Area Forecast Discussion
Issued by NWS Boston, MA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 192048
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
448 PM EDT FRI SEP 19 2014

.SYNOPSIS...
CLEAR SKIES AND CHILLY TEMPERATURES WILL BE IN PLACE TONIGHT
ACROSS THE REGION AS HIGH PRESSURES CRESTS ACROSS THE REGION. AS
THE HIGH MOVES OFFSHORE...MILDER TEMPERATURES WILL BRIEFLY RETURN
FOR SATURDAY AND SATURDAY NIGHT. A COLD FRONT CROSSES NEW ENGLAND
SUNDAY NIGHT...WHILE A LOW PRESSURE CENTER RAPIDLY PASSES
SOUTHEAST OF NANTUCKET ON ITS WAY TO NOVA SCOTIA. AFTER THIS COLD
FRONT PASSES OFFSHORE MONDAY MORNING...HIGH PRESSURE DOMINATES
THROUGH ALL OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...

THROUGH 00Z...SKIES HAVE BEEN MAINLY CLEAR ACROSS MOST OF THE
REGION THROUGH EARLY THIS AFTERNOON. THE ONLY EXCEPTION HAS BEEN
ACROSS E COASTAL MA INTO E RI WHERE OCEAN CLOUDS HAVE BEEN MOVING
ONSHORE WITH THE NE WIND. HOWEVER...THE CLOUDS HAVE BEEN
DISSIPATING ACROSS MOST OF THE COASTAL AREAS AS WINDS HAVE BEEN
SLOWLY DIMINISHING AND VEERING TO EAST. SOME CLOUDS STILL LINGER
ACROSS CAPE COD AND THE ISLANDS BUT SHOULD DISSIPATE BY THIS
EVENING.

TEMPS HAVE REMAINED MAINLY IN THE MID-UPPER 50S ACROSS MOST
AREAS...WITH SOME REPORTS IN THE LOWER-MID 60S ACROSS THE MID AND
LOWER CT VALLEY INTO NE CT/INTERIOR RI. NOTING RATHER LOW
DEWPTS...MAINLY IN THE UPPER 20S TO LOWER 30S ACROSS S NH INTO N
CENTRAL MA...RANGING TO THE MID 30S ALONG THE IMMEDIATE E COAST...
CAPE COD AND THE ISLANDS. THESE READINGS ARE 2-4 DEGS LOWER THAN
FORECAST.

EXPECT GENERALLY CLEAR CONDITIONS WITH WINDS CONTINUING TO
DIMINISH INTO THIS EVENING.

TONIGHT...HIGH PRES CENTER WILL CREST ACROSS EASTERN AREAS THIS
EVENING...THEN PUSH OFFSHORE. TIMING OF THIS WILL BE A BIG
QUESTION...AS LIGHT E WINDS WILL LIKELY DECOUPLE AND DROP OFF IN
THE NORMALLY PRONE INTERIOR AREAS ESPECIALLY ACROSS PORTIONS OF S
NH/N CENTRAL AND NW MA. AS NOTED ABOVE...DEWPTS ARE LOWER THAN
FORECAST. HOW QUICKLY THESE RISE OVERNIGHT...AS CURRENTLY
INDICATED BY SHORT RANGE MODEL GUIDANCE...WILL BE CRITICAL FOR
OVERNIGHT LOWS ACROSS THE INTERIOR. CURRENT FORECASTED LOWS ARE IN
THE MID-UPPER 30S WELL INLAND. IF TEMPS FALL LOWER THAN
FORECAST...POSSIBLE SHORT FUSED HEADLINES FOR FROST OR FREEZE MAY
NEED TO BE ISSUED. THIS ASPECT WILL BE MONITORED CLOSELY.

OTHERWISE...EXPECT MAINLY CLEAR...DRY AND MAINLY CALM CONDITIONS.
MAY START TO SEE SOME HIGH CLOUDS WORK INTO WESTERN AREAS WELL
AFTER MIDNIGHT. LOWS WILL RANGE FROM THE MID 30S TO AROUND 40
INLAND TO THE MID 40S TO AROUND 50 ALONG THE IMMEDIATE SHORE.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...

