Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 311750 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 150 PM EDT FRI JUL 31 2015 .SYNOPSIS... LESS HUMID BUT STILL VERY WARM THIS AFTERNOON. SEASONABLY WARM THIS WEEKEND WITH A RISK OF SCATTERED SHOWERS AND WIDELY SCATTERED THUNDERSTORMS MID TO LATE SATURDAY AFTERNOON. WARM WEATHER CONTINUES INTO EARLY NEXT WEEK ALONG WITH THE RISK OF THUNDERSTORMS BOTH MON AND TUE. NOT AS WARM AND LESS HUMID CONDITIONS ARRIVE MID TO LATE NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 130 PM UPDATE... HAVE ADJUSTED TEMPERATURES UP ACROSS THE CAPE...MARTHAS VINEYARD AND NANTUCKET. A W TO WSW WIND IS LIMITING OCEAN TRAJECTORY AND ALLOWING TEMPERATURES TO REACH MID TO UPPER 80S. ALSO ADJUSTED WIND GUSTS UP A LITTLE ACROSS INTERIOR EASTERN MA. UPDATED SURF ZONE FORECAST TO REFLECT MODERATE RIP CURRENT RISK ALONG MA NE COAST BASED ON SALISBURY BEACH OBSERVATION. 10 AM UPDATE... NO SIGNIFICANT CHANGES NEEDED TO FORECAST. TEMPERATURES LOOK TO BE ON TRACK. DEWPOINTS ARE SLOWLY LOWERING TO MID 60S AS FRONT SETTLES FURTHER S. THIS FEELS CONSIDERABLY LESS HUMID COMPARED TO DEWPOINTS IN LOW TO MID 70S YESTERDAY. WATER VAPOR IMAGERY INDICATES BAND OF VERY DRY AIR OVER US AND THAT IS REFLECTED IN A MOSTLY CLEAR FORECAST. NO SEA BREEZE EXPECTED E COAST AND JUST A HINT OF A SEA BREEZE COMPONENT ALONG S COAST. HAVE PLACED POPS AT ZERO PERCENT. 7 AM UPDATE... STILL MUGGY ACROSS A PORTION OF THE REGION AS COLD FRONT SLOWLY MOVES SOUTHEASTWARD. LATEST DATA SUGGESTS THAT ITS OVER A OWD TO HFD LINE PER 850 MB MOISTURE ANALYSIS. THIS FRONT WILL FINALLY PUSH OFFSHORE AS WEAK SHORTWAVE MOVES THROUGH THE FLOW. PATCHY DENSE FOG ACROSS THE CT VALLEY DOWN INTO SOUTHERN RI WILL BEGIN TO LIFT AS SUNSHINE WILL HELP MIX THE BL. OTHERWISE FORECAST REMAINS ON TRACK...UPPED TEMPS A DEGREE OR TWO AS FULL SUNSHINE WILL GET US CLOSE TO 90. ALSO INCREASED WINDS A TAD AS WESTERLY WINDS WILL ALLOW FOR GOOD MIXING KEEPING DEWPOINTS IN THE 50S. PREVIOUS DISCUSSION... COLD FRONT HAS PROGRESSED INTO EASTERN MA AT 3 AM WITH A WIND SHIFT TO THE WSW. DRIER/LESS HUMID AIR LAGS A BIT TO THE WEST WITH PSF AND AQW DEW PTS DOWN INTO THE U50S! HOWEVER DECOUPLING BLYR AND DEW PTS STILL IN THE U60S AND L70S ACROSS MUCH OF THE REGION IS RESULTING IN RADIATIONAL FOG ACROSS INTERIOR CT AND MA. ALONG THE SOUTH COAST INCLUDING CAPE COD AND THE ISLANDS LOW CLOUDS PERSIST AS WELL. HOWEVER SHORTLY AFTER SUNRISE AS SOLAR HEATING BEGINS TO DEEPEN BLYR LOW LEVEL MOISTURE WILL MIX OUT AND RESULT IN DEW PTS FALLING INTO THE 50S WITH WINDS SHIFTING TO THE WEST AND ERODING SHALLOW FOG AND STRATUS. THUS A VERY NICE DAY AHEAD WITH POST FRONTAL AIRMASS OFFERING PLENTY OF SUNSHINE /BUFKIT RH PROFILES VERY DRY/...TEMPS WELL INTO THE MU80S BUT DEW PTS FALLING INTO THE 50S...YIELDING MUCH LOWER HUMIDITY THAN