Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 261423 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1023 AM EDT TUE APR 26 2016 .SYNOPSIS... A WAVE OF LOW PRESSURE WILL TRACK JUST SOUTH OF NEW ENGLAND TUE PROVIDING A WIDESPREAD APPRECIABLE RAINFALL TO THE REGION ALONG WITH A CHILLY NORTHEAST WIND AND MUCH COOLER THAN NORMAL TEMPS. HIGH PRESSURE BUILDS ACROSS THE REGION WEDNESDAY. A LOW PRESSURE WILL TRACK WELL SOUTH OF NEW ENGLAND THURSDAY INTO FRIDAY AS HIGH PRESSURE REMAINS IN CONTROL BRINGING MAINLY DRY WEATHER AND NEAR SEASONABLE TEMPS INTO THE WEEKEND. AN APPROACHING FRONTAL SYSTEM WILL BRING ANOTHER CHANCE OF RAIN NEXT MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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1030 AM UPDATE... IMPRESSIVE SHORT WAVE MOVING ACROSS LAKE ONTARIO AT 10 AM PER LATEST WATER VAPOR IMAGERY. A MODEST MOISTURE PLUME AHEAD OF THIS FEATURE WITH PWATS OF 1.O TO 1.2 INCHES ACROSS SOUTHERN NY STATE INTO CT AND LONG ISLAND. MARGINAL INSTABILITY ALOFT WITH BOTH 12Z OBSERVED SOUNDINGS FROM OKX AND ALY REPORTING MID LEVEL LAPSE RATES OF 6-6.5C/KM. THUS THE COMBINATION OF GOOD SYNOPTIC SCALE FORCING...MODEST DEEP LAYER MOISTURE AND MARGINAL ELEVATED INSTABILITY WILL RESULT IN A PERIOD OF RAIN THRU 18Z - 21Z FROM WEST TO EAST. ANY ELEVATED CONVECTION SHOULD BE CONFINED TO THE SOUTH COAST OR REMAIN OFFSHORE. APPRECIABLE RAINFALL EXPECTED WITH UPSTREAM HOURLY RAINFALL RATES UP TO 0.18 INCHES AT AQW THIS PAST HOUR. STORM TOTAL AMOUNTS OF 0.25 TO 0.50 SEEM REASONABLE. PREVIOUS FORECAST CAPTURES THESE DETAILS NICELY. ONLY ADJUST WITH THIS UPDATE WAS TO MODIFY HOURLY POPS TO BETTER REFLECT LATEST RADAR TRENDS. AS MENTIONED ABOVE EXPECTING RAIN TO TAPER OFF 18Z-21Z FROM WEST TO EAST ACROSS THE REGION. HOWEVER ACROSS EASTERN MA AND POSSIBLY INTO RI MOIST NE FLOW BENEATH LOW LEVEL INVERSION MAY PROMOTE SPOTTY DRIZZLE INTO THIS EVENING. FRONTAL BOUNDARY SOUTH OF NEW ENGLAND SO COOL NORTHEAST FLOW WILL LIMIT TEMPS TODAY TO THE 40S. HOWEVER GIVEN DEW PTS IN THE 30S TEMPS WILL FALL ONCE RAIN COMMENCES WITH SOME HIGHER TERRAIN LOCATIONS REMAINING IN THE U30S. FOR EXAMPLE ORE AND ORH CURRENTLY AT 39 WITH LIGHT RAIN FALLING. IT WILL FEEL EVEN COOLER ACROSS EASTERN MA WITH NE WINDS UP TO 25 MPH OFF THE CHILLY OCEAN WATERS. AS FOR PTYPE...DESPITE CHILLY TEMPS PTYPE WILL BE ALL RAIN. ALTHOUGH AS WARM LAYER CENTERED AROUND 850 MB SLOWLY ERODES THIS AFTERNOON RAIN MAY MIX WITH SLEET FOR A TIME ACROSS NORTHERN MA TO THE NH BORDER.