Area Forecast Discussion
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000
FXUS61 KBOX 201057
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
657 AM EDT SAT SEP 20 2014

.SYNOPSIS...
MILDER TEMPERATURES RETURN TODAY AND TOMORROW. HOWEVER A FEW
SHOWERS ARE POSSIBLE LATE TONIGHT AND EARLY SUNDAY AS WELL. A
COLD FRONT CROSSES NEW ENGLAND SUNDAY NIGHT...WHILE LOW PRESSURE
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. MILD TEMPS LINGER MONDAY BUT
THEN BECOME COOLER THAN NORMAL THEREAFTER BEFORE MODERATING LATE
NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

7 AM UPDATE...

NO MAJOR CHANGES FROM PREVIOUS FORECAST. QUITE A CONTRAST IN TEMPS
THIS MORNING...WHERE WINDS HAVE DECOUPLED TEMPS ARE IN THE 30S.
MEANWHILE THE HIGHER TERRAIN /ORH 46/...URBAN AREAS /BOS 47/ AND
COASTAL SITES /BID 55/ ARE CONSIDERABLE WARMER GIVEN S-SE WIND.
ITS MOSTLY CLEAR OVER RI AND EASTERN MA WITH PARTLY TO MOSTLY
CLOUDY SKIES ACROSS CT/WESTERN-CENTRAL MA INTO SOUTHWEST NH. AS
OFFSHORE HIGH RETREATS SEAWARD RETURN FLOW WILL BECOME ESTABLISHED
AND INCREASING SSW WINDS WILL ERODE SLOWLY COOL LAYER. PREVIOUS
FORECAST CAPTURES THESE DETAILS...THUS NO MAJOR CHANGES. EARLIER
DISCUSSION BELOW.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

OTHER THAN SOME LOW CLOUDS WHICH IS SPILLING INTO CT AND SW MA
THIS MORNING...THE CLEAR SKIES AND CALM WINDS HAVE LEAD TO A FEW
SPOTS OF LOW 30S AT THE TYPICALLY COOLER OBS SITES. ITS LIKELY
THAT ONLY MAYBE A DEGREE OR SO OF ADDITIONAL COOLING IS LEFT...AS
THIS INCREASE IN CLOUD COVER IS MARKING AN INCREASE IN LOW LVL
DWPTS AS MOISTURE STREAMS AHEAD TWO SYSTEMS WHICH WILL EFFECT THE
REGION LATE TONIGHT INTO TOMORROW.

ALONG WITH WITH THIS MOISTURE FLUX...MODEST WARM ADVECTION IS
EXPECTED TO DEVELOP WITH RETURN FLOW AS HIGH PRES SLIDES FURTHER
TO THE E TODAY. H85 TEMPS START THE DAY MAINLY AROUND +6C BUT END
CLOSE TO +12C. THEREFORE...TEMPS WILL BE WARMER TODAY THAN
YESTERDAY BY A FACTOR AROUND 10F. OUTSIDE OF THE EARLY MORNING
LOW CLOUDS DISSIPATING...MAINLY JUST AN INCREASE IN HIGH CLOUDS
EXPECTED THROUGH THE DAY. THEREFORE...THANKS TO FULL AFTERNOON
MIXING EXPECT HIGHS WILL RETURN CLOSE TO SEASONAL NORMALS. MAINLY
IN THE UPPER 60S AND LOW 70S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
TRICKY FORECAST FOR TONIGHT. GUIDANCE CONTINUES TO REALLY STRUGGLE
WITH A WEAK AREA OF CONVECTION ASSOCIATED WITH TROPICAL MOISTURE
CURRENTLY SITTING OFF OF THE SE COAST. WHILE THE INCOMING AND
DEEPENING TROF TO THE W IS LIKELY TO KICK THIS WAVE TO THE N...THE
SPEED AND EXACT TRAJECTORY REMAIN IN QUESTION DUE TO AN OVERALL
LACK OF BAROCLINICITY TO WORK WITH. 12Z GUIDANCE KEPT THE FINAL
UPPER LVL JET STREAK AND SFC WAVE MAINLY E OF THE 40/70 BENCHMARK
WHILE 00Z RUNS HAVE NOW BROUGHT IT INSIDE BY 12Z. IN ANY
CASE...EXPECT INCREASING MOISTURE TONIGHT AS PWATS APPROACH 1.5
INCHES BY THE EARLY MORNING HOURS /ABOUT 1-2 STD DEVIATIONS ABOVE
NORMAL/. WHILE THE BULK OF THE DYNAMIC FORCING AND INSTABILITY
REMAIN TO THE...DO NOTICE AS AN INVERTED TROF EXTENDS INTO SRN NEW
ENGLAND AFTER 06Z...THAT A POCKET OF MODEST INSTABILITY FOLLOWS.
MU CAPE VALUES OF ABOUT 500-1000J/KG ABOVE THE NEAR SFC WARM
LAYER. THIS IS COLOCATED WITH THE HIGHER PWATS AND K-VALUES NEAR
30...SO IT IS POSSIBLE THAT MODEST CONVECTION /SHOWERS AND A
POSSIBLE T-STORM/ SPILLS ACROSS MAINLY THE SRN TIER OF SRN NEW
ENGLAND THROUGH THE MORNING HOURS /PARTICULARLY ABOUT 09Z-15Z/.
THE HIGHER PWATS SUGGEST A POCKET OF HEAVY RAIN CAN/T BE RULED
OUT. WILL CONTINUE TO HIGHLIGHT CHANCE POPS FROM SRN CT-RI-SE MA
WITH SLIGHT CHANCE POPS FURTHER N UNTIL THIS CAN BE BETTER
RESOLVED. THANKFULLY SHEAR IS MODEST AND STRONGER ASSOCIATED WITH
A COLD FRONT WELL TO THE NW OF NEW ENGLAND...BUT THIS WILL NEED TO
BE WATCHED. THERE ARE A COUPLE OF MITIGATING FACTORS TO
NOTE...HENCE THE CHANCE AND SLIGHT CHANCE POPS...ONGOING
CONVECTION OFFSHORE WHERE UPPER LVL AND LOW LVL JET IS STRONGER
COULD USURP INSTABILITY AND MOISTURE AWAY FROM SRN NEW ENGLAND.
ALSO...SUSPECT AN AREA OF SUBSIDENCE WILL RESIDE ACROSS THE REGION
IN BETWEEN THE NRN SYSTEM AND THIS WEAKER OFFSHORE WAVE. MODELS DO
REFLECT THIS AS A DRY LAYER FROM ABOUT H6 AND UP.