SATURDAY...HIGH PRES WILL SHIFT E OF THE REGION DURING THE DAY.
MILD S-SW FLOW TAKES OVER. TEMPS WILL RESPONSE TO THIS AS RIDGE
REMAINS ACROSS REGION. THE SW FLOW MAY BECOME GUSTY /AROUND 20 KT/
DURING THE AFTERNOON ACROSS INLAND AREAS WITH GOOD MIXING IN
PLACE. WILL ALSO NOTICE INCREASING HUMIDITY AS DEWPTS STEADILY
RISE DURING THE DAY. HIGHS WILL REACH THE LOWER 70S FOR MOST
AREAS...THOUGH A BIT COOLER ACROSS THE HIGHER TERRAIN AND ALONG
THE IMMEDIATE S COAST WITH THE ONSHORE WIND.

NOTING A BROAD INVERTED TROUGH STARTING TO TAKE SHAPE ALONG THE
MID ATLC AND SE U.S. COAST...ALONG WITH LOW PRES OFF THE GA/FL
COAST EARLY SAT. SOME MOISTURE MAY START TO MOVE UP TOWARD THE
REGION LATE IN THE DAY.

SATURDAY NIGHT...AS LOW PRES DEVELOPS AND MOVES NE UP THE
COAST...A PIECE OF MOISTURE MAY WORK INTO CENTRAL AND SOUTHERN
AREAS FOR A TIME OVERNIGHT. HAVE CARRIED LOW CHANCE POPS ACROSS
RI/NE CT THOUGH PLACEMENT OF THE AXIS OF THIS MOISTURE IS
UNCERTAIN. WILL CONTINUE TO SEE S WINDS ALONG WITH MILD AND HUMID
CONDITIONS. MAY SEE SOME PATCHY FOG DEVELOP MAINLY AFTER MIDNIGHT
AS WELL. TEMPS WILL ONLY FALL BACK TO THE MID 50S TO LOWER 60S.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...

* CHANCE OF SHOWERS SUNDAY INTO SUNDAY NIGHT WITH COLD FRONT PASSAGE
* DRY CONDITIONS LIKELY NEXT WEEK

OVERVIEW...NOT MUCH CHANGE IN THE 19/12Z GUIDANCE SUITE FROM
PREVIOUS RUNS. WE STILL EXPECT A FAIRLY SHARP SHORTWAVE TROUGH AND
A COLD FRONT TO CROSS NEW ENGLAND SUNDAY NIGHT. A POTENTIALLY
SIGNIFICANT COMPLICATION IN THE FORECAST IS THE LIKELY PASSAGE OF
A SURFACE LOW JUST SE OF NANTUCKET AHEAD OF THIS COLD FRONT. SINCE
THIS LOW PRESSURE SYSTEM MAY CONTAIN TROPICAL
PROCESSES...CONFIDENCE IN HOW THIS SYSTEM WILL INTERACT WITH THE
MID LATITUDE SHORTWAVE AND COLD FRONT IS LOW.

THE 19/12Z GUIDANCE STILL PROJECTS THE DRAMATIC DEVELOPMENT OF AN
ASSOCIATED UPPER JET WITH THIS COASTAL LOW FROM 80 TO 100+ KT IN
LESS THAN 12 HOURS SUNDAY NIGHT...AND FURTHER INTENSIFIES THIS JET
MONDAY. THE MODEL CONSENSUS CONTINUES TO KEEP THIS SYSTEM
DISTINCTLY SEPARATE FROM THE FRONTAL SYSTEM UNTIL WELL PAST NEW
ENGLAND. AND THERE REMAINS SOME SIGNALS THAT MUCH OF SOUTHERN NEW
ENGLAND COULD BE CAUGHT IN A SUBSIDENCE ZONE BETWEEN THE FRONT AND
COASTAL SURFACE LOW...WITH RESULTING MINIMAL RAINFALL.

AS NOTED BY PREVIOUS FORECASTER...IF THIS COASTAL LOW PRESSURE
SHOULD HAVE A MORE DISTINCT IDENTITY AS A TROPICAL OR SUBTROPICAL
SYSTEM...THEN ONE MIGHT EXPECT A SOMEWHAT SLOWER SPEED AND BACK
BUILDING OF THE UPPER JET TO AT LEAST BRING A HIGHER THREAT OF
SIGNIFICANT RAINFALL TO SOUTHEAST NEW ENGLAND. ALSO AS BEFORE...WE
KEPT THE FORECAST CONSERVATIVE AND WENT NO HIGHER THAN A CHANCE OF
RAIN SHOWERS SUNDAY AND SUNDAY NIGHT...DUE TO HIGHER THAN NORMAL
UNCERTAINTY FOR THIS TIME RANGE OF THE FORECAST.

