Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 290155 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 955 PM EDT SUN SEP 28 2014 .SYNOPSIS... SUMMERLIKE WARMTH WILL COME TO AN END MONDAY AS A FRONT WILL DROP SOUTH ACROSS THE REGION LATE TOMORROW...DROPPING TEMPS AND BRING A FEW SHOWERS. A COOLER NORTHEAST WIND WILL CONTINUE THROUGH THE REMAINDER OF THE WEEK AND ONE OR TWO WEAK LOW PRESSURE CENTERS MAY PASS JUST SOUTH OF THE REGION FOR CHANCE OF SHOWERS. A FRONT AND POSSIBLY SECONDARY LOW PRESSURE AREA WILL LIKELY AFFECT SOUTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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10 PM UPDATE... NO SIGNIFICANT CHANGES TO THE FORECAST. DESPITE LIGHT WINDS AND THIN/HIGH CIRRUS CLOUDS TEMPS WILL NOT BE AS COOL AS LAST NIGHT GIVEN DEW PTS IN THE L60S THIS EVENING. THESE HIGHER DEW HIGH CLOUDS SHOULD HELP MINIMIZE ANY DENSE FOG PATCHES BUT TEMP/DEWPOINT SPREADS WILL LIKELY CLOSE ENOUGH FOR PATCHY 3-5 MILES IN FOG. TEMPERATURES DROPPING A LITTLE FASTER THAN FORECAST AS OF 7 PM BUT FORECAST MINIMUMS STILL LOOK GOOD. LIGHT WINDS EXPECTED OVERNIGHT. 4 PM UPDATE... NO MAJOR CHANGES TO THE FORECAST FOR THE REMAINDER OF THE AFTERNOON. BOTH PVD AND BDL HAVE BROKEN THEIR RECORDS AND LOGAN WARMED UP TO 87F. DEFINITELY A MORE SUMMER LIKE FEEL OUT THERE TODAY. PTS WILL ALSO YIELD PATCHY FOG...LOCALLY DENSE WHERE KEENE NH REPORTING ZERO VSBY AT THE MOMENT. PREVIOUS FORECAST CAPTURES THESE DETAILS NICELY SO AGAIN NO MAJOR CHANGES WITH THIS FORECAST UPDATE. EARLIER DISCUSSION BELOW. ================================================================== TONIGHT... HIGH PRESSURE WILL CONTINUE TO SLIDE OFFSHORE TONIGHT...AS WINDS WILL BE MORE OUT OF THE WEST BUT STILL RELATIVELY LIGHT. HIGH LEVEL CLOUDS WILL CONTINUE TO STREAM INTO THE REGION OVERNIGHT. THIS WILL LIMIT RADIATIONAL COOLING AS WELL AS THE FOG POTENTIAL. MIN TEMPS MAY DROP INTO THE MID TO UPPER 50S. METRO REGIONS OF BOS AND PVD WILL BE IN THE LOWER 60S THANKS TO THE URBAN HEAT ISLAND EFFECT. PATCHY GROUND FOG IS POSSIBLE AGAIN TONIGHT...ESP IN VALLEY REGIONS. THE FOG POTENTIAL WILL NOT BE AS WIDESPREAD AS LAST NIGHT AS TEMP/DEWPOINT SPREAD WILL BE LARGER THAN THE PREV NIGHT.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... TOMORROW AND TOMORROW NIGHT... TRICKY FORECAST FOR TOMORROW AND TOMORROW NIGHT. FIRST THING TO WATCH IS THE BACK DOOR COLD FRONT WHICH WILL MAKE ITS WAY TOWARDS SOUTHERN NEW ENGLAND AROUND 18Z MONDAY AND PUSH TO THE SOUTH SHORE BY 00Z. TEMPS WILL WARM IN THE MORNING BUT BY THE AFTERNOON WILL DROP ESP ACROSS THE MERRIMACK REGION AS