Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 142049 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 449 PM EDT TUE MAY 14 2013 .SYNOPSIS...
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COOL CONDITIONS WILL PERSIST TONIGHT AS A HIGH PRESSURE RIDGE BUILDS ACROSS NEW ENGLAND. A WARM FRONT WILL APPROACH...BRINGING SHOWERS INTO THE REGION WEDNESDAY AFTERNOON AND NIGHT. HIGH PRESSURE BUILDS SOUTH FROM CANADA WITH DRY WEATHER AND SEASONABLE TEMPERATURES FOR MOST OF THURSDAY THROUGH NEXT TUESDAY.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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BAND OF SPRINKLES EXITING THE CAPE AND ISLANDS WHILE OTHER AREA OF SPRINKLES DISSIPATED ACROSS INLAND AREAS AT 20Z AS SEEN ON KBOX 88D RADAR. AREA OF CLOUDS ASSOCIATED WITH H5 COLD POOL /DOWN TO -28C THIS MORNING/ MOVING ACROSS THE REGION WILL BEGIN TO DISSIPATE OVER THE NEXT FEW HOURS AS MAX HEATING HAS PASSED...AND SHOULD BECOME MOSTLY CLEAR BY MIDNIGHT. HIGH PRES RIDGE WILL BUILD OUT OF NY STATE ACROSS NEW ENGLAND TONIGHT...BRINGING DIMINISHING WINDS. HOWEVER...APPEARS THERE WILL BE JUST ENOUGH WIND THROUGH MOST OF THE NIGHT ESPECIALLY ACROSS CENTRAL AND EASTERN AREAS TO ESCAPE A LONG FROST. MAY SEE PATCHY FROST FOR AN HOUR OR TWO AFTER 06Z ACROSS THESE AREAS. BEST SHOT OF PATCHY FROST WILL OCCUR ACROSS S NH/N CENTRAL AND NW MA...WHERE THE GROWING SEASON HAS NOT BEGUN YET. EXPECT OVERNIGHT LOWS IN THE MID TO UPPER 30S ACROSS THE NORMALLY COLDER INLAND LOCATIONS...RANGING TO THE MID 40S ALONG THE IMMEDIATE COAST.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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WEDNESDAY... UPPER LEVEL PATTERN REMAINS PROGRESSIVE ACROSS THE LOWER 48...SO EXPECT NEXT DISTURBANCE TO WORK OUT OF THE GREAT LAKES DURING WED. WILL SEE CLOUDS INCREASE STEADILY DURING THE DAY WITH THE APPROACH OF A WARM FRONT. SHOWERS WILL MOVE INTO THE CT VALLEY IN THE AFTERNOON AND MOVE STEADILY E. MAY HAVE MARGINAL INSTABILITY... WITH TOTAL TOTALS FROM 48 TO 50 MOVING ACROSS SOUTHERN AREAS. HAVE MENTIONED ISOLD THUNDER THERE...BUT LOW CONFIDENCE ON THIS ASPECT. TOTAL QFP WILL BE AROUND 0.25 INCHES...BUT CAN NOT RULE OUT LOCALIZED SPOTTY DOWNPOURS. AS WARM FRONT PASSES...S-SW WINDS WILL PICK UP WITH GUSTS UP TO 20-25 KT FROM AROUND 18Z INTO THE EVENING...HIGHEST ALONG THE S COAST. EXPECT HIGHS IN THE 60S...EXCEPT THE MID-UPPER 50S ALONG THE S COAST. WEDNESDAY NIGHT... TRAILING COLD FRONT WILL STEADILY MOVE ACROSS THE REGION EARLY. SHOWERS SHOULD PUSH E AFTER MIDNIGHT...EXITING THE CAPE AND ISLANDS BY 10Z OR SO. WINDS WILL SHIFT TO W AND DIMINISH. WITH CLOUDS LINGERING...EXPECT TEMPS TO ONLY FALL BACK TO THE MID 40S TO LOWER 50S.