ONCE OUR REGION IS CLEAR OF BOTH THIS COASTAL LOW AND COLD FRONT
MONDAY MORNING...MEDIUM RANGE MODELS ARE IN FAIRLY CLOSE AGREEMENT
ON A HIGH AMPLITUDE UPPER RIDGE BUILDING OVER EASTERN NORTH
AMERICA. THIS MEANS VERY LITTLE CHANCE OF RAIN FOR THE FORESEEABLE
FUTURE ACROSS OUR AREA. WE WOULD ANTICIPATE RELATIVELY MILD
DAYTIME TEMPERATURES AND COOL OVERNIGHT TEMPERATURES IN THIS
PATTERN WITH RELATIVELY HIGH DIURNAL RANGES...NEAR TO ABOVE NORMAL
AFTERNOON TEMPERATURES AND NEAR TO BELOW NORMAL LATE NIGHT/EARLY
MORNING TEMPERATURES.

DETAILS...

SUNDAY...THINKING THAT MUCH OF AREA WILL REMAIN DRY WITH TWO
NOTABLE EXCEPTIONS. ONE EXCEPTION COULD BE ACROSS NORTHWEST MA
AND SOUTHWEST NH...WHERE AIR MASS BECOMES MARGINALLY UNSTABLE AND
MORE MOIST AHEAD OF AN APPROACHING COLD FRONT. CONTINUED TO
INDICATE A CHANCE OF SHOWERS WITH ISOLATED THUNDERSTORMS ROUGHLY
NORTHWEST OF A MANCHESTER NH-WORCESTER MA-HARTFORD CT LINE. THERE
WILL BE INCREASING VERTICAL SHEAR AND CANNOT RULE OUT AN ISOLATED
STRONG OR EVEN SEVERE THUNDERSTORM NW MA AND SW NH LATE SUNDAY
AFTERNOON OR EVENING.

THE OTHER EXCEPTION WILL BE ACROSS CAPE COD AND THE ISLANDS. HAVE
GREATEST CONFIDENCE IN SCATTERED SHOWERS ACROSS NANTUCKET BY LATE
SUNDAY AFTERNOON. THIS TIMING IS RATHER UNCERTAIN. DECIDED TO ONLY
MENTION A SLIGHT CHANCE OF SHOWERS FOR THE VINEYARD AND THE CAPE.
THIS COULD CHANGE IF THE TIMING IS ALTERED BY ONLY A COUPLE OF
HOURS...EITHER FASTER OR SLOWER. WILL NEED TO MONITOR THIS AREA TO
TRACK THE INFLUX OF MOISTURE.

SUNDAY NIGHT...AS PER OVERVIEW SECTION WE HAVE ABOVE AVERAGE
UNCERTAINTY FOR THIS FORECAST PERIOD AS RAIN CHANCES WILL DEPEND
UPON INTERACTION BETWEEN COLD FRONT AND LOW PRESSURE PASSING JUST
OFFSHORE. FOR NOW PLAN ON CHANCE POPS WITH HIGHEST VALUES FAR NW
AND FAR SE. VERTICAL SHEAR INCREASES TO 40 TO 50 KT 0 TO 6 KM
SUNDAY EVENING AND ANY THUNDERSTORMS...MOST LIKELY TOWARDS
NORTHWEST MA AND EXTREME SOUTHWEST NH...COULD CONTAIN STRONG
WINDS.

MONDAY...LINGERING CHANCE OF SHOWERS ACROSS THE CAPE AND ISLANDS
EARLY. OTHERWISE DRIER AS SURFACE HIGH PRESSURE BUILDS INTO THE
REGION. MAY BE BREEZY FROM THE NORTHWEST DUE TO COMBINATION OF
MODERATE SURFACE PRESSURE GRADIENT AND MODERATE COLD AIR
ADVECTION.

TUESDAY THROUGH FRIDAY...RELATIVELY HIGH CONFIDENCE OF DRY CONDITIONS
THROUGH THIS PERIOD WITH MILD DAYS AND COOL NIGHTS. IT IS POSSIBLE
THAT RADIATIONAL COOLING DURING TUESDAY NIGHT AND/OR WEDNESDAY
NIGHT COULD BE ROBUST ENOUGH FOR SOME PATCHY FROST SOUTHWEST NH
AND NORTHWEST MA...BUT CONFIDENCE ON THIS IS QUITE LOW THIS FAR
OUT. OTHERWISE...EXPECT THE MAIN STORY IS THAT WE WILL BE
INCREASING A PRECIPITATION DEFICIT FOR MUCH OF AREA NEXT WEEK.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH SATURDAY NIGHT/...HIGH CONFIDENCE.