WINDS WILL SWITCH TO THE NE AND INCREASE THROUGHOUT THE AFTERNOON. A FEW SHOWERS MAY ACCOMPANY THE FRONT BUT POTENTIAL SEEMS LOW AS THERE IS LACK OF DEEP MOISTURE AND SIGNIFICANT UPPER LEVEL LIFT. CONTINUE TO THE MENTION OF ISOLATED SHOWERS FOR NOW. BY TOMORROW NIGHT A UPPER LEVEL TROUGH WILL SHARPEN UP AS LOW PRESSURE SYSTEM STRENGTHENS. THIS WILL ALLOW FOR MOISTURE TO INCREASE SOUTH OF THE FRONTAL SYSTEM AND BRING IN SHOWERS ACROSS THE SOUTH COAST...CAPE AND ISLANDS. THERE IS STILL SOME UNCERTAINTY WITH THIS PORTION OF THE FORECAST IN REGARDS TO TIMING AND AMOUNT OF PRECIP. THE GFS IS THE MORE ROBUST MODEL WHERE THE NAM HAS NO QPF FOR MON NIGHT AND THE EC IS LESS AMPLIFIED IN BRINGING THE PRECIP INTO THE REGION. DID AN OVERALL BLEND IN THIS PORTION OF THE FORECAST TO ACCOUNT FOR THE UNCERTAINTY. TEMPERATURES WILL BE COOLER THEN TONIGHT...BUT STILL WARMER AS CLOUD COVER WILL KEEP TEMPS FROM RADIATING OUT. && .LONG TERM /TUESDAY THROUGH SUNDAY/...
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HEADLINES... * BELOW AVERAGE CONFIDENCE IN THE FORECAST FOR THIS TIME PERIOD WITH A RISK OF SHOWERS TUESDAY...WEDNESDAY AND THE FIRST PART OF THE WEEKEND OVERVIEW... CONFIDENCE FOR MOST OF THIS FORECAST PERIOD IS BELOW AVERAGE. GENERAL AGREEMENT IN THE MEDIUM RANGE MODELS AND ENSEMBLES OF A WEAK TROF AND AREA OF HIGH MOISTURE THREATENING SOUTHERN NEW ENGLAND HEADING INTO TUESDAY BUT MODELS VARY CONSIDERABLY IN LOCATION AND STRENGTH. SIMILARLY...MEDIUM RANGE MODELS DEPICT CLOSED LOW MOVING ACROSS SOUTHERN NEW ENGLAND DURING MID WEEK BUT LOW CONFIDENCE ON DETAILS AND CHANCES OF MEASURABLE RAIN. A RELATIVELY HIGH AMPLITUDE NEGATIVELY TILT TROF IS ALSO SHOWN BY MEDIUM RANGE MODELS TO CROSS NEW ENGLAND NEXT WEEKEND WITH POSSIBLY A TRIPLE POINT LOW. THERE IS CONSIDERABLE VARIATION AND ENOUGH RUN TO RUN INCONSISTENCY TO HAVE LOW CONFIDENCE ON THE AMOUNT AND DISTRIBUTION OF RAFL WITH THIS SYSTEM. DETAILS... TUESDAY...THE 12Z GFS RUN DEPICTS A FAIR AMOUNT OF RAFL ALONG THE S COAST TUESDAY IN ASSOCIATION WITH A WEAK LEAD SHORT WAVE TROF AHEAD OF THE MORE PRONOUNCED CLOSED LOW...BUT THIS FEATURE IS NOT REFLECTED NEARLY SO MUCH IN THE NAM AND ENSEMBLES. THE 12Z ECMWF DOES PICK UP ON THIS FEATURE BUT NOT TO NEARLY THE DEGREE OF THE GFS. WILL INDICATE CHANCE POPS SOUTHERN ZONES AND SLIGHT CHANCE MOST OTHER ZONES WITH RELATIVELY LOW CONFIDENCE ON JUST HOW THIS FEATURE WILL MANIFAST ITSELF. WEDNESDAY...WEAK UPPER CLOSED LOW IS PROJECTED TO CROSS THE REGION DURING THE WEDNESDAY AND WEDNESDAY NIGHT TIMEFRAME BUT THE MODELS VARY IN STRENGTH AND NEARNESS OF SURFACE LOW REFLECTION WITH