Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 300202 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1002 PM EDT WED JUL 29 2015 .SYNOPSIS... ANOTHER VERY WARM AND HUMID DAY IS IN STORE FOR THURSDAY. AN APPROACHING COLD FRONT WILL TRIGGER SHOWERS AND EMBEDDED THUNDERSTORMS THURSDAY AFTERNOON AND EVENING WITH LOCALLY HEAVY RAINFALL...ESPECIALLY ACROSS THE INTERIOR. NOT AS WARM AND LESS HUMID WEATHER IS EXPECTED FRIDAY INTO THE WEEKEND AND PROBABLY INTO EARLY NEXT WEEK. THERE MAY BE SOME SCATTERED SHOWERS AND A FEW ISOLATED THUNDERSTORMS FROM TIME TO TIME THIS WEEKEND INTO EARLY NEXT WEEK AS WEAK WEATHER SYSTEMS MOVE ACROSS. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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10 PM UPDATE... FORECAST REMAINS ON TRACK THIS EVENING. DRY WEATHER WILL PREVAIL AS UPPER LEVEL RIDGE AXIS MOVES OVER THE REGION. A STICKY NIGHT IS AHEAD AS DEWPOINTS ARE IN THE UPPER 60S TO LOW 70S. THIS COMBINED WITH LIGHT WINDS WILL HELP FOG BECOME ANOTHER ISSUE TONIGHT. RIGHT NOW LOW STRATUS IS SITTING JUST OFF THE COAST OF ACK AND COULD MOVE ONTO THE CAPE. MAY NEED TO WATCH THE CAPE AND ISLANDS FOR WIDESPREAD FOG. PREVIOUS FORECAST... GIVEN HIGH DEWPOINTS AND LIGHT WINDS...WILL ONCE AGAIN SEE SOME PATCHY FOG DEVELOP IN THE TYPICALLY PRONE LOCATIONS. LOW CLOUDS MAY DEVELOP ACROSS THE FAR SOUTHEAST NEW ENGLAND COAST...BUT WITH SOUTHWEST FLOW SHOULD NOT ADVANCE MUCH FURTHER NORTHWEST THAN THAT. LOW TEMPS FOR MOST LOCATIONS WILL ONLY DROP TO BETWEEN 70 AND 75 WITH A FEW UPPER 60S POSSIBLE IN NORTHWEST MA.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... ***SHOWERS AND EMBEDDED THUNDERSTORMS WILL BRING HEAVY RAIN AND THE POTENTIAL FOR LOCALIZED STREET FLOODING THURSDAY AFTERNOON AND EVENING ESPECIALLY ACROSS INTERIOR SOUTHERN NEW ENGLAND*** ***A SECONDARY CONCERN WILL BE FOR A FEW STRONG TO MARGINALLY SEVERE THUNDERSTORMS LATE THURSDAY AFTERNOON/EARLY EVENING ACROSS WESTERN MA AND NORTHERN CT*** THURSDAY AND THURSDAY NIGHT... SOUTHWEST FLOW ALOFT AND AT THE SURFACE WILL TRANSPORT DEEP MOISTURE INTO SOUTHERN NEW ENGLAND. BOTH THE GFS/NAM SHOW PWATS EXCEEDING 2+ INCHES AND A SOUTHWEST LOW LEVEL JUST OF 25 TO 30 KNOTS. WE MAY SEE SOME PEEKS OF SUNSHINE IN THE MORNING...BUT SHOULD SEE CLOUDS BEGIN TO DOMINATE IN THE WARM AIR ADVECTION MOISTURE. GIVEN THE DEEP MOISTURE IN PLACE...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS COULD BREAK OUT ANYWHERE ACROSS THE REGION BY THU AFTERNOON AND PERHAPS EVEN EARLIER. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH THIS ACTIVITY. THE MAIN SHOW WILL ARRIVE LATE THURSDAY AFTERNOON AND EVENING IN ASSOCIATION WITH A PRE-FRONTAL TROUGH AND ASSOCIATED COLD FRONT. POOR MID LEVEL LAPSE RATES AND CLOUD COVER WILL LIMIT INSTABILITY TO SOME DEGREE. NONETHELESS...WE SHOULD BE ABLE TO DEVELOP AROUND 1000 MLCAPES ACROSS THE INTERIOR GIVEN 70+ DEWPOINTS IN PLACE. 