Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 300734 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 334 AM EDT TUE JUN 30 2015 .SYNOPSIS...
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WARMER TEMPERATURES MOVE IN TUESDAY AHEAD OF AN APPROACHING COLD FRONT. THIS FRONT WILL BRING SHOWERS/SCATTERED THUNDERSTORMS VERY LATE TUESDAY NIGHT AND WEDNESDAY...WITH MORE SHOWERS AND STORMS POSSIBLE THURSDAY AS THIS FRONT STALLS OVER NEW ENGLAND. THIS FRONT PUSHES SOUTH OF THE COAST FRIDAY...WITH WEAK HIGH PRESSURE BRINGING MAINLY DRY AND SEASONABLE WEATHER THROUGH THIS WEEKEND.
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&& .NEAR TERM /THROUGH TODAY/...
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A PARTLY SUNNY AND PLEASANT DAY IN STORE FOR THE REGION. SEABREEZES WILL DEVELOP ONCE AGAIN. A MID LEVEL SHORTWAVE WILL RESULT IN SHOWERS AND THUNDERSTORMS DEVELOPING TO OUR WEST THIS AFTERNOON. THE ISSUE AT HAND WILL BE TO SEE HOW MUCH INSTABILITY DEVELOPS OVER THE WESTERN HALF OF SOUTHERN NEW ENGLAND. CANNOT COMPLETELY RULE OUT THE POSSIBILITY OF A THUNDERSTORM...SO WILL CONTINUE TO MENTION ISOLATED THUNDERSTORMS THIS AFTERNOON. AT THIS TIME...THE GREATEST RISK APPEARS TO BE ACROSS NORTHWEST MA.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM WEDNESDAY/...
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OTHER THAN ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS THIS EVENING ACROSS THE WESTERN HALF OF SOUTHERN NEW ENGLAND...DRY WEATHER WILL DOMINATE THROUGH MIDNIGHT. A POTENT SHORTWAVE AND ITS ASSOCIATED COLD POOL ALOFT WILL APPROACH FROM THE WEST TOWARD DAYBREAK. THE TIMING REMAINS UNCERTAIN...BUT THE CONSENSUS INDICATES AN INCREASING RISK FOR RAINFALL AFTER MIDNIGHT...WITH MOST OF THE AREA LIKELY SEEING A RISK FOR SHOWERS BETWEEN 09Z AND 12Z. LOTS OF SHEAR PROJECTED TO BE IN PLACE. THE MAIN QUESTION WILL BE THE AMOUNT OF INSTABILITY. THE CURRENT TIMING IS CLIMATOLOGICALLY UNFAVORED...BUT NOT WITHOUT PRECEDENT. THE LATEST GUIDANCE DOES GENERATE CAPE OF 700-1500 J/KG BY EARLY AFTERNOON. WITH STRONG SHEAR ALREADY IN PLACE...WE STILL CANNOT RULE OUT A FEW STRONG TO SEVERE THUNDERSTORMS WEDNESDAY MORNING INTO WEDNESDAY AFTERNOON... SHOULD ENOUGH INSTABILITY GENERATE FAST ENOUGH. HEAVY RAINFALL WILL ALSO BE A THREAT. THE MAIN QUESTION FOR LATER WEDNESDAY AFTERNOON IS IF A SECOND ROUND OF SHOWERS/TSTMS CAN DEVELOP ACROSS THE INTERIOR AHEAD OF A COLD FRONT. MODELS CONTINUE TO DRY THE COLUMN LATE IN THE DAY...SO THERE IS LIMITED WINDOW FOR A SECOND ROUND OF CONVECTION. THE DEEPER LAYER SHEAR IS PROJECTED TO ALSO WEAKEN INT HE AFTERNOON AS WELL.
