Area Forecast Discussion
Issued by NWS Boston, MA

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487 FXUS61 KBOX 282304 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 704 PM EDT THU APR 28 2016 .SYNOPSIS... A SERIES OF WEAK LOWS WILL TRACK SOUTH OF NEW ENGLAND TONIGHT THROUGH FRI NIGHT...POSSIBLY BRINGING A PERIOD OR TWO OF LIGHT RAIN/SPRINKLES TO CONNECTICUT...RHODE ISLAND AND SOUTHEAST MASSACHUSETTS. OTHERWISE REMAINDER OF THE REGION REMAINS DRY THANKS TO HIGH PRESSURE STRETCHING FROM CENTRAL CANADA TO NORTHERN NEW ENGLAND. THIS WILL YIELD MILD AFTERNOONS AND CHILLY NIGHTS. A RETURN TO UNSETTLED AND COOL WEATHER IS EXPECTED SUNDAY INTO MONDAY AS LOW PRESSURE TRACKS SOUTH OF NEW ENGLAND. A DRYING TREND FOLLOWS TUESDAY...HOWEVER MORE UNSETTLED WEATHER IS POSSIBLE MID TO LATE NEXT WEEK AS A NEW AREA OF LOW PRESSURE MAY FORM ALONG OR NEAR THE EASTERN SEABOARD. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 7 PM UPDATE... PREVIOUS FORECAST VERIFYING NICELY WITH DRY WEATHER LINGERING ACROSS THE ENTIRE REGION. RAIN SHIELD ENTERING SOUTHWEST CT CONTINUES TO ERODE THANKS TO 20+ DEW PT DEPRESSIONS. 15Z SREF... 18Z GFS AND 18Z NAM CONTINUE THREAT FOR A PERIOD OF VERY LIGHT RAIN/SPRINKLES ACROSS CT/RI AND SOUTHEAST MA. CURRENT FORECAST CAPTURES THIS WELL SO NO MAJOR CHANGES WITH THIS FORECAST UPDATE OTHER THAN ADJUSTING HOURLY TEMPS AND DEW PTS TO BETTER REFLECT CURRENT OBSERVATIONS. MARINE LAYER HAS ADVANCED WELL INLAND WITH ALL OF RI AND SOUTHEAST MA NOW ONLY IN THE U40S. MEANWHILE FIT STILL HOLDING ONTO 60 DEGS. EARLIER DISCUSSION BELOW. =========================================================================== CLOUDS THICKENING FROM THE S/W UP AGAINST HIGH PRESSURE AND DRY- SINKING AIR. THIS ACTIVITY PARENT WITH MID LEVEL VORTEX ENERGY STRETCHING THROUGH THE CONFLUENT FLOW PATTERN ACROSS AND TO THE E OF NEW ENGLAND. INTO THIS EVENING ONLY EXPECTING THICKENING CLOUDS OVER S NEW ENGLAND AND REMAINING MOSTLY DRY. THERE IS THE PRESENCE OF SOME MID LEVEL FORCING ALLOWING FOR LIFT OF UPSLOPING MOISTURE RESULTING IN RADAR RETURNS AT HIGHER LEVELS OVER THE LOWER HUDSON RIVER VALLEY. WHILE AN ABUNDANCE OF DRY AIR...CAN NOT RULE OUT IT REACHING THE GROUND. WILL HINT CHANCE POPS OVER THE HARTFORD METRO AND POINTS S/W. TONIGHT... WHERE CAN WE EXPECT TO SEE CLOUDS AND WET WEATHER? CONFIDENCE IS TOWARDS THE S/W WHERE THE MID-UPPER LEVEL CONFLUENCE RELAXES IN A REGIME OF WEAK ISENTROPIC ASCENT AND SOME MID-LEVEL FORCING PARENT WITH STRETCHED VORTEX ENERGY. ANY OUTCOMES WOULD BE LIGHT MAINLY OVER S/W CT N OF A W TO E FRONTAL BOUNDARY OFF THE DELMARVA / NJ COASTLINE. NOT A ROBUST EVENT. HARDLY A WASHOUT. THINKING NUISANCE. SPRINKLES TO VERY LIGHT SHOWERS. FOCUS MAINLY SW CT. DRY ELSEWHERE PER ACCOMPANYING AIRMASS AND SUBSIDENCE ASSOCIATED WITH HIGH TO N. NON-NAM CONSENSUS. SO OVERALL A MOSTLY DRY AND QUIET NIGHT FOR MUCH OF S NEW ENGLAND. INCREASING AND THICKENING CLOUDS FROM THE S/W. SUBSEQUENTLY MILDER WITH LOWS AROUND THE UPPER 30S S BUT COOLER N UNDER THE INFLUENCE OF HIGH PRESSURE AND LIGHT WINDS UNDER LESS CLOUDS. CAN NOT RULE OUT RADIATIONAL COOLING ACROSS THE HIGH TERRAIN AND WITHIN INTERIOR VALLEYS OF N MASSACHUSETTS WHICH COULD DRIVE LOWS DOWN TO THE UPPER 20S IF CONDITIONS ARE RIGHT. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... FRIDAY... KEEPING IT DRY WITH CLOUDS LINGERING. POTENT MID LEVEL VORTEX OUT OF THE S GREAT LAKES INVOKES WEAK LOW PRESSURE ACROSS THE APPALACHIANS TOWARDS THE DELMARVA LATE. ISALLOBARIC RESPONSE MAINTAINS DRY AIR AND HIGH PRESSURE ACROSS MUCH OF NEW ENGLAND WITH A COMPONENT OF DOWN-SLOPING AIR AND SUBSIDENCE THROUGH THE LOW LEVELS. CONSIDERING THE E ONSHORE FLOW AND THE LIKELIHOOD OF CLOUDS LINGERING MAY NUDGE A FEW DEGREES LOWER ON HIGHS FORECAST AROUND THE UPPER 50S. FRIDAY NIGHT... RENEWED FOCUS OF LIGHT SHOWERY WEATHER S/W. VORTEX AND ACCOMPANYING SURFACE LOW EMERGING OFF THE DELMARVA WITH PARENT JET ENERGY AND DYNAMICS. CRUX OF FORCING / ISENTROPIC ASCENT SLIDES S OF THE REGION AS HIGH PRESSURE AND DRY AIR REMAIN INFLUENTIAL N/E WITH SINKING AIR IN THE LOW LEVELS. AM CONFIDENT THAT SW CT COULD SEE LIGHT SHOWERS. MAJORITY OF WET WEATHER WILL STAY S AND OFFSHORE. MAJORITY OF THE ACTIVITY DURING THE EVENING WITH CLOUDS IN GREATER ABUNDANCE S/W. SO OVERALL A DRY FORECAST FOR MUCH OF S NEW ENGLAND. A CLEARING TREND WITH HIGH PRESSURE BUILDING BACK IN AND SINKING AIR BY MIDNIGHT AND CONTINUING THROUGH SATURDAY MORNING. WINDS TURNING LIGHT WITH CLEARING...COULD SEE SOME PLACES RADIATE OUT DECENTLY AS LOWS DROP INTO THE 30S. FOCUS MAINLY N/E ESPECIALLY WITH SANDY SOILS. && .LONG TERM /SATURDAY THROUGH THURSDAY/... HIGHLIGHTS... * DRY AND MILD SATURDAY W/HIGHS 60-65...50S ALONG THE COAST * COOLER WITH PERIODS OF RAIN SUN AND MON * DRYING TREND LIKELY TUE ALONG WITH MILDER TEMPS * MORE UNSETTLED WEATHER POSSIBLE MID TO LATE NEXT WEEK SATURDAY ... WEAK MID LEVEL ANTICYCLONIC FLOW OVER THE AREA PROVIDES SURFACE RIDGING AND DRY WEATHER ACROSS THE REGION. THUS EXPECT LOTS OF SUNSHINE. 850 TEMPS HOVERING AROUND 0C BUT MODEL SOUNDINGS INDICATE A DEEP BLYR WITH MIXING UP TO 800 MB OR SO. THEREFORE HIGHS 60-65 SEEM ACHIEVABLE INLAND WITH SEABREEZES ALONG THE COAST KEEPING TEMPS IN THE 50S NEAR SHORE. OVERALL A REAL NICE DAY BY LATE APRIL STANDARDS. SUN INTO MON ... MODELS CONTINUE TO SPEED UP THE ARRIVAL OF MOISTURE INTO NEW ENGLAND ASSOCIATED WITH UPPER LOW CURRENTLY OVER THE 4 CORNERS REGION AND DESERT SOUTHWEST. THIS FASTER TREND SEEMS REASONABLE GIVEN THE UPPER AIR PATTERN FEATURES CONFLUENT FLOW ACROSS NEW ENGLAND. SUNDAY MAY BEGIN DRY ESPECIALLY ACROSS RI AND EASTERN MA WHERE ALL GUID INCLUDING THE NEW 12Z ECMWF AND 12Z UKMET HAVE PRECIP JUST CROSSING THE NY/WESTERN NEW ENGLAND BORDER AT 12Z SUNDAY. HOWEVER WITH THE FAST CONFLUENT FLOW ALOFT RAIN WILL LIKELY OVERSPREAD THE AREA QUICKLY FROM WEST TO EAST SUNDAY. ALTHOUGH STILL TOO FAR OUT IN TIME TO NAIL DOWN SPECIFIC TIMING. AS PREVIOUS FORECASTER MENTIONED WITH SURFACE WAVE TRACKING SOUTH OF NEW ENGLAND THE COMBINATION OF NE WINDS OFF THE CHILLY OCEAN COMBINED WITH PERIODS OF RAIN WILL LIMIT HIGHS TO THE U40S AND L50S...POSSIBLY COOLER. THEREFORE HIGHS SUNDAY AND MONDAY WERE DERIVED FROM THE COOLER 2 METER MODEL TEMPS VS. THE MILDER MOS TEMPS. COOLEST READINGS LIKELY ACROSS CT