Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 241354 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 954 AM EDT SUN APR 24 2016 .SYNOPSIS... HIGH PRESSURE WILL PASS ACROSS THE REGION TODAY THROUGH TONIGHT AND BRING DRY AND SEASONABLE WEATHER. A FRONT WILL STALL ACROSS THE REGION MONDAY...THEN SLOWLY PUSH SOUTH MONDAY NIGHT AND TUESDAY...BRINGING MUCH NEEDED RAINFALL. DRY BUT COOL CONDITIONS RETURN WITH HIGH PRESSURE FOR MID WEEK. ANOTHER FRONT AND ASSOCIATED LOW PRESSURE MAY APPROACH LATE NEXT WEEK...BRINGING ADDITIONAL RAINFALL. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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1000 AM UPDATE... OVERALL TREND IN THE FORECAST REMAINS ON TRACK FOR TODAY. HIGH PRESSURE OVERHEAD WILL LEAD TO SUNNY SKIES. LIGHT WINDS TODAY WITH A FEW GUSTS ABOVE 15-20 MPH. ANTICIPATE A SEA BREEZE TO DEVELOP OVER THE NEXT HOUR OR TWO ALONG BOTH COASTLINES DROPPING TEMPS INTO THE LOW 50S. PREVIOUS DISCUSSION... A VERY DRY AIR MASS WILL BE IN PLACE TODAY WITH SUNNY SKIES. SEA BREEZES ARE EXPECTED TO DEVELOP ALONG THE COAST AND CAP TEMPERATURES IN THE MID 50S THERE. ACROSS THE INTERIOR UNDER FULL SUNSHINE...TEMPERATURES SHOULD TOP OUT IN THE UPPER 50S TO NEAR 60 WITH LOWER 60S ALONG MUCH OF THE CT VALLEY. NOTE THE FIRE WEATHER SECTION.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... SUNDAY INTO SUNDAY NIGHT... TONIGHT BEGINS WITH CLEAR SKIES...LOW DEWPOINTS...AND LIGHT WINDS TO INITIATE VERY EFFECTIVE RADIATIONAL COOLING TO START BUT THEN HIGH CLOUDS WILL ARRIVE BETWEEN MIDNIGHT DAYBREAK. TEMPERATURES MAY...HOWEVER...DROP TO THE LOWER 30S ACROSS MANY INTERIOR LOCATIONS PRIOR TO THE CLOUDS REVERSING THE TEMPERATURE TREND. A FROST OR FREEZE ADVISORY MAY BE NEEDED FOR TONIGHT...DEPENDING UPON THE PRECISE TIMING OF THE ARRIVAL OF CLOUDS...AT LEAST FOR THOSE EASTERN MA SECTIONS WHERE THE FROST/FREEZE PROGRAM HAS BEGUN. THE UNCERTAINTY ASSOCIATED WITH THE TIMING OF THE CLOUDS TRANSLATES TO LOW CONFIDENCE AND SO WILL HOLD OFF ON ANY ADVISORY ISSUANCE FOR TONIGHT AT THIS TIME. MONDAY... WILL FEATURE INCREASING/THICKENING CLOUDS...ESPECIALLY NORTH OF THE MASS PIKE. DUE TO THE VERY DRY AIR MASS...RAIN ATTEMPTING TO SPREAD INTO THE REGION MAY EVAPORATE BEFORE REACHING THE SURFACE FOR A TIME. THE MORNING WILL PROBABLY REMAIN DRY MOST AREAS BUT HAVE A CHANCE FOR SHOWERS SPREADING WEST TO EAST DURING THE AFTERNOON. WARM ADVECTION TAKES PLACE AND THIS WILL CAUSE TEMPERATURES TO REBOUND INTO THE LOWER TO MID 60S IN MANY LOCATIONS. THE CLOUDS AND POSSIBLE SHOWERS WILL TEMPER THE TEMPERATURES SOME...HOWEVER. