Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 282024
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
424 PM EDT SUN SEP 28 2014

.SYNOPSIS...
SUMMERLIKE WARMTH WILL COME TO AN END TOMORROW 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/...
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.

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.

&&

.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/...
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. WILL 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.

&&

.AVIATION /20Z SUNDAY 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 TOMORROW. MODERATE
CONFIDENCE MONDAY NIGHT.

BEFORE 00Z...VFR TODAY.

AFTER 00Z...PATCHY FOG EXPECTED ONCE AGAIN TONIGHT BUT ANY
IFR/LIFR WILL BE LOCALIZED...LESS SO THAN THIS MORNING.

TOMORROW AND TOMORROW 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. WEAK SEA BREEZE THIS
AFTERNOON.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF.

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
PROVIDENCE...... 84 IN 1943 - REACHED 85 TODAY*
WORCESTER....... 84 IN 1916
WINDSOR LOCKS... 83 IN 1959 - REACHED 84 TODAY*

* OFFICIAL RECORDS WILL BE SENT OUT DURING THE OVERNIGHT CLIMATE

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...DUNTEN/THOMPSON
NEAR TERM...DUNTEN
SHORT TERM...DUNTEN
LONG TERM...THOMPSON
AVIATION...DUNTEN/THOMPSON
MARINE...DUNTEN/THOMPSON
CLIMATE...DUNTEN/SIMPSON



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