AND WESTERN-CENTRAL MA GIVEN DRY WEATHER MAY LINGER FOR A TIME ACROSS RI AND EASTERN MA EARLY SUNDAY. TUE ... SHOULD BE A PERIOD OF DRY WEATHER AFTER SUN/MON RAIN EVENT WITH MEAN TROUGH AXIS MOVING OFFSHORE. GIVEN ENSEMBLE MEAN 850 TEMPS OVER THE AREA ARE AROUND +2C/+3C AND SURFACE PRESSURES NEAR 1015 MB...FULL SUNSHINE COULD POTENTIALLY YIELD HIGHS BACK INTO THE 60S INLAND TUE. OF COURSE COOLER NEAR THE COAST GIVEN WEAK PGRAD SUPPORTING POTENTIAL SEABREEZES. WED INTO THU ... LOOKS UNSETTLED AS ENSEMBLES AND DETERMINISTIC GUIDANCE SUGGEST MEAN TROUGH RELOADS WITH NEW JET ENERGY OVER SOUTHEAST CANADA AND THE NORTHEAST. THIS SEEMS REASONABLE GIVEN THE LARGE SCALE FLOW FEATURES A POSITIVE HEIGHT ANOMALY OVER THE ROCKIES AND A CORRESPONDING DOWNSTREAM NEGATIVE HEIGHT ANOMALY OVER HUDSON BAY. THIS WILL SUPPORT EAST COAST TROUGHING AND POTENTIAL UNSETTLED WEATHER HERE IN THE FORM OF SHOWERS/PERIODS OF RAIN. COOLER TOO GIVEN CLOUDS/PRECIP AND NORTHEAST FLOW. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. 7 PM UPDATE ... NOT MUCH CHANGE TO 18Z AND 21Z TAFS. DRY WEATHER PREVAILS WITH THE EXCEPTION OF SOME VERY LIGHT RAIN/SPRINKLES TONIGHT ACROSS CT/RI AND SOUTHEAST MA. EARLIER DISCUSSION BELOW. =================================================================== SHORT TERM /THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE. VFR THROUGH FRIDAY NIGHT. LOW RISK MVFR ACROSS S/W CT TONIGHT AND AGAIN FRIDAY NIGHT. E/SE FLOW TONIGHT BECOMING MORE E AND BREEZY INTO FRIDAY EVENING BEFORE BECOMING LIGHT AND BACKING N INTO SATURDAY MORNING. KBOS TERMINAL...VFR. SEA-BREEZE ASHORE. FLOW TO REMAIN E THROUGH FRIDAY EVENING. STRONGEST DURING THE AFTERNOON TO EVENING HOURS ON FRIDAY. KBDL TERMINAL...VFR. OUTLOOK /SATURDAY THROUGH TUESDAY/... SAT ... HIGH CONFIDENCE. MAINLY VFR CIGS. SUNDAY INTO MONDAY...MODERATE TO HIGH CONFIDENCE ON TRENDS WITH MVFR AND LOCALIZED IFR POSSIBLE IN PERIODS OF RAIN. TUESDAY ... DRYING TREND WITH VFR POSSIBLE AND LIGHT WINDS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE. MAINLY QUIET BOATING WEATHER AS HIGH PRESSURE REMAINS DOMINANT. THERE IS A LOW RISK OF RAIN SHOWERS ON THE S WATERS CLOSER TO BLOCK / LONG ISLAND TONIGHT AND AGAIN FRIDAY NIGHT. E/SE FLOW BECOMING BREEZY INTO FRIDAY AFTERNOON AND EVENING WITH POSSIBLE GUSTS UP TO 20 KTS DURING WHICH TIME ISOLATED 5 FOOT SEAS ARE POSSIBLE OVER THE WATERS S OF ISLANDS. WINDS BACK NE INTO SATURDAY MORNING. OUTLOOK /SATURDAY THROUGH TUESDAY/... SATURDAY ... QUIET BOATING WEATHER WITH LIGHT WINDS AND TRANQUIL SEAS. SUNDAY INTO MON ... INCREASING EASTERLY WINDS LATE SUN INTO MON AS LOW PRES TRACKS TO THE SOUTH. A PERIOD OF SCA GUSTS POSSIBLE SUN NIGHT INTO MON DEPENDING ON TRACK AND INTENSITY OF LOW PRES. ROUGH SEAS GIVEN THE LONG ENE FETCH. VSBYS REDUCED AT TIMES IN SHOWERS AND PATCHY FOG. TUESDAY ... IMPROVING/DRYING TREND. LEFTOVER ENE SWELLS LIKELY FOR THE OCEAN WATERS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...NOCERA/SIPPRELL NEAR TERM...NOCERA/SIPPRELL SHORT TERM...SIPPRELL LONG TERM...NOCERA AVIATION...NOCERA/SIPPRELL MARINE...NOCERA/SIPPRELL

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