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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HIGHLIGHTS... * CONTINUED THREAT OF SHOWERS AND THUNDERSTORMS THU * LOOKING MAINLY DRY AND SEASONABLE FRI THROUGH THE 4TH OF JULY WEEKEND BUT CONFIDENCE IS NOT HIGH OVERVIEW...HIGH AMPLITUDE TROF FOR THIS TIME OF YEAR ACROSS THE GT LAKES WITH SERIES OF SHORTWAVES ROTATING INTO NEW ENG WILL BRING A PERIOD OF WET WEATHER THU. MODELS HAVE BEEN STRUGGLING WITH THE LOCATION OF A FRONTAL WAVE TOWARD THE END OF THE WEEK. PREVIOUS RUNS OF THE GFS AND ECMWF WERE QUITE WET HERE THU NIGHT INTO FRI BUT 12Z RUNS ARE NOW SUPPRESSED AND KEEP IT DRY HERE RIGHT THROUGH THE WEEKEND WITH WEAK HIGH PRESSURE OVER NEW ENG. HOWEVER...GIVEN PROXIMITY OF A SERIES OF WAVES JUST TO THE SOUTH...CONFIDENCE IN A DRY FORECAST IS NOT HIGH AS A SLIGHT NORTHWARD SHIFT WOULD MEAN A COOL RAIN. THURSDAY...COLD FRONT LIKELY GETS HUNG UP ACROSS SNE AS ANOTHER MID LEVEL SHORTWAVE APPROACHES FROM THE GT LAKES. MODELS SHOW DESTABILIZATION OCCURRING WITH UP TO 1000 J/KG OF SBCAPE AND A SURGE OF HIGHER KI VALUES MOVING BACK INTO THE REGION SO MORE SHOWERS AND TSTMS ARE POSSIBLE ESPECIALLY IN THE AFTERNOON WITH FOCUS MORE IN CENTRAL AND E NEW ENG. 0-6 KM SHEAR IS 35-40 KT SO IF INSTABILITY IS REALIZED CANT RULE OUT A FEW STRONG STORMS BUT MID LAPSE RATES WILL BE A LIMITING FACTOR. FRIDAY THROUGH MONDAY...NOT A HIGH CONFIDENCE FORECAST BUT LATEST GUIDANCE IS SUGGESTING MOSTLY DRY AND SEASONABLE CONDITIONS WITH A WARMING TREND BY SUNDAY AS A SERIES OF WAVES REMAIN TO THE SOUTH THROUGH SAT WITH WEAK HIGH PRES IN CONTROL. HOWEVER...ANY SLIGHT NORTHWARD ADJUSTMENT WOULD RESULT IN COOLER AND WET WEATHER FRI AND SAT.
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&& .AVIATION /06Z 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 /TONIGHT THROUGH TUESDAY NIGHT/... 06Z UPDATE... THROUGH 12Z...HIGH CONFIDENCE. VFR CONDITIONS CONTINUE...OTHER THAN PERHAPS A FEW HOURS OF PATCHY GROUND FOG LATE IN THE TYPICALLY PRONE LOCATIONS. TODAY...HIGH CONFIDENCE IN MAINLY VFR CONDITIONS. AN ISOLATED SPOT SHOWER/THUNDERSTORM OR TWO IS POSSIBLE IN THE AFTERNOON ACROSS PORTIONS OF OUR NORTHERN ZONES...WITH THE BEST SHOT IN FAR NORTHWEST MA. TONIGHT...MODERATE CONFIDENCE. VFR THIS EVENING. MAY SEE SOME LOW CLOUDS DEVELOP LATE AT SOME LOCATIONS...WITH THE GREATEST RISK FOR THIS ALONG THE SOUTHEAST NEW ENGLAND COAST. MAY ALSO SEE AN AREA OF SHOWERS AND THUNDERSTORMS WORK INTO WESTERN NEW ENGLAND TOWARD DAYBREAK. CONFIDENCE IN THE TIMING AT A PARTICULAR LOCATION IS THE LOWEST CONFIDENCE PART. WEDNESDAY...HIGH PROBABILITY FOR WIDESPREAD SHOWERS WITH SCATTERED TSTMS. RISK FOR A FEW STRONG STORMS AND HEAVY RAINFALL. IFR AND MVFR CONDITIONS LIKELY IN SHOWERS. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY... THU...MODERATE CONFIDENCE. MOSTLY VFR...BUT SCT SHOWERS/TSTMS POSSIBLE IN THE AFTERNOON WITH MVFR CONDITIONS. FRI AND SAT...LOW CONFIDENCE. VFR WITH MOSTLY DRY CONDITIONS...BUT IT COULD STILL END UP WET IF WAVES OF LOW PRES TRACK FURTHER N.
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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 /TONIGHT INTO WEDNESDAY/...HIGH CONFIDENCE. TODAY AND TONIGHT...WEAK PRESSURE GRADIENT WILL KEEP WINDS/SEAS BELOW SMALL CRAFT ADVISORY THRESHOLDS. SOME FOG MAY DEVELOP TOWARD DAYBREAK WEDNESDAY ACROSS THE SOUTHERN COASTAL WATERS. WEDNESDAY...HIGH CONFIDENCE. SW WIND GUSTS UP TO 20 KT...WITH SMALL CRAFT ADVISORY SEAS OVER SOUTHERN WATERS. VSBYS LIMITED IN SHOWERS AND SCATTERED TSTMS...ALONG WITH AREAS OF FOG. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY... THU...HIGH CONFIDENCE. LIGHT SW WINDS BUT LEFTOVER SOUTHERLY SWELL WILL RESULT IN SCA SEAS OVER SOUTHERN WATERS. SCT SHOWERS/TSTMS POSSIBLE IN THE AFTERNOON. FRI AND SAT...MODERATE CONFIDENCE. LIGHT EASTERLY WINDS. MARGINAL SCA SEAS POSSIBLE SOUTHERN WATERS ON FRI.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EDT EARLY THIS MORNING FOR ANZ235-237-254>256.
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&& $$ SYNOPSIS...BELK/KJC NEAR TERM...BELK SHORT TERM...BELK LONG TERM...KJC AVIATION...BELK/KJC MARINE...BELK/KJC

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