THE ECMWF BEING MORE ROBUST THAN THE GFS IN THIS CASE. THE GFS DOES DEPICT A FAIRLY PRONOUNCED COLD POOL ALOFT WITH TOTAL TOTALS RISING TO NEAR 48. THERE IS CORRESPONDING VARIATIONS IN THE QPF. WILLHIGH CLOUDS SHOULD HELP MINIMIZE ANY DENSE FOG PATCHES BUT TEMP/DEWPOINT SPREADS WILL LIKELY CLOSE ENOUGH FOR PATCHY 3-5 MILES IN FOG. TEMPERATURES DROPPING A LITTLE FASTER THAN FORECAST AS OF 7 PM BUT FORECAST MINIMUMS STILL LOOK GOOD. LIGHT WINDS EXPECTED OVERNIGHT. 4 PM UPDATE... NO MAJOR CHANGES TO THE FORECAST FOR THE REMAINDER OF THE AFTERNOON. BOTH PVD AND BDL HAVE BROKEN THEIR RECORDS AND LOGAN WARMED UP TO 87F. DEFINITELY A MORE SUMMER LIKE FEEL OUT THERE TODAY. PUT CHANCE POPS UP TO MASSPIKE AND SLIGHT CHANCE NORTH OF THERE BUT CONFIDENCE IS RELATIVELY LOW. THURSDAY AND FRIDAY...CHANCE RAIN THURSDAY MORNING WITH DEPARTING LOW ACROSS CAPE AND ISLANDS BUT OTHERWISE MODELS HAVE SIMILAR TIMING WITH SURFACE AND UPPER RIDGE OVERING ACROSS REGION THURSDAY AFTERNOON THROUGH FRIDAY. FRIDAY NIGHT AND SATURDAY...FAIRLY LARGE AMPLIFIED TROF THAT MAY TAKE ON A NEGATIVE TILT APPROACHES REGION PER ALL MEDIUM RANGE MODELS. THERE IS A SUGGESTION OF A TRIPLE POINT LOW MOVING ACROSS SOUTHERN NEW ENGLAND FRIDAY NIGHT OR SATURDAY MORNING. ACTUAL DURATION OF RAIN IS LIKELY TO BE LESS THAN GRID POPS MIGHT IMPLY ONCE WE ARE ABLE TO BETTER DEFINE THE TIMING. ENOUGH MODEL DIFFERENCE IN THE DETAILS TO MAKE THE QPF VERY UNCERTAIN AT THIS TIME. SUNDAY...LOOKS LIKE SYSTEM WILL BE EXISTING THE REGION WITH DRIER AND COOLER AIR MOVING INTO SOUTHERN NEW ENGLAND. ALTHOUGH IT LOOKS DRY NOW...THERE IS ENOUGH COMPLEXITY WITH THE SITUATION WITH MULTIPLE SHORT WAVE TROFS TO KEEP THE DOOR OPEN FOR SIGNIFICANT CHANGES IN THE SUNDAY FORECAST.
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&& .AVIATION /02Z MONDAY THROUGH FRIDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...HIGH CONFIDENCE THROUGH MONDAY. MODERATE CONFIDENCE MONDAY NIGHT. PATCHY FOG EXPECTED ONCE AGAIN TONIGHT BUT ANY IFR/LIFR WILL BE LOCALIZED...LESS SO THAN THIS MORNING DUE TO THE INFLUENCE OF HIGH CLOUDS. EXPECT TO SEE PATCHY 3-5 MILES IN FOG LATE TONIGHT. MONDAY AND MONDAY NIGHT...A COLD FRONT DROPS S ACROSS REGION SHIFTING THE WINDS TO THE N/NE. VFR CIGS AHEAD OF FRONT BUT EXPECT CIGS TO LOWER TO MVFR BEHIND IT...CLOSER TO 00Z. MAY ALSO BE ISOLD SHOWER. EASTERLY FLOW WILL REMAIN MONDAY NIGHT WHICH WILL ALLOW FOR MOISTURE TO INCREASE AND DROP CIGS TO MVFR. DRIZZLE AND ISO SHOWERS ARE ALSO POSSIBLE. NE WINDS WILL ALSO GUST BETWEEN 15-25 KTS OVERNIGHT ESP ACROSS THE MERRIMACK VALLEY. KBOS TERMINAL...HIGH CONFIDENCE