Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 221954 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 354 PM EDT TUE APR 22 2014 .SYNOPSIS...
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A COLD FRONT SWINGS THROUGH SOUTHERN NEW ENGLAND TONIGHT...ACCOMPANIED BY SHOWERS AND AN ISOLATED THUNDERSTORM. THE AIRMASS REMAINS WINDY AND UNSETTLED WEDNESDAY. HIGH PRESSURE THEN BUILDS IN WITH DRY WEATHER FOR THURSDAY AND FRIDAY. UNSETTLED WEATHER IS LIKELY FOR THE WEEKEND.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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CLOUDS THICKENING FROM WEST TO EAST. SHOWERS IN NEW YORK WILL MOVE THROUGH SOUTHERN NEW ENGLAND THIS EVENING AND EARLY TONIGHT. INITIALLY...THE AIRMASS WILL BE DRY ENOUGH SO THAT ECHOES ON RADAR SHOULD REPRESENT VIRGA. MORE SIGNIFICANT SHOWERS WILL THEN MOVE ACROSS BRINGING MEASUREABLE RAIN. AMOUNTS UPSTREAM HAVE BEEN 0.1 TO 0.2 INCHES...LESS THAN PREVIOUSLY EXPECTED. WE WILL GO WITH THE LOWER QPF WITH THIS FORECAST. NOTE THAT THE TOTAL-TOTALS PARMETER IS FORECAST IN THE LOW 50S DURING FROPA. WE WILL INCLUDE WIDELY SCATTERED TSTMS IN THE FORECAST. TEMPERATURES COME FROM A MODEL BLEND...VALUES MAINLY IN THE 40S. THIS LINES UP WELL WITH EXPECTED DEWPOINTS IN THE 40S DURING THE NIGHT.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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SUPPORTING UPPER LOW TRAILING THE SURFACE SYSTEM TAKES A NEGATIVE TILT AS IT MOVES OVER NEW ENGLAND. THIS WILL SLOW THE PROGRESS OF CLOUDS AND SHOWERS. UPPER COLD POOL MOVES OVER NEW ENGLAND DURING THE DAY AND PROVIDES DESTABILIZATION OF THE AIRMASS. EXPECT CLOUDS AND A CHANCE OF SHOWERS MOST AREAS WITH THE BEST CHANCE ALONG AND NORTH OF THE MASS PIKE. THE UPPER TROUGH MOVES EAST OF OUR AREA DURING THE EVENING WHICH WILL MAKE ROOM FOR CLEARING SKIES WEDNESDAY EVENING AND NIGHT. WINDS...THE DESTABILIZING OF THE AIRMASS WILL ALLOW MIXING UP TO AT LEAST 900 MB /GFS/ AND POSSIBLY 850 MB /NAM/. WINDS IN THIS LAYER ARE FORECAST TO REACH 30 KNOTS BY AFTERNOON AND POSSIBLY 35 KNOTS LATER IN THE DAY. WILL INCLUDE WIND GUSTS TO 30 KNOTS IN THE AFTERNOON. FORECAST ISALLOBARS SHOW PRESSURE RISES OF 3-5 MB/HOUR MOVING INTO OUR AREA IN THE AFTERNOON AND CONTINUING INTO THE NIGHT. SUSTAINED WINDS SHOULD MAINTAIN THEMSELVES WEDNESDAY NIGHT. TEMPS...MIXED LAYER WILL TAP 850-EQUIVILENTS OF 0 TO -3C WHICH WOULD SUPPORT MAX TEMPS IN THE MID 50S TO NEAR 60. NIGHTTIME TEMPS ARE A MODEL BLEND YIELDING 29 TO 41.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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* WINDY...COOLER CONDITIONS EXPECTED WED NIGHT AND THU * UNSETTLED BUT SEASONABLE WEATHER THIS WEEKEND 22/00Z MODELS ARE IN BETTER THAN NORMAL AGREEMENT THROUGH THE LONG TERM PERIOD OF THE FORECAST. WINDY CONDITIONS WILL LEAD OFF THE PERIOD AS THE PRESSURE GRADIENT INCREASES WITH LOW PRESSURE PULLING AWAY FROM SOUTHERN NEW ENGLAND AND HIGH PRESSURE APPROACHING. WEAK HIGH PRESSURE MOVES OVER SOUTHERN NEW ENGLAND THURSDAY AND OFFSHORE FRIDAY. THIS WEEKEND...MODELS HINT AT A MORE BLOCKED PATTERN DEVELOPING WITH RIDGING OVER THE CENTRAL CONUS AND TROUGHING LINGERING OVER THE NE. THIS LEADS TO A LOT OF UNCERTAINTY FOR OUR WEATHER THIS WEEKEND INTO EARLY NEXT WEEK. AT THIS POINT...LOOKS LIKE WHILE TEMPERATURES WILL BE SEASONABLE...THERE COULD BE SOME RAIN SHOWERS WITH A COLD FRONT ON SATURDAY. THEN POTENTIALLY DRIER WEATHER LEADING INTO NEXT WEEK. HOWEVER...IF THIS BLOCKING PATTERN DEVELOPS...THIS COULD CHANGE. THURSDAY...A STRONG LOW LEVEL JET AND STEEP LAPSE RATES...WILL RESULT IN GUSTY WINDS THURSDAY. AT THIS POINT...BELIEVE WINDS WILL REMAIN BELOW WIND ADVISORY CRITERIA. HOWEVER...THEY ARE CLOSE SO WILL KEEP AN EYE ON IT IN THE NEXT DAY OR SO. FRIDAY AND SATURDAY...FRIDAY WILL BE SOMEWHAT OF A TRANSITION DAY BETWEEN THE WIND ON THURSDAY AND A COLD FRONT SATURDAY. TEMPERATURES RETURN TO SEASONABLE NORMS. LOW PRESSURE MOVES THROUGH QUEBEC INTO THE MARITIMES ON SATURDAY BRINGING A COLD FRONT THROUGH SOUTHERN NEW ENGLAND LATE SATURDAY. SCATTERED SHOWERS ARE POSSIBLE AHEAD OF THE FRONT. SUNDAY INTO EARLY NEXT WEEK...AS STATED ABOVE A MORE BLOCKED PATTERN LOOKS TO DEVELOP WITH MID LEVEL TROUGHING OVER THE NE BRINGING UNSETTLED WEATHER TO THE REGION.
