Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 041113 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 713 AM EDT MON MAY 4 2015 .SYNOPSIS...
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TODAY WILL BE THE WARMEST DAY SO FAR...BUT SHOWERS FOLLOW AHEAD OF A COLD FRONT FOR TUESDAY. HIGH PRESSURE BUILDS OVER THE EASTERN USA MIDWEEK WITH DRY WEATHER THROUGH FRIDAY AND WARMING TEMPERATURES THROUGH THE WEEKEND. A COLD FRONT APPROACHES DURING THE WEEKEND AND MAY BRING SCATTERED SHOWERS.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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7 AM UPDATE...PATCHES OF CIRRUS REPORTED IN THE OBSERVATIONS...BUT MAINLY CLEAR SKIES. CONTINUE TO EXPECT A SUNNY DAY. NO SIGNIFICANT CHANGES MADE TO FORECAST. PREVIOUS DISCUSSION... THE COMBINATION OF A SLIGHT INCREASE IN THE SFC PRES GRADIENT AND PERSISTENT CLOUD COVER WHICH ONLY DISSIPATED WITHIN THE LAST FEW HOURS HAS LED TO A MILDER NIGHT OVERNIGHT WITH TEMPS MAINLY IN THE MID 40S AND LOW 50S. PLENTY OF SUNSHINE TODAY...WHICH WILL YIELD VERY EFFICIENT MIXING POSSIBLY AS HIGH AS ABOUT H75 PER LATEST BUFKIT PROFILES. TEMPS AT H85 ARE AROUND +10C TO +12C SO USING EXTRAPOLATION...HIGHS SHOULD BE ABLE TO APPROACH THE UPPER 70S TO LOW 80S ACROSS MUCH OF THE REGION /THE S COAST WILL EXPERIENCE COOLER TEMPS UNDER ONSHORE FLOW/. THE SLIGHT W COMPONENT TO THE OVERALL WIND FIELDS ALLOW FOR SOME DOWNSLOPING SO SOME OF THE BETTER PERFORMING AREAS SUCH AS THE CT AND MERRIMACK RIVER VALLEYS MAY COME CLOSE TO THE MID 80S. THIS W COMPONENT WILL ALSO STAVE OFF THE E COAST SEA BREEZES WE HAVE EXPERIENCED THE LAST FEW DAYS. WITH THESE WARM TEMPERATURES AND GRADUAL INCREASE IN WINDS THIS AFTERNOON...AM STILL SOMEWHAT CONCERNED ABOUT FIRE WEATHER POTENTIAL. SEE THE SECTION BELOW FOR THIS INFORMATION.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... TONIGHT... HIGH PRES WILL GIVE WAY TO AN APPROACHING COLD FRONT FROM THE NW. THIS FRONT WILL BE SLOWING AS IT BEGINS TO PARALLEL STEERING FLOW ALOFT. THEREFORE...ASIDE FROM INCREASING HIGH-MID CLOUDS ACROSS THE REGION ESPECIALLY AFTER MIDNIGHT IT WILL LIKELY TAKE UNTIL 09Z OR LATER FOR ENOUGH MOISTURE FLUX AND LIFT ASSOCIATED WITH THE FRONT TO YIELD -SHRA ACTIVITY MAINLY ACROSS NW MA. THIS BAND WILL GRADUALLY SHIFT TO THE S THROUGH THE MORNING...SO A DAMP COMMUTE IS EXPECTED FOR SOME. LOOKING AT BUFKIT PROFILES...SOUNDINGS ARE RELATIVELY STABLE FOR THE OVERNIGHT AND MORNING TIMEFRAME SO WILL RUN WITH JUST SHOWERS RATHER THAN INCLUDING ANY TSRA. THE INCREASING CLOUDS AND LOW LVL MOISTURE SUPPORT EVEN MILDER MINS THAN SUN NIGHT...MAINLY IN THE 50S ACROSS THE BOARD. TUE... SLOWING AND GRADUALLY DISSIPATING COLD FRONT WILL BE MAKING IT/S WAY FROM N-S ACROSS THE REGION. IT/S TIMING IS SLOW ENOUGH THAT IT WILL LIKELY BE JUST BARELY AT THE N BORDER OF MA BY 12Z AND ONLY JUST OFF THE S COAST BY 00Z. THEREFORE...THERE WILL BE A FOCUS FOR LIFT IN THE VICINITY PRETTY MUCH ALL DAY AND PWATS WILL INCREASE TO AROUND 1.25 INCHES. THEREFORE...LIKELY SEE PLENTY OF -SHRA ACTIVITY ACROSS THE REGION...ALTHOUGH A SLOW IMPROVEMENT WILL BEGIN FROM N-S THROUGH THE AFTERNOON AS STRONG RIDGING MOVES IN BEHIND THE EXITING FRONT. THERE