YESTERDAY. A FEW LOCATIONS INCLUDING BOSTON MAY BRIEFLY TOUCH 90 THIS AFTERNOON. THIS WOULD MAKE IT AN OFFICIAL HEAT WAVE /3 CONSECUTIVE DAYS OF TEMPS 90+/ FOR BOSTON. ALSO A MODEST WEST WIND AT 15 TO 20 MPH WILL HELP TAKE THE EDGE OFF THE WARM TEMPS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... TONIGHT... QUIET WEATHER ALONG WITH SEASONABLE TEMPS AS LOWS DIP INTO THE 60S REGIONWIDE. ONLY WRINKLE IS A LOW RISK OF A FEW SHOWERS TOWARD MORNING AS NEXT NORTHERN STREAM SHORT WAVE APPROACHES FROM THE WEST. GREATEST RISK FOR SHOWERS WILL BE ACROSS WESTERN SECTIONS OF MA AND CT. SATURDAY... NORTHERN STREAM SHORT WAVE TROUGH MOVES ACROSS THE AREA. MOISTURE IS LACKING THRU THE COLUMN BUT MODEST FORCING FOR ASCENT SHOULD BE SUFFICIENT TO TRIGGER SCATTERED SHOWERS. THIS SEEMS REASONABLE AS ALL GLOBAL AND HI RES GUIDANCE GENERATES WIDESPREAD QPF SAT. ALTHOUGH 00Z NAM QPF SEEMS TOO BULLISH. INSTABILITY IS LACKING AS SURFACE DEW PTS WILL BE IN THE U50S TO L60S. HOWEVER COOLING TEMPS ALOFT WITH APPROACHING TROUGH/HEIGHT FALLS WILL STEEPEN LAPSE RATES A BIT. MID LEVEL TROUGH ALSO INCREASES DEEP LAYER SHEAR UP TO ABOUT 40 KT LATE IN THE DAY. NOT EXPECTING ANY STRONG STORMS GIVEN LACK OF INSTABILITY BUT WILL HAVE TO CONTINUE TO WATCH. OVERALL...A TYPICAL SUMMER DAY WITH SEASONABLY WARM HIGHS IN THE 80S ALONG WITH THE RISK OF A FEW SHOWERS OR STORMS IN THE AFTERNOON. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... HIGHLIGHTS... * SEASONABLE TEMPS AND LOWER HUMIDITY FOR THE FIRST HALF OF THE WEEK * PATTERN CHANGE BY MID WEEK BRINGING BELOW AVG TEMPS * HIT OR MISS SHOWERS/TSTORMS THROUGH THE PERIOD OVERVIEW... 00Z GUIDANCE IS IN GOOD AGREEMENT FOR MOST OF THE PERIOD. ISSUES LIE WITHIN THE SMALL SCALE AND TIMING. STRONG UPPER LEVEL LOW WILL CONTINUE TO SPIN OVER HUDSON BAY KEEPING THE NORTHEAST IN SOUTHWESTERLY FLOW FROM ELONGATED TROUGH. SEVERAL WAVES WILL MOVE THROUGH THIS FLOW KEEPING THE CHANCE FOR SHOWERS AND THUNDERSTORMS IN THE FORECAST. UPPER LEVEL LOW WILL BEGIN TO SHIFT EASTWARD DUE TO AMPLIFIED RIDGE OVER THE CENTRAL CONUS AND NORTHWESTERLY LOW STRENGTHENING. THIS SHIFT IN THE PATTERN WILL DROP HEIGHTS AND TEMPS ACROSS THE NORTHEAST...LEADING TO BELOW AVERAGE TEMPERATURES. DAILIES... SUNDAY THROUGH WEDNESDAY...MODERATE CONFIDENCE. MID-LEVEL RIDGE WILL BUILD ACROSS THE REGION SUNDAY INTO MONDAY. MOST OF THE AREA SHOULD REMAIN DRY BUT CANNOT RULE OUT A FEW SPOT SHOWERS OR AIRMASS THUNDERSTORMS. BEST REGION WILL BE ACROSS NORTHWEST ZONES DUE TO THE HIGHER TERRAIN. OTHERWISE TEMPERATURES WILL AT OR SLIGHTLY ABOVE AVERAGE. HIGHS WILL BE NEAR 85F TO 90F WITH LOWS BETWEEN 60-70F. POTENT SHORTWAVE WILL MOVE THROUGH THE FLOW ON TUESDAY. ANTICIPATE SHOWERS AND THUNDERSTORMS TO DEVELOP AHEAD OF THE WAVE ACROSS UPSTATE NY ON MONDAY AND OVER SNE MONDAY NIGHT INTO TUESDAY. SOME MODEST INSTABILITY