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&& .AVIATION /20Z TUESDAY THROUGH SUNDAY/...
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LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH WEDNESDAY NIGHT/...HIGH CONFIDENCE. THIS AFTERNOON...VFR MOST OF THE WAY. LINE OF SHOWERS IN NEW YORK MOVES EAST. THESE WILL MOVE ACROSS THE REGION THROUGH 00Z. TONIGHT...OBSERVATIONS IN WESTERN/CENTRAL NY SHOW THAT WHERE CONDITIONS DO DROP BELOW VFR...THEY ARE MOSTLY MVFR. THE FORECAST FOLLOWS THAT PATH WITH A PERIOD OF MVFR VSBYS DURING ANY SHOWERS THE FIRST HALF OF TONIGHT. SUFFICIENT ELEVATED INSTABILITY TO SUPPORT WIDELY SCATTERED TSTMS LEADING THE WINDSHIFT BUT NOT SUFFICIENT COVERAGE TO INCLUDE IN TAF. WEDNESDAY...VFR CIGS. POTENTIAL MVFR VSBYS IN SHOWERS. INCREASING NORTHWEST WINDS WITH GUST POTENTIAL TO 30 KNOTS. LOW CHANCE OF 35 KNOTS IN THE AFTERNOON. WEDNESDAY NIGHT...VFR WITH GUSTY NORTHWEST WINDS. GUST POTENTIAL TO 30 KNOTS. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...THURSDAY THROUGH SATURDAY... THURSDAY...MODERATE CONFIDENCE. VFR. STRONG AND GUSTY NW WINDS. GUSTS LIKELY REMAIN BELOW 30 KTS MOST AREAS. LOW PROBABILITY OF GUSTS TO 35 KTS ALONG THE COASTS. FRIDAY...HIGH CONFIDENCE. VFR. SATURDAY...MODERATE CONFIDENCE. MAINLY VFR. BRIEF PERIODS OF MVFR IN SCT -SHRA.
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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 WEDNESDAY/...HIGH CONFIDENCE. INCREASING SOUTH TO SOUTHWEST WINDS LEAD A COLD FRONT WHICH WILL CROSS THE WATERS OVERNIGHT. WINDS THEN SHIFT TO WEST AND THEN NORTHWEST OVERNIGHT. THE FRONT WILL BE ACCOMPANIED BY SHOWERS AND POSSIBLY A THUNDERSTORM. COLD AIR AND STRONG PRESSURE RISES WILL BRING STRONG GUSTY WINDS WEDNESDAY...ESPECIALLY IN THE AFTERNOON AND AT NIGHT. NORTHWEST GALES WITH GUSTS 35-40 KNOTS ARE MOST LIKELY WEDNESDAY NIGHT. WE ARE CONVERTING THE PREVIOUS GALE WATCH TO A GALE WARNING WITH COVERAGE OF ALL WATERS. NORTHWEST GALES WEDNESDAY NIGHT WILL CONTINUE INTO THURSDAY. SEAS WILL BUILD TO 5 FEET ON THE SOUTHERN WATERS WEDNESDAY AFTERNOON AND THEN 5 TO 9 FEET ON THE EXPOSED WATERS WEDNESDAY NIGHT. OUTLOOK...THURSDAY THROUGH SATURDAY... THURSDAY...MODERATE TO HIGH CONFIDENCE. SEAS RANGE BETWEEN 5 AND 10 FEET ON THE OUTER WATERS WITH SEAS PEAKING DURING THE DAY THURSDAY. NORTHWESTERLY GALES ARE LIKELY AS OCEAN STORM PULLS EAST INTO THE MARITIMES. A GALE WATCH HAS BEEN ISSUED FOR THIS PERIOD. WINDS AND SEAS DIMINISH THURSDAY NIGHT. FRIDAY...MODERATE CONFIDENCE. QUIET BOATING WEATHER. SATURDAY...LOW TO MODERATE CONFIDENCE. SW WINDS AND SEAS INCREASE AS A COLD FRONT APPROACHES THE WATERS. VISIBILITIES MAY BE REDUCED AT TIMES IN RAIN SHOWERS.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...GALE WARNING FROM 5 PM WEDNESDAY TO 8 PM EDT THURSDAY FOR ANZ230>237-250-251-254>256. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM EDT WEDNESDAY FOR ANZ250-254.
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&& $$ SYNOPSIS...WTB/RLG NEAR TERM...WTB SHORT TERM...WTB LONG TERM...NMB AVIATION...WTB/RLG MARINE...WTB/RLG/JWD

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