Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 260004 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 804 PM EDT WED MAR 25 2015 .SYNOPSIS... A WARM FRONT ALOFT MOVES ACROSS NEW ENGLAND THIS EVENING BRINGING A PERIOD OF RAIN...POSSIBLY MIXED WITH SLEET FOLLOWED BY DRIZZLE AND FOG OVERNIGHT. ANOTHER PERIOD OF RAIN MOVES THROUGH EARLY THURSDAY AFTERNOON FOLLOWED BY ROUND OF SHOWERS THURSDAY EVENING AND NIGHT AS A COLD FRONT SWEEPS ACROSS THE REGION. A SECOND COLD FRONT WILL BRING COLDER TEMPERATURES LATER FRIDAY INTO THIS WEEKEND. WEAK LOW PRESSURE MAY BRING A PERIOD OF LIGHT SNOW FRIDAY NIGHT INTO SATURDAY MORNING. HIGH PRESSURE WILL PUSH S OF NEW ENGLAND SUNDAY. ANOTHER BATCH OF LIGHT SNOW IS POSSIBLE LATE SUNDAY NIGHT INTO MONDAY AHEAD OF A COLD FRONT. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... 740 PM UPDATE... AS NOTED ON PREVIOUS DISCUSSION...TEMPS DROPPED SEVERAL DEGREES AS PRECIP MOVED ACROSS CENTRAL AND WESTERN AREAS OVER THE LAST COUPLE OF HOURS. HAVE ALSO RECEIVED SEVERAL REPORTS OF MIXED SLEET AND SNOW ACROSS PORTIONS OF FRANKLIN AND HAMPSHIRE COUNTIES SINCE AROUND 530 PM. RECEIVING MORE SPOTTER REPORTS OF SLEET INTO INTERIOR E MA...NATICK AND ARLINGTON AT AROUND 745-750 PM. WITH MILD TEMPS AND LATE MARCH SUN ANGLE ALLOWING FOR GOOD SOLAR HEATING EARLIER TODAY...SHOULD NOT SEE MUCH OF A PROBLEM WITH ICING SURFACES. NOTING AREA OF ENHANCED REFLECTIVITIES ON LATEST KBOX 88D RADAR WHICH SEEMS TO BE CORRELATE TO MIXED PRECIP REPORTS. ALSO NOTED VSBYS DROPPED AT BOTH KBDL AND KCEF. WILL SEE TEMPS LEVEL OFF AS PRECIP LIGHTENS UP THEN BECOMES SPORADIC OVER THE NEXT FEW HOURS...THEN TRANSITIONING TO A MORE DRIZZLE AND FOG SITUATION OVERNIGHT. TEMPS MAY BRIEFLY DROP CLOSE TO FREEZING...THEN WILL LEVEL OFF OR RISE A BIT OVERNIGHT AS STEADY PRECIP ENDS AND SOME LOW LEVEL WARM AIR ADVECTION WORKS IN...THOUGH WARM FRONT WILL REMAIN S OF THE REGION UNTIL AROUND MIDDAY OR DURING THU AFTERNOON. NEAR TERM FORECAST UPDATED TO BRING CONDITIONS CURRENT. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... THURSDAY... *** TEMPS AND DEW PTS INTO THE 50S W/APPRECIABLE SNOW MELT *** MAINLY JUST DRIZZLE AND FOG IN THE MORNING HOURS AHEAD OF SURFACE WARM FRONT. THEN AS WARM FRONT LIFTS NORTHWARD DEEP MOISTURE AND LIFT OVERSPREAD THE AREA YIELDING A PERIOD OF RAIN FROM LATE MORNING INTO AT LEAST THE EARLY AFTERNOON. AS LOW LEVEL JET ENTERS THE AREA STRONG LOW LEVEL WARMING YIELDS STEEPENING LAPSE RATES AND MAY RESULT IN A RUMBLE OR TWO OF THUNDER. THINK THE MAIN IMPACT WILL BE FOR THIS INSTABILITY TO ENHANCE RAINFALL RATES WITH RISK OF A FEW HEAVIER DOWNPOURS. WARM SECTOR OVERSPREADS THE REGION DURING LATE AFTERNOON AND EVENING WITH HI RES GUID INDICATING TEMPS AND DEW PTS INTO THE 50S ACROSS EASTERN CT/RI AND EASTERN MA. WARM SECTOR MAY STRUGGLE TO ADVANCE NORTH OF THE MASS PIKE AND WEST OF I-495 IN NORTHEAST MA. THESE HIGHER DEW PTS COUPLED WITH