0 TO 6 KM SHEAR IS RATHER MARGINAL...BUT DOES INCREASE TO BETWEEN 30 AND 35 KNOTS ACROSS OUR NORTHWEST ZONES TOWARDS 00Z. A LOT OF THE MESOSCALE MODELS SHOW A LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS WORKING INTO WESTERN MA/NORTHERN CT SOMETIME LATE THU AFTERNOON/EVENING. THAT ACTIVITY WEAKENS AS IT MOVES EAST INTO AN ENVIRONMENT WITH LESS INSTABILITY WHICH IS TYPICAL WITH SOUTHWEST FLOW ALOFT. BULK OF SHOWERS AND EMBEDDED STORMS SHOULD EXIT THE COASTAL PLAIN BY MIDNIGHT...BUT LINGERING ACTIVITY IS POSSIBLE ACROSS THE CAPE AND ISLANDS. SO TO SUM UP...HEAVY RAIN WITH THE POTENTIAL FOR LOCALIZED STREET FLOODING ACROSS THE INTERIOR WILL BE THE MAIN THREAT WITH THESE STORMS. HOWEVER...A FEW STRONG TO PERHAPS MARGINALLY SEVERE THUNDERSTORMS ARE POSSIBLE MAINLY ACROSS WESTERN MA AND NORTHERN CT. THE MAIN CONCERN WOULD BE LOCALIZED STRONG TO DAMAGING WIND GUSTS. THE HAIL THREAT IS RATHER LOW GIVEN 500 MB TEMPS OF AROUND -6C AND POOR MID LEVEL LAPSE RATES. ONE LITTLE NUANCE WE WANTED TO MENTION WAS THE LOW RISK FOR A BRIEF WEAK TORNADO ACROSS WESTERN MA AND NORTHERN CT. THERE IS ABOUT 25 TO 30 KNOTS OF WIND OFF THE DECK WITH RGEM/NAM SHOWING 0 TO 1 KM HELICITY VALUES NEAR OR OVER 100. GIVEN 70+ DEWPOINTS AND LOW LCL/S THERE IS A LOW RISK FOR THAT. HIGH TEMPS THU SHOULD MAINLY BE IN THE UPPER 80S TO NEAR 90...BUT A FEW PLACES ACROSS EASTERN NEW ENGLAND MAY END UP A FEW DEGREES WARMER IF THEY SEE A LONGER PERIOD OF SUNSHINE. EITHER WAY IT WILL BE VERY HUMID WITH 70+ DEWPOINTS. LOW TEMPS THU NIGHT WILL BE IN THE 60S TO NEAR 70 AND AREAS OF FOG WILL LIKELY DEVELOP IN THE TYPICALLY PRONE LOCATIONS LATE. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... SYNOPTIC OVERVIEW AND MODEL PREFERENCES... MEDIUM RANGE MODELS CONTINUE TO SIGNAL ANOMALOUS H5 CUTOFF VORTEX ACROSS HUDSON AND JAMES BAYS EXTENDING INTO QUEBEC DURING THIS TIMEFRAME. THIS WILL PUSH THE LONG WAVE TROUGH SLOWLY E OUT OF THE GREAT LAKES TOWARD NEW ENGLAND AROUND THE TUE-WED TIMEFRAME. THIS WILL PUSH THE HOT...VERY HUMID AIR S OF THE REGION. EXPECT GENERALLY SEASONABLE BUT DRIER CONDITIONS FROM LATE THIS WEEKEND ONWARD. SEVERAL WEAKENING SHORT WAVES WILL SLIDE AROUND THE BASE OF THE TROUGH AND PUSH TOWARD THE REGION...BUT WILL TEND TO WEAKEN AS THEY CROSS WITH GENERALLY WEAK INSTABILITY IN PLACE. WILL SEE PERIODS OF SCT SHOWERS/ISOLD THUNDERSTORMS...THOUGH TIMING IS IN QUESTION ESPECIALLY TOWARD THE MIDDLE OF NEXT WEEK. USED A BLEND OF AVAILABLE GUIDANCE INTO SUNDAY WITH GOOD CONTINUITY...THEN TRANSITIONED OVER TO THE GEFS/ECENS MEANS WHICH KEPT GOOD TIMING OF FEATURES FROM THE PREVIOUS FORECAST. DETAILS... FRIDAY... COLD FRONT PUSHES FURTHER OFFSHORE FRI MORNING. ANY LEFTOVER SHOWERS WILL PUSH OFF THE CAPE AND ISLANDS EARLY...THEN WILL SEE IMPROVING CONDITIONS MOVING IN. DRIER AIR ALSO PUSHES IN AS DEWPTS FALL AWAY FROM THE S COAST. WINDS WILL BE LIGHT