Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 031736 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 136 PM EDT FRI JUL 3 2015 .SYNOPSIS... HIGH PRESSURE OVER SOUTHERN NEW ENGLAND THIS AFTERNOON WILL SHIFT EAST BY SATURDAY. BIG CHANGES IN THE FORECAST FOR INDEPENDENCE DAY. IT IS NOW LOOKING MORE LIKELY FOR AT LEAST SOME SHOWERS ACROSS SOUTHERN NEW ENGLAND. ANY RAINFALL WILL COME TO AN END SATURDAY NIGHT. HIGH PRESSURE THEN RETURNS WITH WARMING CONDITIONS INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HIGH PRESSURE OVER THE REGION WITH PLENTY OF SUBSIDENCE. THAT MEANS LOTS OF SUNSHINE AND LIGHT WINDS. THE LIGHT WINDS WILL ALLOW SEA BREEZES ALONG THE COASTLINES. MORNING BALLOON SOUNDINGS SHOWED EASY MIXING TO 850 MB...THEN AN ISOTHERMAL LAYER BETWEEN 850 AND 800 MB. MID MORNING AMDAR SOUNDINGS SHOWED THE MIXING HAD INDEED REACHED 850 MB AT THAT TIME. TEMPS AT 850 MB WERE 7C WHICH WOULD SUPPORT SFC TEMPS IN THE LOWER 70S. SIMILAR TEMPS AT 800 MB WOULD BE EQUIVILENT TO 12C AT 850...WHICH WOULD SUPPORT MAX SFC TEMPS IN THE LOWER 80S. WITH PLENTY OF SUN WORKING ON THE AIRMASS WE WOULD EXPECT THE INVERSION TO EVENTUALLY MIX OUT. CONTINUE TO FORECAST MAX SFC TEMPS IN THE UPPER 70S TO MID 80S...EXCEPT COOLER COAST WITH THE SEA BREEZES. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... TONIGHT...HIGH PRESSURE SHIFTS EAST BUT REMAINS IN CONTROL OVER THE WEATHER OF SOUTHERN NEW ENGLAND. ANOTHER SHORTWAVE MOVES OVER THE GREAT LAKES AND FORMS ANOTHER WAVE ALONG A FRONT TO OUR SOUTH. THIS SHOULD GENERATE ANOTHER AREA OF CLOUDS AND SHOWERS THAT APPROACH FROM OUR SOUTH. INDEPENDENCE DAY... HUGE CHANGES TO THE FORECAST. THE CHARGE LEAD BY PREVIOUS RUNS OF THE GFS...HAS BEEN TAKEN UP BY THE REST OF THE 03/00Z GUIDANCE SUITE. MODEL SOLUTIONS NOW FEATURE AN ANOMALOUSLY DEEP MID LEVEL TROUGH MOVING INTO NEW ENGLAND. THE PROXIMITY OF THIS TROUGH HAS SHIFTED THE PROJECTED TRACK OF A LOW PRESSURE FARTHER NORTH FROM THE MID ATLANTIC STATES. GFS REMAINS THE MOST ROBUST...WITH THE SLOWEST TIMING. FAVORED A CONSENSUS APPROACH...AS THE DETAILS ARE STILL SOMEWHAT MURKY. DESPITE THE CONSISTENT SHIFT AMONG ALL THE GUIDANCE MEMBERS... DECIDED TO ONLY TREND THE FORECAST WETTER...RATHER THAN GOING WITH THE WASHOUT FROM PRIOR RUNS OF THE GFS. HEAVIEST RAINFALL WILL BE CLOSER TO THE SOUTH COAST OF NEW ENGLAND. SINCE THIS IS MORE OF A WINTER-TIME SETUP...WENT WITH RAIN INSTEAD OF SHOWERS. THAT SAID...STILL NOT EXPECTING A WASHOUT AS THERE IS A LOT OF LOW LEVEL DRY AIR TO OVERCOME. STAY TUNED FOR MORE POTENTIAL CHANGES TO THIS PORTION OF THE FORECAST. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... HIGHLIGHTS... * RAIN ENDS SATURDAY NIGHT. * HIGH PRESSURE AND WARMING CONDITIONS INTO EARLY NEXT WEEK. * UNSETTLED CONDITIONS RETURN MID-LATE NEXT WEEK. OVERVIEW AND MODEL PREFERENCES...THE MOST RECENT GFS OPERATIONAL GFS REMAINS THE MORE AMPLIFIED OUTLIER IN THE SHORT TERM WITH THE DEEPENING OF A SHORTWAVE AND LOW PRES DEVELOPMENT THIS WEEKEND. THIS OVERAMPLIFCATION CONTINUES BEYOND THE WEEKEND LOOKING AT THE SYNOPTIC PATTERN. THEREFORE...WILL BE LEANING AWAY FROM THE GFS WITH THIS LONG TERM UPDATE AND APPLYING A BLEND OF THE GEFS/ECENS AND PERSISTENCE WITH THE OPERATIONAL ECMWF. A NEAR ZONAL FLOW PATTERN WILL SLOWLY GIVE WAY TO A BUILDING RIDGE ACROSS THE NE...AS DEEPENING CUTOFF ACROSS THE CANADIAN PRAIRIE CONTINUOUSLY FEEDS WARM ADVECTION INTO THE RIDGE. THEREFORE...THE MODERATING TEMPERATURE/DRY WX PATTERN WE HAVE BEEN ADVERTISING FOR EARLY NEXT WEEK STILL LOOKS LIKE A GOOD STARTING POINT. BY MID TO LATE NEXT WEEK...IT IS A MATTER OF THE INFLUENCE OF THIS CUTOFF. THERE IS SOME SUGGESTION OF A MORE E SHIFT IN THE CUTOFF...WHICH WOULD SUGGEST A LONGER UNSETTLED PERIOD. WHILE OTHERS ARE FURTHER W...AND SRN NEW ENGLAND REMAINS IN THE ZONAL FLOW WITHIN THE SE QUADRANT OF THE CUTOFF. IN ANY CASE...COOLER AND MORE PERIODIC WET WX IS POSSIBLE IN COMPARISON TO THE EARLY WEEK. DETAILS... SAT NIGHT INTO SUN...UPPER LVL WAVE WILL BE SLIDING ACROSS THE REGION THROUGH THE PERIOD. THERE ARE TWO SFC FEATURES TO WATCH. THE FIRST...SAT NIGHT IS AN OCEAN LOW PRES WAVE MOVING OFFSHORE WHICH...COULD LEAD TO A FEW REMAINING SHOWERS. THE SECOND IS A WEAK COLD FRONTAL PASSAGE ON SUN. IN EITHER CASE...OVERALL PWATS IN THE COLUMN ARE NEAR SEASONAL NORMALS AND THERE IS A FAIR AMOUNT OF DRY AIR WITH IN THE LOWEST 300HPA. IN EITHER CASE...AN ISOLATED SHOWER IS LIKELY TO BE MOST RAINFALL TO CONTEND WITH. H85 TEMPS NEAR +10C SUGGEST TEMPS NEAR NORMAL...SO HIGHS ON SUN REMAIN IN THE UPPER 70S TO LOW 80S. MON INTO TUE...WITH UPPER LVL RIDGE BUILDING OVER FROM THE W...COMBINING WITH THE BERMUDA HIGH...EXPECT HIGH PRES AND DRY WX TO PREVAIL. TEMPS WILL BE WARMING THROUGH THEE PERIOD...ALONG WITH RISING HUMIDITY. H85 TEMPS ARE CLOSER TO +15C BY TUE. THEREFORE...HIGHS RANGING IN THE 80S WILL BE FORECAST. WED...THE FIRST IN A SERIES OF WAVES EJECTING FROM THE STRONG CUTOFF WELL TO THE W WILL MOVE ACROSS THE REGION. INCREASING COLUMN MOISTURE WITH PWATS APPROACHING 2.0 STD DEVIATIONS ABOVE NORMAL...COOLING H5 TEMPS AND LEFTOVER WARM/MOIST LOWER LEVELS SUGGEST DECREASING STATIC STABILITY. THEREFORE...WITH THE WAVE AND ATTENDANT COLD FRONT...COULD SEE DEVELOPMENT OF T-STORMS AND SHOWERS. SHEAR IS NOT TOO STRONG AT THIS POINT...BUT WILL LIKELY NEED TO MONITOR THIS AS WE GET CLOSER. THU AND FRI...UNCERTAINTY REMAINS HIGH DURING THIS PERIOD AS IT WILL DEPEND ON HOW CLOSE THE UPPER CUTOFF GETS TO THE NE CONUS. THE FRONT WILL STALL IN THE VICINITY AND PROVIDE A FOCUS...BUT EXACTLY HOW MANY WAVE/HOW STRONG AND WHEN THEY OCCUR WILL HAVE TO BE BETTER DEFINED ONCE THE CUTOFF DEVELOPS AND BECOMES BETTER SAMPLED. