Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 280751 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 351 AM EDT TUE JUL 28 2015 .SYNOPSIS...
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A TROUGH OF LOW PRESSURE ALOFT WILL BRING A RISK OF SCATTERED SHOWERS AND THUNDERSTORMS TO EASTERN MASSACHUSETTS AND POSSIBLY RHODE ISLAND TODAY. HOT AND HUMID CONDITIONS EXPECTED THROUGH THURSDAY. A COLD FRONT MAY BRING SCATTERED THUNDERSTORMS LATE THURSDAY AND THURSDAY NIGHT. WARM BUT DRIER AND LESS HUMID WEATHER IS EXPECTED FRIDAY INTO NEXT WEEKEND.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/... 2 AM UPDATE... DEWPOINTS CONTINUE TO RISE OVERNIGHT KEEPING TEMPS NEAR STEADY. IN FACT MOST PLACES WILL REMAIN IN THE LOW 70S TO UPPER 60S OVERNIGHT. SURFACE MOISTURE CONTINUE TO INCREASE ALLOWING FOR A DESCENT INVERSION OVER THE AREA. SEVERAL PLACES HAVE ALREADY DROPPED IN VSBYS...ORE...CEF AND BAF. ANTICIPATE VSBYS TO BE AROUND 1SM DURING THE MORNING COMMUTE SO ENCOURAGE DRIVERS TO USE CAUTION. OTHERWISE PATCHY FOG AND STRATUS IS STARTING TO DEVELOP ACROSS THE SOUTH COAST OF RI AND SHOULD SPREAD INTO MASS OVERNIGHT. ASIDE FROM FOG...THE OTHER FOCUS IS ON THE CONVECTION ACROSS VT. HI-RES GUIDANCE SHOWS THESE STORM DISSIPATING AS IT MOVES TOWARDS SOUTHERN NEW ENGLAND...BUT WITH APPROACHING SHORTWAVE AND LINGERING INSTABILITY CANNOT RULE OUT A FEW OF THESE SHOWERS MOVING INTO NE MASS. WILL CONTINUE TO MONITOR OVER THE NEXT FEW HOURS. && .SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/... ***A FEW STRONG TO SEVERE THUNDERSTORMS POSSIBLE TUESDAY AFTERNOON AND EARLY EVENING ALONG WITH LOCALLY HEAVY RAINFALL ACROSS EASTERN MA AND RHODE ISLAND*** TUESDAY... ANY LOW CLOUDS AND FOG PATCHES SHOULD BURN OFF BY LATE MORNING ACROSS THE REGION. OTHERWISE...EXPECT PARTLY SUNNY SKIES TO RESULT IN A VERY WARM TO EVEN BORDERLINE HOT AFTERNOON. HIGH TEMPS WILL TOP OUT MAINLY IN THE UPPER 80S TO NEAR 90. IN ADDITION...IT WILL BE RATHER HUMID OUTSIDE WITH DEWPOINTS IN THE 60S AND RATHER LIGHT WINDS. MAINLY DRY WEATHER EXPECTED TUESDAY MORNING...BUT WE CAN NOT RULE OUT A SPOT SHOWER OR THUNDERSTORM. THE MAIN CONCERN THEN TURNS TO A STRONG PIECE OF SHORTWAVE ENERGY THAT WILL BE DROPPING SOUTH ACROSS THE EASTERN NEW ENGLAND COAST. GIVEN VERY WARM AND HUMID AIRMASS WITH 500 MB TEMPS AROUND -10C...WE SHOULD BE ABLE TO GENERATE MLCAPE VALUES ON THE ORDER OF 1500 J/KG. THE SHORTWAVE COMBINED WITH THE INSTABILITY SHOULD LEAD TO SCATTERED CONVECTION. WHILE AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE ACROSS THE INTERIOR...GREATEST CONCERN IS ACROSS EASTERN MA AND RHODE ISLAND AS THEY WILL BE CLOSER TO THE SHORTWAVE...BUT CAN NOT COMPLETELY RULE OUT CENTRAL MA. WILL RUN WITH SCATTERED