SOME WIND WILL YIELD APPRECIABLE SNOW MELT. ALSO THIS CONDENSATION WILL RESULT IN AREAS OF DENSE FOG. NOT QUITE SURE ON THE AREAL EXTENT OF THE DENSE FOG SO WILL HOLD OFF ON ANY HEADLINES FOR NOW...BUT DENSE FOG COULD IMPACT THE LATE DAY COMMUTE. LATER SHIFTS WILL NEED TO MONITOR THIS. WINDS...STRONG LOW LEVEL JET WILL NOT TRANSLATE DOWN TO THE SURFACE GIVEN STEEP INVERSION. THUS EXPECTING SSW WINDS TO REMAIN BELOW WIND ADVISORY CRITERIA. HOWEVER BREEZY CONDITIONS OF 20-30 MPH ARE LIKELY ALONG THE SOUTH COAST. THU NIGHT... BAROCLINIC WAVE BEGINS TO TRAVERSE COLD FRONT AS THIS BOUNDARY SAGS SOUTH. GOOD FGEN ALONG AND BEHIND THE FRONT COUPLED WITH SOME NEGATIVE EPV /INSTABILITY/ WILL LIKELY YIELD ANOTHER ROUND OF MODERATE TO HEAVY RAIN BANDS. BLYR IS VERY WARM INITIALLY BUT DOES COOL AS POST FRONTAL AIRMASS BLEEDS SOUTHEAST. ITS POSSIBLE THAT RAIN MAY END AS AN HOUR OR TWO OF SNOW LATE THU NIGHT INTO FRI MORNING. MAY NEED TO WATCH THIS IN CASE BLYR COOLS QUICKER THAN MODELS SUGGEST. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... DETAILS... FRIDAY...MODERATE TO HIGH CONFIDENCE. UPPER LEVEL LONG WAVE TROUGH MOVES SLOWLY E DURING THE DAY...BUT REMAINS ACROSS NY STATE. A SHORT WAVE WORKING OUT AHEAD OF THIS SYSTEM WILL MOVE CLOSE TO OR JUST S OF NEW ENGLAND LATE FRIDAY... ASSOCIATED WITH SECONDARY COLD FRONT WHICH WILL DURING FRI AFTERNOON. EXPECT SPOTTY LIGHT PRECIP TO LINGER THROUGH THE DAY ACROSS MOST OF THE REGION. HIGHS WILL BE IN THE MID 40S TO AROUND 50. FRIDAY NIGHT THROUGH SATURDAY NIGHT...MODERATE CONFIDENCE. SHORT RANGE MODELS SIGNALING THE H5 TROUGH CONTINUES TO DIG DOWN TO THE MID ATLC STATES...AND BECOMES A NEUTRAL TILT. A COUPLE OF MODELS /GFS AND TO A LESSER DEGREE THE ECMWF/ EVEN SHOWING SIGNS OF A CUTOFF FORMING WHILE REMAINING SLOWLY PROGRESSIVE DURING THIS TIMEFRAME. THIS WILL HELP THE SHORT WAVE WRAPPING AROUND THIS DIGGING TROUGH DEVELOP S OF NEW ENGLAND FRI NIGHT. STILL SOME QUESTION AS TO HOW CLOSE TO THE COAST THE PRECIP SHIELD WILL BE... BUT MOST MODELS AND ENSEMBLES HOLDING LIGHT PRECIP ACROSS THE REGION WITH THE BEST CHANCE GENERALLY NEAR OR S OF THE MASS PIKE. COLDER AIR WORKS IN BEHIND THE DEPARTING AND WEAKENING COLD FRONT. PRETTY GOOD LIFT AND FORCING...ALONG WITH COLD TEMPS ALOFT...SO WILL SEE PRECIP CHANGE BACK OVER TO LIGHT SNOW FRI NIGHT. EXPECT MAINLY LESS THAN AN INCH WITH THE BEST CHANCE ACROSS INTERIOR SECTIONS OF EASTERN AND CENTRAL MA/W RI INTO NE CT. WILL NEED TO MONITOR THIS SHORT WAVE AS IT SLOWLY MOVES OFFSHORE. LOWS FRI NIGHT WILL RANGE FROM THE LOWER-MID 20S INLAND TO AROUND 30 NEAR THE S COAST. HAVE CARRIED SLIGHT CHANCE TO LOW CHANCE POPS. SHOULD SEE PRECIP CHANGE BACK TO RAIN SAT AROUND MID MORNING BEFORE TAPERING OFF SAT AFTERNOON. TIMING OF THE EXIT STILL SOMEWHAT IN QUESTION...BUT MODELS AND ENSEMBLES IN PRETTY GOOD AGREEMENT. HIGHS SAT WILL BE IN THE MID 30S TO AROUND 40. WILL BE A BIT BLUSTERY SAT MAINLY