Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 282109 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 509 PM EDT THU MAY 28 2015 .SYNOPSIS... A COLD FRONT MAY BRING A FEW STRONG TO SEVERE THUNDERSTORMS TO THE REGION THIS AFTERNOON. A WIDESPREAD...SOAKING RAINFALL IS NOT EXPECTED. ON FRIDAY...HIGH PRESSURE WILL BRING DRY CONDITIONS. ANOTHER COLD FRONT WILL SLOWLY MOVE ACROSS THE REGION THIS WEEKEND...BRINGING A GREATER CHANCE FOR SHOWERS AND SOME SCATTERED THUNDERSTORMS. THIS FRONT MAY LINGER NEAR OUR AREA INTO THE BEGINNING OF THE NEXT WEEK...WITH HIGH PRESSURE RETURNING BY MIDWEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... *** SEVERE THUNDERSTORM WATCH IN PLACE THROUGH THIS EVENING *** WEAKENING AND SLOWING COLD FRONT IS WITHIN 40 MILES OF THE MA/CT BORDER AND CONTINUING E SHIFT. HAVE SEEN PLENTY OF CLEARING THROUGH THE LATE MORNING AND EARLY AFTERNOON HOURS WHICH HAVE ALLOWED MIX LAYER CAPES TO EXCEED 1000J/KG. 0-6KM SHEAR STILL HOLDING ACROSS MUCH OF CT/MA/NRN RI AT OR AROUND 45 KT WITH SOME LOW LVL HELICITY ESPECIALLY CONCENTRATED IN THE CT VALLEY...WHERE WINDS BACK TO THE S. ALREADY BEGINNING TO SEE CONVECTION FIRING AROUND 18Z. THE CORRIDOR OF LEAST STABILITY LAY FROM CENTRAL CT...THROUGH TO NE MA...SO SUSPECT AS THE FRONT CONTINUES TO MOVE THROUGH THIS REGION CONTINUED FIRING OF MULTI-CELL CLUSTERS UNTIL IT REACHES THE SE AREAS...WHERE INSTABILITY/FORCING ARE BOTH LACKING. MAIN ISSUES WILL CONTINUE TO BE STRONG WINDS WITH LOCALIZED BOWING SEGMENTS ENHANCED BY INVERTED-V SOUNDINGS. SOME HAIL CAPE STILL AVAILABLE...AROUND 200-300 J/KG. SEVERE WATCH REMAINS IN PLACE THROUGH 23Z. MESO-SCALE GUIDANCE SHOWS THE FRONT SLOWING TO A NEAR STALL AROUND THE S COAST BETWEEN 06Z AND 12Z FRI. WITH THE LOSS OF DIURNAL HEATING AND PLENTY OF DRY AIR MOVING ALOFT PER WV IMAGERY...SUSPECT ANY REMNANT CONVECTION WILL COME TO AN END MAINLY 03Z-06Z. ONLY ISSUE IS COASTAL WATERS...WHICH MAY HOLD ON TO A LITTLE BIT MORE MID LVL INSTABILITY ABOVE THE MARINE LAYER. GIVEN THE LATE TIMING...COULD ALSO BE A LITTLE BIT OF TRAPPED MOISTURE BENEATH THE BUILDING SUBSIDENCE INVERSION/DRYING ALOFT. THIS MAY LEAD TO SOME PATCHY GROUND FOG PARTICULARLY AREAS WHERE SIG RAINFALL FELL IN STORMS AND/OR NEAR THE SOUTH COAST OVERNIGHT. HAVE PATCHY FOG IN THE FORECAST. DWPTS WILL BE DROPPING...BUT LEFTOVER CONVECTIVE DEBRIS CLOUDS AND THE SLOW MOVEMENT OF THE FRONT WILL PREVENT TEMPS FROM COMPLETELY FALLING OFF THE TABLE. EXPECT MINS MAINLY IN THE MID 50S. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... TOMORROW... WEAK RIDGE OF HIGH PRES WILL GRADUALLY CREST OVER THE REGION THROUGH THE DAYLIGHT HOURS. WINDS WILL BE LIGHT...BUT GRADUALLY SHIFTING BACK TO THE S...FROM THE NW THROUGH THE DAY. GIVEN THE LIGHT WINDS...EXPECT LOCAL SEA BREEZES TO LIMIT DIURNAL TEMP TRENDS NEAR THE COASTLINES. INLAND HOWEVER...WITH SOME DOWNSLOPING...CT VALLEY LOCATIONS WILL MAKE A RUN AT THE MID 80S. MAINLY UPPER 70S ELSEWHERE AWAY FROM THE COAST. TOMORROW NIGHT... ALTHOUGH SFC HIGH PRES CENTER WILL BE SHIFTING TO WELL S OF NOVA SCOTIA...UPPER LVL RIDGE WILL CONTINUE TO BUILD THANKS TO STEADY WARM ADVECTION UPSTREAM. THIS WILL KEEP ANY ACTIVITY ASSOCIATED WITH ANOTHER SLOW MOVING COLD FRONT...WELL TO THE W. EXPECT ONLY INCREASING HIGH CLOUDS ACROSS THE W OVERNIGHT. THE ONLY CAVEAT MAY BE NEAR S COASTAL REGIONS...WHERE SLY FLOW AND SLIGHT INCREASE IN DWPTS COULD PROMOTE DEVELOPMENT OF SOME LOCALIZED MARINE FOG AND STRATUS ONCE AGAIN. THIS RISE IN DWPTS WILL ALSO KEEP MINS UP A BIT...MAINLY DIPPING INTO THE UPPER 50S IN THE COOLEST SPOTS. && .LONG TERM /SATURDAY THROUGH THURSDAY/... OVERVIEW AND MODEL PREFERENCES... OVERALL UPPER LEVEL RIDGING ALONG EASTERN SEABOARD APPEARS TO BREAK DOWN SATURDAY...THEN TROUGH OUT OF CENTRAL CANADA BEGINS TO SHIFT E LATE THIS WEEKEND INTO EARLY NEXT WEEK. ASSOCIATED COLD FRONT WILL BE SLOW TO CLEAR THE REGION AS IT RUNS PARALLEL TO THE UPPER FLOW. TIMING ISSUES COME IN PLAY FROM MONDAY ONWARD... DEPENDING UPON HOW FAR S THE FRONT FINALLY SETTLES WHILE HIGH PRES BUILDS OUT OF SOUTHERN ONTARIO AND THE GREAT LAKES EASTWARD. LEANED TOWARD THE AVAILABLE GUIDANCE EARLY IN THIS PERIOD THEN TRANSITIONED OVER THE GEFS AND ECENS GUIDANCE WHICH SHOWED A BIT BETTER CONTINUITY. DETAILS... SATURDAY...HIGH PRES OFF THE EASTERN SEABOARD PUSHES FURTHER OFFSHORE DURING THIS TIMEFRAME...WITH GOOD SW WIND FLOW AND INCREASING HUMIDITY MOVING NE INTO THE REGION. MODELS TENDING TO SLOW THE PROGRESS OF THE APPROACHING FRONT OUT OF WESTERN QUEBEC AS THE UPPER RIDGE SLOWLY BREAKS DOWN AND SHIFTS E. HAVE MENTION OF CHANCE POPS MOVING INTO WESTERN AREAS DURING SAT AFTERNOON... THEN SHOULD PUSH SLOWLY SE SAT NIGHT. GOOD INSTABILITY WITH THIS FRONT AS K INDICES INCREASE TO THE LOWER-MID 30S. HAVE MENTIONED CHANCE POPS...BUT MENTIONED ONLY SLIGHT CHANCE OF THUNDERSTORMS SAT NIGHT. NOTING INCREASING PWATS ALONG AND AHEAD OF THIS FRONT AS WELL...UP TO 1.7 INCHES DURING SAT NIGHT SO COULD SEE SOME LOCALLY HEAVY DOWNPOURS WITH ANY ACTIVITY. WILL SEE HIGH TEMPS REACH AROUND 80 INLAND...BUT ONLY IN THE UPPER 60S TO LOWER 70S ALONG THE IMMEDIATE S COAST. MAY SEE SW WINDS GUSTING UP TO AROUND 25-30 MPH ACROSS RI/SE MA SAT AFTERNOON/NIGHT. SUNDAY...LOOKS LIKE BEST SHOT OF MOISTURE MOVES ACROSS THE REGION SUN/SUN NIGHT. CARRYING CAT POPS NEAR/ALONG THE SLOWLY MOVING FRONT...AS WELL AS SOME SCT THUNDERSTORMS. PWATS INCREASE TO 1.7 TO 1.8 INCHES...SO COULD ALSO SEE SOME HEAVY