Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 191353 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 953 AM EDT TUE MAY 19 2015 .SYNOPSIS... A CLUSTER OF SHOWERS WILL MOVE ACROSS THE REGION THIS MORNING INTO THE EARLY AFTERNOON BEFORE MOVING OFFSHORE. THEN A FEW STRONG THUNDERSTORMS ARE POSSIBLE LATE THIS AFTERNOON/EARLY EVENING ACROSS WESTERN PORTIONS OF MA AND CT IN ASSOCIATION WITH A COLD FRONT. A FEW SPOT SHOWERS ARE POSSIBLE FRIDAY AND MONDAY...BUT IN GENERAL DRY WEATHER AND SEASONABLE TEMPS ARE EXPECTED FROM MID WEEK THROUGH THE WEEKEND. AN ACTIVE WET WEATHER PATTERN MAY DEVELOP NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... 950 AM UPDATE... ***A FEW STRONG TO PERHAPS A MARGINALLY SEVERE THUNDERSTORM OR TWO POSSIBLE BETWEEN 5 AND 10 PM ACROSS WESTERN MA/NORTHERN CT*** CLUSTER OF SHOWERS WITH BRIEF LOCALLY HEAVY RAINFALL WORKING ACROSS SOUTHERN NEW ENGLAND FROM WEST TO EAST AT LATE MORNING. THIS IS IN A RESPONSE TO A BURST OF MARGINAL INSTABILITY. BULK OF THE SHOWERS SHOULD BE CONFINED TO EASTERN NEW ENGLAND BY LUNCH TIME AND THEN THE FAR SOUTHEAST NEW ENGLAND COAST BY MID TO LATE AFTERNOON. OTHERWISE...AT LEAST SEVERAL HOURS OF DRY WEATHER ARE THEN EXPECTED ACROSS THE SOUTHERN NEW ENGLAND. THE LATEST MESOSCALE MODELS DO SHOW PARTIAL CLEARING DEVELOPING ACROSS THE INTERIOR BY MID TO LATE AFTERNOON ALLOWING TEMPS TO MAKE A LATE DAY RALLY WELL INTO THE 70S. PERHAPS A FEW LOCATIONS TOUCH 80. MEANWHILE...THE FAR SOUTHEAST NEW ENGLAND COAST PROBABLY REMAINS IN THE 60S GIVEN CLOUDS AND SOUTHWEST SLOW. THE MAIN QUESTION BECOMES HOW MUCH INSTABILITY DEVELOPS LATE THIS AFTERNOON/THIS EVENING ACROSS WESTERN MA/NORTHERN CT. BASED ON THE LATEST DATA WE ARE THINKING THAT 500 TO 1000 J/KG OF CAPE DEVELOP TOWARD EVENING. AT THE SAME TIME...0 TO 6 KM SHEAR VALUES ARE INCREASING TO BETWEEN 40 AND 45 KNOTS AS A STRONG SHORTWAVE WORKS INTO THE REGION AHEAD OF A COLD FRONT. THIS SETUP IN SOUTHERN NEW ENGLAND IS A TYPICAL MARGINAL EVENT. DESPITE...VERY GOOD SHEAR MARGINAL INSTABILITY WILL BE A LIMITING FACTOR. IN ADDITION...TIMING LOOKS TO BE BETWEEN 5 AND 10 PM THIS EVENING SO A FEW HOURS AFTER PEAK HEATING/INSTABILITY. ALL IN ALL...NOT REALLY MUCH CHANGE FROM THE PREVIOUS FORECAST. A FEW STRONG THUNDERSTORMS WITH PERHAPS A MARGINALLY SEVERE THUNDERSTORM OR TWO ARE POSSIBLE BETWEEN 5 AND 10 PM THIS EVENING ACROSS WESTERN MA/NORTHERN CT. THE MAIN CONCERN IS VERY LOCALIZED STRONG TO DAMAGING WIND GUSTS WITH HAIL A SECONDARY CONCERN. ITS CONDITIONAL AND WILL DEPEND ON THE AMOUNT OF INSTABILITY THAT IS ABLE TO DEVELOP. AS PREVIOUS FORECAST NOTED...ACTIVITY WILL TRY TO ENTER EASTERN NEW ENGLAND GIVEN DECENT FLOW ALOFT. IF IT DOES MAKE IT INTO EASTERN MA/RI...PROBABLY MAINLY JUST SOME LEFT OVER SHOWERS WITH PERHAPS A RUMBLE OF THUNDER. && .SHORT TERM /WEDNESDAY/... WEDNESDAY... REAL NICE DAY AS POST FRONTAL AIRMASS OVERSPREADS THE REGION WITH DEW PTS FALLING INTO THE 30S! TEMPS SEASONABLE WITH HIGHS IN THE 60S. ALSO A REFRESHING BREEZE WITH WEST NORTHWEST WINDS GUSTING UP TO 25 MPH. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... */ HIGHLIGHTS... - SEASONABLE AND DRY UNDER HIGH PRESSURE THURSDAY - SWEEPING COLD FRONT FRIDAY - RETURN OF DRY AND SEASONABLE CONDITIONS FOR THE WEEKEND - PERHAPS A RETURN OF WET-WEATHER EARLY NEXT WEEK */ DISCUSSION... PER A CONSENSUS OF FORECAST GUIDANCE...QUIET OVERALL. HIGH PRESSURE IN CONTROL FOR WEDNESDAY NIGHT INTO THURSDAY NIGHT. NW-FLOW VEERS SW...LIGHT ENOUGH TO ALLOW SEA-BREEZES DURING THE DAY. EXPECT MOSTLY CLEAR CONDITIONS WITH SCATTERED CLOUDS THROUGH THE DAY. QUITE DRY WITH DEEP-LAYER MIXING UP TO H7. RELATIVE HUMIDITY VALUES LIKELY BELOW THE 30-PERCENT THRESHOLD TOWARDS ELEVATED FIRE WEATHER POTENTIAL...THOUGH DEPENDS ON HOW MUCH RAIN WE SEE ON TUESDAY. A COLD FRONT SWEEPS SE THROUGH THE REGION FRIDAY AS A PRONOUNCED STORM PASSES OFFSHORE. SCATTERED SHOWER ACTIVITY NOT OUT OF QUESTION WITH LOW- TO MID-LEVEL FORCING OF LIMITED MOISTURE AS THE BOUNDARY- LAYER IS FORECAST TO BE WELL-MIXED UP TO H7. BUFKIT SOUNDINGS QUITE DRY WITH PWATS AROUND 0.6-0.7. SCATTERED TO BROKEN CLOUD-DECKS AND WILL KEEP WITH THE SLIGHT-CHANCE POPS FROM THE PRIOR FORECASTER. IF WE DO NOT SEE ANY RAIN TUESDAY...AND NONE AGAIN WITH THIS COLD FRONT THEN BRISK W-WINDS WITH FORECAST RELATIVE HUMIDITY VALUES BELOW 30- PERCENT YIELD A REPEAT OF POTENTIAL ELEVATED FIRE WEATHER CONCERNS. DRY AND SEASONABLE CONDITIONS INTO THE WEEKEND WITH HIGH PRESSURE IN CONTROL...LIGHT WINDS...SEA-BREEZES DURING THE DAY. THAT MAY CHANGE BY LATE SUNDAY INTO NEXT WEEK. AN INITIAL COLD FRONT FOLLOWED BY RETURN S-FLOW AS HIGH PRESSURE PUSHES E AND ANOTHER STORM SYSTEM DEVELOPS TO THE W...COULD BE LOOKING AT A RETURN OF WET WEATHER ALONG A LIFTING WARM-FRONT. EARLY TO SAY WITH CERTAINTY. WE COULD SURELY USE THE RAIN WITH THE 3 TO 4 INCH DEFICIT OF RAINFALL SINCE MARCH 1ST. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH WEDNESDAY/... TODAY...MODERATE CONFIDENCE. LOW END MVFR TO IFR CONDITIONS PREVAILED ACROSS THE REGION AT LATE MORNING. EXPECT TO SEE IMPROVEMENT TO MAINLY VFR AWAY FROM THE SOUTHEAST NEW ENGLAND COAST AS THE AFTERNOON WEARS ON AND LOW CLOUDS MIX OUT. ACROSS THE FAR SOUTHEAST NEW ENGLAND COAST...LOW CLOUDS WILL HOLD CONDITIONS AT LOW END MVFR TO IFR. OTHERWISE...BULK OF SHOWERS WILL CONFINE ITSELF TO EASTERN NEW ENGLAND BY LUNCH TIME AND THEN THE FAR SOUTHEAST NEW ENGLAND COAST BY MID TO LATE