SHOWERS/THUNDERSTORMS MAINLY ACROSS THE EASTERN HALF OF THE REGION TUESDAY AFTERNOON AND EARLY EVENING WITH SOME ENHANCED WORDING. AS FOR SEVERE WEATHER POTENTIAL...LOW LEVEL WIND FIELDS ARE RATHER WEAK WHICH WILL BE A LIMITING FACTOR. NONETHELESS...STRONG WINDS ALOFT WILL LIKELY GENERATE 0 TO 6 KM SHEAR VALUES OF 35 TO 45 KNOTS AND THERE IS AN INVERTED V LOOK TO THE SOUNDINGS. THIS MEANS THAT THERE IS THE RISK FOR A FEW STRONG TO SEVERE THUNDERSTORMS...MAINLY ACROSS EASTERN MA AND RHODE ISLAND...BUT CAN NOT RULE OUT CENTRAL MA. LOCALLY DAMAGING WIND GUSTS AND HAIL ARE THE CONCERNS FOR TUESDAY AFTERNOON AND EARLY EVENING. HIGHEST RISK MIGHT BE ALONG THE SEA BREEZE FRONT THAT SETS UP ACROSS EASTERN MA AND RHODE ISLAND AS IT WILL PROVIDE A FOCUS FOR CONVECTION. ALSO...SOMETIMES WE END UP WITH SOME TRAINING ON THESE BOUNDARIES AND THE RISK FOR VERY LOCALIZED FLOODING. && .LONG TERM /THURSDAY THROUGH MONDAY/...
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350 AM UPDATE... HIGHLIGHTS... * VERY WARM AND HUMID THU * SCATTERED STORMS POSSIBLE LATE THU/THU NIGHT * DRIER/LESS HUMID FRI THRU MON BUT STILL WARM WED NIGHT/THU/THU NIGHT... GOOD MODEL AGREEMENT ON SHORT WAVE RIDGING OVER THE AREA WED NIGHT INTO THU. THUS DRY WEATHER TO START THIS PERIOD HOWEVER THE RISK OF SHOWERS/T-STORMS INCREASES LATE THU INTO THU NIGHT AS POTENT NORTHERN STREAM TROUGH CURRENTLY EXITING THE NORTHERN ROCKIES INTO THE HIGH PLAINS BEGINS TO APPROACH NEW ENGLAND FROM THE WEST. APPEARS TIMING OF THE FRONT COMES THROUGH OVERNIGHT...WELL AFTER PEAKING HEATING. THIS COMBINED WITH MARGINAL SHEAR KEEPS THE RISK LOW FOR STRONG CONVECTION LATE THU INTO THU NIGHT. HOWEVER GOOD SYNOPTIC SCALE LIFT WITH THIS TROUGH SUGGEST AT LEAST SHOWERS SHOULD BE ABLE TO HOLD TOGETHER AND MOVE ACROSS THE AREA LATE THU AND THU NIGHT. PWATS ABOVE NORMAL AND DEW PTS 65 TO 70 WILL INCREASE THE RISK FOR HEAVY DOWNPOURS. ALTHOUGH STILL 2 DAYS AWAY WILL NEED TO MONITOR LATER MODEL TRENDS. OTHERWISE VERY WARM AND HUMID CONDITIONS THU AHEAD OF APPROACHING COLD FRONT. A MODEL BLEND OFFERS HIGHS U80S TO L90S. FRIDAY THROUGH MONDAY... ANOMALOUS CLOSED LOW/VORTEX SETS UP OVER HUDSON/JAMES BAY THIS TIME PERIOD. THIS RESULTS IN BELOW NORMAL HEIGHTS AND MEAN TROUGH OVER THE GREAT LAKES INTO THE NORTHEAST. THIS WILL KEEP TEMPERATURES NEAR NORMAL /HIGHS MU80S/ AND LOWS IN THE 60S ALONG WITH TOLERABLE HUMIDITY AS DEW PTS AVERAGE IN THE 50S DURING THE DAYLIGHT HOURS. HOWEVER WITH THE NORTHERN STREAM JET SUPPRESSED SOUTHWARD INTO THE GREAT LAKES AND NORTHEAST THERE WILL BE THE RISK OF SCATTERED DIURNAL SHOWERS/T-STORMS JUST ABOUT EVERY DAY. TOO DIFFICULT AT THIS TIME RANGE TO TIME INDIVIDUAL SHORT WAVES. NOT A WASHOUT BUT THE RISK OF CONVECTION FROM TIME TO TIME.
