Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 300752 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 352 AM EDT WED JUL 30 2014 .SYNOPSIS... MAINLY DRY/PLEASANT WEATHER TODAY OTHER THAN PERHAPS A BRIEF PASSING SPRINKLE. A FEW SHOWERS AND PERHAPS A THUNDERSTORM OR TWO ARE POSSIBLE THU AND FRI...BUT MOST OF THE TIME WILL FEATURE DRY WEATHER. A PERIOD OF STEADY RAIN IS POSSIBLE SOMETIME THIS WEEKEND IF LOW PRESSURE TRACKS CLOSE ENOUGH TO THE COAST...BUT CONFIDENCE IS LOW. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A MOISTURE STARVED SHORTWAVE WILL RESULT IN A FAIR AMOUNT OF MID LEVEL CLOUDINESS TODAY...ALTHOUGH STILL EXPECT PEEKS OF SUNSHINE. MUCH OF THE DAY WILL BE DRY...BUT THE SHORTWAVE COULD RESULT IN A FEW PASSING SPRINKLES. VERY LITTLE FORCING/INSTABILITY IS AVAILABLE FOR MUCH MORE THAN THAT. ANOMALOUS UPPER LEVEL TROUGH WILL CONTINUE TO RESULT IN LOW HUMIDITY WITH TEMPS A BIT BELOW NORMAL FOR LATE JULY. HIGH WILL TOP OUT IN THE 70S TO NEAR 80. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... TONIGHT... A WEAK RIDGE OF HIGH PRESSURE WILL RESULT IN LIGHT WINDS ALONG WITH PARTLY CLOUDY SKIES. THE RELATIVELY DRY AIRMASS SHOULD ALLOW LOWS TO FALL BACK INTO THE 50S TO LOWER 60S IN MOST LOCATIONS. THURSDAY... POTENT SHORTWAVE WILL BE LIFTING INTO NORTHERN NEW ENGLAND ON THURSDAY. MARGINAL INSTABILITY WILL DEVELOP ACROSS OUR NORTHERN AND WESTERN ZONES WITH CAPES ON THE ORDER OF 500 TO 1000 J/KG. 0 TO 6 KM SHEAR WILL BE AROUND 40 KNOTS ALONG WITH 500 TEMPS AROUND -15C...WHICH IS QUITE COLD FOR THIS TIME OF YEAR. ALL IN ALL...THE BEST DYNAMICS WILL BE TO OUR NORTH. HOWEVER...ENOUGH PARAMETERS ARE IN PLACE FOR A FEW HIT AND MISS SHOWERS/THUNDERSTORMS ACROSS THE INTERIOR AND ESPECIALLY IN NORTHWEST MA/SOUTHWEST NH. WHILE INSTABILITY IS VERY MARGINAL...COLD POOL ALOFT/GOOD SHEAR MAY RESULT IN A FEW STRONG STORMS PRODUCING SMALL HAIL AND GUSTY WINDS. BEST SHOT OF THAT IS IN OUR FAR NORTHWEST ZONES. HIGH TEMPS WILL BE IN THE UPPER 70S TO LOWER 80S UNDER A MIXTURE OF CLOUDS AND SUNSHINE. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... HIGHLIGHTS... * A FEW SHOWERS POSSIBLE ON THURSDAY AND FRIDAY * LOW PRES COULD BRING RAIN SATURDAY AND SUNDAY THE HIGH AMPLITUDE UPPER LEVEL TROUGH ACROSS THE EASTERN U.S. CONTINUES TO BE THE DOMINANT FEATURE THROUGH THE FIRST PART OF THE LONG TERM. AT THE SURFACE...DURING THURSDAY AND FRIDAY SOUTHERN NEW ENGLAND IS IN BETWEEN A HIGH PRESSURE CENTERED WELL OFFSHORE...AND A LOW PRESSURE SYSTEM CENTERED NORTH OF THE GREAT LAKES REGION. RETURN FLOW ON THE WEST SIDE OF THE HIGH WILL BRING SOME INCREASE IN MOISTURE TO OUR AREA FOR THURSDAY AND FRIDAY...SUFFICIENT TO WARRANT A CHANCE FOR MAINLY DIURNAL SHOWERS. ON THURSDAY THERE WILL ALSO BE A SHORTWAVE ROTATING AROUND THE TROUGH WHICH WOULD ALSO CONTRIBUTE TO THE CHANCE FOR SHOWERS. FORECAST MODEL SOUNDINGS FOR THURSDAY INDICATE MINIMAL CAPE...SO THUNDER NOT ANTICIPATED AT THIS TIME. FRIDAY CAPE OVER THE INTERIOR MAY INCREASE TO A FEW HUNDRED J/KG...SOME ISOLATED THUNDER MAY OCCUR. DAYTIME HIGHS MAINLY IN THE UPPER 70S TO LOW 80S ARE EXPECTED...BUT OVER THE COURSE OF THU AND FRI SURFACE DEWPOINTS WILL CLIMB INTO THE 60S...BRINGING A SLIGHTLY MORE MUGGY FEEL. DURING THIS WEEKEND