Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 300835 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 435 AM EDT TUE JUN 30 2015 .SYNOPSIS... WARMER TEMPERATURES MOVE IN TUESDAY AHEAD OF AN APPROACHING COLD FRONT. THIS FRONT WILL BRING SHOWERS/SCATTERED THUNDERSTORMS VERY LATE TUESDAY NIGHT AND WEDNESDAY. THE FRONT STALLS NEAR THE SOUTH COAST INTO THURSDAY...WITH A FEW MORE SHOWERS OR THUNDERSTORMS POSSIBLE. THIS FRONT PUSHES SOUTH OF THE COAST FRIDAY...WITH WEAK HIGH PRESSURE BRINGING MAINLY DRY AND SEASONABLE WEATHER THROUGH THIS WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 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. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... 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. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... HIGHLIGHTS... * CONTINUED THREAT OF SHOWERS AND THUNDERSTORMS THU * LOOKING MAINLY DRY AND SEASONABLE FRI THROUGH THE 4TH OF JULY WEEKEND WITH CONFIDENCE INCREASING SOMEWHAT. OVERVIEW AND MODEL PREFERENCES... PERSISTENT E PACIFIC BLOCK REMAINS IN PLAY THROUGH THE LONG TERM. HOWEVER. SHORTWAVE ENERGY WILL BE MOVING OUT OF NRN CANADA...SHIFTING THE LONGWAVE TROF OVER THE GREAT LAKES NE...LEADING TO MAINLY ZONAL FLOW ACROSS THE AREA TOWARD THE END OF THE WEEK. THERE IS ACTUALLY REASONABLE AGREEMENT BETWEEN 30.00Z MODEL GUIDANCE. WHILE THIS ZONAL FLOW DOES SUGGEST LOWER CONFIDENCE IN TIMING OF ANY SPECIFIC FEATURE...IT ALSO SUGGESTS THAT ANYTHING THAT DEVELOPS WILL BE WEAKENED AND MAINLY OPEN. GIVEN THE GENERALLY GOOD AGREEMENT...AND LACK OF SIGNIFICANT DIFFERENCES A BLEND OF THE OPERATIONAL RUNS WITH THE PREVIOUS FORECAST SHOULD WORK WELL FOR THIS UPDATE. DETAILS... WED NIGHT INTO THU... A COLD FRONT WILL BE SLOWLY CROSS THE THE REGION WED NIGHT...STALLING INVOF OF THE S COAST AS IT BECOMES PARALLEL TO THE UPPER STEERING FLOW. COLUMN STILL HAS ENOUGH MOISTURE...SHEAR AND MODERATE MID LVL LAPSE RATES DURING THE OVERNIGHT HOURS TO MAINTAIN AT LEAST SOME RISK OF TS/SHRA AS THE FRONT MOVES THROUGH. HOWEVER...WITH THE LACK OF A SFC CONNECTION...WILL LIKELY SEE A DRYING TREND TOWARD THE MORNING HOURS. BY DAY ON THU...A POCKET OF STEEP UPPER LVL LAPSE RATES IN PLACE...AND WITH THE FRONT STALLING NEARBY COMBINING WITH ONE LAST UPPER LVL SHORTWAVE ROTATING THROUGH TO YIELD YET ANOTHER ROUND OF DIURNAL -SHRA AND POSSIBLY A TS. AS PREVIOUS FORECASTER NOTED...SHEAR REMAINS ELEVATED AS WELL. FRI... WITH UPPER LVL ZONAL FLOW IN PLACE...A WEAK RIDGE AND ATTENDANT HIGH PRES WILL BE MOVING ACROSS THE AREA...FORCING THE WEAK FRONT FURTHER TO THE S. MAINLY DRY DAY AS AVAILABLE BUFKIT DATA SHOWS A DRY COLUMN AND SUBSIDENCE. A SLIGHT INCREASE IN H85 TEMPS SUGGEST HIGHS ARE SLIGHTLY ON THE WARMER SIDE OF NORMAL AWAY FROM THE COASTLINES WHERE SEA BREEZE WILL DOMINATE. THE WEEKEND... CONFIDENCE IN THE FORECAST BEGINS TO WAIN HERE MAINLY DUE TO THE DEVELOPMENT OF A WEAK WARM WAVE TO THE S OF THE UPPER LVL RIDGE WHICH COULD GENERATE ENOUGH LIFT FOR -SHRA DEVELOPMENT SAT OR SUN. HOWEVER...AT THE SAME TIME...THE BERMUDA LOOKS TO GAIN STRENGTH...AMPLIFYING THE RIDGE UPSTREAM OF A STRONGER WAVE IN CENTRAL CANADA. THEREFORE...IT/S A BATTLE BETWEEN THIS RIDGING AND THE WEAK WAVE TO THE S. GIVEN THE ROBUST NATURE OF THE RIDGE AND AMPLIFICATION OF THE BERMUDA HIGH...WILL LEAN TOWARD THE DRIER...HIGH PRES SOLUTION AT THIS TIME. BUT THERE IS ROOM FOR A SHOWER SHOULD THE WEAK WAVE TO THE S SHIFT A BIT FURTHER N WITHIN THE WEAK FLOW REGIME TO THE S OF THE RIDGE. BUILDING RIDGE AND INCREASING MID LVL TEMPS SUGGEST TEMPS MAINLY ABOVE NORMAL. EARLY NEXT WEEK... THE ROBUST SHORTWAVE TO THE W ACROSS SRN CANADA WILL BE MOVING E AND COULD LEAD TO A MORE UNSETTLED PATTERN HOWEVER...THIS WILL BE DEPENDENT ON THE FINAL AMPLITUDE OF THE RIDGE IN PLACE ACROSS THE REGION. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... 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...THURSDAY THROUGH SATURDAY... THU...MODERATE CONFIDENCE. MOSTLY VFR...BUT SCT SHOWERS/TSTMS POSSIBLE IN THE AFTERNOON WITH MVFR CONDITIONS. FRI AND SAT...MODERATE CONFIDENCE. MAINLY VFR WITH HIGH PRES...BUT STILL A BIT OF UNCERTAINTY REGARDING A SHOWER RISK FRI-SAT. && .MARINE... 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...THURSDAY THROUGH SATURDAY... THU...HIGH CONFIDENCE. WINDS WEAKENING AND SHIFT TO THE W. LINGERING SWELL REMAINS ACROSS THE WATERS...WITH WAVE HEIGHTS AVERAGING 5-7 FT. SMALL CRAFT ADVISORIES REMAIN FOR THIS SWELL. SOME SHOWERS AND THUNDERSTORMS LINGER...ESPECIALLY ACROSS THE SOUTHERN WATERS. FRI AND SAT...HIGH CONFIDENCE. HIGH PRES OVER THE WATERS LEADS TO A PERIOD OF MAINLY QUIET BOATING WEATHER. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EDT THIS MORNING FOR ANZ255- 256. && $$ SYNOPSIS...BELK/DOODY NEAR TERM...BELK SHORT TERM...BELK LONG TERM...DOODY AVIATION...BELK/DOODY MARINE...BELK/DOODY

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