Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 210924
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
424 AM EST FRI NOV 21 2014

.SYNOPSIS...
BLUSTERY AND UNSEASONABLY COLD CONDITIONS TODAY. TEMPERATURES
MODERATE SATURDAY WITH GUSTY SOUTHWEST WINDS...THEN A SIGNIFICANT
WARM-UP IS IN STORE SUNDAY AND MONDAY...BUT IT WILL LIKELY BE
ACCOMPANIED BY A PERIOD OF RAIN. A COASTAL STORM MAY AFFECT THE
REGION SOMETIME DURING THE MIDDLE OF NEXT WEEK BUT IT IS UNCERTAIN
HOW CLOSE IT WILL TRACK TO NEW ENGLAND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MID LEVEL TROF AND CORE OF COLD AIR ALOFT MOVES INTO NEW ENG
TODAY BUT COLUMN IS VERY DRY SO EXPECT MOSUNNY SKIES. UNSEASONABLY
COLD CONDITIONS AS 850 MB TEMPS -13/14C WHICH TRANSLATES TO MAXES
UPPER 20S NW HIGHER TERRAIN TO MID 30S COASTAL PLAIN. WIND WILL BE
A FACTOR AS PRESSURE GRADIENT AND GOOD MIXING SUPPORTS NW WIND
GUSTS TO 25-30 MPH WHICH WILL MAKE IT FEEL CONSIDERABLY COLDER IN
THE TEENS AND 20S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
TONIGHT...
CENTER OF HIGH PRES MOVES TO THE MID ATLC COAST BUT RIDGE AXIS
BUILDS INTO NEW ENG WHICH WILL RESULT IN CLEAR SKIES AND
DIMINISHING WIND AS PRESSURE GRADIENT RELAXES. GIVEN VERY DRY
AIRMASS IT WILL BE A COLD NIGHT AS DECENT RADIATIONAL COOLING
DEVELOPS. MINS WILL BE MOSTLY IN THE TEENS...EXCEPT LOWER 20S
ALONG THE IMMEDIATE COAST. LOW PROB FOR SOME SINGLE NUMBER MIN
TEMPS W MA AND SW NH.

SATURDAY...
HIGH PRES BUILDS S OF NEW ENG WITH SUNSHINE GIVING WAY TO
INCREASING AFTERNOON CLOUDS AS LOW AND MID LEVEL MOISTURE
INCREASES FROM THE WEST. INCREASING SW FLOW BRINGS MILDER AIR
INTO SNE AS PRONOUNCED LOW AND MID LEVEL WARMING OCCURS. AFTER A
RATHER COLD START...TEMPS WILL RECOVER INTO THE MID 30S TO LOWER
40S. 40 KT LOW LEVEL JET DEVELOPS BY LATE DAY WHICH WILL LEAD TO
GUSTY SW WINDS IN THE AFTERNOON/EVENING...ESPECIALLY NEAR THE
COAST WHERE BETTER LOW LEVEL LAPSE RATES.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
OVERVIEW AND MODEL PREFERENCES...
WITH THE ECMWF AND GFS OPERATIONAL RUNS CONTINUING TO SHOW
MODERATE AGREEMENT THROUGH THE MID TERM...A GENERAL BLEND WILL BE
USED AS A BASELINE. ITS NOT UNTIL LATER ABOUT MID WEEK THAT THE
STRONGEST DIVERGENCE IN MODEL SOLUTIONS EVEN AMONG
ENSEMBLES/MEANS...SO CONFIDENCE THROUGH MON-TUE REMAINS RELATIVELY
HIGH WHILE CONFIDENCE BECOMES LOW FROM MID NEXT WEEK THROUGH THE
THANKSGIVING HOLIDAY PERIOD.

THE ISSUE IS LIKELY THE SHIFTING PATTERN THROUGH THE
PERIOD...STARTING WITH BUILDING RIDGE SUN-MON AS PHASING NORTHERN
AND SOUTHERN STREAM WAVES DEVELOP INTO OCCLUDING SYSTEM AROUND THE
GREAT LAKES. THIS DEVELOPING TROF IS THEN EXPECTED TO GRADUALLY
DEEPEN AND DIG INTO A SLOWER LONGWAVE TROF TO THE
W...SIMILAR...THOUGH NOT AS COLD AS THIS WEEK/S DEEP TROUGH BUT
WITH THE AXIS FURTHER TO THE W. THEREFORE...TIME-MEAN JET REMAINS
SOUTHWESTERLY AND WARMING UNTIL THE CORE CAN SLIDE TO THE E LATER
IN THE WEEK. AGREE WITH THE PREVIOUS FORECASTER...THAT THIS
SUGGEST THE NEAR NORMAL TO WARM WEATHER CONTINUES UNTIL A COOLING
TREND OCCURS LATER IN THE WEEK.

