Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS61 KBOX 191945
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
345 PM EDT SUN OCT 19 2014

.SYNOPSIS...
GUSTY NORTHWEST WINDS WILL BRING COLDER AIR TO SOUTHERN NEW
ENGLAND TONIGHT. HIGH PRESSURE MOVES OVER THE REGION ON MONDAY. A
DISTURBANCE DROPPING THROUGH THE GREAT LAKES WILL GENERATE A LONG
DURATION COASTAL STORM TUESDAY THROUGH FRIDAY WITH PERIODS OF
HEAVY RAIN.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
REMAINDER OF THIS AFTERNOON...
UPPER TROUGH OVERHEAD WILL MOVE OFF TO THE EAST BY THIS EVENING.
TEMPERATURES AT 500 MB HAVE BEEN RUNNING AROUND -22C WHICH IS COLD
ENOUGH TO DESTABILIZE THE AIRMASS...ESPECIALLY COMBINED WITH ANY
SOLAR HEATING OF THE SURFACE. EXPECT PLENTY OF DIURNAL CLOUDS AND
POSSIBLY A FEW LIGHT SHOWERS.

OBSERVED WINDS ALOFT BELOW 850 MB ARE 25 KNOTS. MIXING WILL TAP
THESE WINDS AND SUPPORT NORTHWEST GUSTS OF 25-30 MPH.

TONIGHT...
HIGH PRESSURE BUILDS OVER THE REGION WITH CLEARING SKIES AND
DIMINISHING WIND. THE LIGHT WIND AND CLEAR SKIES WILL ALLOW FOR
RADIATIONAL COOLING ESPECIALLY AWAY FROM THE COAST. OBSERVED
AFTERNOON DEW POINTS ARE IN THE 30S WITH 20S UPSTREAM IN ONTARIO
AND WESTERN NY. WITH THIS VALUES ADVECTING OVER NEW
ENGLAND...EXPECT PLENTY OF ROOM FOR TEMPERATURES TO FALL BELOW
FREEZING IN INTERIOR SOUTHERN NEW ENGLAND WHILE COASTAL AREAS FALL
INTO THE 30S. EXPECTED VALUES ARE SIMILAR TO THE PREVIOUS TWO
FORECASTS. WE WILL CONTINUE THE FREEZE WARNING FOR MUCH OF
SOUTHERN NEW ENGLAND WITH FROST ADVISORY ALONG NARRAGANSETT BAY
AND THE MASS EAST COAST.

MODELS START TO BRING HIGH CLOUDS IN LATE AT NIGHT. WITH
SUFFICIENT THICKNESS...THESE CLOUDS COULD SLOW THE COOLING AND
KEEP SOME OF THE INTERIOR ABOVE FREEZING. BUT WE EXPECT THE
INITIAL CLOUDS TO BE THIN ENOUGH TO HAVE LITTLE EFFECT.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
MONDAY...
HIGH PRESSURE CRESTS OVER THE REGION. WINDS WILL SHIFT AROUND TO
SOUTHWEST DURING THE AFTERNOON. EXPECT SOME INCREASE IN MID AND
HIGH CLOUDS BUT OVERALL A FAIR WEATHER DAY. MIXING SHOULD REACH TO
925 MB...POSSIBLY A LITTLE HIGHER. TEMPS EQUIVILANT TO -1C/-3C AT
850 MB...SUPPORTS MAX TEMPS IN THE 50S.

MONDAY NIGHT...
RIDGE MOVES OFF TO THE EAST WHILE A TROUGH DIGS OVER THE GREAT
LAKES. THIS TURNS OUR UPPER FLOW INTO A SOUTHWEST FLOW. WEAK HINTS
IN THE MODEL DATA OF A 70-KNOT JET OVERHEAD OF THE NORTHEAST
USA. THE RIGHT ENTRANCE REGION OF THIS POSSIBLE JET IS LOCATED
SOUTH OF THE REGION SUGGESTING THE BEGINNING OF CYCLOGENESIS ALONG
THE MID ATLANTIC COAST. MEANWHILE THE SOUTHWEST FLOW WILL BE
TRANSPORTING MOISTURE UP THE COAST IN CLOUDS. EXPECT INCREASING
AND THICKENING CLOUDS THROUGH THE NIGHT WITH POTENTIAL FOR
INCREASING LIFT. THE MOISTURE AND LIFT WOULD LEAD TO A CHANCE OF
RAIN LATE AT NIGHT. TEMPS WILL INITIALLY COOL IN THE EVENING WITH
ENOUGH TIME TO DROP 10-15 DEGREES FROM DAYTIME HIGHS. WE USED A
RANGE OF MIN TEMPS IN THE UPPER 30S AND 40S.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
HIGHLIGHTS...

