE COAST. GOOD OVERRUNNING SIGNATURE WITH A PERIOD OF MID LEVEL FGEN AND DECENT PWATS WILL BRING A SLUG OF PRECIP INTO SNE SUN NIGHT. THERMAL PROFILES COLD ENOUGH FOR ALL SNOW...EXCEPT PERHAPS FOR THE ISLANDS WHERE BOUNDARY LAYER WARMING MAY EVENTUALLY FORCE A CHANGE TO RAIN. MODELS IN GOOD AGREEMENT ON QPF WITH 0.25"-0.50"+ FROM NORTH TO SOUTH...HEAVIEST ALONG THE SOUTH COAST. CROSS SECTIONS DO SHOW A PERIOD OF DECENT SNOW GROWTH WITH MAX OMEGA NUDGING INTO -10C LAYER. GENERALLY EXPECTING A GOOD ADVISORY EVENT WITH 3 TO 6 INCHES WITH MAX SNOW ALIGNED ALONG AND SOUTH OF THE MASS PIKE BUT INLAND FROM THE S COAST WHERE SLR MAY BE LOWER DUE TO BL WARMING. A FEW LOCALLY HIGHER AMOUNTS CANT BE RULED OUT ACROSS N CT...N RI AND ADJACENT SE MA. THE SYSTEM IS PROGRESSIVE AND BULK OF SNOW SHOULD BE MOVING OUT BEFORE THE MONDAY MORNING COMMUTE. MONDAY... SOME LINGERING LIGHT SNOW POSSIBLE IN THE MORNING...OTHERWISE MAINLY DRY AS DEEPENING LOW PRES MOVES INTO THE GULF OF MAINE WITH GOOD MID LEVEL DRYING MOVING INTO THE REGION. EXPECT CLEARING SKIES IN THE AFTERNOON BUT BECOMING BLUSTERY WITH NW WINDS GUSTING TO 35 MPH. MAX TEMPS IN THE 30S. MONDAY NIGHT INTO TUE... HIGH PRES BUILDS IN FROM THE WEST. GUSTY WINDS MON EVENING WILL GRADUALLY DIMINISH LATER MON NIGHT INTO TUE AS THE RIDGE CRESTS OVER NEW ENG. TEMPS BELOW NORMAL. TUESDAY NIGHT INTO WEDNESDAY NIGHT... MODELS IN AGREEMENT ON DEEPENING LOW PRES MOVING UP THROUGH THE LAKES WITH NOT MUCH HINT OF SECONDARY LOW DEVELOPMENT. WITH LOW LEVEL S/SW FLOW IT WILL BE VERY DIFFICULT TO LOCK IN THE COLD AIR SO AN EVENTUAL CHANGE TO RAIN IS EXPECTED...QUICKEST ALONG THE COAST TUE NIGHT...BUT ECMWF IS QUITE A BIT COLDER THAN GFS ON THE FRONT END OF THE STORM TUE NIGHT AND WOULD SUGGEST A DECENT ACCUM OF SNOW/ICE IN THE INTERIOR BEFORE GOING TO RAIN WED. GFS WOULD SUGGEST A FAIRLY RAPID TRANSITION FROM SNOW TO RAIN TUE NIGHT. DUE TO UNCERTAINTY WE BLENDED THE GFS/ECMWF PARTIAL THICKNESSES AND HAVE PRECIP STARTING AS SNOW EVERYWHERE TUE NIGHT THEN TRANSITIONING TO A MIX/ICE OVERNIGHT IN THE INTERIOR WITH RAIN ALONG THE COAST...THEN ALL RAIN WED. SNOWPACK WILL BE ABLE TO ABSORB THE RAINFALL AND OTHER THAN AREAS OF POOR DRAINAGE FLOODING DUE TO CLOGGED DRAINS...FLOODING IS NOT ANTICIPATED. THE OTHER ITEM OF UNCERTAINTY IS HOW QUICKLY THE RAIN EXITS. GFS IS MOST PROGRESSIVE AND DRIES IT OUT WED NIGHT...WHILE ECMWF HAS MORE AMPLIFIED UPSTREAM TROF WHICH SLOWS THE FRONT DOWN WITH POTENTIAL FRONTAL WAVE