DETAILS...

SAT NIGHT INTO SUN EVENING...
SFC WARM FRONT WILL BE NOSING IN FROM THE W WHILE SHIFTING TO THE
N WITH TIME TOWARD 12Z SUN. NOTE MODEST MID LVL ISENTROPIC LIFT
WITH SOME MOISTURE SUGGESTING LOW END CHANCE FOR LIGHT PRECIP
ESPECIALLY N OF THE MA PIKE AND W OF I-495. TIMING WILL BE THE KEY
HERE...AGREE WITH PREVIOUS FORECASTER THAT IF THE CLOUDS BUILD IN
TOO QUICKLY TEMPS MAY REMAIN NEAR OR ABOVE FREEZING WHILE
ALLOWANCE FOR MORE COOLING SUGGESTS THAT SFC TEMPS MAY BE A FEW
DEGREES BELOW FREEZING. THEREFORE...MAY HAVE TO MONITOR FOR LIGHT
FREEZING RAIN...IF THE TEMPS FALL BACK INTO THE MID-UPPER 20S
LIGHT ICING IS NOT OUT OF THE QUESTION...BUT AGAIN TOTAL RAINFALL
WOULD BE LIGHT AND TEMPS MAY PRECLUDE ANY IMPACTS. WILL NEED TO
WATCH THIS AS WE APPROACH. OTHERWISE SUN...WARMING EXPECTED WITH
AREAS REACHING THE MID 40S TO LOW 50S BY LATE IN THE DAY IN SPITE
OF INCREASING CLOUDS. DWPTS ALSO RISE AS WELL.

SUN NIGHT INTO MON...
OCCLUDING LOW PRES TO THE W WILL PUSH 60-65 KT LLJ THROUGH THE
REGION DURING THE EARLY MORNING HOURS MON. THIS WILL BE
COINCIDENT WITH 1.0 INCH PWATS /ABOUT 2 STD DEVIATIONS FROM
NORMAL/. THEREFORE...EXPECT SOME WIDESPREAD RAINFALL WITH MODEST
CONVECTIVE ELEMENTS AS K VALUES HOVER AROUND 30...SUGGESTING HEAVY
RAIN. THIS COULD ALSO YIELD SOME STRONG WINDS AND POSSIBLY EVEN A
FINE-LINE DEVELOPMENT WHICH WILL NEED TO BE WATCHED. OVERALL
RAINFALL VALUES OF 0.5-1.0 INCHES EXPECTED...WITH HIGHER AMOUNTS
POSSIBLE. AFTER A LULL THE THREAT FOR SHOWERS CONTINUES INTO MON
EVENING AS THE UPPER LVL SHORTWAVE PIVOTS THROUGH. MILD WX
CONTINUES AS HIGHS COULD APPROACH THE UPPER 50S TO NEAR 60F.

TUE...
HIGH PRES BUILDS IN BRIEFLY FOR TUE. WARM TEMPS STILL EXPECTED AS
THE CORE OF THE COLD AIR REMAINS TO THE W. EXPECT HIGHS RANGING
FROM THE UPPER 40S TO UPPER 50S.

WED-WED NIGHT...
STILL UNCERTAINTY HERE...BUT WITH STALLED FRONTAL BOUNDARY TO THE
SOUTHEAST...A DEVELOPING WAVE OF LOW PRES MAY PASS JUST CLOSE
ENOUGH THE 40/70 BENCHMARK TO INITIATE TROWAL BASED PRECIP ACROSS
PORTIONS OF SRN NEW ENGLAND. REGARDING THERMAL PROFILES...WHICH
ARE LIKELY TO CHANGE GIVEN BOTH OPERATIONAL AND ENSEMBLE MEMBERS
ARE ONLY RECENTLY CONVERGING ON THIS...TEMPS APPROACHING -6C TO
-10C AT H85 SUGGEST THE POSSIBILITY OF WINTERY PRECIP IN THE
INTERIOR...BUT MAY BE TOO WARM ALONG THE COAST. STILL TOO
UNCERTAIN HERE TO MAKE ANY CALLS...BUT WORTH WATCHING GIVEN THE
POTENTIAL TRAVEL IMPLICATIONS.

THU-FRI...
DEPENDENT ON THE FINAL TIMING TRACK OF THE OFFSHORE SYSTEM...HIGH
PRES WOULD FOLLOW FOR THE LATE WEEK PERIOD...WITH COLDER DRIER AIR
BUILDING IN FROM THE NW.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM...HIGH CONFIDENCE.