IS SOME QUESTION OF CONVECTIVE POTENTIAL. SOUNDINGS ARE CONDITIONALLY UNSTABLE IN A NARROW CORRIDOR MAINLY THROUGH CT/RI AND SE MA /IN ESSENCE WHERE BETTER EARLY MORNING HEATING IS EXPECTED/. THIS WILL LIKELY YIELD CAPE VALUES ON THE ORDER OF 300-500J/KG BY THE AFTERNOON WITH MID LVL LAPSE RATES AROUND 6.5C/KM. THEREFORE...STILL CAN/T RULE OUT SOME ISOLATED THUNDER MAINLY ACROSS THE S AND MAINLY DURING THE AFTERNOON HOURS. MAIN ISSUE WILL BE A BRIEF HEAVY DOWNPOUR THANKS TO THE HIGHER PWAT AIRMASS. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... BIG PICTURE... SHORTWAVE RACING ACROSS EASTERN CANADA PASSES NORTH AND EAST OF SOUTHERN NEW ENGLAND MIDWEEK. UPPER RIDGE BUILDS OVER THE EASTERN USA WHILE UPPER TROUGH DIGS OVER THE WESTERN USA. MODELS SHOW A COUPLE OF SHORTWAVES MOVING THROUGH THE RIDGE NEXT WEEKEND AND PUSHING A COLD FRONT INTO OR THROUGH OUR AREA. OVERALL A DRY WARM PATTERN FOR SOUTHERN NEW ENGLAND THROUGH FRIDAY. MODELS SUGGEST A COUPLE OF SHORTWAVES MOVING OVER THE RIDGE DURING NEXT WEEKEND BUT AT TIMES FEATURE POPS WITH MOSTLY CLEAR SKIES...SO CONFIDENCE IN PCPN IS LOW AT THIS TIME. WE USED OUR USUAL BLEND OF LONG RANGE DATA. ONE DEPARTURE WAS WITH TEMPERATURES...FOR WHICH THE MODEL DATA SEEMED 3-5F TOO COOL FOR THE EXPECTED THERMAL PROFILE ALOFT. WE ADJUSTED WEDNESDAY THROUGH FRIDAY MAX TEMPS A LITTLE WARMER THAT GUIDANCE TO BE MORE CONSISTENT WITH OTHER DATA. THE DAILIES... TUESDAY NIGHT... COLD FRONT ALONG THE SOUTH COAST MOVES FARTHER OFFSHORE. HIGH PRESSURE BUILDS OVER NEW ENGLAND OVERNIGHT. ANY LINGERING SHOWERS ALONG THE COAST SHOULD MOVE OFF. EXPECT CLEARING SKIES AND A LIGHT NORTHEAST WIND. WEDNESDAY THROUGH FRIDAY...SURFACE HIGH PRESSURE BUILDS OVER THE REGION. MOISTURE PROFILES ARE MAINLY DRY ALTHOUGH CROSS SECTIONS SHOW SOME HIGH LEVEL MOISTURE WHICH MAY BE THIN CIRRUS. CROSS SECTIONS ALSO SHOW SOME LOW LEVEL MOISTURE THURSDAY NIGHT AND FRIDAY NIGHT WHICH MAY BE FOG AND/OR STRATUS. MIXING PROFILES REACH TO 800 MB WEDNESDAY AND THURSDAY...AND BETWEEN 800 AND 850 MB FRIDAY. TEMPS AT THE TOP OF THE MIXED LAYER SUPPORT 70S WEDNESDAY...WARMING TO 80 OR LOWER 80S BY FRIDAY. ONSHORE FLOW WILL KEEP COASTAL AREAS IN THE 60S. INLAND MAX TEMPS WERE ADJUSTED WARMER DURING THIS PERIOD BASED ON EXPECTED TEMPERATURES ALOFT. SATURDAY-SUNDAY...SHORTWAVES MOVE THROUGH THE UPPER RIDGE. THIS DRAWS A COLD FRONT THROUGH NEW ENGLAND. MOISTURE IS LIMITED SATURDAY BUT COULD GENERATE A SHOWER IN NORTHERN/WESTERN AREAS. BETTER CHANCE OF SHOWERS SUNDAY AS THE FRONT MOVES THROUGH SOUTHERN NEW ENGLAND. && .AVIATION /11Z MONDAY THROUGH FRIDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TODAY AND TONIGHT...HIGH CONFIDENCE. VFR. WINDS BECOME SW. GUSTS OF 20-25 KT ARE POSSIBLE LATE AFTERNOON AND EVENING. WINDS DIMINISH OVERNIGHT WITH SKY COVER INCREASING. TUE...MODERATE CONFIDENCE. A COLD FRONT BRINGS A RISK OF -SHRA FROM N-S THROUGH THE DAY. VFR LIKELY DOMINATES...BUT PERIODIC MVFR DUE TO LOWERED CIGS ARE POSSIBLE. KBOS TAF...HIGH CONFIDENCE IN TAF. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY...MODERATE TO HIGH CONFIDENCE. MAINLY VFR. AREAS OF FOG MAY DEVELOP EACH NIGHT BETWEEN MIDNIGHT AND SUNRISE WITH LOCAL IFR CIGS/VSBYS.