DOWNPOURS. AT THIS POINT...THINK THE FRONT WILL PUSH NEAR OR S OF THE MASS PIKE AROUND SUN NIGHT...BUT WILL TEND TO SLOW DOWN ACROSS SOUTHERN AREAS OVERNIGHT. THIS WILL LOWER THE CHANCE FOR THUNDERSTORMS AS MORE STABLE AIR MOVES INTO N MA SUN NIGHT...BUT STILL COULD SEE SPOTTY CONVECTION ACROSS N CT/RI/SE MA. HAVE KEPT LIKELY POPS GOING THROUGH AROUND 06Z...THEN SLOWLY LOWER ACROSS CENTRAL AND NORTHERN AREAS AFTER THAT. PRECIP LOOKS TO TAPER OFF ACROSS THE ROUTE 2 AREA BY AROUND SUNRISE MON...BUT TIMING IS STILL IN QUESTION. MONDAY...A LOT OF UNCERTAINTY CONTINUES AS MOVING THE FRONT ACROSS THE REGION...WITH TIMING DIFFERENCES AMONGST THE MODEL SUITE. LOOKS LIKE THE CHANCE FOR PRECIP LINGERS THROUGH MON AND EVEN INTO MON NIGHT...WITH THE BEST CHANCE ACROSS N CT/RI/SE MA. WINDS DO START TO SHIFT AROUND TO N-NE ACROSS CENTRAL AND N MA SO THIS WILL CUT BACK ON THUNDERSTORM ACTIVITY AS COOLER AIR MOVES IN. FOR NOW...TEND TO TAPER OFF PRECIP BY MON NIGHT ACROSS MOST AREAS...BUT DO LINGER IT ALONG THE S COAST THROUGH AT LEAST MIDNIGHT MON NIGHT. IT WILL BE MUCH COOLER WITH HIGHS ONLY IN THE 60S...AND MAY NOT EVEN BREAK 60 ALONG THE E COAST WITH ONSHORE WINDS. TUESDAY-WEDNESDAY...PRECIP SHOULD FINALLY PUSH OFF THE S COAST BY AROUND MIDDAY TUE AT THE LATEST. NE WINDS PICK UP AS HIGH PRES CROSSES NORTHERN NEW ENGLAND DURING THIS TIMEFRAME. HAVE CARRIED A DRY AND SEASONABLE FORECAST ON WEDNESDAY. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. THROUGH 00Z...HIGH CONFIDENCE...LOWER IN EXACT TIMING. EXPECT GRADUAL DEVELOPMENT OF THUNDERSTORMS AND SHOWERS ACROSS WESTERN MA AT 18Z...REACHING CENTRAL MA/CT BY 20Z...THEN ERN MA AND RI AROUND 22Z. COULD BE STRONG WINDS AND HAIL WITH SOME OF THESE STORMS...AS WELL AS HEAVY DOWNPOURS. THESE WILL BEGIN TO DISSIPATE MAINLY ACROSS SE MA TOWARD 00Z THIS EVENING. BRIEF IFR/MVFR CONDITIONS POSSIBLE WITHIN THE STORMS. TONIGHT...MODERATE CONFIDENCE. WINDS WILL SHIFT MAINLY W-NW...WITH MAINLY VFR AFTER SKIES/SHRA DISSIPATE THIS EVENING. MAY BE SOME LOCALIZED GROUND FOG AT TYPICALLY PRONE AIRPORTS. TOMORROW AND TOMORROW NIGHT...HIGH CONFIDENCE. MAINLY VFR. EXPECT SEA BREEZES WITH WINDS SHIFTING MAINLY TO THE E LATE IN THE DAY. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. ONLY ISSUE IS EXACT TIMING OF POTENTIAL STRONG THUNDERSTORMS LATE THIS AFTERNOON. KBDL TERMINAL...HIGH CONFIDENCE IN TAF TRENDS. EXACT TIMING OF ANY THUNDERSTORMS THIS AFTERNOON MAY BE OFF BY AN HOUR OR SO. OUTLOOK...SATURDAY THROUGH TUESDAY...MODERATE CONFIDENCE. SATURDAY...PATCHY EARLY MORNING FOG WITH MVFR-IFR CONDITIONS... THEN CONDITIONS IMPROVE. SHRA AND SCT TSRA SAT AFTERNOON THROUGH SAT NIGHT...WITH AREAS OF MVFR-IFR CONDITIONS. SW WINDS GUSTING TO 20-25 KT MAINLY