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&& .AVIATION /08Z TUESDAY THROUGH SATURDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY AFTERNOON/... BEFORE 00Z...LOW TO MODERATE CONFIDENCE. DRY WEATHER DOMINATES OVERNIGHT...A FEW SPOT SHOWERS ARE POSSIBLE IN NE MASS AROUND DAYBREAK. OTHERWISE...LOW CLOUDS AND FOG HAVE STARTED TO DEVELOP ACROSS SOUTH COAST AND CT VALLEY. LOCALLY DENSE FOG IS POSSIBLE DROPPING TERMINALS TO LIFR. TODAY...MODERATE TO HIGH CONFIDENCE. ANY LOW CLOUDS AND FOG PATCHES SHOULD IMPROVE TO VFR BY LATE MORNING. SCATTERED SHOWERS/THUNDERSTORMS WILL DEVELOP GENERALLY ACROSS EASTERN MA/RHODE ISLAND. WHILE ACTIVITY WILL BE HIT AND MISS...THE POTENTIAL IS THERE FOR ISOLATED STRONG TO SEVERE STORMS WITH LOCALLY HEAVY RAINFALL. TONIGHT...MODERATE CONFIDENCE. VFR FOR MOST SITES. CANNOT RULE OUT IFR IN STRATUS AND FOG ACROSS SE MASS INCLUDING THE CAPE AND ISLANDS. WEDNESDAY...HIGH CONFIDENCE. VFR WITH DIURNAL CU DEVELOPING AROUND 5K. A SPOT SHOWER IS POSSIBLE. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. SEA BREEZE AROUND 14-16Z. LOW CONFIDENCE ON STRONG/SEVERE THUNDERSTORM HITTING THE TERMINAL. KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. LOW CLOUDS AND SOME FOG MAY DEVELOP EARLY THIS MORNING. OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/... 350 AM UPDATE... WED NGT/THU...PATCHY MVFR/IFR IN FOG WED NGT BUT QUICKLY IMPROVING TO VFR THU MORNING. LOW PROB THAT MVFR/IFR IN STRATUS LINGERS ALONG THE SOUTH COAST THU. THEN UNCERTAINTY ON HOW QUICK THIS FOG/STRATUS BURNS OFF SOUTH COAST. THU NIGHT...VFR-MVFR IN SCATTERED SHOWERS/T-STORMS. SOME UNCERTAINTY ON HOW WIDESPREAD PRECIP WILL BE. FRI AND SAT...VFR LIKELY. HIGH FORECAST CONFIDENCE.
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&& .MARINE...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY AFTERNOON/...HIGH CONFIDENCE. WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS THROUGH TUESDAY AFTERNOON. A FEW SPOT SHOWERS AND PERHAPS A THUNDERSTORM WILL BE POSSIBLE TONIGHT. HOWEVER...A BETTER CHANCE OF A FEW STRONG TO SEVERE THUNDERSTORMS TUESDAY AFTERNOON WHICH MAY RESULT IN BRIEFLY STRONG WIND GUSTS AND HAIL. SPECIAL MARINE WARNINGS MAY BE NEEDED WITH THE HIGHEST RISK ACROSS OUR WATERS ADJACENT TO EASTERN MA. OUTLOOK /TUESDAY NIGHT THROUGH SATURDAY/... 350 AM UPDATE... WED NIGHT AND THU...FAIRLY TRANQUIL WIND AND SEAS. POSSIBLE PATCHY FOG IN HUMID AIRMASS. THU NIGHT...MODEST SSW WIND AHEAD OF APPROACHING COLD FRONT. SCATTERED SHOWERS WITH EMBEDDED THUNDER POSSIBLE. FRI AND SAT...COLD FRONT SLOWLY MOVES OFFSHORE. ANOTHER WEAK FRONT MAY ENTER THE WATERS SAT. WSW WINDS EXPECTED.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...NOCERA/DUNTEN NEAR TERM...DUNTEN SHORT TERM...FRANK LONG TERM...NOCERA AVIATION...NOCERA/DUNTEN MARINE...FRANK/NOCERA

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