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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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 FRIDAY NIGHT/... THIS AFTERNOON...HIGH CONFIDENCE. VFR. SEA BREEZES ALONG THE COAST. TONIGHT...HIGH CONFIDENCE. VFR. SATURDAY...MODERATE CONFIDENCE. VFR TO START. MVFR POSSIBLE IN SCATTERED AREAS OF LIGHT RAIN LATE IN THE DAY...BEST CHANCE IS AT TERMINALS ALONG THE SOUTH COAST. WE ARE MONITORING THE POSSIBILITY OF LOW CONDITIONS AT BOSTON TOWARD EVENING DEPENDING ON THE STRENGTH OF DEVELOPING EAST/NORTHEAST FLOW AT THAT TIME. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/... SAT NIGHT...MODERATE CONFIDENCE. SOME RAIN...MAINLY ACROSS SE MA/RI WILL GRADUALLY COME TO AN END. ANY MVFR CONDITIONS WILL GIVE WAY TO VFR THROUGH THE NIGHT. MON INTO TUE...HIGH CONFIDENCE. MAINLY VFR. A FEW SHOWERS OR THUNDERSTORMS POSSIBLE ON TUE.
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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 /THROUGH SATURDAY/...RELATIVELY LIGHT WINDS WINDS AND SEAS EXPECTED THROUGH THIS PERIOD. A DEVELOPING LOW PRESSURE TO OUR SOUTH SHOULD LEAD TO BUILDING SEAS ACROSS THE SOUTHERN COASTAL WATERS LATE TONIGHT INTO SATURDAY. SMALL CRAFT ADVISORIES MAY BE NEEDED DUE TO ROUGH SEAS. ONLY MODERATE CONFIDENCE IN THE TRACK AND TIMING OF THIS LOW PRESSURE. OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/... SAT NIGHT INTO SUN...MODERATE CONFIDENCE. WINDS WILL SHIFT FROM EASTERLY TO NE AS LOW PRES MOVES E OF THE WATERS. WIND GUSTS MAY APPROACH 20-25 KT THROUGH THE EVENING...BUT IT WILL TAKE SEAS ON THE WATERS S AND SE OF NEW ENGLAND INTO SUN TO DECLINE FROM 5-7 FT BELOW SMALL CRAFT ADVISORY CONDITIONS. THEREFORE...SMALL CRAFT ADVISORIES MAY LINGER THROUGH THE DAY ON SUN. SUN NIGHT INTO MON NIGHT...HIGH CONFIDENCE. HIGH PRES YIELDS MAINLY QUIET BOATING WEATHER. TUE...MODERATE CONFIDENCE. WINDS SHIFT TO THE S...AND WHILE QUIET BOATING WEATHER IS LIKELY TO DOMINATE...THERE IS A LOW CHANCE THAT INCREASING SEAS AND WINDS WILL APPROACH SMALL CRAFT ADVISORY THRESHOLDS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...BELK/DOODY NEAR TERM...WTB/BELK/DOODY SHORT TERM...BELK LONG TERM...DOODY AVIATION...WTB/DOODY MARINE...BELK/DOODY

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