Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 290531 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 131 AM EDT WED JUL 29 2015 .SYNOPSIS... ISOLATED TO SCATTERED THUNDERSTORMS WILL COME TO AN END THIS EVENING. OTHERWISE...HOT AND HUMID CONDITIONS EXPECTED THROUGH THURSDAY. A COLD FRONT WILL BRING SCATTERED THUNDERSTORMS LATE THURSDAY AND THURSDAY NIGHT. WARM AND LESS HUMID WEATHER IS EXPECTED FRIDAY INTO THE WEEKEND. THERE WILL BE CHANCES FOR MORE SHOWERS AND THUNDERSTORMS LATE THIS WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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2 AM UPDATE... OVERALL TREND IN THE FORECAST IS ON TRACK. DRY WEATHER PREVAILS AS UPPER LEVEL RIDGING BEGINS TO TAKE HOLD OF THE REGION. TEMPERATURES HAVE DROPPED A DEGREE OR TWO BUT ANTICIPATE LOW TEMPS TO REMAIN IN THE UPPER 60S TO LOW 70S. ANOTHER MILD NIGHT AS DEWPOINTS HAVE REACHED IN THE UPPER 60S TO LOW 70S AS WELL. THIS LOW TEMPS/DEWPOINT SPREAD HAS ALLOWED FOG TO DEVELOP ACROSS SE MASS/RI AND THE ISLANDS. EXPECT FOG TO SLOWLY INCREASE ESP IN REGIONS THAT RECEIVED RAIN TODAY AND ALONG THE SOUTH COAST. MAY NEED TO ISSUE A DENSE FOG ADV IF VSBYS DROP ANY LOWER...RIGHT NOW MANY SITES ARE HOLDING AROUND 2-4SM.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... ***HOT BUT DRY WEATHER ON WEDNESDAY*** UPPER LEVEL RIDING WILL BUILD ACROSS SOUTHERN NEW ENGLAND. THIS SHOULD RESULT IN PARTLY TO MOSTLY SUNNY SKIES...DESPITE SOME DIURNAL CUMULUS CLOUDS. 850 MB TEMPS AROUND +18C WILL YIELD HIGHS BETWEEN 90 AND 95 ACROSS MOST OF THE REGION. WEAK PRESSURE GRADIENT WILL RESULT IN TEMPS A BIT COOLER ALONG PORTIONS OF THE COAST. WHILE THERE IS A LOW RISK OF A VERY ISOLATED SHOWER/THUNDERSTORM...GIVEN UPPER LEVEL RIDGING OPTED FOR A DRY FORECAST. EVEN IF ONE WERE TO HAPPEN IT PROBABLY WOULD BE VERY BRIEF AND COVER SUCH A SMALL AREA OF OUR REGION...NOT WORTH A MENTION AT THIS POINT. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... SYNOPTIC OVERVIEW AND MODEL PREFERENCES... AS H5 CUTOFF LOW SETS UP ACROSS HUDSON BAY/ONTARIO/W QUEBEC AND A NEGATIVE NAO PATTERN IN PLACE...A FAST UPPER FLOW WILL CONTINUE ACROSS THE NORTHERN STREAM THROUGH THIS PERIOD. SHORT WAVES IN THIS FLOW WILL BRING CHANCES FOR SHOWERS/THUNDERSTORMS...THOUGH TIMING OF EACH INDIVIDUAL SYSTEM IS IN QUESTION BEYOND FRIDAY DUE TO THE FAST FLOW. MAY START TO SEE THIS LONG WAVE PATTERN BREAK DOWN EARLY NEXT WEEK...THOUGH LOW CONFIDENCE ON THIS TIMING THIS FAR OUT. NOTED VERY GOOD CONTINUITY AND TIMING OF APPROACHING SYSTEM LATE THIS WEEK AMONGST THE MEDIUM MODEL SUITE...THEN TIMING AND PLACEMENT OF SYSTEMS THIS WEEKEND INTO EARLY NEXT WEEK IN QUESTION. SO... WENT WITH A BLEND OF 12Z GFS/00Z ECMWF OP MODEL RUNS THROUGH FRIDAY NIGHT...THEN TRANSITIONED OVER TO AN OVERALL BLEND OF AVAILABLE GUIDANCE INCLUDING GEFS/ECENS LATER IN THE PERIOD WHICH GAVE GOOD