ACROSS E MA/RI SAT AFTERNOON/EVENING. DIMINISHING WINDS OVERNIGHT SAT. SUNDAY...NUMEROUS SHOWERS WITH SCATTERED TSTMS POSSIBLE DURING THE DAY WITH LOCAL MVFR CONDITIONS. LIGHT WINDS SHIFT TO N-NE DURING THE DAY...THEN BECOME NE SUN NIGHT WHICH MAY GUST UP TO AROUND 20 KT ALONG THE S COAST. SHOWERS LINGER SUNDAY NIGHT. MONDAY...SCT SHOWERS LINGERING WITH LOCAL MVFR CONDITIONS EARLY BUT WILL IMPROVE FROM N-S DURING THE DAY EXCEPT ALONG THE S COAST WHERE SHOWERS WILL HANG IN THROUGH SUN NIGHT. MAY SEE BRIEF MVFR IN ANY SHOWERS THERE SUN NIGHT. NE WINDS GUSTING TO 20-25 ACROSS OUTER CAPE COD AND THE ISLANDS. TUESDAY...MAINLY VFR CONDITIONS. MAY SEE ISOLD SHOWERS EARLY TUE ALONG S COAST BUT SHOULD MOVE OFFSHORE. NE WIND GUSTS TO 25 KT STILL POSSIBLE ACROSS THE OUTER CAPE AND ISLANDS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TODAY INTO FRIDAY/... THROUGH TONIGHT...HIGH CONFIDENCE. WILL MAINTAIN ONGOING SMALL CRAFT ADVISORIES AS THEY STAND. SEAS ARE NEARING 5 FT ON THE OCEAN WATERS AND WIND GUSTS NEAR SHORE ARE 25-30 KT. CURRENT TIMING IS THROUGH ABOUT 10PM LOCAL...WHICH IS PRETTY CLOSE TO WHEN CONDITIONS SHOULD COME TO AN END. WILL NEED TO MONITOR FOR SOME LEFTOVER THUNDERSTORMS THOUGH MAINLY 22Z- 02Z ALONG THE E COAST OF MA...LOCALLY STRONGER CONDITIONS POSSIBLE. TOMORROW AND TOMORROW NIGHT...HIGH CONFIDENCE. HIGH PRES BUILDS OVER THE WATERS. MAINLY QUIET BOATING WEATHER EXPECTED ALTHOUGH SOME STRATUS/FOG IS POSSIBLE MAINLY ON THE SRN WATERS TOMORROW NIGHT. OUTLOOK...SATURDAY THROUGH TUESDAY...MODERATE CONFIDENCE. SATURDAY...SW WINDS WILL LIKELY GUST UP TO 25 KT ACROSS THE EASTERN OUTER WATERS...AND POSSIBLY ON THE NEAR SHORE WATERS SAT AFTERNOON. SEAS BUILD TO AROUND 5 FT ON ALL THE OUTER WATERS... POSSIBLY INTO RI AND BLOCK ISLAND SOUNDS. WINDS SHOULD DIMINISH DURING SAT NIGHT. VSBY RESTRICTIONS IN PATCHY FOG ALONG S COASTAL WATERS EARLY...THEN SHOULD IMPROVE. SUNDAY...COLD FRONT SLOWLY CROSSES THE WATERS. MAY SEE BRIEF GUSTS TO 25 KT AS FRONT PASSES DURING SUNDAY...THEN WILL STALL NEAR OR JUST S OF THE S COAST SUN NIGHT. WINDS SHIFT TO E-NE AS FRONT PASSES. AREAS OF SHOWERS WITH SCT THUNDERSTORMS. LOCAL VSBY RESTRICTIONS. MONDAY-TUESDAY...EXPECT MAINLY NE WINDS. GUSTS TO 25 KT ACROSS THE SOUTHERN OPEN WATERS AS THE FRONT SLOWLY MOVES OFFSHORE. SEAS BUILD UP TO 6-8 FT ON THE SOUTHERN OUTER WATERS TO E OF CAPE COD...AND UP TO 5 FT ON THE EASTERN OUTER WATERS. MAY SEE LINGERING SHOWERS DURING MONDAY ACROSS THE SOUTHERN WATERS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ230>237-250-251-254>256. && $$ SYNOPSIS...DOODY/EVT NEAR TERM...DOODY SHORT TERM...DOODY LONG TERM...EVT AVIATION...DOODY/EVT MARINE...DOODY/EVT

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