Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 201854 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 254 PM EDT MON OCT 20 2014 .SYNOPSIS...
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HIGH PRESSURE WILL SLIDE TO THE SOUTH OF THE REGION TODAY KEEPING THE WEATHER QUIET. A LONG DURATION COASTAL STORM WILL BRING PERIODS OF RAIN TUESDAY AND WEDNESDAY WITH LINGERING SHOWERS THURSDAY AND FRIDAY AS THE STORM MOVES OVER NEW ENGLAND AND THEN SLOWLY PULLS AWAY. DRY AND MILD WEATHER IS EXPECTED NEXT WEEKEND.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/... 145 PM UPDATE... MOSTLY SUNNY SKIES AT MID AFTERNOON WILL GRADUALLY GIVE WAY TO MORE MID LEVEL CLOUDINESS THAT WILL WORK IN FROM THE WEST THROUGH EARLY EVENING. HIGH TEMPS WILL TOP OUT IN THE MIDDLE TO UPPER 50S IN MOST LOCATIONS...BUT LESS WIND THAN YESTERDAY WILL MAKE IT FEEL MUCH MILDER OVER THE NEXT FEW HOURS. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... TONIGHT AND TOMORROW... LOW PRESSURE SYSTEM WILL BEGIN TO DEVELOP ACROSS THE GREAT LAKES OVERNIGHT. THIS PUTS THE REGION IN MORE OF A SOUTHWEST FLOW AND BEGIN TO MOISTEN THE COLUMN. ANTICIPATE CLOUDS TO BE ON THE INCREASE OVERNIGHT LIMITING THE POTENTIAL FOR RADIATIONAL COOLING. THEREFORE KEPT TEMPS IN THE LOW TO MID 40S...WARMER ALONG THE SOUTH COAST THANKS TO THE SW FLOW. SW LLJ WILL BEGIN TO INCREASE CLOSER TO DAYBREAK AND WITHIN THE SW WAA FLOW...SHOWERS WILL DEVELOP IN THE MORNING HOURS. THE BEST SHOT WILL BE ACROSS THE CAPE AND ISLANDS AND PERHAPS THE COASTAL PLAIN...ALIGN WITH THE LOCATION OF THE LLJ. THERE IS A SLIGHT CHANCE FOR SOME THUNDER OVER THE SOUTHEASTERN WATERS AND EVEN THE CAPE AND ISLANDS ON TUESDAY WITH CAPE VALUES NEAR 500 J/KG COMBINED WITH STEEP LAPSE RATES AND LI VALUES BELOW 0. BECAUSE OF THIS AND THE INCREASING LLJ HAVE INSERTED ISO THUNDER INTO THE FORECAST. UPPER LEVEL LOW WILL BECOME CUTOFF OVER THE EASTERN GREAT LAKES DURING THE DAY...AND WILL DOMINATE THE REGION FOR THE REMAINDER OF THE WEEK. ALTHOUGH THE MAIN SHORTWAVE/LIFT WILL BE AWAY FROM THE REGION...THERE IS STILL THE POTENTIAL FOR A FEW SHOWERS TO DEVELOP ACROSS THE WESTERN ZONES. RIGHT NOW HAVE THE HIGHER CONFIDENCE THAT THE CAPE AND THE ISLANDS WILL SEE THE BEST CHANCE FOR RAINFALL ON TUESDAY. BECAUSE OF THE RETURN FLOW AND THAT SOUTHERN NEW ENGLAND IS IN WARM AIR ADVECTION SIDE OF THE SYSTEM...TEMPS WILL WARM INTO THE UPPER 50S TO MID 60S. && .LONG TERM /WEDNESDAY THROUGH MONDAY/...
