Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 300750 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 350 AM EDT TUE SEP 30 2014 .SYNOPSIS... COOL TEMPERATURES EXPECTED THROUGH MOST OF THIS WEEK AS PERSISTENT NORTHEAST WINDS REMAIN IN PLACE. ONE OR TWO WEAK WAVES OF LOW PRESSURE MAY BRING A CHANCE OF SHOWERS FOR THE REGION. AN APPROACHING FRONT WITH ASSOCIATED LOW PRESSURE LOOKS TO AFFECT SOUTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... NORTHEASTERLY FLOW CONTINUES ALLOWING FOR AREAS OF LOW CLOUDS... FOG...AND DRIZZLE THROUGH THE MORNING HOURS. AS THE BOUNDARY LAYER STARTS TO MIX A BIT THOUGH...DRIZZLE SHOULD COME TO AN END. A FEW STEADIER SHOWERS ARE POSSIBLE ACROSS RHODE ISLAND AND SOUTHEASTERN MASSACHUSETTS LATER TODAY AS A WEAK SHORTWAVE MOVES ACROSS SOUTHERN NEW ENGLAND. EXPECT TEMPERATURES TO BE ABOUT 5 DEGREES BELOW NORMAL. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... TONIGHT...EXPECTING ANOTHER NIGHT MUCH LIKE THE LAST WITH LOW PRESSURE WELL SOUTHEAST OF NANTUCKET. AREAS OF LOW CLOUDS... FOG...AND DRIZZLE ARE LIKELY ONCE AGAIN WITH VERY MOIST AIR IN THE LOW LEVELS. MORE WIDESPREAD SHOWERS ARE POSSIBLE ACROSS RHODE ISLAND AND SOUTHEASTERN MASSACHUSETTS AS THE MID LEVEL LOW PUSHES INTO SOUTHERN NEW ENGLAND. OVERNIGHT LOWS WILL BE FAIRLY MILD THANKS TO THE LOW LEVEL HUMIDITY WITH MOST LOCATIONS REMAINING IN THE 50S. WEDNESDAY...BEST SHOT OF SHOWERS AS MID LEVEL LOW MOVES OVER SOUTHERN NEW ENGLAND. THESE WILL LIKELY BE LIMITED MAINLY TO SOUTHEASTERN MASSACHUSETTS AND RHODE ISLAND WHERE THE BEST LIFT EXISTS. OTHERWISE...MORE OF THE SAME LOW CLOUDS...DRIZZLE...AND FOG. OVERCAST SKIES AND WET WEATHER WILL KEEP TEMPERATURES IN THE LOW TO MID 60S. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... HIGHLIGHTS... * NORTHEAST WINDS AND CLOUDS THIS WEEK WILL KEEP TEMPS NEAR NORMAL * CHANCE FOR SHOWERS AND DRIZZLE ON WED AND THU * COLD FRONTAL PASSAGE ON SATURDAY WILL BRING PRECIP TO THE REGION OVERVIEW... FALL IS HERE TO STAY FOR SOUTHERN NEW ENGLAND AS 12Z GUIDANCE CONTINUES TO SHOW PERSISTENT NORTHEASTERLY WINDS. OVERALL THE 12Z GUIDANCE IS IN GENERALLY AGREEMENT WITH THE UPPER LEVEL PATTERN WITH ISSUES DOWN AT THE SURFACE. THE TREND FOR THE GLOBAL GUIDANCE IS THAT THE EC IS MORE AMPLIFIED WHERE THE GFS IS MORE PROGRESSIVE IN THE OVERALL PATTERN. THE CMC IS ALSO LESS AMPLIFIED THEN THE EC WHERE THE UKMET IS THE IN BETWEEN MODEL. BECAUSE OF THE DIFFERENCES IN GUIDANCE DID A MODEL BLEND AS WELL AS HPC FORECAST FOR THE EXTENDED. HAVE A HIGHER