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... OVERVIEW... UPPER LEVEL FLOW ACROSS THE LOWER 48 REMAINS PROGRESSIVE WITH BROAD H5 CUTOFF LOW ACROSS THE LOWER ROCKIES WHILE H5 VORTEX CONTINUES TO SPIN ACROSS QUEBEC/LABRADOR EARLY NEXT WEEK KEEPING A CYCLONIC FLOW ACROSS THE REGION. WILL STILL SEE A GENERAL W-NW UPPER LEVEL STEERING CURRENT...THOUGH THIS WILL FLATTEN TO A MORE W FLOW AS THE CUTOFF MEANDERS N OF NEW ENGLAND. FIRST H5 SHORT WAVE IN THE STEERING FLOW APPROACHES DURING TUE...BUT AT THE SURFACE WILL SEE DEVELOPING FRONTAL ZONE AS IT SHIFT SE MON NIGHT. THIS FRONT WILL SLOWLY CROSS THE REGION MON NIGHT/TUE AS IT BECOMES PARALLEL TO THE UPPER FLOW...WHILE WEAK WAVES OF LOW PRES MOVE ALONG IT. THIS WILL ENHANCE THE RAINFALL SOMEWHAT MON NIGHT/TUE. HIGH PRES RIDGING OUT OF CENTRAL CANADA WILL PUSH THE FRONT S OF THE REGION DURING TUE. AS THIS FRONT STALLS ACROSS THE MID ATLC STATES...MID WEEK LOOKS TO BE DRY. ANOTHER SHORT WAVE MOVES ALONG IN THE STEERING FLOW LATE THIS WEEK...WHICH COULD LIFT THE SOUTHERN STALLED FRONT BACK N AS A SURFACE LOW FORMS ALONG IT. TIMING ISSUES CONTINUE ON THE OPERATIONAL MODEL RUNS SO LOWER CONFIDENCE IN THE THU-SAT TIMEFRAME. DETAILS... MONDAY NIGHT-TUESDAY NIGHT... H5 SHORT WAVE APPROACHES IN THE W-NW WIND FLOW ALOFT. COLD FRONT SINKS SLOWLY S OUT OF NY STATE AND NORTHERN NEW ENGLAND. PRECIP DEVELOPS IN INCREASING ISENTROPIC LIFT AS IT SHIFTS SE. SHOWERS WILL MOVE IN DURING MON NIGHT...WITH THE BEST CHANCE FOR SHOWERS DURING TUESDAY AS WEAK LOW PRES WAVE MOVES ALONG THE FRONT. MAY SEE SOME BRIEF HEAVY RAINFALL WITH SOME OF THESE SHOWERS AS PWATS RANGE FROM 1.1 TO 1.25 INCHES...HIGHEST ACROSS S COASTAL AREAS. QPF AMOUNTS RANGING FROM 0.5 TO 0.75 INCHES...BUT COULD SEE A FEW SPOTS THAT RECEIVE A BIT MORE. DID NOTE SOME MARGINAL INSTABILITY PARAMETERS... K INDICES IN THE LOWER 30S S OF THE MASS PIKE OVERNIGHT MON AND SURFACE BASED LI/S NEAR ZERO. AT THIS POINT...DO NOT THINK WILL SEE CONVECTION AS FRONT PUSHES S. SOMETHING TO KEEP AN EYE ON THOUGH. AS COLD FRONT SINKS DOWN THE COAST MON NIGHT INTO TUE MORNING... NOTING A STRONG LOW LEVEL NE JET WORKING DOWN FROM THE MAINE COAST. WINDS UP TO 20-25 KT AT H95 AND H9 WHICH SHOULD GUST AS THE FRONT PASSES E COASTAL AREAS INTO TUE MORNING. WHEN THE FRONT REACHES THE S COAST TUE AFTERNOON...GUSTS UP TO 20-25 KT SHOULD ALSO KICK IN FOR A TIME. H5 SHORT WAVE MOVES ACROSS THE REGION TUE NIGHT. EXPECT PRECIP TO END FAIRLY QUICKLY AFTER THAT...SHOULD BE OFF THE S COAST BY MIDNIGHT OR SO AS DRIER AIR WORKS IN. TEMPS TUE NIGHT MAY BOTTOM OUT CLOSE TO OR JUST BELOW FREEZING ACROSS N CENTRAL AND W MA...RANGING TO AROUND 40 ALONG THE S COAST. WEDNESDAY... HIGH PRES RIDGE BUILDS SE OUT OF CENTRAL CANADA. EXPECT MOSTLY SUNNY