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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BIG PICTURE... UPPER TROUGH OVER NEW ENGLAND AND THE MARITIMES LATE WEEK AND OVER THE WEEKEND. UPPER RIDGE BUILDS ON MONDAY-TUESDAY. MODEL PREFERENCES... MODEL MASS FIELDS THIS SIDE OF THE GREAT LAKES LOOK RATHER SIMILAR THROUGH THE PERIOD. WE USED A BLEND OF THE LONG RANGE HPC/GMOS TEMPS AND GFS/ECMWF SKY COVER. POP CONTOURS WERE HAND DRAWN BASED ON OVERLAID QPF FIELDS. THE DAILIES... THURSDAY... COLD FRONT MOVES OFFSHORE EARLY. UPPER TROUGH AND COLD POOL MOVE ACROSS DURING THE DAY. SOME DESTABILIZATION/CAA ALOFT/ OVER OUR AREA...BUT THE FOCUS OF THIS WILL TAKE PLACE OVER VT/NH/MAINE. EXPECT DIURNAL CUMULUS BUT AIRMASS LOOKS TOO DRY FOR SHOWERS. MIXING WILL BE DEEP...REACHING ABOVE 800 MB. WINDS IN THIS LAYER ARE EXPECTED TO REACH 35 KNOTS...EVEN A FEW INDICATIONS OF NEAR 40 KNOTS HIGH IN THE LAYER. SO WIND GUSTS ABOVE 30 KNOTS ARE ALSO EXPECTED DURING THE AFTERNOON. CLOUDS AND WIND DIMINISH IN THE EVENING. TEMPS ARE A BLEND OF MOS. FRIDAY THROUGH SUNDAY... DRY THROUGH THE PERIOD AS HIGH PRESSURE BUILDS SOUTH FROM NORTHERN QUEBEC. THE HIGH SHIFTS OFFSHORE DURING SUNDAY. THERE MAY BE ADDITIONAL DIURNAL CUMULUS ESPECIALLY ON FRIDAY- SATURDAY AND IN THIS RESPECT THE FORECAST MAY BE TOO OPTIMISTIC WITH SUNSHINE. BUT THE AIRMASS LOOKS SUFFICIENTLY DRY TO LIMIT CLOUD DEVELOPMENT. TEMPS ARE A BLEND OF LONG-RANGE MOS. SUNDAY NIGHT-MONDAY-TUESDAY... BUILDING RIDGE ALOFT WILL WORK TO KEEP THE WEATHER DRY. WARM ADVECTION WEST OF THE SURFACE HIGH WILL BRING ISENTROPIC LIFT AND WORK TO INCREASE SKY COVER. CLOUDS OVER THE MID ATLANTIC/OHIO VALLEY WILL GET CAUGHT UP IN THE RETURN FLOW AND GET DRAWN NORTH. NOT A LOT OF CONFIDENCE IN THIS PART OF THE FORECAST...BUT MOST OF THE FAVORABLE PARAMETERS FOR SHOWERS WILL REMAIN TO OUR WEST OVER NY/PA THIS PERIOD. SOME SEMBLANCE OF A WARM FRONT MOVES THROUGH LATER SUNDAY NIGHT/MONDAY...AND WE HAVE INCLUDED CHANCE POPS DURING THIS PERIOD IN OUR WESTERN AND NORTHERN ZONES. MORE SHOWERS APPROACH FROM THE WEST LATE TUESDAY...AND SO WE HAVE CHANCE POPS ENTER FROM THE WEST TUESDAY NIGHT. STAY TUNED FOR LATER FORECAST CYCLES AS THIS SETUP BECOMES CLEARER.
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&& .AVIATION /20Z 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/... TONIGHT...HIGH CONFIDENCE. VFR. NW WINDS GUSTING TO AROUND 20 KT MAINLY ACROSS CENTRAL AND EASTERN AREAS INTO THE EVENING...THEN SHOULD DIMINISH AS RIDGE BUILDS IN TONIGHT. WEDNESDAY...MODERATE TO HIGH CONFIDENCE. VFR MOST OF THE DAY. MAY SEE PATCHY MVFR CIGS/VSBYS MOVE INTO CT VALLEY LATE IN THE DAY. SCT SHOWERS MOVE IN FROM W-E DURING THE DAY AS WARM FRONT APPROACHES. WEDNESDAY NIGHT...MODERATE CONFIDENCE. CIGS/VSBYS LOWERING TO MVFR WITH POCKETS OF IFR CONDITIONS IN SCT-WIDESPREAD SHOWERS AND FOG. S-SW WINDS MAY GUST TO 25 KT EARLY BEFORE WIND SHIFT. LOW CONFIDENCE OF ISOLD THUNDER. CONDITIONS IMPROVE ACROSS WESTERN AREAS AFTER MIDNIGHT ON W-NW WINDS. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...THURSDAY THROUGH SUNDAY... THURSDAY... AREAS OF IFR IN MORNING FOG...OTHERWISE VFR. VFR LEVEL CLOUDS DEVELOP MIDDAY/AFTERNOON ESPECIALLY SOUTHERN NH/NORTHERN MASS. WEST-NORTHWEST WINDS INCREASE DURING THE MORNING...WITH GUSTS TO 35 KNOTS EXPECTED IN THE AFTERNOON AND DIMINISHING IN THE EVENING. FRIDAY THROUGH SUNDAY... VFR THROUGH THE PERIOD. LIGHTER WINDS WITH POTENTIAL FOR MIDDAY/AFTERNOON SEABREEZES EACH DAY.
