Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 022038 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 438 PM EDT TUE SEP 2 2014 .SYNOPSIS...
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A COLD FRONT WILL CROSS THE REGION OVERNIGHT BRINING SOME SHOWERS WITH A FEW RUMBLES OF THUNDER. DRIER BUT WARM WEATHER FOLLOWS THE FRONT WEDNESDAY AND THURSDAY. HUMIDITY WILL ONCE AGAIN INCREASE BY THE END OF THE WEEK...AS THE NEXT COLD FRONT BRINGS THE RISK FOR MORE SCATTERED SHOWERS/THUNDERSTORMS BY SATURDAY. COOLER AND LESS HUMID WEATHER FOLLOWS BY NEXT SUNDAY AND MON.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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4 PM UPDATE... SHOWERS AND THUNDERSTORMS FROM THE PRE-FRONTAL LIKE TROUGH WILL CONTINUE TO MOVE EASTWARD AND EVENTUALLY OFFSHORE OVER THE NEXT HOUR OR TWO. A FEW ISOLATED SHOWERS ARE POSSIBLE ACROSS THE INTERIOR...BUT WITH THE LACK OF DEEP MOISTURE THEY WILL STRUGGLE TO GROW LATE THIS AFTERNOON. INTERESTING NOTE...AFTER THE STORMS PASS MANY SITES DROP DOWN INTO THE MID-70F FOR TEMPS. BUT BECAUSE OF HOW JUICY AND TROPICAL THE AIRMASS IS THEY BOUNCE RIGHT BACK UP TO 90F WITHIN AN HOUR. ASIDE FROM A FEW ISO THUNDERSTORMS THIS AFTERNOON...EXPECT A MOSTLY QUIET EVENING BEFORE THE COLD FRONT APPROACHES LATER TONIGHT. TONIGHT... STRONG COLD FRONT WILL MOVE ACROSS THE NORTHEAST OVERNIGHT. THIS FRONT IS EXPECTED TO MOVE INTO THE WESTERN ZONES AROUND 02-04Z AND OFFSHORE BETWEEN 10-12Z. ANTICIPATE CONVECTION WILL BE ONGOING AS IT APPROACHES THE REGION PER THE AMOUNT OF SURFACE HEATING AND DYNAMICS OUT AHEAD OF IT IN WESTERN CWA`S. BY THE TIME IT APPROACHES THE REGION A GOOD AMOUNT OF INSTABILITY WILL BE LOSS SO WE MAY SEE DYING CONVECTION. HOWEVER SOME MODELS...ESP THE HIGH-RES GUIDANCE SHOWS ABOUT 500 J/KG OF CAPE LINGERING BY THE TIME THE FRONT APPROACHES. ON TOP OF THE POSSIBLE INSTABILITY...850MB LLJ DOES INCREASE AS THE FRONT APPROACHES AND SHEAR VALUES INCREASE AS WELL. IN FACT...GUIDANCE SHOWS THAT 0-6KM SHEAR INCREASES TO 25KTS...BUT IT IS THE 0-1 KM SHEAR THAT INCREASES TO 30-40KTS. LASTLY K-INDEX PLUME MOVES OVER THE REGION DURING THIS TIMEFRAME GIVING THE REGION THE MOISTURE IT NEEDS FOR THUNDERSTORMS TO CONTINUE. THEREFORE BELIEVE THAT ALL THE INGREDIENT MENTIONED ABOVE MAY ALLOW FOR A FEW STRONG TO PERHAPS A SEVERE STORM AS THE FRONT MOVES THE REGION. KEEP IN MIND THAT THIS IS AN OVERNIGHT EVENT WHICH IS NOT IN THE NORTHEAST FAVOR PER CLIMO...BUT CONDITIONS DO SHOW THAT A FEW STRONG STORMS ARE POSSIBLE. LASTLY...EVEN THOUGH THE REGION DID SEE SOME ACTION TODAY...THE ATMOSPHERE DID BOUNCE BACK VERY WELL AFTER THE STORMS PASSED. AS THE FRONT MOVES THROUGH THE K-INDEX VALUE AS WELL AS THE INSTABILITY DO DROP AFTER 06Z SO THAT THE CHANCE FOR ANY CONVECTION TO OCCUR DISSIPATES SIGNIFICANTLY. IN FACT...THE SHOWERS AND THUNDERSTORMS FROM THE FRONT WILL FRAGMENT AND BECOME VERY ISO IN NATURE BY THIS TIME FRAME AND MAY EVEN STRUGGLE TO REACH THE EAST COAST. WITH THE AMOUNT OF MOISTURE IN THE ATMOSPHERE BELIEVE THAT A FEW SHOWERS WILL REACH SO CONTINUED THE SLIGHT CHANCE POP FOR NOW. OVERNIGHT TEMPS WILL STRUGGLE TO DROP AS CLOUD COVER WILL KEEP TEMPS FROM RADIATING OUT OVERNIGHT AND DEWPOINTS WILL REMAIN IN THE 70S UNTIL FRONTAL PASSAGE.