Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 040204 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1004 PM EDT MON AUG 3 2015 .SYNOPSIS... SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP TOWARDS TUESDAY MORNING...CONTINUING THROUGH THE DAY INTO THE EVENING HOURS. SOME OF THESE STORMS COULD BECOME STRONG TO SEVERE. DRY...WARM AND LESS HUMID WEATHER ARRIVES WEDNESDAY AND CONTINUES INTO THURSDAY. A PERIOD OF UNSETTLED WEATHER IS POSSIBLE THURSDAY NIGHT INTO SATURDAY BUT CONFIDENCE IS LOW ON THE TIMING OF POTENTIAL WET WEATHER. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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10 PM UPDATE... WE CONTINUE TO WATCH BULK OF ACTIVE CONVECTION ROLL NW OF THE REGION ALONG THE PERIPHERY OF THE FIRST IN A SERIES OF WEAK SHORTWAVES AND A PRE-FRONTAL TROF WHICH CONTINUES TO DIMINISH. THE NEXT ROUND TO WATCH WILL BE THE DEVELOPING CONVECTION COLOCATED WITH A SECONDARY TROF ACROSS PA AND SE NY. WITH THE MODIFIED EML SETTLING FURTHER E AND INCREASING MOISTURE THROUGH THE COLUMN /SOMETHING WE WERE LACKING MOST OF THE DAY/...PLUS A SLIGHT UP- TICK IN SHEAR WILL NEED TO WATCH THIS DEVELOPMENT AS IT MOVES E INTO NY/SNE DURING THE EARLY MORNING HOURS. SOME MESOSCALE GUIDANCE SUGGESTS THE TYPICAL RIGHT-TURN AS THE CONVECTION DIVES S TOWARD BETTER INSTABILITY WHILE OTHERS LEAVE THE STEERING FLOW IN CONTROL...TAKING IT ACROSS CT/SE MASS. HAVE INCREASED POPS IN THIS AREA PRIMARILY WHILE LOWERING THEM SOMEWHAT ELSEWHERE. IT WILL BE INTERESTING TO OBSERVE THROUGH THE OVERNIGHT HOUR CONVECTION SURVIVES WITH LITTLE SFC BASED SUPPORT. OTHERWISE...MILD...MIN TEMPS IN THE MID 60S TO AROUND 70. PREVIOUS DISCUSSION... TONIGHT... POTENTIAL CONVECTIVE WEATHER OUTCOMES INTO SE NEW ENGLAND TOWARDS TUESDAY MORNING. FORECAST GUIDANCE CONSENSUS NOTES AN INSTABILITY BURST ELEVATED AND MAINTAINED BY A S/SW WARM-MOIST PLUME OF HIGHER THETA-E AIR ABOVE A SUBSEQUENT INVERSION. PWATS OF 1.50-1.75 INCHES. ACTIVITY LOOKS TO ORIGINATE ALONG THE NOSE OF A H925-85 JET WITHIN A H85-7 ENVIRONMENT OF 6-7C/KM LAPSE RATES. YET THERE IS A LACK OF DEEP-LAYER FORCING AS THE BETTER AREA OF PVA / MID-LEVEL TROUGH / SURFACE COLD FRONT REMAIN TO THE W. THINKING IS THAT WE MAY SEE A WIDESPREAD AREA OF ACTIVITY OF SHOWERS AND THUNDERSTORMS COLLOCATED WITH THE CONVERGENT LOW-LEVEL PLUME. UNCERTAINTY IF ANY THUNDERSTORMS BECOME STRONG TO SEVERE. HEAVY RAIN LOOKS TO BE THE MAIN THREAT ALONG WITH LIGHTNING. THINKING LOW RISK SEVERE AND POTENTIAL FOR SOME OF THE STORMS TO BECOME STRONG. WILL SEE COLLOCATED UNI-DIRECTIONAL SW-NE 0-6 KM BULK SHEAR EXCEEDING 40 KTS AND FREEZING LEVELS OF AROUND 11 KFT. SOME EVIDENCE OF TURNING WITHIN THE 0-1/0-3 KM LAYER. SREF DOES DENOTE DECENT PROBABILITIES OF INSTABILITY EXCEEDING 2K J/KG IN ADDITION TO THE AFOREMENTIONED SHEAR AND TURNING ENVIRONMENT. THOUGH SREF PROBS NOT SO MUCH HELPFUL WITH RESPECT TO PRECIP ACCUMULATIONS...THUS CONFIDENCE WITH RESPECT TO POSSIBLE FLOODING IS LOW DESPITE THE ANTICIPATED OUTCOMES