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... TONIGHT...ANY LINGERING SHOWERS WILL COME TO AN END QUICKLY THIS EVENING. CLEAR SKIES ARE EXPECTED IN THE DRIER AIR MOVING DOWN FROM THE NORTH. WINDS MAY BE JUST HIGH ENOUGH TO PRECLUDE OPTIMAL RADIATIONAL COOLING. HOWEVER...TEMPERATURES SHOULD FALL INTO THE LOW TO MID 30S FOR MUCH OF THE AREA. FROST/FREEZE HEADLINES WILL LIKELY BE NECESSARY WHERE THE GROWING SEASON HAS BEGUN. WEDNESDAY...HIGH PRESSURE BUILDS INTO SOUTHERN NEW ENGLAND AND TEMPERATURES REBOUND A BIT FROM THE COLD OF TODAY. STILL A FEW DEGREES BELOW NORMAL FOR LATE APRIL BUT A WELCOME DIFFERENCE AFTER THE 40S TODAY. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... HIGHLIGHTS... * MAINLY DRY WEATHER WITH TEMPS MODERATING TO NEAR SEASONABLE NORMALS DURING THE WEEKEND * RAIN POSSIBLE NEXT MONDAY OVERVIEW... STRONG HIGH LATITUDE BLOCK OVER GREENLAND WILL WEAKEN LATE IN THE WEEK INTO THE WEEKEND RESULTING IN ANOMALOUS VORTEX OVER EASTERN CANADA LIFTING NORTHWARD...WITH GRADUAL MODERATION IN TEMPS TO NEAR SEASONABLE LEVELS. 00Z GUIDANCE INCLUDING MAJORITY OF GEFS MEMBERS HAVE TRENDED SOUTH WITH LOW PRES MOVING OFF MID ATLC COAST THU-FRI AS INFLUENCE FROM E CANADIAN VORTEX AND UPPER LEVEL CONFLUENCE WILL LIKELY LEAD TO A MORE SUPPRESSED SHORTWAVE. MAINLY DRY WEATHER EXPECTED INTO THE WEEKEND WITH NEXT CHANCE OF RAIN COMING SUN NIGHT OR MON AS FRONTAL SYSTEM APPROACHES...BUT TIMING IS UNCERTAIN AS ECMWF IS ABOUT 24 HOURS SLOWER THAN GFS. DETAILS... WED NIGHT... SFC RIDGING FROM HIGH PRES NORTH OF THE LAKES WILL BUILD INTO NEW ENG WITH MAINLY CLEAR SKIES AND LIGHT NORTHERLY FLOW DEVELOPING. GOOD RADIATIONAL COOLING WILL LEAD TO A COLD NIGHT WITH MINS DROPPING INTO THE UPPER 20S TO MID 30S ACROSS MUCH OF THE REGION. FROST/FREEZE HEADLINES WILL LIKELY BE NEEDED FOR THOSE AREAS ACTIVATED. THU INTO FRI... LOW PRES MOVING OFF MID ATLC COAST WITH MODEL CONSENSUS FAVORING A MORE SUPPRESSED SOLUTION WITH HIGH PRES REMAINING IN CONTROL. WE LOWERED POPS AND HAVE A MAINLY DRY FORECAST...WITH JUST A VERY LOW PROB FOR A FEW SHOWERS NEAR THE S COAST. TEMPS WILL BE MOSTLY IN THE 50S...TO AROUND 60 DEGREES IN THE CT VALLEY. COASTAL SEABREEZES LIKELY BOTH DAYS. SAT INTO SUN... HIGH PRES REMAINS IN CONTROL WITH MAINLY DRY WEATHER...ALTHOUGH NORTHERN STREAM SHORTWAVE MOVING THROUGH IN NW FLOW ALOFT MAY TOUCH OFF A FEW SHOWERS DURING SUNDAY. MODERATING TEMPS TO NEAR SEASONABLE NORMS. MON... LOW CONFIDENCE FORECAST REGARDING TIMING OF MOISTURE WITH NEXT FRONTAL SYSTEM. ECMWF IS SLOWER AND MAINTAINS RIDGING AND DRY WEATHER...WHILE GFS AND MAJORITY OF GEFS MEMBERS ARE WET. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. 