ALONG THE IMMEDIATE COAST WITH SOME GUSTS UP TO AROUND 25 KT BUT SHOULD DIMINISH LATE IN THE DAY. SHOULD SEE CLEARING CONDITIONS MOVE IN SAT NIGHT AS HIGH PRES RIDGE WORKS E. SOME MODELS DO LINGER THE PRECIP INTO EARLY SAT NIGHT...SO SOMEWHAT LOWERED CONFIDENCE DURING THIS TIMEFRAME. N-NW WINDS WILL STIR AS TEMPS FALL BACK TO THE UPPER TEENS TO LOWER 20S WELL INLAND TO AROUND 30 ACROSS THE OUTER CAPE AND NANTUCKET. SUNDAY AND SUNDAY NIGHT...HIGH CONFIDENCE. RIDGING AT THE SURFACE AND ALOFT BUILDS ACROSS THE REGION. WILL SEE A GOOD AMOUNT OF SUN. HOWEVER...H85 TEMPS RANGE FROM ONLY -9C TO -11C EARLY SUN THEN ONLY SLOWLY RISE. HIGHS WILL BE IN THE UPPER 30S TO MID 40S...WELL BELOW SEASONAL NORMALS FOR LATE MARCH. CLOUDS WILL MOVE IN SUNDAY NIGHT AS FAST NW FLOW ALOFT BEGINS TO BRING IN HIGH LEVEL MOISTURE FROM NEXT APPROACHING SYSTEM. WINDS SHIFT TO SW OVERNIGHT...SO LOWS SUN NIGHT FALL BACK TO THE UPPER 20S TO LOWER 30S /ONLY SLIGHTLY BELOW SEASONAL NORMS/. MONDAY...LOW TO MODERATE CONFIDENCE. ANOTHER SHORT WAVE IN FAST FLOW ALOFT APPROACHES NORTHERN NEW ENGLAND DURING THIS TIMEFRAME. S-SW WINDS BRING MILDER TEMPS. LOOKS LIKE MOST OF THE ENERGY AND LIMITED MOISTURE WILL REMAIN ACROSS NORTHERN NEW ENGLAND...THOUGH COULD SEE SOME WIDELY SCT SHOWERS WITH HIGHS IN THE 40S WITH A FEW SPOTS POSSIBLY TOUCHING 50. CARRIED SLIGHT CHANCE POPS WITH THIS SYSTEM. THIS SYSTEM DOES MOVE ALONG...SO SHOULD SEE IMPROVEMENT MON EVENING. TUESDAY AND WEDNESDAY...LOW CONFIDENCE. WIDE VARIANCE IN MODEL SOLUTIONS LENDS TO LOW CONFIDENCE DURING THIS TIMEFRAME. FOR NOW...CARRIED DRY CONDITIONS ON TUESDAY AND WEDNESDAY WITH HIGH PRES BUILDING ACROSS. HOWEVER...NEXT SYSTEM MAY BEGIN TO APPROACH THE E SLOPES OF THE BERKSHIRES WED AFTERNOON. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. HIGH CONFIDENCE ON OVERALL FORECAST...BUT SOME UNCERTAINTY ON EXACT TIMING. TONIGHT... WILL SEE -RA WITH LOCAL MIX WITH SLEET THROUGH 02Z-03Z WITH BRIEF PERIODS OF MVFR-IFR VSBYS. CIGS/VSBYS WILL LOWER FURTHER AFTER 03Z ESPECIALLY ACROSS RI/E MA. EXPECT RAIN TO CHANGE TO DRIZZLE ALONG WITH PATCHY FOG AFTER MIDNIGHT. LLWS DEVELOPS AROUND OR AFTER 05Z AS SW LOW LEVEL JET AT 50-60 KT MOVES ACROSS RI/E MA. THU... IFR/LIFR FOR MOST TERMINALS. DRIZZLE AND FOG IN THE MORNING GIVE WAY TO A PERIOD OF RAIN EARLY AFTERNOON. LOW PROB OF ISOLATED THUNDER. STRONG LOW LEVEL SSW JET DEVELOPS ALONG SOUTH COAST IN THE AFTERNOON AND EVENING YIELDING POTENTIAL LLWS. THU NIGHT... LLWS DIMINISHES AS LOW LEVEL JET MOVES OFFSHORE. A FEW BANDS OF HEAVY RAIN POSSIBLE AS COLD FRONT SLIDES THRU THE AREA. IFR/LIFR BUT SLOW IMPROVEMENT TOWARD MORNING NW TO SE. KBOS TAF...HIGH CONFIDENCE ON OVERALL TRENDS BUT SOME UNCERTAINTY ON EXACT TIMING OF LOWER CIGS/VSBYS. KBDL TAF...HIGH CONFIDENCE ON OVERALL TRENDS BUT SOME UNCERTAINTY ON EXACT TIMING OF LOWER CIGS/VSBYS. OUTLOOK...FRIDAY THROUGH MONDAY...MODERATE TO HIGH CONFIDENCE FRIDAY