THROUGH 00Z...VFR. ANY LEFTOVER CLOUDS AT 3-4KFT ACROSS S COASTAL
MA/E RI WILL DISSIPATE BY EARLY EVENING.

TONIGHT...MAINLY VFR...EXCEPT FOR PATCHY FOG AFTER MIDNIGHT ACROSS
INTERIOR AREAS WITH LOCAL MVFR-IFR CONDITIONS POSSIBLE.

SATURDAY AND SATURDAY NIGHT...EXPECT MAINLY VFR CONDITIONS
THROUGH THE PERIOD. ANY LEFTOVER PATCHY FOG SHOULD DISSIPATE BY
14Z AT THE TYPICAL TERMINALS. WINDS OUT OF THE S-SW ON SAT...WITH
AFTERNOON GUSTS TO 20 KT POSSIBLE.

KBOS TERMINAL...HIGH CONFIDENCE IN TAF.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF.

OUTLOOK...SUNDAY THROUGH TUESDAY...

HIGH CONFIDENCE THROUGH THE PERIOD...EXCEPT MODERATE CONFIDENCE
SUNDAY AFTERNOON AND NIGHT.

SUNDAY...VFR EXPECTED...EXCEPT MVFR CIGS/VSBYS IN VICINITY OF
SCATTERED SHOWERS/THUNDERSTORMS NW OF A MHT-ORH-BDL LINE SUNDAY
AFTERNOON. A SECOND AREA OF MVFR CIGS/VSBYS MAY DEVELOP SUNDAY
AFTERNOON ALONG AND S OF A BID-HYA-CQX LINE IN AREAS OF SHOWERS.

SUNDAY NIGHT...MVFR CIGS/VSBYS POSSIBLE IN SHOWERS ACROSS THE
REGION.

MONDAY THROUGH TUESDAY...VFR CONDITIONS EXPECTED.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH SATURDAY NIGHT/...HIGH CONFIDENCE.

THROUGH 00Z...CONDITIONS ACROSS MOST OF THE WATERS HAVE SUBSIDED
SO WHERE SMALL CRAFTS WERE STILL IN EFFECT HAVE BEEN DROPPED. KEPT
SMALL CRAFTS GOING FOR OUTER WATERS S AND E OF CAPE COD AND
NANTUCKET INTO THIS EVENING FOR LEFTOVER 5 FOOT SEAS.

TONIGHT...EXPECT WINDS TO DIMINISH SOMEWHAT AS THEY VEER TO E-SE
DURING THE NIGHT.

SATURDAY...S-SW WIND FLOW TAKES OVERNIGHT. MAY SEE SOME GUSTS
CLOSE TO SMALL CRAFT CRITERIA...SOMETHING TO MONITOR. SEAS SHOULD
REMAIN BELOW 5 FT.

SATURDAY NIGHT...MAINLY S WINDS IN PLACE. GUSTS UP TO 25 KT MAY
LINGER EARLY ON THE EASTERN OUTER WATERS. HOWEVER...SEAS MAY REACH
5 FT ON THE OUTER WATERS OVERNIGHT.

OUTLOOK...SUNDAY THROUGH TUESDAY...MODERATE CONFIDENCE.

SUNDAY...HIGH CONFIDENCE OF WINDS AND SEAS BELOW SMALL CRAFT
ADVISORY LEVELS EXCEPT POSSIBLE BUILDING SWELL OVER THE SOUTHERN
COASTAL WATERS LATE SUNDAY.

SUNDAY NIGHT INTO MONDAY...MODERATE CONFIDENCE. MAY SEE SEAS
BUILDING TO SMALL CRAFT ADVISORY LEVELS ACROSS AT LEAST THE OUTER
WATERS SUNDAY NIGHT AND PERSISTING INTO MONDAY. IN ADDITION...MAY
HAVE A PERIOD OF SMALL CRAFT ADVISORY GUSTS FROM THE NW DURING THE
DAY MONDAY. LOW PRESSURE CENTER PASSING SE OF NANTUCKET MAY HAVE
VERY SIGNIFICANT WINDS AND SEAS ON ITS EAST SIDE...BUT PROBABLY
WELL OFFSHORE OF OUR COASTAL WATERS.

TUESDAY...MODERATE TO HIGH CONFIDENCE OF WINDS AND SEAS BELOW SMALL
CRAFT ADVISORY LEVELS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ254-
     255.

&&

$$
SYNOPSIS...BELK/EVT
NEAR TERM...EVT
SHORT TERM...EVT
LONG TERM...BELK
AVIATION...BELK/EVT
MARINE...BELK/EVT


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