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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 TUESDAY/... THROUGH TODAY...HIGH CONFIDENCE. SW WINDS WILL INCREASE THIS AFTERNOON WITH A FEW GUSTS TO AROUND 20-25 KT NEAR SHORE. SUSPECT CONDITIONS WILL REMAIN MOSTLY BELOW SMALL CRAFT ADVISORY THRESHOLDS HOWEVER...GIVEN COOL OCEAN WATERS. TONIGHT INTO TOMORROW...MODERATE CONFIDENCE. THE SW FLOW WILL SLOWLY GIVE WAY TO W FLOW AS A COLD FRONT CROSS THE WATERS DURING THE TUE EVENING HOURS. WITH THE PERSISTENT SW FLOW TODAY...SOME SUGGESTION WIND DRIVEN SEAS COULD APPROACH 5 FT ON THE OCEAN WATERS...BUT DO NOT HAVE HIGH ENOUGH CONFIDENCE TO ISSUE A SMALL CRAFT ADVISORY AT THIS TIME. THIS WILL NEED TO BE MONITORED. CONDITIONS IMPROVE ON TUE IF THEY REACH CRITERIA AT ALL...BUT SOME SHOWERS AND POSSIBLY EVEN A THUNDERSHOWER OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY...MODERATE TO HIGH CONFIDENCE. HIGH PRESSURE MOVES OVER THE WATERS. WIND DIRECTIONS BECOME SOUTHWEST BY FRIDAY...BUT SPEEDS REMAIN 15 KNOTS OR LOWER THROUGH THE PERIOD. LIGHT FLOW WILL ALSO MEAN LIGHT SEAS WITH HEIGHTS BELOW 5 FEET THROUGH THE PERIOD. NO SMALL CRAFT HEADLINES ARE EXPECTED. && .FIRE WEATHER...
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HAVE ISSUED A RED FLAG WARNING PRIMARILY FOR THE TERRAIN INFLUENCE IN WESTERN MASSACHUSETTS. SPECIAL STATEMENTS WILL BE ISSUED ELSEWHERE. PLENTY OF SUNSHINE WILL ALLOW TEMPERATURES TO RISE INTO THE UPPER 70S AND LOW 80S ACROSS THE REGION BY THIS AFTERNOON. EFFICIENT MIXING WILL ALLOW DEWPOINTS TO DROP BACK INTO THE UPPER 30S AND LOW 40S...WHICH YIELD MIN RH VALUES AROUND THE 20 PERCENT MARK THIS AFTERNOON. WINDS WILL START RELATIVELY LIGHT OUT OF THE SW...BUT THEN INCREASE DURING THE AFTERNOON. SUSTAINED WINDS SHOULD GENERALLY REMAIN BETWEEN 10 AND 15 MPH. GUSTS WILL PEAK MAINLY BETWEEN 3PM AND 7PM THIS AFTERNOON/EVENING...AND A PERIOD WITH GUSTS TO AROUND 25 MPH IS LIKELY.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 8 PM EDT THIS EVENING FOR MAZ002>004-008>012-026. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...WTB/DOODY NEAR TERM...WTB/DOODY SHORT TERM...DOODY LONG TERM...WTB AVIATION...WTB/DOODY MARINE...WTB/DOODY FIRE WEATHER...

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