SKIES. HOWEVER...EXPECT TEMPS TO ONLY REACH TO THE 50S TO AROUND 60 AS GOOD MIXING BRINGS COOLER AIR DOWN FROM AROUND 850 HPA. THE FRONT THAT PASSED THROUGH TUE STALLS ALONG THE MID ATLC COAST. HOWEVER...WITH THE FAST FLOW ALOFT AND ANOTHER SHORT WAVE IN THE FLOW...MAY START TO SEE MORE CLOUDS RETURN LATE WED NIGHT. TEMPS MAY STILL FALL BACK TO NEAR OR BELOW FREEZING IN THE NORMALLY COLDER INLAND LOCATIONS...RANGING TO THE LOWER 40S ALONG THE S COAST. THURSDAY-FRIDAY... ANOTHER H5 SHORT WAVE MOVES E IN THE FAST FLOW ALOFT...BUT SOME QUESTION ON TIMING IN THE PRECIP DURING THU. THE 00Z GFS AND GGEM IN PRETTY GOOD AGREEMENT IN BRINGING PRECIP IN DURING THE DAY THU...BUT THE 00Z ECMWF IS MUCH SLOWER AND FURTHER S. LEANED TOWARD GFS/GGEM AND ENSEMBLES WHICH WERE IN GENERALLY GOOD AGREEMENT THOUGH HAVE LOWERED CONFIDENCE DURING THIS TIMEFRAME. CARRYING LOW END POPS THU INTO FRIDAY MORNING THEN SHOULD IMPROVE. SATURDAY...ANOTHER CANADIAN HIGH BUILDS ACROSS THE NORTHEAST BRINGING MORE DRY AND SEASONABLE CONDITIONS. TEMPS SHOULD REACH INTO THE LOWER-MID 60S INLAND...BUT WILL HOLD IN THE 50S ALONG THE IMMEDIATE COAST WITH SEA BREEZES. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/...
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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 MONDAY/...HIGH CONFIDENCE. TODAY...HIGH CONFIDENCE. VFR CONDITIONS. CLEAR SKIES SHOULD PREVAIL. SEA BREEZES LIKELY AT COASTAL TERMINALS. TONIGHT...HIGH CONFIDENCE. VFR CONDITIONS. HIGH CLOUDS WILL BEGIN TO INCREASE AFTER 06Z. MONDAY...MODERATE TO HIGH CONFIDENCE. VFR CONDITIONS ARE ANTICIPATED THROUGH THE MORNING. MVFR CIGS AND VSBYS IN -RA MAY SPREAD W TO E DURING THE AFTERNOON ESPECIALLY N OF A BOS-ORH-BAF LINE. KBOS TAF...HIGH CONFIDENCE. VFR CONDITIONS WITH GENERALLY CLEAR SKIES THROUGH 06Z MON. SEA BREEZE LIKELY DEVELOPING BETWEEN 15-16Z. KBDL TAF...HIGH CONFIDENCE. LOW PROBABILITY OF MVFR CIGS/VSBYS IN -SHRA LATE MON AFTERNOON. OUTLOOK /MONDAY NIGHT THROUGH THURSDAY/...MODERATE CONFIDENCE. MONDAY NIGHT...MVFR TO LOCAL IFR CIGS/VSBYS IN DEVELOPING SHOWERS AND PATCHY FOG. SW WINDS SHIFT TO N ACROSS CENTRAL AND N MA OVERNIGHT WITH GUSTS UP TO AROUND 20 KT ALONG E COASTAL TERMINALS. TUESDAY...MVFR CONDITIONS THROUGH MOST OF THE DAY...WITH PATCHY IFR CIGS/VSBYS IN ANY HEAVIER SHOWERS AND PATCHY FOG. COLD FRONT MOVES S AS WINDS SHIFT TO NE ACROSS N CT/RI/SE MA...GUSTING UP TO 20 KT ALONG S COASTAL TERMINALS AS WELL AS CAPE COD AND THE ISLANDS. CONDITIONS SHOULD IMPROVE TO VFR FROM N-S TUE NIGHT. WEDNESDAY...VFR. THURSDAY...VFR EARLY...THEN AREAS OF MVFR CIGS/VSBYS MOVING IN FROM SW-NE FROM LATE THURSDAY MORNING ONWARD...CONTINUING INTO THU NIGHT.