AFTERNOON. OTHERWISE...DRY WEATHER TAKES OVER BUT A FEW STRONG THUNDERSTORMS MAY WORK INTO WESTERN MA/NORTHERN CT AFTER 5 PM OR SO. TONIGHT...MODERATE CONFIDENCE. SHRA / TSRA OVER W MA / CT MAY HOLD TOGETHER INTO RI / E MA. HELD PREVAILANCE IN TAF. MVFR / IFR CIGS MAY LINGER / REDEVELOP OVER SE MA PRIOR TO FRONTAL PASSAGE LATE TONIGHT. WEDNESDAY...HIGH CONFIDENCE. VFR ALONG WITH A DRY GUSTY WNW WIND UP TO 25 KT POSSIBLE. KBOS TERMINAL...MODERATE CONFIDENCE ON TAF. MAINLY MVFR CONDITIONS BUT AN IMPROVEMENT TO VFR MAY OCCUR BY LATE AFTERNOON EARLY EVENING. KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. IFR CONDITIONS SHOULD IMPROVE TO A PERIOD OF VFR BY MID TO LATE AFTERNOON. A LOCALIZED STRONG THUNDERSTORM IS POSSIBLE AFTER 5 OR 6 PM UNTIL AROUND 10 PM...BUT ODDS OF IT GOING DIRECTLY OVER THE TERMINAL ARE LOW. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...MODERATE CONFIDENCE. WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...HIGH CONFIDENCE. SCT VFR CIGS. NW-FLOW VEERING SW. SEA-BREEZES DURING THE DAY. FRIDAY...HIGH CONFIDENCE. SCT-BKN VFR CIGS. SW-FLOW BACKING NW WITH FRONTAL PASSAGE. LOW CONFIDENCE SCT -SHRA. FRIDAY NIGHT THROUGH SATURDAY NIGHT...HIGH CONFIDENCE. VFR. LIGHT WINDS. SEA-BREEZES DURING THE DAY. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... TODAY... SE WINDS BECOME SSW BY AFTERNOON. VSBY BELOW 1/2MILE AT TIMES IN PATCHY DENSE FOG. SHOWERS THIS MORNING AND EARLY AFTERNOON MOVE OFFSHORE BY MID AFTERNOON. TONIGHT... SSW WINDS BECOME WNW LATE WITH FRONTAL PASSAGE. EVENING SHOWERS POSSIBLE. VSBY IMPROVES WITH THE WIND SHIFT. WEDNESDAY... SMALL CRAFT ADVISORY MAY BE REQUIRED AS WNW WINDS MAY GUSTS UP TO 25 KT AT TIMES NEAR SHORE. OTHERWISE DRY WEATHER AND GOOD VSBY. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...MODERATE CONFIDENCE. HIGH CONFIDENCE FORECAST. WILL SEE WINDS AND SEAS REMAIN BELOW SMALL- CRAFT ADVISORY CRITERIA. NW-FLOW VEERS SW WEDNESDAY NIGHT THROUGH THURSDAY NIGHT WITH SEA-BREEZES ALONG THE SHORES. COLD FRONT SWEEPS THE WATERS LATE ON FRIDAY WHEN WINDS BACK NW. WINDS TURN LIGHT INTO THE WEEKEND WITH HIGH PRESSURE IN CONTROL. SEA-BREEZES ALONG SHORES. && .FIRE WEATHER... WEDNESDAY... MIN RH VALUES MAY APPROACH 30-35 PERCENT IN THE AFTERNOON. WNW WINDS MAY GUSTS UP TO 25 MPH. THUS IF RAINFALL TODAY AND THIS EVENING IS LESS THAN A 0.25 INCHES...ELEVATED FIRE WEATHER CONDITIONS ARE POSSIBLE WED AFTERNOON. HEADLINES MAY BE NEEDED. STAY TUNED. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...NOCERA/SIPPRELL NEAR TERM...FRANK SHORT TERM...NOCERA LONG TERM...SIPPRELL AVIATION...FRANK/NOCERA/SIPPRELL MARINE...NOCERA/SIPPRELL FIRE WEATHER...STAFF

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