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BIG PICTURE... CLOSED UPPER LOW OVER THE MID ATLANTIC COAST WEDNESDAY MIGRATES ACROSS NEW ENGLAND THURSDAY AND INTO THE MARITIMES FRIDAY. SHORTWAVE FROM THE PACIFIC NORTHWEST RACES ACROSS THE NORTHERN TIER OF STATES THIS WEEK AND CROSSES NEW ENGLAND SATURDAY. HIGH PRESSURE RIDGE THEN BUILDS OVER THE NORTHEAST USA SUNDAY AND MONDAY. HEIGHT CONTOURS ARE BELOW NORMAL MUCH OF THE WEEK UNDER THE INFLUENCE OF THE UPPER LOW...THEN RECOVER TO NORMAL LEVELS BY SUNDAY AS THE RIDGE BUILDS. THIS PATTERN FAVORS A COOL WET MID AND LATE WEEK...THEN DRY AND SEASONABLE BY SUNDAY AND MONDAY. MODERATE CONFIDENCE IN THE TYPES OF WEATHER...BUT LOW CONFIDENCE IN EXACT TIMING. THE DAILIES... WEDNESDAY-THURSDAY...COASTAL LOW SURFACE AND ALOFT WILL DOMINATE OUR WEATHER AS IT MOVES UP THE COAST. LOW PRESSURE TO OUR SOUTH AND AN EAST 50-60 KNOT LOW LEVEL JET ACROSS COASTAL MAINE AND WRAPPING INTO NH/VT. THIS MAY BRING ENHANCED ISENTROPIC LIFT ACROSS SOUTHERN NH AND NORTHERN MASS...WITH WEAKER LIFT FARTHER SOUTH. BY THURSDAY THE COLD CORE IS DIRECTLY OVERHEAD. SO WEDNESDAY IS A TRANSITION FROM STRATIFORM TO CONVECTIVE...THURSDAY MAINLY CONVECTIVE. SUFFICIENT INSTABILITY BOTH DAYS TO INDICATE A CHANCE OF THUNDER. FRIDAY...LOW PRESSURE SURFACE AND ALOFT WILL MOVE OFF TO THE EAST. COLD CORE STILL CLOSE ENOUGH TO PROVIDE CLOUDS AND SOME INSTABILITY. SHOULD CONTINUE TO BE A DIMINISHING CHANCE OF SHOWERS. SATURDAY...COLD FRONT ASSOCIATED WITH UPPER SHORTWAVE MOVES THROUGH LATER SATURDAY OR SATURDAY NIGHT. THE APPROACH OF THIS FRONT MAY ACTUALLY BE THE NUDGE THAT GETS THE LAST OF THE COLD POOL CLOUDS OUT OF OUR AREA. THE FRONT WILL BRING A PERIOD OF CLOUDS. THE POTENTIAL FOR SHOWERS IS LESS DEFINED AND SO WE FEATURE JUST SLIGHT CHANCE POPS IN SRN NH AND NRN MASS. TEMPS ALOFT SUPPORT DAYTIME MAX TEMPS IN THE 60S. SUNDAY-MONDAY...HIGH PRESSURE BUILDS OVER THE NORTHEAST WITH TEMPS ALOFT WARMER FROM SUNDAY TO MONDAY. TEMPS ALOFT SUPPORT 60S BOTH DAYS.
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&& .AVIATION /19Z MONDAY THROUGH SATURDAY/...
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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 TUESDAY NIGHT/... THIS AFTERNOON...HIGH CONFIDENCE IN VFR. TONIGHT...HIGH CONFIDENCE IN VFR. SCATTERED SHOWERS MAY DEVELOP ACROSS EASTERN NEW ENGLAND TOWARD DAYBREAK. TUESDAY...MODERATE CONFIDENCE. CONDITIONS PROBABLY DETERIORATE TO MAINLY MVFR THRESHOLDS...BUT BRIEF IFR CIGS/VSBYS ARE POSSIBLE. SCATTERED SHOWERS EXPECTED WITH AN ISOLATED THUNDERSTORM OR TWO POSSIBLE. BULK OF THE FOCUS ACROSS EASTERN NEW ENGLAND. TUESDAY NIGHT...MODERATE CONFIDENCE. LOW END MVFR TO PERHAPS IFR CONDITIONS DOMINATE IN LOW CLOUDS...SCATTERED SHOWERS AND FOG PATCHES. THE BULK OF THE ACTIVITY WILL LIKELY BE FOUND ACROSS OUR NORTHERN ZONES. KBOS...HIGH CONFIDENCE IN TAF TONIGHT WITH MODERATE CONFIDENCE ON TUESDAY. LOW PROBABILITY OF AN ISOLATED THUNDERSTORM ON TUESDAY. KBDL...HIGH CONFIDENCE IN TAF TONIGHT WITH MODERATE CONFIDENCE ON TUESDAY. OUTLOOK...WEDNESDAY THROUGH SATURDAY...MODERATE CONFIDENCE. WEDNESDAY-THURSDAY...PROLONGED PERIOD OF MIXED MVFR/IFR...WITH MORE IFR IN RAIN WEDNESDAY AND MORE MVFR IN SHOWERS THURSDAY. CHANCE OF THUNDER BOTH DAYS. CHANCE OF 30 KNOT EAST-NORTHEAST WIND GUSTS WEDNESDAY MORNING ALONG THE OUTER CAPE AND MASSACHUSETTS NORTH SHORE AREAS. FRIDAY-SATURDAY...VFR. AREAS OF MVFR CIGS/VSBYS IN SHOWERS ON FRIDAY...WITH THE BEST CHANCE IN SOUTHERN NH AND EASTERN MASS.