* TRANQUIL WEATHER MON WITH COOL TEMPS/SUNSHINE AND LIGHT WINDS

* A LONG DURATION COASTAL STORM WILL IMPACT NEW ENGLAND FROM TUE
  THROUGH FRI.  OCCASIONAL HEAVY RAIN APPEARS TO BE THE PRIMARY
  THREAT AS THE AXIS OF STRONGEST WINDS MAY BE FOCUSED ACROSS
  NORTHERN NEW ENG

OVERVIEW...
DETERMINISTIC AND ENSEMBLE GUIDANCE REMAIN IN GOOD AGREEMENT ON THE
EVOLUTION OF THE MID/LATE WEEK CLOSED LOW...DEVELOPING OVER THE MID
ATLC REGION LATE TUE/TUE NIGHT AND SLOWING TRACKING NE OFF THE MID
ATL COAST TO SE NEW ENG BY FRI.  THERE REMAINS SOME DIFFERENCES IN
THE TRACK OF THE SFC LOW BUT THE OVERALL TREND IS FURTHER N WHICH
KEEPS THE AXIS OF THE EASTERLY LOW LEVEL JET TO THE N ACROSS MAINE.
AS A RESULT...THE THREAT OF STRONG WIND AND COASTAL FLOODING HAS
LESSENED SOMEWHAT. OCCASIONAL HEAVY RAIN IS THE PRIMARY THREAT...BUT
TIMING AND LOCATION OF HEAVIEST RAINFALL REMAINS UNCERTAIN. IT MUST
BE EMPHASIZED THAT THERE IS STILL INHERENT UNCERTAINTY IN THE STORM
TRACK AT THIS TIME RANGE AND A SOUTHWARD SHIFT IS STILL POSSIBLE
WHICH WOULD INCREASE THE OVERALL IMPACT TO SNE.

DAILIES...

TUESDAY... PRIMARY LOW OVER THE GT LAKES WILL GRADUALLY FILL WITH
SECONDARY LOW DEVELOPING ALONG THE MID ATLC COAST AS NORTHERN
STREAM TROF AMPLIFIES AND EVOLVES INTO A CLOSED MID LEVEL
CIRCULATION. LIGHT RAIN AHEAD OF THE PRIMARY LOW WILL EXPAND
ACROSS SNE DURING TUE AS WARM ADVECTION INCREASES IN RESPONSE TO
DEVELOPING SECONDARY LOW OFF THE MID ATLC COAST. WITH SOUTHERLY
FLOW TO START THE DAY ON TUE IT WILL BE A MILD DAY WITH TEMPS
REACHING WELL INTO 60S IN THE COASTAL PLAIN...COOLER INTERIOR.

TUESDAY NIGHT THROUGH FRIDAY...
EXACT STORM DETAILS REMAIN UNCERTAIN AND DUE TO VARIABLE NATURE OF
INDIVIDUAL DETERMINISTIC GUIDANCE SOURCES...WE FOLLOWED A SUPERBLEND
OF ALL MODEL SOLUTIONS WITH PREV FORECAST AS A BASIS FOR THE CURRENT
FORECAST. PERIODS OF RAIN OF VARYING INTENSITY EXPECTED BUT TIMING
OF HEAVIEST RAINFALL REMAINS UNCERTAIN.  A BLEND OF MODEL QPF YIELDS
STORM TOTAL RAINFALL OVER THE 3-4 DAY PERIOD OF 1-2 INCHES SOUTH OF
THE MASS PIKE INCREASING TO 2-4 INCHES TO THE NORTH. TREND WILL BE
FOR RAIN TO TRANSITION TO MORE SCT SHOWERY PRECIP BY FRI AS LOW PRES
MOVES E OF CAPE COD.

IT APPEARS STRONG WIND THREAT HAS DIMINISHED AS MAIN CORE OF LOW
LEVEL JET IS FORECAST TO THE NORTH.  IN FACT 00Z GEFS INDICATES
STRONGEST EASTERLY WIND ANOMALIES /3-4SD/ FOCUSED ACROSS NORTHERN
NEW ENG.

THE COASTAL FLOODING THREAT HAS ALSO DIMINISHED SOMEWHAT AS
STRONGEST EASTERLY WINDS AND HIGHEST SEAS ARE EXPECTED TO SET UP TO
THE NORTH ACROSS MAINE...AND ASTRONOMICAL TIDES ARE SOMEWHAT LOW
DURING THIS PERIOD. HOWEVER AT THIS TIME RANGE IT IS STILL POSSIBLE
FOR THIS RISK AREA TO SHIFT SOUTHWARD. THE RISK OF COASTAL EROSION
APPEARS GREATER THAN INUNDATION GIVEN WAVE ACTION OVER SEVERAL HIGH
TIDE CYCLES FOR CONSECUTIVE DAYS.