AND LI VALUES BELOW -4C LEADS TO THE POTENTIAL FOR OVERNIGHT THUNDERSTORMS. LOW CONFIDENCE ON STRONG TO SEVERE. TEMPERATURES ON TUESDAY WILL BE SLIGHTLY COOLER BUT STILL NEAR SEASONABLE AS DRY AIR FROM THE WEST MOVES INTO THE AREA. WEDNESDAY AND BEYOND...HIGH CONFIDENCE IN TEMPS...LOW CONFIDENCE IN PRECIP. CLOSED LOW ALOFT WILL SHIFT EASTWARD PUSHING A POTENT SHORTWAVE OVER THE REGION. THIS WAVE WILL DEVELOP A COASTAL LOW OVER THE MID- ATLANTIC AND MOVE CLOSE TO THE BENCHMARK....GRAZING THE SOUTH COAST WITH PRECIP. HOWEVER EXACT PLACEMENT CAN CHANGE...DEPENDING ON IF PATTERN AMPLIFIES MORE. OTHERWISE ANTICIPATE COOLER CONDITIONS AS UPPER LEVEL TROUGH TAKES HOLD OVER THE NORTHEAST SENDING SEVERAL WAVES TO REINFORCE THE COOLER AIRMASS. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH SATURDAY/...HIGH CONFIDENCE. THIS AFTERNOON...VFR FOR ALL TERMINALS THE REST OF TODAY. TONIGHT...VFR WITH ONLY A VERY LOW RISK OF A FEW SHOWERS ACROSS WESTERN MA TOWARD DAYBREAK. SATURDAY...VFR BUT SCATTERED SHOWERS AND WIDELY SCATTERED THUNDERSTORMS IN THE AFTERNOON...WITH HIGHEST CHANCE OF SHOWER/THUNDERSTORM ACROSS INTERIOR SE MA...NORTHERN RI AND EASTERN CT. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. ONLY ISSUE IS THAT WIND DIRECTION RUNNING MORE SW VERSUS THE W DIRECTION EXPECTED FROM GUIDANCE. DO NOT DEPICT ANY SHOWERS/THUNDERSTORMS IN TAF BUT NOT ISOLATED THUNDERSTORMS IN VICNITY OF BOS NOT OUT OF THE QUESTION FOR SATURDAY MID TO LATE AFTERNOON. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. ISOLATED THUNDERSTORM NOT OUT OF THE QUESTION SATURDAY AFTERNOON. OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/...MODERATE CONFIDENCE. VFR MUCH OF THE TIME WITH A LOW RISK FOR SCATTERED SHOWERS MONDAY INTO TUESDAY MORNING. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM /THROUGH SATURDAY/...HIGH CONFIDENCE. TODAY...WINDS BELOW SMALL CRAFT ADVISORY CRITERIA BUT A FEW GUSTS 20 TO 22 KNOTS POSSIBLE NEAR SHORE. HAVE ABOUT A 3 FOOT SWELL PROPAGATING TOWARD MA E COAST...SEEMINGLY ENOUGH TO CAUSE MODERATE RIP CURRENT ACTIVITY NE MA COAST PER BEACH OBSERVATION FROM SALISBURY. HENCE...UPDATED SURF ZONE FORECAST FOR THE SALISBURY TO ROCKPORT PORTION OF MA COASTLINE. TONIGHT...TRANQUIL DRY WEATHER WITH GOOD VSBY AND LIGHT SW WIND. SATURDAY...A FEW SHOWERS/T-STORMS POSSIBLE ESPECIALLY NEAR SHORE AND OVER LAND. OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/... FAIRLY TRANQUIL BOATING WEATHER THIS PERIOD WITH MODEST SW WINDS...GOOD VSBY AND MAINLY DRY WEATHER. LOW RISK OF SCATTERED SHOWERS AND T-STORMS LATE MONDAY. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...NOCERA/DUNTEN/THOMPSON NEAR TERM...NOCERA/DUNTEN/THOMPSON SHORT TERM...NOCERA LONG TERM...DUNTEN AVIATION...NOCERA/DUNTEN/THOMPSON MARINE...NOCERA/DUNTEN/THOMPSON

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