Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 021109 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 709 AM EDT MON MAY 2 2016 .SYNOPSIS... A WARM FRONT LIFTS INTO THE REGION TODAY...THEN SLIDES BACK TO THE SOUTH AND STALLS ALONG THE SOUTH COAST TONIGHT. LOW PRESSURE TRAVELS UP ALONG THE FRONT TUESDAY WHICH WILL BRING ANOTHER PERIOD OF RAIN TO THE REGION. YET ANOTHER LOW PRESSURE AREA DROPS THROUGH THE GREAT LAKES WEDNESDAY AND STALLS OVER THE WATERS SOUTH OF NEW ENGLAND FOR THURSDAY THROUGH SATURDAY BRINGING A CONTINUED THREAT OF SHOWERS ALTHOUGH THERE WILL BE DRY PERIODS AS WELL. A COLD FRONT WILL MOVE THROUGH NEXT SUNDAY WITH MORE SHOWERS. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 7 AM UPDATE... JUST SOME PATCHY DRIZZLE ACROSS SE NEW ENG THIS MORNING ALONG WITH LOW CLOUDS AND PATCHY FOG. NEXT BATCH OF RAIN ASSOCD WITH SHORTWAVE AND WARM FRONT MOVING NE FROM CENTRAL NY AND NE PA AND SHOULD OVERSPREAD MOSTLY INTERIOR LOCATIONS 15-21Z AS THE SHORTWAVE LIFTS INTO NORTHERN NEW ENG...WITH LESS COVERAGE NEAR THE COAST. ADJUSTED POPS TO REFLECT FORECAST TIMING AND AREAL COVERAGE OF RAIN. MODELS ARE STILL INDICATING SOME MARGINAL INSTABILITY ALONG THE SOUTH COAST. THEREFORE...THERE COULD BE SOME EMBEDDED THUNDER WITH THE RAIN ALONG THE SOUTH COAST. NOT HIGH ENOUGH CONFIDENCE IN THIS OCCURRING TO PUT IT IN THE GRIDS AT THIS POINT...BUT DEFINITELY SOMETHING TO KEEP IN MIND THROUGH THE DAY. LOW PRESSURE TO THE SOUTH HAS AN ACCOMPANYING WARM FRONT THAT MODELS DIFFER ON HOW FAR NORTH THE WARM FRONT COULD MOVE. DEPENDING ON WHICH MODEL VERIFIES...THE WARM FRONT COULD SURGE AS FAR NORTH AS THE MA/NH BORDER...OR STAY JUST ALONG OR SOUTH OF THE SOUTH COAST. THIS MAKES FOR A TRICKY TEMPERATURE FORECAST...AS AREAS SOUTH OF THE WARM FRONT COULD SOAR INTO THE 60S...WHILE THOSE NORTH OF THE FRONT WILL STAY IN THE LOW TO MID 50S. AT THIS POINT...HAVE THE WARM FRONT STAYING JUST OFF THE SOUTH COAST WITH MOST LOCATIONS IN THE 50S FOR HIGHS. WILL HAVE TO BE MONITORED THROUGHOUT THE DAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... WET PATTERN CONTINUES THROUGH TUESDAY WITH THE FRONT STALLED JUST SOUTH OF SOUTHERN NEW ENGLAND AND SEVERAL AREAS OF LOW PRESSURE TRAVELING ALONG IT. NOT EXPECTING THE ENTIRE PERIOD TO BE RAINY...BUT PERIODS OF RAIN COUPLED WITH AREAS OF DRIZZLE AND FOG WILL KEEP THE AREA IN THE GRAY...DAMP...COOL THAT WE OFTEN ASSOCIATE WITH APRIL RATHER THAN MAY. THERE IS A LITTLE BIT OF LINGERING ELEVATED INSTABILITY EARLY TONIGHT...BUT AT MOST EXPECT A FEW RUMBLES OF THUNDER OVER THE SOUTHERN WATERS. TEMPERATURES WILL BE RATHER STEADY GIVEN THE MOISTURE WITH LOWS IN THE MID 40S NORTH TO UPPER 40S SOUTH AND HIGH TEMPERATURES BARELY CLIMBING INTO THE 50S DURING THE DAY. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... HIGHLIGHTS... * UNSETTLED WEATHER WITH PERIODS OF SHOWERS AT TIMES INTO NEXT WEEKEND BUT THERE WILL BE DRY PERIODS AS WELL * MOSTLY BELOW NORMAL TEMPS...BUT MILDER NEXT WEEKEND OVERVIEW... MODELS ARE IN GOOD AGREEMENT ON THE OVERALL PATTERN IN THE EXTENDED PERIOD FEATURING A DEVELOPING OMEGA BLOCK ACROSS THE CENTRAL US WITH CLOSED LOWS MOVING INTO THE WEST COAST AND DROPPING SOUTH FROM THE GT LAKES TO THE MID ATLC COAST. STRONG BLOCKING DOWNSTREAM RIDGE OVER THE ATLANTIC WILL ENSURE THAT THIS PATTERN WILL BE SLOW TO BREAK DOWN SO WE ARE LOOKING AT AN UNSETTLED PERIOD INTO THE WEEKEND WITH SHOWERS FROM TIME TO TIME...BUT DRY PERIODS AS WELL. THERE ARE SIGNS THAT THE CLOSED LOW COULD GET KICKED EAST BY THE END OF THE WEEKEND AS NORTHERN STREAM VORTEX DROPS S FROM HUDSON BAY...DELIVERING A COLD FRONTAL PASSAGE. LOW CONFIDENCE ON TEMPS AS WELL AS TIMING AND DETAILS OF PRECIP WHICH WILL DEPEND ON THE PLACEMENT OF THE UPPER LOW AND ATTENDING SFC LOW. DETAILS... TUE NIGHT... LOW PRES S OF NEW ENG TUE EVENING WILL BE MOVING OFFSHORE AS SFC RIDGING BUILDS S INTO NEW ENG. ANY LIGHT RAIN SHOULD BE EXITING THE REGION IN THE EVENING AND MOST OF THE NIGHT SHOULD BE DRY...BUT CANT RULE OUT A FEW SHOWERS...ESPECIALLY INTERIOR AS MID LEVEL SHORTWAVE LIFTS TO THE N OF THE REGION. WEDNESDAY... A MID LEVEL SHORTWAVE MOVING THROUGH MID ATLC REGION THEN NE ALONG THE COAST WILL LIKELY GENERATE ANOTHER SFC WAVE S OF NEW ENG. WEAK WARM ADVECTION COMBINED WITH DEEPENING MOISTURE WILL LIKELY LEAD TO MORE SHOWERS DEVELOPING IN THE AFTERNOON...WITH BEST FOCUS ACROSS THE INTERIOR UNDER THE RIGHT ENTRANCE REGION OF THE UPPER JET. LOW CONFIDENCE TEMP FORECAST GIVEN WIDE RANGE IN MODEL GUIDANCE WITH ECMWF IN THE 40S...GFS 50S AND NAM 60S. LOW LEVEL NE FLOW AND DAMMING SIGNATURE WILL RESULT IN BELOW NORMAL TEMPS BUT LOW CONFIDENCE ON HOW COOL. WE WILL LEAN TOWARD GFS WITH HIGHS IN THE 50S WHICH IS A COMPROMISE...BUT POTENTIAL FOR COOLER EXITS. THURSDAY THROUGH SUNDAY... UNSETTLED CONDITIONS EXPECTED AT TIMES DURING THIS PERIOD BUT LOW CONFIDENCE ON TIMING...DURATION AND EXTENT OF SHOWER ACTIVITY. CLOSED LOW OVER THE OHIO VALLEY WILL GRADUALLY MOVE OFF THE MID ATLC COAST...BUT EXACT LOCATION SOUTH OF