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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 /THROUGH MONDAY/...MODERATE TO HIGH CONFIDENCE. GUSTY WINDS WILL CONTINUE TO DISSIPATE TODAY AS HIGH PRESSURE MOVES OVERHEAD. SEAS WILL CONTINUE TO BE ABOVE 5 FEET BUT WILL DISSIPATE THIS AFTERNOON/EVENING. SCA HAVE BEEN ADJUSTED FOR TODAY. SW WINDS MAY GUST 15 TO 20 KT ON MONDAY BUT ANTICIPATE TO REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS. OUTLOOK /MONDAY NIGHT THROUGH THURSDAY/...MODERATE CONFIDENCE. MONDAY NIGHT...S-SW WINDS TO START...THEN WILL SHIFT TO NE ACROSS THE EASTERN WATERS TO NEAR CAPE COD BAY OVERNIGHT. WINDS WILL GUST UP TO 25 KT AFTER MIDNIGHT. SMALL CRAFTS LIKELY NEEDED. WINDS WILL REMAIN SW GUSTING TO NEAR 20 KT ON THE SOUTHERN WATERS WITH SEAS BUILDING TO AROUND 5 FT. VSBY RESTRICTIONS IN SHOWERS AND PATCHY FOG. TUESDAY...WINDS WILL SHIFT TO N-NW ACROSS THE SOUTHERN WATERS TUE MORNING...GUSTING UP TO 25 KT...WHILE N-NE WINDS REMAIN ON THE EASTERN WATERS. WINDS WILL DIMINISH DURING THE AFTERNOON FROM N-S. SEAS WILL REMAIN AROUND 5 FT ON THE SOUTHERN OPEN WATERS AS WELL AS THE WATERS E OF CAPE COD. VSBY RESTRICTIONS IN SHOWERS AND PATCHY FOG CONTINUE. TUESDAY NIGHT...N-NE WINDS WILL BACK TO NW. GUSTS TO 20 KT TUE EVENING WILL DIMINISH. SEAS REMAIN AT AROUND 5 FT ON THE SOUTHERN WATERS. VSBY RESTRICTIONS TUE NIGHT IN SHOWERS...IMPROVING FROM N-S OVERNIGHT. WEDNESDAY...NW WINDS EARLY WILL BECOMING LIGHT S-SW. SEAS AROUND 5 FT ON THE SOUTHERN WATERS EARLY...THEN SUBSIDE. THURSDAY...LIGHT S WINDS BACK TO E-NE THU NIGHT WITH GUSTS UP TO 20 KT. SEAS UP TO 4 FT ON THE SOUTHERN WATERS. VSBY RESTRICTIONS IN SCATTERED SHOWERS.
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&& .FIRE WEATHER... TODAY...VERY DRY AIR WILL BE IN PLACE WITH MINIMUM RELATIVE HUMIDITIES BETWEEN 15 AND 20 PERCENT ACROSS MUCH OF THE REGION. SEA BREEZES ARE EXPECTED DURING THE AFTERNOON WHICH WILL INCREASE RH VALUES ALONG THE IMMEDIATE COASTLINE. WINDS WILL GENERALLY BE LIGHT...ALTHOUGH MIXING COULD INDUCE A FEW GUSTS BETWEEN 15 AND 20 MPH. A SPS REMAINS IN EFFECT DUE TO THE ELEVATED FIRE WEATHER POTENTIAL. MONDAY-TUESDAY...A SLOW MOVING COLD FRONT WILL BRING ABOUT ONE- HALF TO THREE-QUARTERS OF AN INCH OF RAIN TO THE REGION. WEDNESDAY...HIGH PRESSURE WILL BRING DRY CONDITIONS. MINIMUM RH VALUES OF 25 TO 35 PERCENT EXPECTED AWAY FROM THE COAST...AND 35 TO 50 PERCENT IN COASTAL AREAS. LIGHT NORTHWEST WINDS UNDER 15 MPH BECOME SOUTHWEST BY EVENING. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ250- 254. SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR ANZ255. SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR ANZ256.
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&& $$ SYNOPSIS...EVT/THOMPSON NEAR TERM...DUNTEN/THOMPSON SHORT TERM...THOMPSON LONG TERM...EVT AVIATION...EVT/THOMPSON/DUNTEN MARINE...EVT/THOMPSON/DUNTEN FIRE WEATHER...STAFF

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