Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 031807 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 207 PM EDT WED JUN 3 2015 .SYNOPSIS... COOL MARITIME HIGH PRESSURE BUILDS INTO NEW ENGLAND TODAY AND THURSDAY PROVIDING DRY BUT COOL WEATHER TO THE REGION. A SPOT SHOWER IS POSSIBLE THU NIGHT THROUGH FRIDAY NIGHT FOLLOWED BY DRY WEATHER THIS WEEKEND. THE CHANCE FOR MORE RAINFALL RETURNS MONDAY. TEMPERATURES WARM NEXT WEEK TO MORE SEASONABLE LEVELS. && .NEAR TERM /THROUGH TONIGHT/... 2 PM UPDATE... THIS AFTERNOON AND EVENING... LOW LEVEL MOISTURE IN THE FORM OF STRATO-CU CLOUDS OVER EASTERN MA AND RI WILL CONTINUE TO SLOWLY ADVECT EASTWARD BENEATH SUBSIDENCE INVERSION. WESTERN EDGE OF CLOUD SHIELD IS SLOW TO PROGRESS WESTWARD GIVEN STRONG SURFACE HEATING. HOWEVER RH CROSS SECTIONS FROM BOTH THE NAM AND GFS SUGGEST THIS WILL ACCELERATE TONIGHT ONCE BLYR COOLS WITH FOCUS FOR CLOUDS THEN OVER NW AND N-CENTRAL MA. HOWEVER FOR THE REMAINDER OF THE AFTERNOON INTO EARLY THIS EVENING SOME CLEARING AT TIMES WILL WORK ITS WAY IN FROM THE EAST PER LATEST VISIBLE SATELLITE IMAGERY. CLOUD COVER WILL COMBINE WITH COOL MARITIME AIRMASS TO YIELD TEMPS BELOW NORMAL THIS AFTERNOON WITH COOLEST READING OVER EASTERN MA... ALTH NOT AS COOL AS THE PREVIOUS 2 DAYS. OVERNIGHT... MARITIME HIGH OVER NEW BRUNSWICK NOSES INTO SOUTHERN NEW ENGLAND. COMBINATION OF LIGHT WINDS/MOSTLY CLEAR SKIES AND RELATIVELY DRY AIRMASS WILL YIELD SOME PATCHY VALLEY FOG. THESE CONDITIONS WILL ALSO SET THE STAGE FOR ANOTHER CHILLY NIGHT. NOT RECORD BREAKING BUT LOWS IN THE 40S REGION-WIDE. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... 2 PM UPDATE... THURSDAY AND THU NIGHT... MOISTURE FROM CLOSED LOW OVER THE TN VALLEY BEGINS TO STREAM NORTHWARD. HOWEVER CONFLUENT FLOW AND ASSOCIATED SUBSIDENCE OVER NEW ENGLAND KEEPS MID/UPPER LEVEL CLOUDS AT BAY AND JUST OFF THE SOUTH COAST DURING MOST OF THE DAYLIGHT HOURS. THUS DAYLIGHT HOURS WILL REMAIN DRY HOWEVER CLOUDS WILL BE ON THE INCREASE FROM THE S-SW HORIZON. HOWEVER TOWARD SUNSET NORTHERN STREAM TROUGH ENTERING THE GREAT LAKES WILL BEGIN TO BACK THE MID LEVEL FLOW TO THE SW AND ADVECT THIS MOISTURE INTO SOUTHERN NEW ENGLAND THU NIGHT. DESPITE DEEP LAYER MOISTURE GOOD MODEL AGREEMENT THAT FORCING FOR ASCENT VERY WEAK AND IN A STABLE ENVIRONMENT. THUS NOT EXPECTING MUCH MORE THAN SOME SPOTTY LIGHT RAIN THU NGT. IN FACT WOULD NOT/T BE SURPRISED IF MUCH OF THE NIGHT REMAINS DRY. AS FOR TEMPS...CONFLUENT FLOW OVER THE AREA RESULTS IN MARITIME HIGH AND ASSOCIATED COOL AIRMASS TO LINGER OVER THE REGION. HOWEVER MORE SUNSHINE TOMORROW THAN TODAY FOR EASTERN MA AND RI. THUS STRONG/HIGH JUNE SUN ANGLE WILL MODIFY AIRMASS WITH TEMPS NOT AS COOL AS TODAY. && .LONG TERM /FRIDAY THROUGH TUESDAY/... HIGHLIGHTS... * A A SPOT SHOWER FRI-SAT * DRY AND SEASONABLE SUN THEN THREAT OF SHOWERS RETURNS MON AND