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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TOMORROW AND TOMORROW NIGHT... SURFACE FRONT WILL MOVE OFFSHORE BY EARLY TOMORROW MORNING AS UPPER LEVEL TROUGH WILL PUSH THROUGH AS WELL. 850 MB RIDGE WILL BEGIN TO SET UP OVER THE REGION ALLOWING FOR DRY AIR TO MOVE INTO THE AREA. THIS WILL KEEP THE WEATHER DRY FOR BOTH TOMORROW AND TOMORROW NIGHT. 850 MB TEMPS DROP DOWN TO -14C AND WITH MIXING UP TO 850MB WILL ALLOW FOR TEMPS TO REACH INTO THE MID TO UPPER 80S. DIFFERENCE WILL BE THE HUMIDITY AS DRY AIR WILL MIX DOWN DROPPING DEWS DOWN INTO THE UPPER 50S. WINDS WILL BE GUSTY REACHING ABOUT 20 MPH. OVERNIGHT...WITH CLEAR SKIES AND WINDS BECOME LIGHT AND VARIABLE...ANTICIPATE RADIATIONAL COOLING. LOWS WILL DROP INTO THE MID TO LOW 50S. A FEW SITES COULD EVEN DROP INTO THE UPPER 40S ACROSS CT VALLEY.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/... HIGHLIGHTS: * DRY THU/FRI WITH VERY WARM AFTERNOON/S * HUMID WITH SCT SHOWERS/STORMS POSSIBLE SAT * COOLER AND LESS HUMID SUN INTO MON DETAILS: WEDNESDAY NIGHT... HIGH PRESSURE OVERHEAD WILL RESULT IN MAINLY CLEAR SKIES AND LIGHT WINDS. THIS WILL ALLOW LOW TEMPS TO BOTTOM OUT MAINLY IN THE 50S...TO LOWER 60S. PATCHY FOG MAY DEVELOP LATE IN THE TYPICALLY PRONE LOCATIONS. THURSDAY AND FRIDAY... HIGH PRESSURE IN CONTROL WILL KEEP THE WEATHER DRY WITH WARM AFTERNOON/S...PARTICULARLY BY FRIDAY. HIGH TEMPS SHOULD BE WELL UP INTO THE 80S ON THURSDAY...BUT HUMIDITY WILL BE IN CHECK. AS THE HIGH MOVES FURTHER OFF THE COAST BY FRIDAY...850 MB TEMPS REACH +16C AS SOUTHWEST FLOW ALOFT INCREASES. THIS SHOULD ALLOW HIGHS WELL UP INTO THE 80S TO NEAR 90. HUMIDITY WILL ALSO INCREASE ON FRIDAY...ALTHOUGH IT WILL NOT BE OPPRESSIVE. SATURDAY... A COLD FRONT WILL APPROACH THE REGION AND LIKELY TRIGGER SCATTERED SHOWERS/THUNDERSTORMS DURING THE DAY SATURDAY. NOT EXPECTING THE ENTIRE DAY TO BE A WASHOUT...BUT APPEARS ENOUGH INSTABILITY/MOISTURE AND FORCING AVAILABLE FOR CONVECTION. PWATS APPROACHING 2 INCHES WILL MAKE HEAVY RAIN AND VERY LOCALIZED FLOODING THE MAIN CONCERN. WHILE MORE CLOUDS WILL LIKELY KEEP TEMPS A FEW DEGREES LOWER THAN FRIDAY...IT WILL BE QUITE HUMID AHEAD OF THE COLD FRONT WITH DEWPOINTS NEAR 70. SUNDAY AND MONDAY... THE COLD FRONT SHOULD HAVE EXITED THE SOUTHEAST NEW ENGLAND COAST EARLY SUNDAY. THIS WILL ALLOW COOLER AND LESS HUMID AIR TO WORK INTO THE REGION SUNDAY AND MONDAY. WILL ALSO HAVE TO WATCH A COUPLE WAVES OF LOW PRESSURE OFF THE MID ATLANTIC COAST. FOR NOW MOST OF THE MODELS KEEP THEM FAR ENOUGH AWAY TO RESULT IN MAINLY DRY WEATHER AND THAT WILL BE SHOWN IN OUR DETERMINISTIC FORECAST. HOWEVER... THERE CERTAINLY IS AT LEAST A LOW PROBABILITY THAT ONE OF THEM ENDS UP FURTHER NORTH AND WE END UP WITH A PERIOD OF SHOWERS. && .AVIATION /21Z TUESDAY THROUGH SUNDAY/...
