Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 252028 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 428 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. AN OCEAN STORM MAY BRING A PERIOD OF SNOW FRI NIGHT INTO SAT NIGHT. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... *** A PERIOD OF RAIN AND QUICK TEMP DROP THIS EVENING *** WARM ADVECTION CLOUDS RAPIDLY OVERSPREADING THE REGION FROM WEST TO EAST LATE THIS AFTERNOON. THIS IS IN RESPONSE TO ROBUST MID LEVEL JET AND ASSOCIATED WARMING ALOFT. RAIN ALREADY INTO THE NYC AREA AND LOWER HUDSON VALLEY. BOTH GLOBAL AND HI RES GUID IN GOOD AGREEMENT ON TIMING WITH RAIN OVERSPREADING CT AND WESTERN-CENTRAL MA 5 PM TO 7 PM...THEN 7 PM TO 9 PM ACROSS RI AND EASTERN MA. EXPECT A NOTICEABLE TEMP DROP TOO AS LOW LEVEL DRY AIR YIELDS CHILLY WET BULB TEMPS. SO AS TEMPS NEAR 50 LATE THIS AFTERNOON AS RAIN DEVELOPS AND IN HEAVIER SHOWERS TEMPS WILL FALL QUICKLY INTO THE 30S! SOUNDINGS ALSO SUGGEST A LOW PROB OF SOME SLEET MIXING IN FOR A TIME THIS EVENING. SURFACE TEMPS MAY BRIEFLY APPROACH 32 IN SOME OF THE HIGHER ELEVATIONS BUT THINKING WITH HIGHS TODAY MU40S AND HIGH LATE MARCH SUN ANGLE ENOUGH SOLAR HEAT WAS ABSORBED BY PAVED SURFACES TO PRECLUDE ANY ICING ISSUES. LATER THIS EVENING AND OVERNIGHT DRY AIR ALOFT OVERSPREADS THE REGION RESULTING IN RAIN TRANSITIONING TO MORE DRIZZLE AND FOG OVERNIGHT. NOT AS COOL AS PREVIOUS NIGHTS GIVEN WEAK LOW LEVEL WARM ADVECTION...HOWEVER TRUE WARM SECTOR DOESN/T OVERSPREAD THE AREA UNTIL THU AFTN. && .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/... HIGHLIGHTS... * BLUSTERY AND BELOW AVERAGE TEMPS FOR THE WEEKEND * WEAK DISTURBANCE POSSIBLE ON MONDAY MODEL GUIDANCE... OVERALL AMPLIFIED TROUGH PATTERN WILL CONTINUE WITH 00Z GUIDANCE IN GOOD AGREEMENT. STILL SOME TIMING/INTENSITY ISSUES FOR UPCOMING SYSTEMS. DEEP TROUGH AXIS WILL MOVE OVERHEAD SAT INTO EARLY SUNDAY FOLLOWED BY A QUICK MOVING RIDGE. BY LATE SUNDAY INTO MONDAY ANOTHER SHORTWAVE WILL MOVE INTO SOUTHERN NEW ENGLAND. GUIDANCE IS SPLIT ON THIS SYSTEM AS THE GFS IS MORE AMPLIFIED COMPARED TO THE EC. OTHERWISE...MIDDLE OF NEXT WEEK LOOKS TO BE A POSSIBLE PATTERN CHANGE. DETAILS... * FRIDAY INTO SATURDAY...MODERATE CONFIDENCE. DEEP SHORTWAVE WILL DIG FROM THE GREAT LAKES DOWN INTO THE SOUTHEAST ALLOWING FOR DEEP TROUGH TO SETTLE OVER THE NORTHEAST BY LATE FRIDAY/SATURDAY. PRIOR TOO THIS SECONDARY COLD FRONT WILL SWEEP ACROSS THE AREA FROM WEST TO EAST ON FRIDAY PUSHING MOST OF THE PRECIP OFFSHORE...BUT USHERING COLDER AIR ALOFT. THIS FRONTAL PASSAGE WILL OCCUR LATE IN THE DAY/EVENING HOURS TO MUCH OF THE REGION MAY REACH INTO THE MID 40S TO LOW 50S. COULD SEE A FEW POP UP SHOWERS ALONG THE FRONT AS IT PASSES THROUGH AS THERE IS SOME LINGER MOISTURE. AM NOT EXPECTING MUCH IN THE WAY OF ACCUMULATIONS. COLD AIR WILL USHER ACROSS THE REGION FRIDAY NIGHT INTO SATURDAY. AS UPPER LEVEL TROUGH PUSHES OVERHEAD...COULD SEE SOME SCT SNOW SHOWERS DURING THE DAY ON SATURDAY. FEEL THESE MAY BE MORE CONVECTIVELY DRIVEN AS THERE IS SOME MOISTURE IN THE LOW LEVELS AND LAPSE RATES STEEPEN DURING THE DAY. THEREFOR INSERT SLIGHT CHC POP INTO THE FORECAST...WITH THE AREA WITH THE BEST CHANCE OF SEEING A SNOW SHOWER BEING WEST OF I-95. TEMPS OVERNIGHT WILL FALL WELL BELOW NORMALS WITH LOWS AROUND THE TEENS TO LOW 20S. TEMPS MAY BE SLIGHTLY COLDER AT WE COULD RADIATE OUT THANKS TO CLEARING SKIES AND LIGHT WINDS ACROSS THE INTERIOR. * SUNDAY...HIGH CONFIDENCE. SUNDAY IS A TRANSITION DAY AS