THROUGH SATURDAY...MVFR CIGS/VSBYS LINGERING THROUGH A GOOD PORTION OF THIS PERIOD. WILL SEE SCT -SHRA DURING FRI...CHANGING OVER TO -SHSN FRI NIGHT FROM N-S...THOUGH WILL LIKELY BE MIXED -RASN ALONG THE IMMEDIATE COAST. SATURDAY NIGHT INTO SUNDAY...VFR CONDITIONS LIKELY. SUNDAY NIGHT AND MONDAY...VFR CONDITIONS EARLY SUN NIGHT WILL LOWER TO MVFR TO LOCAL IFR IN ISOLD -SN MAINLY AROUND OR AFTER MIDNIGHT. EXPECT -SN TO CHANGE TO -RA MONDAY MORNING WITH CONTINUED MVFR CONDITIONS. SHOULD SEE CONDITIONS IMPROVE TO VFR FROM W-E MONDAY AFTERNOON/EVENING. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TONIGHT...MODEST S-SW WINDS. VSBY MAY LOWER IN FOG LATE. EVENING SHOWERS...THEN PATCHY FOG AND DRIZZLE AFTER MIDNIGHT. THU...INCREASING S-SW WINDS 20-30 KT...STRONGEST AFTERNOON AND EVENING. SEAS BUILD ON THE SOUTHERN WATERS. DENSE FOG POSSIBLE. SHOWERS WITH ISOLATED TSTM POSSIBLE. THU NIGHT...S-SW WINDS 20-30 KT EARLY SHIFT TO N-NW TOWARD MORNING. HEAVY SHOWERS LIKELY. FOG EARLY SHOULD LIFT WITH WIND SHIFT. OUTLOOK...FRIDAY THROUGH MONDAY... HIGH CONFIDENCE FRIDAY. MODERATE CONFIDENCE FRIDAY NIGHT THROUGH MONDAY. FRIDAY AND FRIDAY NIGHT....WINDS SHIFT TO N-NW WITH GUSTS UP TO 25-30 KT. LOW PROB OF GALE GUSTS LATE IN THE DAY INTO FRI NIGHT. EXPECT SEAS TO REMAIN AOA 5 FT...MAINLY ACROSS THE OUTER WATERS. SATURDAY AND SATURDAY NIGHT...EXPECT NW WINDS TO CONTINUE TO GUST TO SMALL CRAFT LEVELS WITH SEAS BUILDING UP TO 6-9 FT ON THE OUTER WATERS THROUGH SAT NIGHT. SUNDAY THROUGH MONDAY...WINDS AND SEAS BRIEFLY SUBSIDE AS WINDS BACK TO SW SUN/SUN NIGHT...THOUGH SEAS MAY REMAIN AROUND 5 FT ON THE FAR OUTER WATERS. WINDS AND SEAS INCREASE AGAIN MONDAY AHEAD OF NEXT SYSTEM SO SMALL CRAFTS WILL LIKELY BE RENEWED. && .HYDROLOGY... BASIN AVERAGE RAINFALL AMOUNTS RANGE FROM 0.5 TO 1 INCH ACROSS THE REGION...POSSIBLY 1.25 TO 1.50 IN SPOTS...NOT WIDESPREAD. NOHRSC MODELING ADDS 1 TO 3 INCHES OF WATER FROM MELTING SNOW DUE TO TEMPERATURES IN 40S/LOWER 50S COMBINED WITH DEWPOINTS RISING INTO 40S AND SW WINDS. THIS WILL BRING RISES ON RIVERS AND STREAMS THROUGH THU...ESPECIALLY SMALLER ONES WHICH MAY APPROACH MINOR FLOOD STAGE. HOWEVER GIVEN RAINFALL IS SPREAD OUT OVER A LONG DURATION WITH MANY DRY PERIODS ALONG WITH DEW PTS ONLY BRIEFLY JUMPING INTO THE 50S...RISK OF FLOODING IS TOO LOW FOR HEADLINES. IN FACT RFC ONLY HAS A FEW POINTS ENTERING ACTION STAGE WITH NONE IN MINOR FLOOD. THUS NO HEADLINES. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON TO 11 PM EDT THURSDAY FOR ANZ231>237. SMALL CRAFT ADVISORY UNTIL NOON EDT THURSDAY FOR ANZ250. SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ254. SMALL CRAFT ADVISORY FROM NOON THURSDAY TO 6 AM EDT FRIDAY FOR ANZ255-256. && $$ SYNOPSIS...NOCERA/EVT NEAR TERM...NOCERA/EVT SHORT TERM...NOCERA LONG TERM...EVT AVIATION...NOCERA/EVT MARINE...NOCERA/EVT HYDROLOGY...NOCERA

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