SO WITH A WEAK PRES GRADIENT SO WILL SEE SOME PATCHY FOG DEVELOP LATE FRI NIGHT IN THE NORMALLY PRONE INLAND LOCATIONS AS WELL AS ALONG THE S COAST WHERE HIGHER DEWPTS WILL LINGER. HIGHS ON FRIDAY WILL GENERALLY BE IN THE 80S. SATURDAY-SUNDAY... ANOTHER COLD FRONT APPROACHES LATE SAT...CROSSING THE REGION SAT NIGHT. FRONT AND PRECIP WITH IT TENDS TO WEAKEN AS IT MOVES INTO MORE STABLE AIR...BUT WILL STILL SEE WIDELY SCT SHOWERS AND MAYBE A THUNDERSTORM OR TWO. LOOKS LIKE THE BEST CHANCE OCCURS ACROSS THE E SLOPES OF THE BERKSHIRES INTO THE WESTERN CT VALLEY. PRECIP WILL TEND TO DISSIPATE AFTER SUNSET SAT NIGHT...THOUGH CAN NOT RULE OUT A LINGERING SHOWER ACROSS CAPE COD AND THE ISLANDS. ON SUNDAY...WEAK HIGH PRES RIDGE BUILDS ACROSS SO WILL SEE DRY CONDITIONS WITH HIGHS AGAIN IN THE 80S...THOUGH HOLDING IN THE MID- UPPER 70S ACROSS OUTER CAPE COD AND NANTUCKET. A FEW SHOWERS MIGHT APPROACH FAR WESTERN AREAS WELL AFTER MIDNIGHT SUN NIGHT. MONDAY THROUGH WEDNESDAY... MODELS HAVING A TOUGH TIME WITH TIMING OF SHORT WAVES IN THE SLOWLY MIGRATING UPPER FLOW ACROSS THE NORTHEAST...AS WELL AS WHICH SHORT WAVE WILL HAVE MORE ENERGY THAN OTHERS. FOR NOW...HAVE LOW CHANCE POPS MENTIONED LATE MON/MON NIGHT AS ANOTHER FRONT MOVES ACROSS. SHOWERS MAY LINGER INTO TUE...THEN NOTING DRIER CONDITIONS FOR NEXT WED. RATHER LOW CONFIDENCE DURING THIS TIMEFRAME DUE TO WIDE MODEL SOLUTIONS. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH THURSDAY NIGHT/... TONIGHT...MODERATE TO HIGH CONFIDENCE. MAINLY VFR CONDITIONS. WILL SEE PATCHY FOG DEVELOP LATE IN THE TYPICALLY PRONE LOCATIONS. IN ADDITION...LOW CLOUDS MAY WORK ONTO THE ISLANDS AND CAPE COD...BUT SHOULD NOT MAKE IT MUCH FURTHER NORTHWEST THAN THAT WITH SOUTHWEST FLOW. THURSDAY...MODERATE CONFIDENCE. PROBABLY VFR CONDITIONS DOMINATE INTO THE MID AFTERNOON...EXCEPT THE SOUTH COAST/CAPE AND ISLANDS WHERE LOW CLOUDS/FOG PATCHES WILL BE AT LEAST NEARBY. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE POSSIBLE IN THE WARM AIR ADVECTION PATTERN DURING THE DAY. HOWEVER...THE MAIN FOCUS WILL BE A LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS THAT WILL LIKELY WORK INTO WESTERN MA/NORTHERN CT BY LATE AFTERNOON/EARLY EVENING. A FEW OF THESE STORMS MAY CONTAIN LOCALIZED STRONG WIND GUSTS AND TORRENTIAL RAINFALL. IN ADDITION...SOUTHWEST WIND GUSTS OF 25 TO 30 KNOTS ARE EXPECTED TO DEVELOP ALONG THE COASTAL PLAIN DURING THE AFTERNOON. THURSDAY NIGHT...MODERATE CONFIDENCE. IFR CIGS/VSBYS LIKELY ACROSS SOUTHEAST NEW ENGLAND COAST WITH MAINLY BROKEN MVFR TO VFR CIGS ELSEWHERE. SHOWERS AND EMBEDDED THUNDERSTORMS WILL WEAKEN AS THEY PUSH INTO EASTERN MA AND RHODE ISLAND THU EVENING...BUT SOME LOCALLY HEAVY RAIN IS STILL POSSIBLE. BULK OF ACTIVITY OVER AFTER MIDNIGHT EXCEPT PERHAPS CAPE AND ISLANDS...BUT PATCHY FOG AND LOW CLOUDS MAY DEVELOP. KBOS TERMINAL...HIGH CONFIDENCE THROUGH TONIGHT. SEA BREEZE