1030 AM UPDATE ... NOT MUCH CHANGE FROM 12Z TAFS. BULK OF PRECIP OCCURS NOW THRU 18Z WEST...21Z EAST. CIGS SLOWLY LOWER FROM VFR TO MVFR TODAY. RAIN INTENSITY WILL MAINLY BE LIGHT TO MODERATE AT TIMES. ANY ELEVATED T-STORMS SHOULD BE CONFINED TO THE SOUTH COAST OR OFFSHORE. EARLIER DISCUSSION BELOW. ===================================================================== SHORT TERM /THROUGH WEDNESDAY/... TODAY...HIGH CONFIDENCE. DETERIORATING CONDITIONS TO MVFR AS ANOTHER BATCH OF RAIN MOVES INTO THE REGION FROM THE WEST. AREAS OF IFR POSSIBLE THIS AFTERNOON. SOME SLEET MAY MIX IN WITH THE RAIN IN N MA. NE WINDS GUSTING TO 15 TO 20 KTS ESPECIALLY ALONG THE EAST COAST. LOW PROBABILITY OF THUNDER ALONG THE SOUTH COAST AND ISLANDS. TONIGHT...HIGH CONFIDENCE. MVFR/IFR CONDITIONS IMPROVE QUICKLY TO VFR. WEDNESDAY...HIGH CONFIDENCE. VFR. KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN EXACT TIMING. KBDL TERMINAL...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN EXACT TIMING. OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/... HIGH CONFIDENCE. MAINLY VFR THROUGH THE PERIOD.
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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. 1030 AM UPDATE ... ONLY CHANGE FROM PREVIOUS FORECAST WAS TO SPEED UP ARRIVAL OF SCA WINDS TO LATE THIS MORNING ACROSS SOUTH COASTAL WATERS AND CONTINUING AT LEAST INTO THIS AFTERNOON. EARLIER DISCUSSION BELOW. ========================================================================= SHORT TERM /THROUGH WEDNESDAY/...MODERATE CONFIDENCE. TODAY...LOW PRESSURE TRACKS ALONG STALLED FRONT OVER THE SOUTHERN WATERS. EXPECT INCREASING SEAS AND GUSTY NORTHEASTERLY WINDS. WIND GUSTS ARE EXPECTED TO BE JUST UNDER SMALL CRAFT CRITERIA BUT WILL BE CLOSE ENOUGH THAT AM NOT COMFORTABLE TAKING IT DOWN AT THIS POINT. WIDESPREAD RAIN AND AREAS OF FOG WILL LIMIT VISIBILITIES. THERE IS ALSO A LOW PROBABILITY OF THUNDER OCCURRING ON THE SOUTHERN WATERS. TONIGHT...COLD FRONT MOVES SOUTH OUT OF THE COASTAL WATERS. NORTHEASTERLY WINDS CONTINUE BUT GRADUALLY DIMINISH. SEAS REMAIN AOA 5 FEET SO WILL CONTINUE SMALL CRAFT ADVISORIES. WEDNESDAY...HIGH PRESSURE BUILDS OVER THE WATERS. WINDS AND SEAS CONTINUE TO DIMINISH. OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/... HIGH CONFIDENCE. QUIET BOATING WEATHER WITH WINDS AND SEAS REMAINING BELOW SCA THRESHOLDS. WINDS BECOMING LOCALLY ONSHORE THU AFTERNOON AS SEABREEZES DEVELOPS. MAINLY E/NE WINDS FRI/SAT.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ231- 232. SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM EDT WEDNESDAY FOR ANZ235-237. SMALL CRAFT ADVISORY UNTIL 3 AM EDT WEDNESDAY FOR ANZ250-251. SMALL CRAFT ADVISORY UNTIL 6 PM EDT WEDNESDAY FOR ANZ254. SMALL CRAFT ADVISORY UNTIL 3 PM EDT WEDNESDAY FOR ANZ255-256. && $$ SYNOPSIS...KJC/RLG NEAR TERM...KJC/NOCERA/RLG SHORT TERM...RLG LONG TERM...KJC AVIATION...KJC/NOCERA/RLG MARINE...KJC/NOCERA/RLG

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