CONSISTENCY. WEDNESDAY NIGHT... WEAK SHORT WAVE RIDGING WILL CROSS THE REGION WED NIGHT. WILL SEE SULTRY CONDITIONS...WHICH WILL LIKELY LEAD TO PATCHY FOG WHICH MAY BECOME LOCALLY DENSE ALONG THE S COAST...CAPE COD AND THE ISLANDS AFTER MIDNIGHT. EXPECT OVERNIGHT LOWS IN THE UPPER 60S TO LOWER 70S THOUGH A BIT MILDER IN THE URBAN CENTERS. THURSDAY THROUGH FRIDAY NIGHT... PRETTY VIGOROUS H5 SHORT WAVE MOVES ALONG IN W-NW FLOW ALOFT. CURRENT TIMING SUGGESTS ARRIVING AFTER 18Z THU ACROSS THE E SLOPES OF THE BERKSHIRES THAN PUSHING INTO THE CT VALLEY LATE IN THE DAY. LOOKS LIKE MOST ACTION WILL OCCUR THU NIGHT INTO FRI AS FRONT MOVES SLOWLY BUT STEADILY ACROSS. WITH GOOD PUSH OF DRIER AIR BEHIND THIS FRONT...NOTING PWATS INCREASE TO 1.9 TO 2.1 INCHES DURING THE NIGHT WITH HIGHEST VALUES ACROSS S COASTAL AREAS. ALSO GOOD ELEVATED CONVECTION SIGNALS...WITH TQ VALUES IN THE LOW 20S ALONG WITH K INDICES IN THE MID 30S. SPC HAS ALSO MENTIONED MARGINALLY SEVERE CONDITIONS AS THE PRECIP MOVES INTO FAR WESTERN AREAS LATE IN THE DAY. SOMETHING TO BE WATCHED. HAVE LIKELY SHOWERS/SCT TSTMS MOVING ACROSS THE REGION OVERNIGHT. ALSO USED ENHANCED WORDING FOR HEAVY RAINFALL. EXPECT FRONT TO CLEAR THE COAST FRI MORNING. ISOLD THUNDER MAY LINGER THROUGH MID MORNING AS BEST INSTABILITY MOVES OFFSHORE. SOME SHOWERS MAY LINGER ACROSS THE CAPE AND ISLANDS UNTIL AROUND MIDDAY THEN SHOULD EXIT. NOTING A BRIEF BREAK IN THE HUMID CONDITIONS AS DEWPTS FALL BACK TO THE 50S AWAY FROM THE COAST. TEMPS WILL STILL BE WARM THOUGH...WITH HIGHS MAINLY IN THE LOWER- MID 80S. FRIDAY NIGHT WILL BE DRY AND COMFORTABLE ESPECIALLY ACROSS CENTRAL AND W MA INTO N CT. EXPECT LOWS IN THE 60S...THOUGH MAY LINGER AROUND 70 ACROSS THE OUTER CAPE AND ISLANDS. SATURDAY-SUNDAY... NOTING ANOTHER DIP IN THE LONG WAVE TROUGH ACROSS THE GREAT LAKES AS A SHORT WAVE MOVES IN THE UPPER FLOW. OPERATIONAL MODELS HAVING TROUBLE HANDLING THIS FEATURE...THOUGH DOES LOOK LIKE THERE MAY BE SOME ISOLD SHOWER/TSTM ACTIVITY AS WEAK FRONT CROSSES SAT NIGHT INTO SUN MORNING. LOOKS LIKE BEST SHOT FOR NOW WILL BE ACROSS THE CT VALLEY AND ALONG E COAST...THOUGH COULD SEE ISOLD ACTIVITY ANYWHERE. SOMEWHAT LOWER CONFIDENCE DURING THIS TIMEFRAME. MONDAY-TUESDAY... THE H5 CLOSED LOW OVER HUDSON/JAMES BAYS HINTS IN SHIFTING SLOWLY E ACROSS N QUEBEC DURING THIS TIMEFRAME...BUT STILL SEEING LONG WAVE TROUGHING ACROSS THE GREAT LAKES. MAY SEE PERIODS OF SHOWERS/TSTMS MAINLY DURING THE DAYLIGHT HOURS BOTH MON AND TUE...THOUGH SOME QUESTION ON EXACT TIMING THIS FAR OUT. WILL REMAIN WARM AND HUMID DURING THIS TIMEFRAME. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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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 WEDNESDAY AFTERNOON/... TONIGHT...MODERATE CONFIDENCE. VFR FOR MANY SITES...HOWEVER ANTICIPATE PATCHY DENSE FOG TO DEVELOP DROPPING SOME SITES DOWN TO IFR OR EVEN LIFR. BEST SPOT WILL BE ACROSS THE CAPE...ISLANDS AND SOUTH COAST WHERE DEWPOINTS ARE IN THE 70S. WEDNESDAY INTO WEDNESDAY NIGHT...HIGH CONFIDENCE IN VFR CONDITIONS. MAY SEE PATCHY FOG OVERNIGHT DROPPING CONDITIONS TO IFR. THURSDAY...VFR TO START CONDITIONS DROPPING TO MVFR IN -SHRA/TSRA BETWEEN 18-00Z. A FEW STRONG STORMS ARE POSSIBLE. KBOS TERMINAL...HIGH CONFIDENCE. SEA BREEZE DEVELOPS BETWEEN 14-15Z. KBDL TERMINAL...HIGH CONFIDENCE. OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/... THURSDAY NIGHT...MODERATE CONFIDENCE. PATCHY MVFR CIGS/VSBYS IN SCATTERED SHOWERS/THUNDERSTORMS. LOCALLY HEAVY RAINFALL LIKELY... ESPECIALLY ACROSS RI/SE MA AROUND OR AFTER MIDNIGHT. IMPROVING CONDITIONS AFTER MIDNIGHT ACROSS N CENTRAL AND W MA INTO N CENTRAL CT. FRIDAY AND SATURDAY...MODERATE TO HIGH CONFIDENCE. LINGERING SHOWERS/ISOLD THUNDERSTORMS AND PATCHY FOG ALONG S COAST... OTHERWISE MAINLY VFR THROUGH THE REMAINDER OF FRIDAY THROUGH SAT. ISOLD SHOWERS/TSTMS POSSIBLE SAT NIGHT WITH LOCAL MVFR CONDITIONS. LOWER CONFIDENCE ON TIMING. SUNDAY...MODERATE CONFIDENCE. MAINLY VFR.
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&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TONIGHT THROUGH WEDNESDAY AFTERNOON/...HIGH CONFIDENCE. WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS THROUGH WEDNESDAY AFTERNOON. MAIN CONCERN WILL BE A FEW STRONG TO SEVERE STORMS ACROSS THE ADJACENT SOUTH COASTAL WATERS THROUGH 7 OR 8 PM. LOCALLY STRONG WIND GUSTS AND PERHAPS ISOLATED HAIL ARE THE MAIN CONCERNS. ALSO...SOME PATCHY FOG IS POSSIBLE THIS EVENING NEAR THE ISLANDS BUT VISIBILITIES SHOULD IMPROVE AFTER MIDNIGHT AS WINDS TURN WEST. OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/... WEDNESDAY NIGHT AND THURSDAY...EXPECT LIGHT SW WINDS WED NIGHT INTO THU...THEN PICKING UP DURING THU AFTERNOON. MAY SEE GUSTS TO 20 KT. SEAS 4 FT OR LESS. PATCHY FOG WED NIGHT INTO THU MORNING LOWERING VSBYS. THURSDAY NIGHT...SW WINDS GUSTING TO 20 KT MAINLY OVER THE OPEN WATERS. SEAS REACHING AROUND 5 FT. PATCHY FOG ALONG WITH SCT SHOWERS/TSTMS LOWERING VSBYS. FRIDAY AND SATURDAY...COLD FRONT SLOWLY MOVES OFFSHORE. ANOTHER WEAK FRONT MAY ENTER THE WATERS LATE SAT OR SAT NIGHT. SEAS OVER THE OPEN WATERS UP TO AROUND 5 FT DURING FRI...SUBSIDING FRI NIGHT BUT MAY BUILD AGAIN SAT NIGHT. SUNDAY...WINDS AND SEAS BELOW SMALL CRAFT CRITERIA. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...AIR QUALITY ALERT FROM 11 AM THIS MORNING TO 11 PM EDT THIS EVENING FOR MAZ017>024. RI...AIR QUALITY ALERT FROM 11 AM THIS MORNING TO 11 PM EDT THIS EVENING FOR RIZ005>008. MARINE...NONE.
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&& $$ SYNOPSIS...FRANK/EVT NEAR TERM...DUNTEN SHORT TERM...FRANK LONG TERM...EVT AVIATION...DUNTEN/EVT MARINE...FRANK/EVT

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