SHOULD COME TO AN END BETWEEN 21Z AND 23Z THIS EVENING. KBDL TERMINAL...HIGH CONFIDENCE THROUGH TONIGHT. PATCHY FOG MAY AFFECT THE TERMINAL FOR A FEW HOURS BEFORE DAYBREAK THURSDAY. OUTLOOK /FRIDAY THROUGH MONDAY/... FRIDAY...MODERATE TO HIGH CONFIDENCE. MAINLY VFR. PATCHY FOG MAY DEVELOP IN NORMALLY PRONE INLAND LOCATIONS AS WELL AS ALONG S COAST LATE FRI NIGHT WITH LOCAL MVFR-IFR VSBYS. SATURDAY...MODERATE CONFIDENCE. MAINLY VFR. SCT SHOWERS/ISOLD THUNDERSTORMS LATE SAT THROUGH AROUND MIDNIGHT SAT NIGHT. LOCAL MVFR-IFR CONDITIONS IN ANY PRECIP. SUNDAY...MODERATE CONFIDENCE FOR VFR CONDITIONS. MONDAY...LOW TO MODERATE CONFIDENCE. MAINLY VFR. LOCAL MVFR-IFR IN ANY SHOWERS/ISOLD THUNDERSTORMS MAINLY AWAY FROM S COAST. SHOWERS LINGER INTO MON NIGHT WITH BRIEF LOCAL MVFR. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... TONIGHT...HIGH CONFIDENCE. WEAK PRESSURE GRADIENT SHOULD KEEP WINDS AND SEAS BELOW SMALL CRAFT ADVISORY THRESHOLDS. MAY SEE SOME AREAS OF FOG DEVELOP LATE ACROSS THE SOUTHERN WATERS. THURSDAY AND THURSDAY NIGHT...MODERATE TO HIGH CONFIDENCE. DEVELOPING LOW LEVEL JET WILL RESULT IN NEAR SHORE SOUTHWEST WIND GUSTS OF 25 TO 30 KNOTS DEVELOPING THU AFTERNOON. IN ADDITION...LONG SOUTHWEST FETCH WILL ALLOW FOR SEAS TO BUILD TO BETWEEN 3 TO 5 FEET ACROSS MOST OPEN WATERS. SCA HEADLINES GO INTO EFFECT FOR ALL WATERS THU AFTERNOON. WINDS DIMINISH THU EVENING...BUT WILL NEED TO KEEP HEADLINES UP THROUGH THU NIGHT FOR THE OUTER-WATERS THROUGH THU NIGHT FROM THE LEFT OVER SWELL. OUTLOOK /FRIDAY THROUGH MONDAY/... FRIDAY...MODERATE CONFIDENCE. SW WINDS MAY GUST CLOSE TO 20 KT ALONG SOUTHERN WATERS. SEAS 4 FT OR LESS. SATURDAY THROUGH MONDAY...GENERAL W-SW WINDS IN PLACE BELOW SMALL CRAFT CRITERIA. MAY SEE GUSTS UP TO 20 KT ON THE SOUTHERN WATERS SAT NIGHT AND AGAIN MON/MON NIGHT. WITH LONG SW FETCH IN PLACE... SEAS WILL BUILD UP TO 5-6 FT ON THE SOUTHERN OUTER WATERS DURING THIS TIMEFRAME SO SMALL CRAFTS MAY BE NEEDED. && .CLIMATE... HERE ARE THE HIGH TEMPS FOR OUR CLIMATE SITES TODAY THROUGH 7 PM... BOSTON 92 AT 649 PM BRADLEY 95 AT 407 PM WORCESTER 88 AT 426 PM PROVIDENCE 93 AT 434 PM MILTON/BLUE HILL 91 AT 510 PM /ASOS/ RECORD HIGHS FOR TODAY... BOSTON 97 ON 1933 & 1931 PROVIDENCE 95 ON 2002 & 1949 BRADLEY 96 ON 1933 WORCESTER 94 ON 1892 MILTON/BLUE HILL 97 IN 1949 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR MAZ017>024. RI...AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR RIZ005>008. MARINE...SMALL CRAFT ADVISORY FROM NOON TO 7 PM EDT THURSDAY FOR ANZ230>234-236-251. SMALL CRAFT ADVISORY FROM NOON TO 11 PM EDT THURSDAY FOR ANZ235-237. SMALL CRAFT ADVISORY FROM NOON THURSDAY TO 8 AM EDT FRIDAY FOR ANZ250-254>256. && $$ SYNOPSIS...FRANK/EVT NEAR TERM...FRANK/DUNTEN SHORT TERM...FRANK LONG TERM...EVT AVIATION...FRANK/EVT MARINE...FRANK/EVT CLIMATE...

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