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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 NIGHT/... HIGH CONFIDENCE THROUGH PERIOD. EXPECT WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT THROUGH WEDNESDAY MORNING. S-SW WINDS WILL PICK UP...GUSTING TO 25 KT OVER THE OPEN WATERS. SEAS WILL ALSO BUILD...UP TO 8 FT ON THE OUTER WATERS. WINDS WILL SHIFT TO W AND GRADUALLY DIMINISH LATE WED AS COLD FRONT PASSES. SEAS WILL REMAIN AOA 5 FT THROUGH WED NIGHT. OUTLOOK...THURSDAY THROUGH SUNDAY... THURSDAY...SEAS 5 TO 7 FEET ON THE OUTER WATERS AND RI/BID SOUNDS...SO A SMALL CRAFT ADVISORY FOR SEAS WILL CONTINUE TO BE NEEDED. WINDS OVER LAND WILL INCREASE TO 25-35 KNOTS MIDDAY AND AFTERNOON. SOME OF THIS WIND MAY AFFECT THE NEARSHORE WATERS AND REQUIRE A SMALL CRAFT HEADLINE AS WELL. FRIDAY THROUGH SUNDAY... WINDS AND SEAS EXPECTED TO REMAIN BELOW SMALL CRAFT CRITERIA MOST OF THE PERIOD. SEAS ON THE OUTER WATERS MAY APPROACH 5 FEET ON SUNDAY.
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&& .FIRE WEATHER...
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WEDNESDAY...EXPECT MINIMUM RH VALUES TO RANGE FROM THE MID 30S ACROSS E MA TO 50-60 PERCENT ACROSS S COAST...CAPE COD AND THE ISLANDS EARLY WED...THEN WILL INCREASE AS CLOUDS AND SHOWERS MOVE IN. GREEN-UP ALSO CONTINUES...AS MUCH OF THE REGION REMAINS BELOW NORMAL FOR TOTAL RAINFALL OVER THE LAST TWO MONTHS. S-SW WINDS WILL BECOME GUSTY...UP TO 20-25 KT WED AFTERNOON AND NIGHT BUT SHOULD SEE WIDESPREAD SHOWERS MOVING IN. NOT EXPECTING A LOT OF RAINFALL LATE WED AND WED NIGHT...MAINLY AROUND 0.25 INCHES. THE FORECASTED RAINFALL WILL BE OF SOME HELP TOWARDS THE BELOW NORMAL RAINFALL CONDITIONS. HOWEVER...THE REGION REMAINS DRY POSSIBLY CONDUCIVE TOWARDS FUTURE FIRE WEATHER POTENTIAL. OUTLOOK... MINIMUM RELATIVE HUMIDITY FOR THURSDAY AND FRIDAY IS EXPECTED AT 20 TO 30 PERCENT. WEST-NORTHWEST WINDS ON THURSDAY WILL INCREASE BY MIDDAY WITH AFTERNOON GUSTS TO 35 KNOTS POSSIBLE. THESE CONDITIONS ON THURSDAY WILL NEED TO BE WATCHED.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 PM WEDNESDAY TO 2 AM EDT THURSDAY FOR ANZ232. SMALL CRAFT ADVISORY FROM 2 PM WEDNESDAY TO 8 AM EDT THURSDAY FOR ANZ235-237-250-254>256. SMALL CRAFT ADVISORY FROM 2 PM WEDNESDAY TO 6 AM EDT THURSDAY FOR ANZ251.
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&& $$ SYNOPSIS...WTB/EVT NEAR TERM...EVT/THOMPSON SHORT TERM...EVT LONG TERM...WTB AVIATION...WTB/EVT/THOMPSON MARINE...WTB/EVT FIRE WEATHER...WTB/EVT

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