&&

.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 /THROUGH MONDAY/...HIGH CONFIDENCE.

THROUGH 00Z/8 PM...

VFR WITH CLOUD BASES AROUND 4500 FEET. NORTHWEST WINDS GUSTING
25-30 KNOTS...DIMINISHING IN THE EVENING.

TONIGHT AND MONDAY...VFR. CLEARING SKIES WITH LIGHT WINDS.

MONDAY NIGHT...VFR MOST OF THE NIGHT. PATCHES OF MVFR CIGS IN
LIGHT RAIN POSSIBLE LATE AT NIGHT.

KBOS...HIGH CONFIDENCE IN TAF.

KBDL...HIGH CONFIDENCE IN TAF.

OUTLOOK...TUESDAY THROUGH THURSDAY...

TUESDAY THROUGH THU...HIGH CONFIDENCE ON OVERALL THEME...WITH
CONDITIONS LOWERING TO MVFR/IFR IN DEVELOPING RAIN BUT LOW
CONFIDENCE ON EXACT TIMING OF DETAILS. STRONGEST WINDS EXPECTED TO
THE NORTH OF THE REGION.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

SHORT TERM /TODAY THROUGH MONDAY/...HIGH CONFIDENCE.

THROUGH 8 PM/00Z...
WIND GUSTS 25 TO 30 KNOTS CONTINUE. SEAS LINGER AT 5-6 FEET ON THE
OUTER WATERS. PLENTY OF CLOUDS MOVING OFF LAND WITH SPRINKLES
POSSIBLE. SMALL CRAFT ADVISORY LINGERS THROUGH THIS EVENING.

TONIGHT...HIGH PRESSURE APPROACHES FROM THE WEST. EXPECT NORTHWEST
WINDS TO DIMINISH OVERNIGHT WITH GUSTS 15 TO 20 KNOTS AFTER
MIDNIGHT. LINGERING 5 FOOT SEAS ON THE OUTER WATERS...BUT WITH A
DIMINISHING TREND OVERNIGHT. SMALL CRAFT ADVISORY LINGERS THROUGH
EARLY TONIGHT...THEN DIMINISHES TO JUST THE OUTER WATERS LATE AT
NIGHT.

MONDAY...
HIGH PRESSURE BUILDS OVER THE WATERS. DIMINISHING NORTHWEST WINDS
BECOME SOUTHWEST IN THE AFTERNOON. SEAS DIMINISH BELOW 5 FEET
DURING THE MORNING.

MONDAY NIGHT...
HIGH PRESSURE MOVES OFFSHORE. WINDS TURN SOUTHWEST BUT REMAIN
BELOW SMALL CRAFT THRESHOLDS. SEAS BUILD A LITTLE BUT REMAIN BELOW
5 FEET. LIGHT RAIN MOVES UP FROM THE MID ATLANTIC COAST LATE AT
NIGHT.

OUTLOOK...TUESDAY THROUGH THURSDAY...

TUE...HIGH CONFIDENCE. SOUTHERLY WINDS GRADUALLY BECOMING EAST
BY LATE TUE...BUT SPEEDS AND SEAS BELOW SCA.

TUE NIGHT THROUGH THU...MODERATE CONFIDENCE. EXPECT STRONGEST E/NE
GALE FORCE WINDS TO REMAIN NORTH OF THE WATERS. STRONGEST WIND GUSTS
TO 30 KT WITH LOW PROB OF GALES AND HIGHEST SEAS UP TO 10+ FT
EXPECTED ACROSS NE MA COASTAL WATERS LATE TUE NIGHT INTO WED WITH
LESS WIND AND SEAS OVER SOUTH COASTAL WATERS.  WINDS AND SEAS
EXPECTED TO SUBSIDE WED NIGHT INTO THU. PERIODS OF HEAVY RAIN WILL
REDUCE VSBY.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR
     CTZ002>004.
MA...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR
     MAZ007-015-016-019-022-023.
     FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR
     MAZ005-006-009>014-017-018-020-021.
NH...NONE.
RI...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR
     RIZ002-004-005-007.
     FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR
     RIZ001-003-006.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT MONDAY FOR ANZ231>234-251.
     SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ230-
     235>237.
     SMALL CRAFT ADVISORY UNTIL 11 AM EDT MONDAY FOR ANZ250-254.
     SMALL CRAFT ADVISORY UNTIL 8 AM EDT MONDAY FOR ANZ255.
     SMALL CRAFT ADVISORY UNTIL 4 AM EDT MONDAY FOR ANZ256.

&&

$$
SYNOPSIS...WTB/KJC
NEAR TERM...WTB/KJC
SHORT TERM...WTB
LONG TERM...KJC
AVIATION...WTB/KJC
MARINE...WTB/KJC


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.