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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 WEDNESDAY NIGHT/...HIGH CONFIDENCE IN TRENDS. THROUGH 00Z...SCT TSRA NORTH OF THE PIKE WITH ISO TSRA SOUTH OF THE PIKE. ANTICIPATE BRIEF LOCALIZED LOWER CONDITIONS TIL ABOUT 22Z. TONIGHT...A LULL IN ACTIVITY AFTER 00Z. BEFORE ANOTHER ROUND OF SHOWERS WITH ISO THUNDER MOVES THROUGH AFTER 03/04Z. THIS CONVECTION IS ASSOCIATED WITH AN APPROACHING COLD FRONT WHICH WILL PASS THROUGH THE REGION OVERNIGHT. EXPECT CONVECTION TO WEAKEN AS IT MOVES THROUGH WITH BRIEF LOWERING IN CIG HEIGHTS. PATCHY FOG IS EXPECT AHEAD OF THE FRONT AND SHOULD DISSIPATE AS IT PASSES THROUGH. WED INTO WED NIGHT...VFR. PATCHY FOG IN CT VALLEY WED NIGHT. KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS. MAY BE A SHOWER OR THUNDERSHOWER IN THE AFTERNOON. KBDL TERMINAL...HIGH CONFIDENCE. OUTLOOK...THURSDAY THROUGH SATURDAY... WEDNESDAY NIGHT THROUGH FRIDAY...HIGH CONFIDENCE. MAINLY VFR CONDITIONS OTHER THAN LATE NIGHT/EARLY MORNING PATCHY GROUND FOG IN THE TYPICALLY PRONE LOCATIONS. FRIDAY NIGHT AND SATURDAY...MODERATE CONFIDENCE. A PERIOD OF MVFR- IFR CONDITIONS EXPECTED IN LOW CLOUDS/FOG PATCHES AND SCT SHOWERS/THUNDERSTORMS. TIMING HIGHLY UNCERTAIN AT THIS POINT.
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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. HIGH CONFIDENCE THROUGH THE PERIOD WEDNESDAY NIGHT. TONIGHT... SW FLOW BEGINS TONIGHT BEFORE A COLD FRONT PASSES OVER THE WATERS OVERNIGHT. EXPECT A FEW GUSTS TO AROUND 20 KT ARE POSSIBLE AS THE WINDS SHIFT TO THE W-NW. A FEW SHOWERS AND THUNDERSTORMS MAY MOVE OVER THE SOUTHERN WATERS BY MIDNIGHT LASTING TIL ABOUT 3AM. SEAS MAY APPROACH 5 FT ON THE SOUTH OCEAN WATERS BUT HAVE LOW CONFIDENCE AND HELD OFF ON ISSUING A SCA. OTHERWISE...SOME FOG MAY LEAD TO VSBY REDUCTIONS TONIGHT BEFORE THE FRONT PASSES. WED INTO WED NIGHT...QUIET BOATING WEATHER. A FEW GUSTS NEAR 15KTS POSSIBLE DURING THE DAY. OUTLOOK...THURSDAY THROUGH SATURDAY... MODERATE CONFIDENCE THROUGH THIS PERIOD. WEDNESDAY NIGHT AND THURSDAY...HIGH CONFIDENCE. WEAK PRESSURE GRADIENT SHOULD KEEP WINDS/SEAS BELOW SCA THRESHOLDS. GOOD VISIBILITIES SHOULD MAKE FOR NICE BOATING WEATHER. FRIDAY...MODERATE TO HIGH CONFIDENCE. NEAR SHORE SOUTHWEST WIND GUSTS OF 20 TO 25 KNOTS MAY DEVELOP IN THE AFTERNOON WITH GOOD MIXING OVER THE LAND. SEAS SHOULD REMAIN BELOW SCA THRESHOLDS...BUT MAY BECOME CHOPPY ESPECIALLY NEAR SHORE. FRIDAY NIGHT AND SATURDAY...MODERATE CONFIDENCE. AREAS OF FOG MAY AFFECT THE SOUTHERN WATERS. SOUTHWEST WIND GUSTS AROUND 20 KNOTS ARE EXPECTED AHEAD OF AN APPROACHING COLD FRONT. THERE WILL BE THE RISK OF SCT SHOWERS AND THUNDERSTORMS DURING THE DAY SATURDAY.
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&& .CLIMATE...
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BOSTON LOGAN AIRPORT REACHED 93 DEGREES TODAY. THIS IS THE WARMEST TEMPERATURE IN BOSTON SO FAR THIS SUMMER.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...NOCERA/DUNTEN NEAR TERM...DUNTEN SHORT TERM...DUNTEN LONG TERM...NOCERA AVIATION...NOCERA/DUNTEN MARINE...NOCERA/DUNTEN CLIMATE...STAFF

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