TUE OVERVIEW AND MODEL PREFERENCES... CONTINUATION OF MODEL STRUGGLES WITH THE 03.00Z RUNS. THE LIKELY ISSUE IS THE RATHER AMPLIFIED SRN STREAM...WHICH FEATURES A CENTRAL CONUS BLOCK WITH OMEGA CHARACTERISTICS. SO THEN THE QUESTION BECOMES...DO A COUPLE OF NRN STREAM WAVES PHASE WITH THE TROF ACROSS THE MID ATLANTIC /THE E SIDE OF THE BLOCK/ AND TO WHAT EXTENT. THE FIRST SHOT IS FRI INTO SAT. EXACTLY HOW DEEP WILL ULTIMATELY DEFINE WHETHER THE INFLUENCE OF A WEAK BAROCLINIC WAVE NEAR THE SFC...DEEPENING OFF THE MID ATLANTIC WILL INTERACT WITH AN INCREASED MOISTURE STREAM. MODELS ARE BACK AND FORTH ON THIS...BUT THE ECENS MEAN CONTINUES TO SHOW RELATIVELY GOOD CONSISTENCY. A COLD FRONTAL PASSAGE ALIGNED WITH THE STRONGEST VORTEX OF THE WAVE MOVES THROUGH EARLY SAT. WHILE THIS MAY ALSO INCREASES CHANCES FOR PRECIP...AT ODDS IS A REMNANT SUBSIDENCE INVERSION WHICH BUFKIT CONTINUES TO SUGGEST FOR BOTH DAYS. FOLLOWING THIS FEATURE...THE NRN STREAM BECOMES DOMINANT AS THE BLOCK BREAKS DOWN AND EJECTS WEAK RIDGING INTO THE NRN STREAM...YIELDING HIGH PRES FOR EARLY NEXT WEEK. BUT...ONCE AGAIN STREAM PHASING WITH A MORE ROBUST /AND COLDER/ NRN STREAM WAVE WILL MAKE A DIFFERENCE IN HOW ACTIVE THE PATTERN IS THROUGH THE MID POINT OF NEXT WEEK. INCREASING POPS...BUT EXACT DETAILS WILL NEED TO BE IRONED OUT. DETAILS... THU NIGHT INTO FRI... INCREASING MOISTURE THROUGH THE COLUMN WITH PWATS APPROACHING 1.50 INCHES BY FRI /ABOUT 1 STD DEVIATION ABOVE NORMAL/. EXPECTING INCREASING CLOUDS WITH THIS MOISTURE BUT ANY PRECIP WILL BE ASSOCIATED WITH WEAK BAROCLINIC WAVE DEVELOPING WELL TO THE S. ECMWF OPERATIONAL CURRENTLY THE MOST ROBUST WITH QPF. WITH THE ECENS KEEPING MORE OF THE PRECIP OFFSHORE. THEREFORE...WILL MAINTAIN SOME POPS BUT LIKELY LOWER THEM SOMEWHAT FROM PREVIOUS FORECAST. SHOWERY IN NATURE...SO IT/S POSSIBLE SOME LOCATIONS REMAIN DRY ESPECIALLY TOWARD THE NRN HALF OF THE REGION. TEMPS REMAIN NEAR TO BELOW NORMAL. FRI NIGHT INTO SAT... AS THE UPPER LVL TROF MOVES ACROSS THE AREA...A COLD FRONT WILL APPROACH FROM THE W. SUBSIDENCE INVERSION AND INVERTED RIDGE REMAIN IN PLACE...SO ANY PRECIP WILL LIKELY BE FROM LEFTOVER CONVECTION UPSTREAM...OR DEVELOP WEAKLY IN SITU. ONCE AGAIN...GOING WITH THE LOWER END OF POPS HERE AS IT/S LIKELY SOME AREAS ONCE AGAIN REMAIN DRY. SAT NIGHT THROUGH EARLY MON... THE REMNANTS OF A CENTRAL CONUS BLOCK WILL MOVE E OF THE REGION WITH 1020+ HPA SFC HIGH PRES IN TOW. EXPECT A PERIOD OF MAINLY DRY WX. TEMPS AT OR NEAR SEASONAL NORMALS. LATE MON INTO MID WEEK... ONCE AGAIN...UNCERTAINTY ABOUNDS HERE DUE TO DIFFERENCES IN THE FINAL STRENGTH OF A DEEPENING WAVE ALOFT. SOME ACTUALLY SHOW THIS WAVE CUTTING OFF COMPLETELY /A VERY SLOW SOLUTION FROM THE ECMWF/ WHILE OTHERS ARE SLOW...BUT A BIT MORE PROGRESSIVE. IN ANY CASE...NOTING INCREASED RISK FOR PERIODIC -SHRA AND POSSIBLY EVEN T-STORMS THROUGH THIS PERIOD. THE DEEPER WAVE IS ALSO ABLE TO HARNESS MORE SUBTROPICAL MOISTURE THAN IS AVAILABLE FOR THE END OF THIS WEEK. PWATS MAY APPROACH 2+ STD DEVIATIONS ABOVE NORMAL FOR THIS PERIOD. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. 2 PM UPDATE... THRU 00Z... MVFR-VFR CLOUDS WILL IMPACT EASTERN MA AND RI TERMINALS. HOWEVER DRY WEATHER PREVAILS ALONG WITH LIGHT WINDS. HIGH CONFIDENCE EXPECT SOME UNCERTAINTY ON AREAL COVERAGE OF CLOUDS. AFTER 00Z... MVFR-VFR CLOUDS SHIFT INTO NORTHERN CT/WESTERN AND CENTRAL MA. WINDS BECOME LIGHT AND VARIABLE. MVFR VSBYS POSSIBLE IN THE VALLEYS WITH PATCHY FOG. HIGH CONFIDENCE. THURSDAY... ANY MVFR MORNING CIGS AND VSBYS BURN OFF TO VFR BY LATE MORNING. OTHERWISE VFR WITH RAIN SHOWERS APPROACHING THE SOUTH COAST TOWARD SUNSET. LIGHT SE WINDS. HIGH CONFIDENCE. THU NIGHT... VFR TRENDING TOWARD MVFR LATE AND ACROSS CT/RI AND SOUTHEAST MA. LOW RISK OF SOME SPOTTY LIGHT RAIN IN THIS REGION AS WELL. MODERATE TO HIGH CONFIDENCE. KBOS TERMINAL...HIGH CONFIDENCE ON TRENDS BUT SOME UNCERTAINTY ON EXACTLY WHEN MVFR-VFR CIGS WILL DEPART. KBDL TERMINAL...HIGH CONFIDENCE EXCEPT LOWER ON TIMING OF MARGINAL MVFR-VFR CIGS THIS EVENING AND OVERNIGHT. OUTLOOK...FRIDAY THROUGH SUNDAY... FRI INTO FRI NIGHT...MODERATE CONFIDENCE. MAINLY VFR. SOUTHERLY FLOW. ALTHOUGH THU NIGHT AND EARLY FRI NIGHT SOME PATCHY FOG IS POSSIBLE WITH LOCALLY LOWER CATEGORIES. A BRIEF SHOWER NOT OUT OF THE QUESTION...BUT MOST RUNWAYS REMAIN DRY. LATE SAT INTO SUN...HIGH CONFIDENCE. HIGH PRESSURE WITH VFR CONDITIONS. WINDS NNE...WITH E SEA BREEZES LIKELY ALONG THE E COAST. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. 2 PM UPDATE... THROUGH THURSDAY... MARITIME HIGH PRES NOSES INTO NEW ENGLAND THIS PERIOD. THIS RESULTS IN LIGHT WINDS/TRANQUIL SEAS/DRY WEATHER AND GOOD VSBY. THU NIGHT... MOISTURE IN THE FORM OF SPOTTY LIGHT RAIN ADVANCES NORTHWARD FROM THE MID ATLC WATERS AND MAY ENTER THE SOUTHERN RI AND MA WATERS THU NIGHT. THIS MAY REDUCE VSBY AT TIMES. OUTLOOK...FRIDAY THROUGH SUNDAY... FRI INTO SAT...HIGH CONFIDENCE. A PERIOD OF MAINLY QUIET BOATING WEATHER CONTINUES...ALTHOUGH THERE REMAINS THE POSSIBILITY OF SOME RAINFALL/FOG OCCASIONALLY MAINLY ACROSS THE SRN WATERS. WINDS MAINLY SOUTHERLY...WITH A LIGHT SOUTHERLY SWELL AROUND 3-4FT POSSIBLE. LATE DAY SAT INTO SUN...MODERATE CONFIDENCE. MAINLY QUIET BOATING WEATHER CONTINUES ON THE E COASTAL WATERS. ON THE SOUTH COASTAL WATERS...NNE FLOW MAY AT TIMES APPROACH 20-25 KT. A BUILDING SWELL OUT OF THE S...FROM A DEEPENING STORM SYSTEM WELL SOUTH OF THE REGION MAY REACH 5-6 FT AT TIMES. THEREFORE...MAY REQUIRE SMALL CRAFT ADVISORIES. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...NOCERA NEAR TERM...NOCERA SHORT TERM...NOCERA LONG TERM...DOODY AVIATION...NOCERA/DOODY MARINE...NOCERA/DOODY

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