SUN...
THREAT FOR MODEST CONVECTION LINGERS INTO TO ABOUT MID DAY AS THE
OFFSHORE WAVE MAKES ITS CLOSEST PASS. HOWEVER...SUSPECT THAT A
PERIOD OF MAINLY DRY CONDITIONS MAY PREVAIL AS THE SYSTEM MOVES
OFFSHORE AND A DRY SLOT WITH SUBSIDENCE DEVELOPS ACROSS THE AREA
DURING THE AFTERNOON AND EARLY EVENING. THIS AREA OF SUBSIDENCE IS
THE RESULT OF THE OFFSHORE STORM SYSTEM AND A SLOW APPROACHING
COLD FRONT TO THE W...ALONG WHICH IS LIKELY TO BE SOME AFTERNOON
AND EVENING CONVECTION. AT THIS TIME...INSTABILITY LOOKS MODEST AT
BEST DESPITE THE INCREASE IN SFC DWPTS. BREAKS OF SUN ARE
POSSIBLE...WHICH MAY HAVE TO BE WATCHED...BUT AT THIS TIME...AT
LEAST THROUGH 00Z MON...SUSPECT THE SHOWERS AND THUNDERSTORMS
REMAIN MOSTLY TO THE W. HIGH TEMPS IN THE MID-UPPER 70S ARE
EXPECTED...ALTHOUGH A FEW SPOTS MAY REACH AROUND THE 80F MARK
ESPECIALLY IF SOME BREAKS OF SUN ARE OBSERVED.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HIGHLIGHTS...

* LOW RISK OF SHOWERS SUN NIGHT THEN DRY MUCH OF NEXT WEEK
* MILD SUN NIGHT/MON THEN COOLER THAN NORMAL MIDWEEK BEFORE
  MODERATING LATE NEXT WEEK

     SYNOPTIC OVERVIEW AND GUIDANCE EVALUATION...

00Z DETERMINISTIC AND ENSEMBLE GUIDANCE ARE IN GOOD AGREEMENT ON THE
LARGE SCALE FLOW WHICH FEATURES A HIGH AMPLITUDE TROUGH MOVING
ACROSS THE NORTHEAST SUN NIGHT AND MON...THEN SLOWLY LIFTING OUT
INTO THE MARITIMES THE MIDDLE OF NEXT WEEK.  THIS WILL YIELD A LOW
RISK OF SHOWERS SUN NIGHT FOLLOWED BY COOLER WEATHER MON NIGHT INTO
THE MIDDLE OF NEXT WEEK. HEIGHT RISES LOOK TO BE A GOOD BET AS
SUBTROPICAL RIDGE BUILDS INTO THE REGION LATE NEXT WEEK. PRECISE
TEMPS WILL BE DIFFICULT AT THIS TIME RANGE AS ALL MODEL GUIDANCE
INDICATES SOME WEAKNESSES WITHIN THE NORTHEASTERN PERIPHERY OF THE
SUBTROPICAL RIDGE WITHIN THE NORTHEAST STATES.

SUN NIGHT...TRAILING NORTHERN STREAM SHORT WAVE AND ATTENDING
SURFACE COLD FRONT SWEEP ACROSS THE REGION. MODEST QG FORCING AND
DEEP LAYER MOISTURE ACCOMPANY THE TROUGH AND SURFACE FRONT. THUS
EXPECT SCT SHOWERS WITH HIGHEST PROBS NORTHWEST MA INTO SOUTHWEST
NH. IT WILL REMAIN MILD GIVEN FROPA NOT UNTIL AFTER DAYBREAK MONDAY.