CONFIDENCE THAT AVERAGE TEMPS WILL OCCUR ACROSS THE REGION THIS WEEK. LOW CONFIDENCE ON THE PRECIP POTENTIAL FOR WED AND THURSDAY. HIGH CONFIDENCE THAT PRECIP WILL OCCUR ON SATURDAY BUT STILL TOO MUCH UNCERTAINTY ON TIMING AND WHO WILL SEE THE HIGHER QPF. DETAILS... WEDNESDAY THROUGH THURSDAY... UPPER LEVEL LOW WILL CUT OFF RIGHT OVER SOUTHERN NEW ENGLAND DURING THIS TIME FRAME...KEEPING A SURFACE TROUGH/NORTHEASTERLY FLOW OVER THE REGION. THIS LOW WILL BRING A FEW SHORTWAVES ACROSS THE REGION INCREASING THE POTENTIAL FOR SCT SHOWERS. EASTERN MA HAS THE BEST CHANCE TO SEE ACCUMULATING PRECIP ESPECIALLY ON WED INTO WED NIGHT. ANTICIPATE DRIZZLE AND FOG FOR THURSDAY ESP IN EASTERN AREAS AS UPPER LEVEL LOW BEGINS TO MOVE OFFSHORE AND UPPER LEVEL RIDGE INCHES EASTWARD INTO THE REGION. THUNDER IS NOT ANTICIPATED ON WED AS THE MARINE LAYER WILL KEEP THE ATMOSPHERE STABLE AND GUIDANCE IS NOT SHOWING ANY INSTABILITY AT THIS TIME. TEMPERATURES WILL BE AT OR BELOW NORMAL FOR THIS TIMEFRAME. FRIDAY... QUICK MOVING RIDGE WILL CREST OVER THE REGION ON FRIDAY. THIS WILL ALLOW FOR RETURN FLOW AND TEMPS INTO THE UPPER 60S TO LOW 70S. DRY WEATHER SHOULD PREVAIL AS WE WILL BE BETWEEN SYSTEMS. WEEKEND... STRONG UPPER LEVEL TROUGH WILL SWING THROUGH THE GREAT LAKES ON FRIDAY AND IMPACT SOUTHERN NEW ENGLAND ON SATURDAY. THIS WILL PUSH A COLD FRONT THROUGH THE REGION AND BRING SOME MUCH NEEDED RAINFALL. STILL A LOT OF UNCERTAINTY IN REGARDS TO THE DETAILS OF THIS SYSTEM AS THE EC SEEMS TO BE OUT OF PHASE WITH THE MAJORITY OF THE GUIDANCE. THEREFORE TRENDED MORE TOWARDS THE 12Z GFS AND ENSEMBLES FOR THIS PORTION. NOTE THAT IT APPEARS THAT THE ENERGY ASSOCIATED WITH THIS SYSTEM DOES GET STRETCHED AND IS NOT AS ROBUST AS IT IS ACROSS UPSTATE NEW YORK. THE OTHER POINT IS THAT THE RIDGE ON FRIDAY...HOW STRONG WILL IT GET AND HOW MUCH DRY AIR WILL LINGER AS THE FRONT APPROACHES THE REGION ON SATURDAY. RIGHT NOW PLAN ON KEEPING CHC POPS TO THE SOUTH AND LIKELY POPS TO THE NORTH...CLOSER TO THE UPPER LEVEL ENERGY. HOPEFULLY GUIDANCE WILL LINE UP WITHIN THE COMING DAYS. TRENDING WITH THE GFS/CMC...HIGH PRESSURE WILL BUILD IN ON SUNDAY BUT STILL COULD SEE SOME ISOLATED SHOWERS LINGER EARLY SUN MORNING ACROSS THE CAPE AND ISLANDS. CAA BEHIND THE FRONT WILL KEEP TEMPS BELOW AVERAGE WITH BREEZY CONDITIONS. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...HIGH CONFIDENCE ON TRENDS BUT LOWER CONFIDENCE IN TIMING. THROUGH 12Z...IFR CONDITIONS EXPECTED ACROSS MUCH OF THE REGION IN LOW CLOUDS/PATCHY FOG/DRIZZLE. TODAY...IFR CONDITIONS SLOWLY IMPROVE FROM WEST TO EAST FIRST TO MVFR THEN TO VFR ACROSS THE WESTERN TERMINALS. SHOWERS ARE POSSIBLE PARTICULARLY ACROSS EASTERN MA/RI WHERE MVFR/IFR CONDITIONS ARE LIKELY TO CONTINUE THROUGHOUT THE DAY. TONIGHT...MORE OF THE SAME WITH IFR CONDITIONS LIKELY IN LOW CLOUDS...FOG...AND DRIZZLE. WEDNESDAY...CONDITIONS IMPROVE ONCE AGAIN AT LEAST TEMPORARILY IN THE WEST. SHOWERS ARE POSSIBLE PARTICULARLY ACROSS EASTERN MA/RI. KBOX...HIGH CONFIDENCE ON TRENDS...LOWER CONFIDENCE ON TIMING. KBDL...HIGH CONFIDENCE ON TRENDS...LOWER CONFIDENCE ON TIMING. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY... WEDNESDAY NIGHT...MODERATE CONFIDENCE. PATCHY IFR CIGS/VSBYS POSSIBLE ACROSS EAST COASTAL SECTIONS WEDNESDAY NIGHT. THURSDAY AND FRIDAY...MODERATE CONFIDENCE. MAY SEE LEFTOVER MVFR CIG/VSBYS EARLY THU ALONG THE E COAST BUT CONDITIONS WILL IMPROVE FROM WEST TO EAST ON THURSDAY TO VFR. FRIDAY WILL BE VFR. SATURDAY...HIGH CONFIDENCE. CONDITIONS WILL LOWER TO MVFR TO LOCAL IFR IN A LINE OF SHOWERS MOVING FROM WEST TO EAST THROUGHOUT THE DAY. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...HIGH CONFIDENCE THROUGH WED. PERSISTENT NORTHEASTERLY FLOW WILL RESULT IN BUILDING SEAS THROUGH THE PERIOD. INCREASED WAVE WATCH GUIDANCE BY 20 PERCENT TO ACCOUNT FOR A GENERAL LOW BIAS IN THIS TYPE OF SCENARIO. SCA CONTINUES FOR THE NORTHEASTERN WATERS THROUGH THIS MORNING. ALSO ISSUED SCA FOR SEAS ACROSS THE SOUTHERN AND SOUTHEASTERN OUTER WATERS FOR TONIGHT AND WEDNESDAY. OUTLOOK...WEDNESDAY THROUGH SATURDAY... PERSISTENT NORTHEAST WINDS WILL BE IN PLACE ACROSS THE WATERS THROUGH THURSDAY NIGHT. COMBINED WITH EASTERLY SWELL WILL HELP BUILD SEAS UP TO 5-7 FEET. SCA WILL BE NEEDED. WEAK HIGH PRESSURE WILL MOVE OVER THE WATERS ON FRIDAY ALLOWING FOR BOTH SEAS AND WINDS TO RELAX. LINGERING SEAS OF 5 OR 6 FEET WILL KEEP THE SCA IN PLACE FOR THE OUTER WATERS. APPROACHING COLD FRONT ON SATURDAY WILL ALLOW FOR RETURN FLOW AND INCREASE IN GUSTS...CLOSE TO 30 KTS. SEAS WILL ALSO BUILD AHEAD OF AND BEHIND THE FRONT...NEAR 7 FEET. SCA WILL BE NEEDED. MAY EXPERIENCE A STORM SURGE OF 1 TO 1.5 FEET DURING MIDWEEK BUT THE ASTRONOMICAL TIDES ARE NOT ALL THAT HIGH. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR ANZ250- 251. SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 8 PM EDT WEDNESDAY FOR ANZ254>256. && $$ SYNOPSIS...WTB/RLG NEAR TERM...RLG SHORT TERM...RLG LONG TERM...WTB AVIATION...WTB/RLG MARINE...WTB/RLG

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