IN TAF THROUGH MONDAY...MODERATE CONFIDENCE THEREAFTER. VFR THROUGH MONDAY BUT THEN MVFR WITH RISK OF IFR CIGS MONDAY NIGHT AS NE FLOW BECOMES ESTABLISHED BEHIND BACKDOOR COLD FRONT. KBDL TERMINAL...HIGH CONFIDENCE IN TAF THROUGH MONDAY...MODERATE CONFIDENCE THEREAFTER. MVFR VSBY IN FOG POSSIBLE AFTER MIDNIGHT...THEN VFR THROUGH MONDAY. MVFR CIGS POSSIBLE MONDAY NIGHT. OUTLOOK...TUESDAY THROUGH FRIDAY... LOW TO MODERATE CONFIDENCE TUESDAY THROUGH WEDNESDAY AND MODERATE CONFIDENCE THURSDAY AND FRIDAY. TUESDAY THROUGH WEDNESDAY...WIDESPREAD MVFR CIGS AND AREAS OF MVFR VSBYS IN SHOWERS. AREAS OF IFR CIGS AND VSBYS POSSIBLE ACROSS EAST COASTAL SECTIONS FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. THURSDAY AND FRIDAY...GENERALLY VFR CONDITIONS EXPECTED. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...HIGH CONFIDENCE THROUGH MON. HIGH PRESSURE STILL OVERHEAD ALLOWING FOR LIGHT WINDS AND CALM SEAS TONIGHT. COLD FRONT PUSHES S ACROSS WATERS TOMORROW...FIRST NEAR MERRIMACK RIVER IN MORNING AND PROBABLY NOT REACHING S COAST UNTIL LATE AFTERNOON. SW WINDS GIVE WAY TO WIND SHIFT TO N/NE BEHIND FRONT...AND MAY REACH 25 KT LATE IN DAY FROM BOSTON TO MERRIMACK RIVER AS SEAS BUILD TO 3 TO 6 FT. SCA MAY BE NEEDED FOR THESE AREAS. OUTLOOK...TUESDAY THROUGH FRIDAY... THIS WEEK MAY FEATURE A FAIRLY PERSISTENT EAST TO NORTHEAST FLOW. SMALL CRAFT ADVISORY SEAS POSSIBLE TUESDAY MORNING BEHIND BACKDOOR COLD FRONT. FOR WEDNESDAY AND WEDNESDAY NIGHT...THERE IS A FAIRLY STRONG SIGNAL FOR E TO NE WIND GUSTS ABOVE SMALL CRAFT ADVISORY THRESHOLDS AS WELL AS SEAS IN ZONES EXPOSED TO AN EASTERLY FETCH ABOVE SMALL CRAFT ADVISORY THRESHOLDS. HAVE UPPED SEAS ABOVE WAVE WATCH GUIDANCE BASED ON EXPERIENCE WITH NE FLOW AND SYNOPTIC PATTERN RECOGNITION. IF THE MEDIUM RANGES MODELS HAVE A FAIR IDEA ON THE MID WEEK SYNOPTIC PATTERN...THEN WOULD NOT BE SURPRISED TO SEE SEAS BUILD TO NEAR 10 FEET EAST OF CAPE COD AND NANTUCKET BY LATE WEDNESDAY. MAY EXPERIENCE A STORM SURGE OF 1 TO 1.5 FEET DURING MIDWEEK BUT THE ASTRONOMICAL TIDES ARE NOT ALL THAT HIGH. && .CLIMATE... RECORD HIGHS FOR TODAY 9/28 BOSTON.......... 90 IN 1881 AND PREVIOUS YEARS - REACHED 87 PROVIDENCE...... 84 IN 1943 - REACHED 86 TODAY* WORCESTER....... 84 IN 1916 - REACHED 79 WINDSOR LOCKS... 83 IN 1959 - REACHED 87 TODAY* * RER SENT FOR PVD AND BDL && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...DUNTEN/THOMPSON NEAR TERM...NOCERA/DUNTEN/THOMPSON SHORT TERM...DUNTEN LONG TERM...THOMPSON AVIATION...DUNTEN/THOMPSON MARINE...DUNTEN/THOMPSON CLIMATE...

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