NEW ENG IS UNCERTAIN AND THIS WILL IMPACT SENSIBLE WEATHER. WHILE IT MAY BE WET AT TIMES THERE WILL BE PERIODS OF DRY WEATHER AS WELL. IT DOES APPEAR COLD FRONT WILL BE MOVING THROUGH ON SUNDAY WHICH WILL KICK LOW PRES OUT TO SEA BUT BRING A PERIOD OF SHOWERS. FORECAST CONFIDENCE ON TEMPS IS ALSO LOW AND WILL DEPEND ON EXTENT OF CLOUD COVER AND WHETHER THERE IS ANY BREAKS OF SUN. TEMPS WOULD LIKELY REACH WELL INTO THE 60S IN THE INTERIOR WITH ANY SUN...BUT COOLER ALONG THE COAST WITH PERSISTENT E/NE FLOW. MILDEST DAY MAY BE SUN AS WINDS TURN SW AHEAD OF APPROACHING FRONT WITH 70+ DEGREE READINGS POSSIBLE AWAY FROM THE COAST. && .AVIATION /11Z MONDAY THROUGH FRIDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY/...MODERATE CONFIDENCE. WIDESPREAD IFR CONDITIONS IN PLACE ACROSS SOUTHERN NEW ENGLAND EXPECTED TO CONTINUE THROUGH MUCH OF THE PERIOD. AT BEST...A FEW BRIEF POP UPS TO MVFR ACROSS NW MA. SCT -RA AND -DZ AS WELL AS AREAS OF FG LIKELY THROUGH THE PERIOD. KBOS TERMINAL...HIGH CONFIDENCE IN IFR CONDITIONS CONTINUING IN ON AND OFF PERIODS OF -RA AND FG. KBDL TERMINAL...HIGH CONFIDENCE IN IFR CONDITIONS CONTINUING IN ON AND OFF PERIODS OF -RA AND FG. OUTLOOK /TUESDAY NIGHT THROUGH FRIDAY/...MODERATE CONFIDENCE TUE NIGHT AND WEDNESDAY...AREAS OF MVFR/IFR CIGS WITH A FEW SHOWERS AT TIMES. THURSDAY AND FRIDAY...AREAS OF MVFR/IFR WITH SCT SHOWERS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY/...HIGH CONFIDENCE. SMALL CRAFT ADVISORIES FOR SEAS CONTINUE THROUGH TONIGHT FOR THE OUTER WATERS. SEAS WILL BE AROUND 5 FEET ON THESE WATERS. OTHERWISE...WINDS AND SEAS REMAIN BELOW CRITERIA AND MAIN ISSUE WILL BE PERIODS OF RAIN AND FOG LIMITING VISIBILITIES. THIS AFTERNOON AND EVENING...THERE MAY BE A FEW RUMBLES OF THUNDER ON THE SOUTHERN WATERS. OUTLOOK /TUESDAY NIGHT THROUGH FRIDAY/...MODERATE CONFIDENCE SURFACE FLOW IS MOSTLY EAST TO NORTHEAST THROUGH THE PERIOD WITH SPEEDS BELOW SCA. SEAS WILL LIKELY APPROACH 5 FT OVER THE OUTER WATERS FROM SWELL GENERATED BY THE PERSISTENT EASTERLY FLOW. VSBYS MAY BE REDUCED AT TIMES IN SHOWERS AND FOG. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 9 AM EDT TUESDAY FOR ANZ250-254. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 9 AM EDT TUESDAY FOR ANZ255. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 PM EDT THIS EVENING FOR ANZ256. && $$ SYNOPSIS...KJC/RLG NEAR TERM...KJC/RLG SHORT TERM...RLG LONG TERM...KJC AVIATION...KJC/RLG MARINE...KJC/RLG

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