DEEP TROUGH BEGINS TO PULL OFFSHORE AND UPPER LEVEL RIDGE MOVES INTO THE REGION. TEMPS ON SUNDAY WILL WARM INTO THE LOW TO MID 40S...WHICH IS STILL SEVERAL DEGREES BELOW AVERAGE. EXPECT MOSTLY CLEAR SKIES IN THE MORNING BUT THEY WILL BEGIN TO CLOUD UP DURING THE AFTERNOON AS THE NEXT SYSTEM APPROACHES FROM THE WEST. * MONDAY INTO TUESDAY...LOW CONFIDENCE. NEXT UPPER LEVEL DISTURBANCE WILL IMPACT SOUTHERN NEW ENGLAND LATE SUNDAY INTO MONDAY. STILL A GOOD AMOUNT OF SPREAD AMONGST THE GUIDANCE WITH THE EC KEEPING THE SYSTEM TO THE NORTH WHILE THE GFS BRINGS THE SYSTEM OVER SNE. CONTINUED TO KEEP PRECIP IN THE FORECAST FOR NOW WITH THIS SYSTEM. SURFACE LOW ACROSS THE GREAT LAKES WILL PASS JUST NORTH OF SNE...DRAGGING ASSOCIATED COLD FRONT WITH IT. TEMPS AT THE ONSET LOOK TO BE COOL THEN WARM UP DURING THE DAY ON MONDAY PRIOR TO FRONTAL PASSAGE. THIS MAY CAUSE P-TYPE ISSUES...BUT BECAUSE THIS IS SEVERAL DAYS AWAY WILL NEED TO REEVALUATE. FRONT WILL PASS THROUGH LATE MONDAY WITH HIGH PRESSURE AND COOLER TEMPS IN ITS WAKE FOR TUESDAY. && .AVIATION /21Z WEDNESDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. HIGH CONFIDENCE ON FORECAST THEME BUT SOME UNCERTAINTY ON EXACT TIMING. THRU 00Z... A PERIOD OF RAIN OVERSPREADS CT AND WESTERN-CENTRAL MA BY 00Z WITH MVFR CONDITIONS. LOW RISK OF SOME SLEET MIXED IN. FARTHER EAST DRY WITH VFR ACROSS RI AND EASTERN MA. AFTER 00Z... A PERIOD OF MVFR IN RAIN THIS EVENING WITH LOW RISK OF SOME SLEET MIXED IN AT TIMES. LOWERING TO IFR/LIFR AFTER MIDNIGHT ESPECIALLY ACROSS RI AND EASTERN MA. RAIN TRANSITIONS TO DRIZZLE AND PATCHY FOG SECOND HALF OF THE NIGHT. LOW RISK OF LLWS AROUND 06Z IN RESPONSE TO 50-60 KT SW JET OVER RI AND EASTERN 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 SUNDAY...MODERATE TO HIGH CONFIDENCE FRIDAY THROUGH SATURDAY...MVFR CONDITIONS IMPROVING TO VFR FROM WEST TO EAST ON FRIDAY. COULD SEE ISO/SCT MVFR CIGS ALONG COLD FRONT ON FRIDAY AND AGAIN DIURNALLY DRIVEN ON SATURDAY. SATURDAY NIGHT INTO SUNDAY...VFR CONDITIONS LIKELY. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TONIGHT...MODEST SSW WINDS. VSBY MAY LOWER IN FOG LATE. EVENING SHOWERS TOO. THU...INCREASING SSW WINDS 20-30 KT...STRONGEST AFTERNOON AND EVENING. SEAS BUILD ON THE SOUTHERN WATERS. DENSE FOG POSSIBLE. SHOWERS WITH ISOLATED TSTM POSSIBLE. THU NIGHT...SSW WINDS 20-30 KT EARLY SHIFT TO NNW TOWARD MORNING. HEAVY SHOWERS LIKELY. FOG EARLY SHOULD LIFT WITH WIND SHIFT. OUTLOOK...FRIDAY THROUGH SUNDAY... MODERATE TO HIGH CONFIDENCE FRIDAY. MODERATE CONFIDENCE FRIDAY NIGHT INTO SUNDAY. FRIDAY...WINDS SHIFT TO NW DURING THE DAY AS COLD FRONT PASSES. BUILDING SEAS WILL SLOWLY BEGIN TO SUBSIDE BY FRIDAY NIGHT. GUSTY WINDS LOW END GALES WILL ALSO BEGIN TO DISSIPATE AS THE FRONT PASSES THROUGH. FRIDAY NIGHT INTO SUNDAY...HIGH PRESSURE WILL SLIDE SOUTH OF THE REGION FRIDAY NIGHT/SATURDAY ALLOWING FOR THE WIND AND SEAS TO BEGIN TO SUBSIDE. THIS MAY TAKE SOME TIME AS WE COULD SEE LINGERING SCA WIND GUSTS THANKS TO CAA. SCA MAY BE NEEDED FOR THE WHOLE PERIOD. && .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 FROM 8 PM THIS EVENING TO NOON EDT THURSDAY FOR ANZ250. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT FRIDAY FOR ANZ254. SMALL CRAFT ADVISORY FROM NOON THURSDAY TO 6 AM EDT FRIDAY FOR ANZ255-256. && $$ SYNOPSIS...NOCERA NEAR TERM...NOCERA SHORT TERM...NOCERA LONG TERM...DUNTEN AVIATION...NOCERA/DUNTEN MARINE...NOCERA/DUNTEN HYDROLOGY...NOCERA

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