THAT WERE DISCUSSED ABOVE. WILL AVOID ENHANCED WORDING WITH THE FORECAST FOR THE TIME BEING. SHOULD BETTER FORCING AND VENTING ALOFT WITH THE H3 JET SHIFT E... THERE WOULD BE GREATER IMPETUS UPON THE ENVIRONMENT TO GENERATE GREATER AND LIKELY STRONGER CONVECTIVE WEATHER. INTERESTING AS TO WHETHER CONVECTIVE REMNANTS W FROM EARLIER IN THE DAY SHIFT E AND ACT AS A CRUX OF FORCING VIA LOW- TO MID-LEVEL CONVERGENCE. OVERALL INDIVIDUAL MODELS CONTINUE TO WOBBLE AND THERE IS JUST AN UNDERLYING LEVEL OF UNCERTAINTY OTHER THAN THE FOCUS BEING ON SE NEW ENGLAND. IT MAY BE QUIET THROUGHOUT AS THE PRESENT DRY SUBSIDING WEDGE OF AIR ACROSS THE REGION MAINTAINS. OTHERWISE SW-FLOW CONTINUES OVERNIGHT USHERING HIGHER DEWPOINT AIR ACROSS INTERIOR NEW ENGLAND. SHOULD REMAIN BREEZY ALONG THE S/SE- COAST. INCREASING CLOUD COVER SHOULD YIELD MILD LOW TEMPERATURES AROUND THE MID- TO UPPER-60S AND MAY SUBSEQUENTLY LIMIT PATCHY DENSE FOG TO JUST ACROSS S/SE NEW ENGLAND IN HIGHER DEWPOINT AIR.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... TUESDAY... A COMBINATION OF RISING HEIGHTS WITHIN THE MID-LEVELS COMBINED WITH DRIER AIR ALOFT COULD SUBDUE THE POTENTIAL CONVECTIVE ENVIRONMENT. BENEATH CYCLONIC FLOW ALOFT THRU WHICH ADDITIONAL MID-LEVEL IMPULSES AND ACCOMPANYING JET-STREAKS RESIDE...THE OVERALL QUESTION IS AS TO WHETHER A SURFACE FRONTAL BOUNDARY CAN BECOME THE FOCUS FOR SHOWERS AND THUNDERSTORMS. SWEEPING THROUGH AN ENVIRONMENT OF ROBUST THETA-E AIR AND INSTABILITY ON THE ORDER OF 2K J/KG IN WHICH LAPSE RATES ARE STEEP ESPECIALLY H85-7 AND SHEAR PROFILES ARE MODERATE TO STRONG TO 50 KTS WITH SLIGHT TURNING WITHIN THE 0-1/0-3 KM PROFILE...THERE APPEARS TO BE MECHANISMS FOR FORCING...BUT SHOULD MID-LEVEL RIDGING PROCEED...THIS SEEMS TO SQUASH THE POSSIBILITY FOR CONVECTION. THERE IS ALSO THE POSSIBILITY THAT SHOULD ACTIVITY DEVELOP TOWARDS MORNING OVER SE NEW ENGLAND AS NOTED EARLIER IT COULD SUBDUE THE ENVIRONMENT FROM BECOMING CONVECTIVE /I.E. CLOUD COVER/. A VERY COMPLICATED FORECAST. BUT STILL CAN NOT RULE OUT THE POSSIBILITY OF SOMETHING POPPING ACROSS THE INTERIOR. AM SOMEWHAT CONCERNED NOTING THE CIPS ANALOG GUIDANCE IN WHERE SEVERAL OF THE ANALOGS WITNESSED SUBSTANTIAL WIND AND HAIL IMPACTS OVER N- AND W-PORTIONS OF S NEW ENGLAND. THE STRONG TO SEVERE WEATHER POTENTIAL IS SEEMINGLY THERE THOUGH THERE IS SOME LEVEL OF DOUBT. EVEN SPC WILL WAIT ON HOW THE ENVIRONMENT DEVELOPS WITH RESPECT TO THEIR CONVECTIVE WEATHER OUTLOOKS...WHETHER THE ENVIRONMENT WILL DESTABILIZE. CAN NOT RULE IT OUT COMPLETELY AND WILL PREPARE FOR THE POTENTIAL ACCORDINGLY. FOCUS OF A HEAVY RAIN THREAT ALONG WITH POTENTIAL HAIL AND STRONG TO DAMAGING WIND POSSIBILITIES. CAN NOT RULE OUT THE POSSIBILITY OF A TORNADO. BUT NOT ENOUGH CONFIDENCE AT THIS TIME TO GO WITH ENHANCED WORDING IN THE FORECAST. WHILE FORECAST GUIDANCE SEEMS MIXED WITH AN UNCERTAIN EVOLUTION OF SYNOPTICS...THERE IS GREATER CONFIDENCE OF SHOWER AND THUNDERSTORM ACTIVITY AROUND THE VICINITY OF SE NEW ENGLAND AND