THE UPPER TROUGH SHIFTS SOMEWHAT TO THE WEST...ENABLING A FRONT TO APPROACH THE REGION FROM THE SOUTHEAST. IN ADDITION A WAVE OF LOW PRESSURE MAY MOVE ALONG THE FRONT. THIS WILL BRING THE POTENTIAL FOR STEADY RAIN TO AT LEAST A PORTION OF THE REGION. THERE CONTINUE TO BE SOME RUN TO RUN MODEL DISCREPANCIES REGARDING HOW CLOSE THE FRONT COMES TO OUR AREA...AND HOW LONG IT LINGERS NEARBY. THE CLOSER THE FRONT COMES TO THE AREA...THE MORE WIDESPREAD THE RAIN. THE 12Z GFS AND ECMWF HAVE SOME DIFFERENCES IN PRECIP TIMING...BUT BOTH SHOW THE POTENTIAL FOR PERIODS OF RAIN SATURDAY AND/OR SUNDAY. WILL GO WITH CHANCE POPS FOR MOST OF THIS TIMEFRAME. 12Z GFS SHOWS ROBUST MOISTURE WITH A RIBBON OF UP TO 2 INCH PWATS LINGERING IN OUR AREA. IF THIS SCENARIO DOES COME TO FRUITION THERE COULD BE SOME LOCALLY HEAVY RAINFALL DURING THE WEEKEND. CONSIDERABLE MODEL SPREAD ON CONDITIONS FOR MONDAY...ECMWF INDICATES FRONT MAY BE OFFSHORE AT THIS POINT...WILL GO WITH ONLY A LOW CHANCE POP. DRIER CONDITIONS MAY PREVAIL FOR TUESDAY...AS BY THIS TIME THE FRONT SHOULD BE FURTHER OFFSHORE. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...TODAY THROUGH THURSDAY... TODAY...HIGH CONFIDENCE. VFR CONDITIONS DESPITE SCATTERED TO BROKEN DECK OF MID LEVEL CLOUDINESS. SEA BREEZES DEVELOP THIS AFTERNOON ALONG PORTIONS OF THE IMMEDIATE COAST. TONIGHT AND THURSDAY...HIGH CONFIDENCE. MAINLY VFR CONDITIONS. A FEW HIT AND MISS SHOWERS/THUNDERSTORMS ARE EXPECTED DURING THE DAY THURSDAY ACROSS THE INTERIOR...WHICH MAY RESULT IN BRIEFLY LOWER CIGS/VSBYS. KBOS TAF...HIGH CONFIDENCE IN TAF. SEA BREEZES ARE EXPECTED TO DEVELOP BY EARLY AFTERNOON. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY... THURSDAY NIGHT AND FRIDAY...HIGH CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF A BRIEF PERIOD OF MVFR CONDITIONS IN -SHRA. DURING FRI ISOLATED THUNDER POSSIBLE IN THE AFTERNOON/EVENING...MAINLY OVER THE INTERIOR. SATURDAY AND SUNDAY...LOW CONFIDENCE. MAINLY VFR NW...CHANCE FOR MVFR CIGS/VSBYS IN SCATTERED SHOWERS. MVFR CONDITIONS MORE PROBABLE TOWARDS EASTERN MA/RI IN -SHRA. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...TODAY THROUGH THURSDAY... HIGH CONFIDENCE. WINDS/SEAS SHOULD GENERALLY REMAIN BELOW SCA LEVELS TODAY THROUGH THURSDAY ALONG WITH GOOD VISIBILITIES. LOW RISK OF MARGINAL 5 FOOT SWELL REACHING INTO THE SOUTHERN AND EASTERN ATLANTIC WATERS TONIGHT AND THURSDAY WITH DISTANT LOW PRESSURE. HOWEVER...BASED ON MOST WAVE GUIDANCE CAPPED SEAS AT 4 FEET FOR NOW BUT LATER SHIFTS WILL HAVE TO RE-EVALUATE. OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY... THURSDAY NIGHT AND FRIDAY...HIGH CONFIDENCE. LINGERING ROUGH SEAS ON THE OUTER WATERS ON THURSDAY FROM AN OFFSHORE LOW SHOULD SUBSIDE DURING THE DAY...WITH HIGH PRESSURE OVER THE WATERS. WINDS BELOW SCA THRESHOLDS THROUGH THE PERIOD. SATURDAY AND SUNDAY...LOW CONFIDENCE. MORE UNSETTLED WEATHER POSSIBLE WITH AN APPROACHING FRONT AND POSSIBLE WAVE OF LOW PRESSURE. THERE IS A CHANCE OF SCA SEAS/WINDS DEVELOPING DURING THIS TIMEFRAME. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...FRANK NEAR TERM...FRANK SHORT TERM...FRANK LONG TERM...NMB AVIATION...FRANK/NMB MARINE...FRANK/NMB

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