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&& .MARINE...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TODAY THROUGH TUESDAY/...HIGH CONFIDENCE. TODAY... HIGH PRESSURE BUILDS OVER THE WATERS ALLOWING FOR THE WINDS TO SLOWLY DIMINISH. WESTERLY WINDS WILL SWITCH TO THE SOUTHWEST BY THE AFTERNOON. SEAS WILL LINGERING AROUND 5 FEET DURING THE THE AFTERNOON SO HAVE EXPANDED SCA ACCORDINGLY. WOULD NOT BE SURPRISED IF IT IS CANCELLED EARLIER. TONIGHT... HIGH PRESSURE MOVES OFFSHORE. SOUTHWEST WINDS WILL REMAIN BELOW 25 KTS AND SEAS WILL REMAIN BELOW 5 FEET. LIGHT RAIN MOVES UP FROM THE MID ATLANTIC COAST LATE AT NIGHT. TOMORROW...SOUTHWEST FLOW WILL ALLOWING RAIN SHOWERS TO MOVE ACROSS THE SOUTHEASTERN WATERS. CONDITIONS WILL REMAIN BELOW SCA BUT THERE IS A LOW PROB FOR AN ISO THUNDERSTORM DURING THE DAY. OUTLOOK...WEDNESDAY THROUGH SATURDAY...MODERATE CONFIDENCE. WEDNESDAY-THURSDAY...LOW LEVEL EAST-NORTHEAST JET WILL BE FEEDING INTO THE MAINE MID-COAST WEDNESDAY. THE POTENTIAL FOR STRONG SURFACE WINDS SHOULD REMAIN NORTH OF OUR WATERS. WINDS OF 25-30 KNOTS MAY EXTEND AS FAR SOUTH AS THE MERRIMACK RIVER AND POSSIBLY CAPE ANN. WINDS DIMINISH AND BECOME VARIABLE THURSDAY AS THE COASTAL LOW MOVES ACROSS THE WATERS. SEAS WEDNESDAY REACH 5 FEET ON THE OUTER WATERS WITH 8 TO 10 FEET POSSIBLE FROM CAPE ANN TO MERRIMACK RIVER. BY THURSDAY THE PERSISTANT NORTHEAST FLOW WILL EXPAND THE AREA OF 8 TO 10 FOOT SEAS ACROSS THE EASTERN WATERS. SMALL CRAFT ADVISORY WILL BE NEEDED FOR THE EASTERN WATERS AND SOUTHERN OUTER WATERS. FRIDAY... AS THE COASTAL LOW PRESSURE MOVES OFF TOWARD THE MARITIMES...WINDS WILL BECOME NORTHWEST WITH GUSTS AROUND 20 KNOTS. WITH THE SHIFTING OF THE WIND DIRECTION TO OFFSHORE...WE EXPECT SEAS TO DIMINISH. BUT 5 FOOT SEAS MAY LINGER ON THE OUTER WATERS THROUGH THE DAY. SATURDAY...WINDS AND SEAS SHOULD REMAIN BELOW SMALL CRAFT LEVELS.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE.
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&& $$ SYNOPSIS...WTB/DUNTEN NEAR TERM...FRANK SHORT TERM...DUNTEN LONG TERM...WTB AVIATION...WTB/FRANK MARINE...WTB/DUNTEN

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