ADJACENT WATERS WHERE THE SW-NE PLUME OF HIGHER THETA-E AIR RESIDES AS WELL AS BOTH A STRONGER AND CONVERGENT SW-NE H925-85 WIND PROFILE. WOULD EXPECT A CONTINUATION BEGINNING IN THE MORNING AS OUTLINED IN THE EARLIER DISCUSSION OF SCATTERED SHOWERS AND THUNDERSTORMS...SOME OF WHICH ALSO COULD BE STRONG AND POSSIBLY SEVERE. OVERALL...A MILD AND MUGGY DAY WITH HIGHS INTO THE MID- TO UPPER-80S AS DEWPOINTS RANGE AROUND THE MID- TO UPPER-60S. TUESDAY NIGHT... FRONTAL BOUNDARY PUSHES THE HIGHER THETA-E / INSTABILITY OUT TO SEA INTO THE OVERNIGHT PERIOD. SO ANTICIPATING A DRYING TREND. W-FLOW PROCEEDING USHERING LOWER DEWPOINT AIR ACROSS THE INTERIOR. AS CONDITIONS GRADUALLY CLEAR...TEMPERATURES DROP INTO THE LOW- TO MID- 60S. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... HIGHLIGHTS... * UNSETTLED WEATHER POSSIBLE AROUND FRIDAY * TEMPERATURES TRENDING BELOW NORMAL DURING THIS PERIOD OVERALL...THE MODELS HAVE RATHER POOR AGREEMENT ON THE GENERAL PATTERN AND TIMING THROUGH THE LONG TERM. IN SOME TIME PERIODS IT SEEMS THAT THE GFS MAY JUST BE SLOWER THAN THE ECMWF. IN OTHERS... THEY ARE JUST COMPLETELY DIFFERENT. THE ENSEMBLES ARE NOT MUCH HELP IN THAT THE ECMWF ENSEMBLES LOOK VERY SIMILAR TO THE OPERATIONAL MODEL AND THE GEFS IS VERY SIMILAR TO THE GFS. BASICALLY HAVE TWO FAIRLY DIFFERENT SOLUTIONS FOR MUCH OF THE LONG TERM. HOWEVER... GENERAL TRENDS ARE SIMILAR. LOOKING AT A PERIOD OF UNSETTLED WEATHER WITH TEMPERATURES TRENDING BELOW NORMAL THROUGH MUCH OF THE WEEK. WEDNESDAY...LOOKS TO BE THE WARMEST DAY OF THE PERIOD WITH TEMPERATURES AROUND OR JUST ABOVE NORMAL. DESPITE THE POTENTIAL FOR A FEW SHOWERS OR THUNDERSTORMS ACROSS THE NORTHWESTERN ZONES AS A SHORTWAVE PUSHES INTO THE REGION...EXPECT MUCH OF THE DAY AND MUCH OF THE AREA TO REMAIN DRY. THURSDAY...MUCH OF THE DAY LOOKS TO BE DRY WITH HIGH PRESSURE BUILDING INTO THE AREA. THIS IS ONE OF THOSE TIMES THE TIMING IS OFF BETWEEN THE ECMWF AND THE GFS. THE ECMWF IS QUICK TO MOVE THE HIGH PRESSURE OUT OF THE REGION...PUSHED BY LOW PRESSURE MOVING INTO THE MID-ATLANTIC FROM THE GREAT LAKES. THE GFS KEEPS THAT HIGH PRESSURE OVER SOUTHERN NEW ENGLAND AND THE LOW PRESSURE IN THE GREAT LAKES. THURSDAY NIGHT THROUGH SATURDAY...THIS LOOKS TO BE THE MOST UNSETTLED TIME WITH LOW PRESSURE MOVING INTO THE MID-ATLANTIC AND THEN POSSIBLY UP THE EAST COAST OVER THE 40/70 BENCHMARK SOUTHEAST OF SOUTHERN NEW ENGLAND. THE ECMWF IS THE MOST BULLISH WITH THIS... TRACKING THE LOW DIRECTLY OVER THE BENCHMARK AND BRINGING AN EXTENDED PERIOD OF RAIN TO MUCH OF SOUTHERN NEW ENGLAND. THE GFS DEVELOPS SOME SORT OF BOUNDARY ALONG WHICH SEVERAL AREAS OF LOW PRESSURE TRAVEL...BRINGING PERIODS OF RAIN TO THE REGION. BELOW NORMAL TEMPERATURES ARE A GIVEN WITH LOWERING HEIGHTS/TEMPS ALOFT AND MOSTLY CLOUDY TO OVERCAST SKIES FOR MUCH OF THIS TIME. WOULDN/T BE SURPRISED TO SEE TEMPS TOP OUT IN THE UPPER 60S TO LOWER 70S ON FRIDAY. SUNDAY AND MONDAY...MUCH OF THIS FORECAST WILL DEPEND ON HOW FRIDAY AND SATURDAY SHAKE OUT...BUT IN GENERAL THE WEATHER LOOKS DRIER AND QUIETER WITH REBOUNDING TEMPERATURES. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM /THROUGH TUESDAY NIGHT/... TONIGHT...MODERATE CONFIDENCE. SW-WINDS. SCT -SHRA SWEEP FROM THE W AND INCREASE IN COVERAGE OVER SE TERMINALS TOWARDS MORNING WITH THE POSSIBILITY OF TSRA / +RA AND LOWERING CIGS TO MVFR. PATCHY FOG. VFR ELSEWHERE. TUESDAY...LOW CONFIDENCE. SW-WINDS GUSTY AT TIMES 20-25 KTS. SCT SHRA/TSRA POSSIBLE OVER THE INTERIOR THOUGH BETTER CHANCES OVER SE NEW ENGLAND INTO EVENING. OTHER THAN MVFR LINGERING OVER SE TERMINALS DURING THE MORNING... TEMPO MVFR-IFR POSSIBLE WITH ANY WEATHER. TUESDAY NIGHT...MODERATE CONFIDENCE. WINDS BACK W WITH FRONTAL PASSAGE. TERMINALS CLEAR OUT W TO E. PREVAILING VFR WITH MVFR CIGS LINGERING OVER SE TERMINALS TOWARDS MORNING. KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. MVFR CIGS MAY DEVELOP ACROSS THE TERMINAL TOWARDS TUESDAY MORNING. KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. OUTLOOK /WEDNESDAY THROUGH SATURDAY/... WEDNESDAY THROUGH THURSDAY...HIGH CONFIDENCE. VFR. LOW PROBABILITY OF A FEW SHOWERS/STORMS ACROSS NW MA WEDNESDAY. ANY STORMS THAT DEVELOP MAY HAVE MVFR/IFR CONDITIONS. THURSDAY NIGHT THROUGH SATURDAY...LOW CONFIDENCE ON TIMING...HIGHER CONFIDENCE ON TRENDS. MVFR/IFR CONDITIONS IN WIDESPREAD RAIN LIKELY SOMETIME DURING THIS PERIOD. VFR BEFORE AND AFTER PERIOD OF RAIN. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM /THROUGH TUESDAY NIGHT/... TONIGHT...MODERATE CONFIDENCE. SW-WINDS CONTINUE WITH GUSTS AROUND 20 KTS...STRONGER OVER THE S- WATERS AT 25 KTS. WAVES BUILDING TO 5 FEET. PERHAPS SOME PATCHY FOG ISSUES. INCREASING AREAL COVERAGE OF SHOWERS AND POSSIBLE THUNDER- STORMS TOWARDS MORNING. STORMS MAY BE STRONG TO SEVERE. TUESDAY...MODERATE CONFIDENCE. SW-WINDS WITH GUSTS 20-25 KTS. WAVES AT 5-6 FEET. CONTINUED SHOWER AND THUNDERSTORM ACTIVITY WITH SOME OF THOSE STORMS BEING STRONG TO SEVERE. TUESDAY NIGHT...MODERATE CONFIDENCE. SW-WINDS BACKING W THROUGH THE NIGHT. GUSTS SUBSIDING. WAVES AT 5-6 FEET. SHOWER / THUNDERSTORM CHANCES CONCLUDE W TO E TOWARDS MORNING. OUTLOOK /WEDNESDAY THROUGH SATURDAY/...MODERATE CONFIDENCE. WEDNESDAY THROUGH FRIDAY...HIGH CONFIDENCE. QUIET BOATING WEATHER WITH LIGHT WINDS AND SEAS BELOW 5 FEET EXPECTED. RAIN IS LIKELY THURSDAY NIGHT THROUGH FRIDAY...LIMITING VISIBILITIES AT TIMES. FRIDAY NIGHT AND SATURDAY...MODERATE CONFIDENCE. EASTERLY WINDS AND SEAS INCREASE AS LOW PRESSURE PASSES SOUTH OF THE WATERS. SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED FOR THE OUTER WATERS. RAIN IS LIKELY FRIDAY NIGHT INTO SATURDAY...LIMITING VISIBILITIES AT TIMES. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT TUESDAY FOR ANZ230>234-236- 250-251. SMALL CRAFT ADVISORY UNTIL 2 AM EDT WEDNESDAY FOR ANZ235-237- 254>256. && $$ SYNOPSIS...RLG/SIPPRELL NEAR TERM...DOODY/SIPPRELL SHORT TERM...SIPPRELL LONG TERM...RLG AVIATION...RLG/SIPPRELL MARINE...RLG/SIPPRELL

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