BRINGING ANOTHER PERIOD OF RAIN WED NIGHT INTO EARLY THU. CONSENSUS OF THE GUIDANCE FAVORS ECMWF SOLUTION. STILL LOTS OF UNCERTAINTY THIS FAR OUT AND HOW THIS PLAYS OUT WILL AFFECT FORECAST POPS/TEMPS/PTYPE. A SOLUTION CLOSER TO ECMWF WOULD RESULT IN MILDER TEMPS WED NIGHT WITH MORE RAIN. THURSDAY AND FRIDAY... PRECIP COULD LINGER INTO THU MORNING IF ECMWF SOLUTION IS CORRECT...BUT TREND THROUGH THE END OF THE WEEK WILL BE FOR COLDER AND DRY CONDITIONS WITH TEMPS DROPPING WELL BELOW NORMAL...ESPECIALLY THU NIGHT AND FRI. && .AVIATION /23Z 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 /TODAY THROUGH SATURDAY AFTERNOON/... TONIGHT THROUGH SATURDAY NIGHT...HIGH CONFIDENCE. VFR KBOS TAF...HIGH CONFIDENCE. VFR. KBDL TAF...HIGH CONFIDENCE. VFR. OUTLOOK...SUNDAY THROUGH WEDNESDAY... SUNDAY...HIGH CONFIDENCE. VFR...THEN CIGS/VSBYS LOWERING TO MVFR LATER IN THE AFTERNOON FROM WEST TO EAST AS LIGHT SNOW OVERSPREADS THE REGION. SUNDAY NIGHT...HIGH CONFIDENCE. IFR IN PERIODS OF SNOW. EXPECTING 3 TO 6 INCHES AT AREA TERMINALS...LESS ON THE ISLANDS. MONDAY...MODERATE CONFIDENCE. MVFR/IFR POSSIBLE EARLY...THEN IMPROVING TO VFR. NW WIND GUSTS TO 30 KT DEVELOPING IN THE AFTERNOON. TUESDAY...HIGH CONFIDENCE. MAINLY VFR. TUESDAY NIGHT INTO WEDNESDAY...CONDITIONS LOWERING TO IFR WITH SNOW CHANGING TO ICE THEN RAIN...QUICKEST ALONG THE COAST.
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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 NIGHT/...HIGH CONFIDENCE. HIGH PRESSURE BUILDS OVER THE WATERS FROM THE WEST ALLOWING WINDS AND SEAS TO SUBSIDE GRADUALLY. SEAS REMAIN ABOVE 5 FEET ON THE OUTER WATERS SO AM ALLOWING THE SMALL CRAFT ADVISORY TO CONTINUE ON THOSE WATERS THROUGH TONIGHT. OUTLOOK...SUNDAY THROUGH WEDNESDAY...HIGH CONFIDENCE. SUNDAY...LIGHT WINDS AND SEAS SUN...THEN SW INCREASING TO 10-20 KT SUN NIGHT. VSBYS REDUCED IN RAIN/SNOW SUN NIGHT. MONDAY...INCREASING NW WINDS DEVELOP WITH GALE FORCE GUSTS POSSIBLE IN THE AFTERNOON AND EVENING BEFORE DIMINISHING OVERNIGHT. TUESDAY...WINDS BELOW SCA WITH SUBSIDING SEAS AS HIGH PRES CRESTS OVER THE WATERS. LATE TUE NIGHT INTO WEDNESDAY...INCREASING SW WINDS WITH GUSTS TO SCA THRESHOLDS. LOWERING VSBYS IN SNOW CHANGING TO RAIN. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST SATURDAY FOR ANZ250- 254>256. && $$ SYNOPSIS...KJC/RLG NEAR TERM...KJC/RLG SHORT TERM...RLG LONG TERM...KJC AVIATION...KJC/RLG MARINE...KJC/RLG

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