TODAY...VFR. GUSTY NW WINDS TO 25 KT.

TONIGHT...VFR WITH DIMINISHING WIND.

SATURDAY...VFR. INCREASING SW WINDS IN THE AFTERNOON WITH GUSTS TO
25-30 KT DEVELOPING IN THE COASTAL PLAIN.

KBOS TERMINAL...HIGH CONFIDENCE.

KBDL TERMINAL...HIGH CONFIDENCE.

OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY...

SATURDAY NIGHT...MODERATE CONFIDENCE.
CLOUDS MOVE IN AT NIGHT...BRIEF MVFR POSSIBLE OVERNIGHT IN LIGHT
SPRINKLES ESPECIALLY NORTH OF THE MASS PIKE. COULD BE LIGHT
FREEZING DRIZZLE/FREEZING SPRINKLES NORTH AND WEST OF I-495.

SUNDAY...HIGH CONFIDENCE.
VFR. DIMINISHING WIND.

SUNDAY NIGHT-MONDAY...CIGS/VSBYS LOWER TO MVFR/IFR IN RAIN/FOG.
SOUTH WIND AT 2000 FEET INCREASES TO 60-65 KNOTS ALONG THE COASTAL
PLAIN LATE NIGHT AND MONDAY MORNING AND MAY GENERATE ANOTHER ROUND
OF LOW LEVEL WIND SHEAR IN THAT AREA. CONDITIONS THEN IMPROVE TO VFR
IN THE AFTERNOON WITH GUSTY SOUTHWEST WINDS.

A COLD FRONT MOVES INTO SOUTHERN NEW ENGLAND AT NIGHT AND SHOULD
GENERATE BRIEF MVFR IN SHOWERS. WIND WILL SHIFT FROM SSW TO WSW WITH
THE WIND SHIFT.

TUESDAY...VFR. A FEW BRIEF SHOWERS POSSIBLE IN EASTERN MASS/RI

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

HIGH FORECAST CONFIDENCE THRU SATURDAY.

TODAY...WE CONVERTED GALE WARNINGS TO SMALL CRAFT ADVISORIES FOR
ALL WATERS. EXPECT WIND GUSTS TODAY WILL FALL JUST SHY OF GALES
WITH NW GUSTS TO 30 KT.

TONIGHT...WINDS GRADUALLY DIMINISH WITH SPEEDS DROPPING BELOW 20
KT LATE TONIGHT.

SATURDAY...EXPECT INCREASING SW WINDS IN THE AFTERNOON AS DECENT
LOW LEVEL JET DEVELOPS ACROSS THE REGION. GIVEN STILL WARM SST...
GOOD MIXING OVER WATER SUPPORTS WIND GUSTS TO 30 KT WITH MARGINAL
GALES POSSIBLE BY EVENING.

OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY...

SAT NIGHT...SOUTHWEST WINDS CONTINUE TO GUST TO 35 KNOTS DURING
THE DAY AND THEN DIMINISH IN THE EVENING. SEAS 5-8 FEET WILL
DIMINISH IN THE EVENING.

SUNDAY-MONDAY...A WARM FRONT MOVES UP ACROSS THE WATERS. VSBYS
WILL LOWER TO 1-3 MILES IN RAIN AND FOG STARTING AROUND MIDNIGHT
CONTINUING INTO THE MORNING. STRONG SOUTH WINDS...ROUGHLY 60-65
KNOTS...AT 2000 FEET ALTITUDE WILL MOVE OVER THE WATERS AFTER
MIDNIGHT AND THROUGH MONDAY MORNING. SOME OF THIS WIND MAY BE
DRAWN TO THE SURFACE IN HEAVIER BURSTS OF RAIN. AT THE
LEAST...SOUTH WINDS WILL BE ON THE HIGH END OF SMALL CRAFT
ADVISORY THRESHOLDS AT OR NEAR GALE. THIS WILL DRIVE SEAS TO 5-10
FEET ON THE EXPOSED WATERS.

TUESDAY...SOUTHWEST WINDS WILL GUST NEAR SMALL CRAFT THRESHOLDS.
SEAS WILL SLOWLY DIMINISH BUT REMAIN ABOVE 5 FEET ON THE EXPOSED
WATERS.  SMALL CRAFT ADVISORY WILL BE NEEDED.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST SATURDAY FOR ANZ230-
     232>237.
     SMALL CRAFT ADVISORY UNTIL 3 AM EST SATURDAY FOR ANZ231-251-
     255-256.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST SATURDAY FOR ANZ250-254.

&&

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


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