MONDAY...ANY LINGERING SHOWERS ASSOCIATED WITH THE FRONT WILL CLEAR
CAPE COD EARLY IN THE MORNING. THEREAFTER EXPECTING A MIX OF SUN AND
CLOUDS ALONG WITH A WELL MIXED BLYR AS WEST WINDS GUST UP TO 25 MPH.
HIGHS SHOULD CLIMB WELL INTO 70S INCLUDING CAPE COD AND THE ISLANDS
AS WIND DIRECTION WILL BE WESTERLY.

TUESDAY THROUGH THURSDAY...1035 MB HIGH CREST OVER NEW ENGLAND THIS
PERIOD BRINGING MILD DAYS BUT COOL NIGHTS. LEANED TOWARD THE COOLER
MAVMOS DURING THE NIGHTS. DRY WEATHER PREVAILS ALONG WITH LIGHT
WINDS.

FRIDAY...SUBTROPICAL RIDGE BUILDS NORTHWARD ALONG WITH MODERATING
TEMPS. DIFFICULT TO SAY HOW WARM GIVEN SOME GUIDANCE SUGGEST A
WEAKNESS WITHIN THE RIDGE.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH SUNDAY/...

7 AM UPDATE...

NO MAJOR CHANGES TO 06Z TAFS. EARLIER DISCUSSION BELOW.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

THROUGH TODAY...HIGH CONFIDENCE.
MAINLY VFR OUTSIDE OF SOME LOCALIZED FOR AT TYPICALLY PRONE
TERMINALS THIS MORNING. WINDS S-SW WITH A FEW GUSTS TO AROUND 20
KT TODAY.

TONIGHT...MODERATE CONFIDENCE.
VFR TO START...BUT SOME TERMINALS SEE MVFR CIGS AND POSSIBLY IFR
VSBYS IN SOME LOW CLOUDS AND FOG ESPECIALLY AFTER 04Z. BEST CHANCE
LOOKS TO BE CT AND W MA TERMINALS...BUT SOME LOWER CATEGORIES
FURTHER E NOT OUT OF THE QUESTION. LATE NIGHT SHOWER OR POSSIBLY
EVEN AN ISOLATED T-STORM POSSIBLE MAINLY SRN CT/RI AND SE MA.

SUN...
MVFR/VFR START GIVES WAY TO MAINLY VFR DURING THE AFTERNOON AND
EARLY EVENING. ISOLATED -SHRA POSSIBLE.

KBOS TERMINAL...HIGH CONFIDENCE IN TAF.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF THROUGH TODAY...LOWER
CONFIDENCE IN TIMING OF MVFR POSSIBLE LATE TONIGHT/EARLY SUN
MORNING.

OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...

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

VFR THRU THE PERIOD. THE ONLY EXCEPTION WILL BE SUNDAY NIGHT WHEN
POSSIBLE MVFR MAY ACCOMPANY SCT SHOWERS. MODEST W WIND MON 15-20 KT.
OTHERWISE FAIRLY LIGHT WINDS AND DRY WEATHER PREVAILS.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH SATURDAY NIGHT/...

TODAY...HIGH CONFIDENCE.
S-SW WINDS DEVELOP THROUGH THE DAY TODAY. WIND GUSTS MAY APPROACH
25 KT AT TIMES ALONG THE NRN TIER OF WATERS AGAINST THE GULF OF
MAINE...BUT MOST GUSTS SHOULD REMAIN BELOW. SEAS MAINLY 4 FT OR
LESS.

TONIGHT...MODERATE CONFIDENCE.
S WIND CONTINUE...BUT DIMINISH SOMEWHAT OVERNIGHT TONIGHT.
CONDITIONS REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS ALONG WITH
SEAS. SOME SHOWERS AND EVEN A POSSIBLE T-STORM OVER THE SE WATERS
AFTER 04Z ALONG WITH THE POTENTIAL FOR FOG AND REDUCED VSBYS.

SUN...MODERATE CONFIDENCE.
WINDS REMAIN S AND EVEN SHIFT TO THE SE THROUGH THE DAY. WHILE
WIND GUSTS GENERALLY REMAIN BELOW SMALL CRAFT THRESHOLDS...NOT OUT
OF THE QUESTION SEAS REACH THE 5 FT MARK ON THE SRN OCEAN WATERS
BY LATE IN THE DAY. OTHERWISE...BULK OF THE SHOWERS AND
THUNDERSTORMS SHOULD SHIFT OFFSHORE THROUGH THE MORNING HOURS.

OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...

MODEST W WIND MON INTO TUE THEN LIGHT WINDS AS HIGH PRES CREST OVER
THE AREA TUE NIGHT AND BEYOND.

&&

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

&&

$$
SYNOPSIS...NOCERA/DOODY
NEAR TERM...DOODY
SHORT TERM...DOODY
LONG TERM...NOCERA
AVIATION...NOCERA/DOODY
MARINE...NOCERA/DOODY


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