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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 091417
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1017 AM EDT SUN MAR 9 2014

.SYNOPSIS...
HIGH PRESSURE BUILDS OVER NEW ENGLAND TODAY WITH FAIR SKIES AND
COOLER TEMPERATURES. EXPECT ANOTHER FRONTAL BOUNDARY TO ENTER THE
REGION MONDAY ALONG WITH RISK OF LIGHT SNOW SHOWERS OR FLURRIES.
DRY AND MILDER WEATHER FOLLOWS BEHIND THE FRONT TUESDAY. A WINTER
STORM REMAINS POSSIBLE FROM WEDNESDAY INTO THURSDAY...BUT AT THIS
TIME THERE IS LOW CONFIDENCE IN ANY DETAILS. COLD DRIER WEATHER
RETURNS THURSDAY NIGHT THROUGH SATURDAY.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...

-- Changed Discussion --
10 AM UPDATE...

LATEST WATER VAPOR SATELLITE IMAGERY CLEARLY SHOWS MID/UPPER LEVEL
TROUGH-PV ANOMALY MOVING ACROSS EASTERN NEW ENGLAND. MODELS
INDICATE STRONG SYNOPTIC SCALE SUBSIDENCE BEHIND THIS FEATURE.
THIS WILL KEEP THE COLUMN MAINLY DRY TODAY. THUS EXPECTING MOSTLY
SUNNY SKIES. ALTHOUGH IT WILL BE INEFFECTIVE SUNSHINE AS STRONG
COLD AIR ADVECTION /-12C 850MB TEMPS/ WILL OFFSET THE STRONG MARCH
SUN. 12Z UPSTREAM OBSERVED SOUNDING AT ALY HAS -10C AIR AT THE TOP
/900 MB/ OF THE BOUNDARY LAYER. THIS COMBINED WITH DOWNSLOPE NW
WINDS WILL SUPPORT HIGHS ONLY IN THE 30S TODAY. PREVIOUS FORECAST
CAPTURES THIS NICELY SO NO WHOLESALE CHANGES EXPECTED TO TEMPS.
BRISK NW WINDS 15-20 MPH WILL ADD TO THE CHILLY CONDITIONS TODAY.
-- End Changed Discussion --

&&

.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM MONDAY/...

TONIGHT INTO MONDAY...
ANOTHER UPPER LEVEL SYSTEM WILL FILTER THROUGH THE NORTHWEST FLOW
VERY LATE TONIGHT AND INTO TOMORROW. MODEL CROSS SECTIONS SHOW
MORE MOISTURE ASSOCIATED WITH THIS SYSTEM ALLOWING FOR DEEP
SATURATION THROUGH THE MOISTURE PROFILE. ALSO THERE IS A SOURCE OF
LIFT WITHIN THE SNOW GROW REGION SO THE CONFIDENCE FOR SCATTERED
SNOW SHOWERS IS HIGHER THEN LAST NIGHTS POTENTIAL. SNOW SHOULD
START DURING THE EARLY MORNING HOURS AND SLOWLY INCREASE INTO THE
MORNING COMMUTE. ALTHOUGH SNOW ACCUMULATIONS WILL BE LIGHT...AND
INCH OR LESS...THE TIMING IS NOT FAVORABLE. LOCATIONS ACROSS THE
HIGHER TERRAIN MAY SEE HIGHER AMOUNTS...CLOSER TO TWO INCHES. SNOW
SHOULD COME TO AN END BY THE NOON TIMEFRAME KEEPING THE EVENING
COMMUTE PRECIP FREE.

TEMPERATURES OVERNIGHT WILL BE SLOW TO FALL AS CLOUDS WILL LIMIT
RADIATIONAL COOLING. EXPECT TEMPS TO RANGE IN THE UPPER TEENS TO MID
20S. ON MONDAY AS THE SYSTEM PASSES...CLOUD COVER WILL CLEAR OUT AND
WEAK WAA BEGINS TO MOVE INTO THE AREA. THIS MAY ALLOW FOR TEMPS
TO REACH BACK TO AVERAGE....UPPER 30S TO LOW 40S.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
BIG PICTURE... UPPER LOW HOVERS OVER NORTHERN QUEBEC WHILE UPPER
RIDGE BUILDS INTO THE PACIFIC COAST. TWO SHORTWAVES OF NOTE. ONE
ROUNDS THE UPPER LOW AND MOVES SOUTH THROUGH THE CANADIAN
PRAIRIES...THE SECOND MOVES INLAND AHEAD OF THE WEST COAST RIDGE.
THESE PHASE AND DIG OVER THE CENTRAL PLAINS LATER TUESDAY AND OVER
THE EASTERN USA WEDNESDAY-THURSDAY.  THE PHASED TROUGH MOVES OFF
THROUGH THE MARITIMES FRIDAY...ONLY TO BE FOLLOWED BY ANOTHER
SHORTWAVE DIPPING SOUTHEAST FROM CANADA AT THE END OF THE WEEK.

MODEL PREFERENCES... WITH THE VARIATIONS IN INDIVIDUAL MODEL
SOLUTIONS REGARDING THE MIDWEEK COASTAL STORM...WE ARE FAVORING A
BLEND OF DATA.

THE DAILIES...

MONDAY NIGHT-TUESDAY... SHORTWAVE MOVES ACROSS NEARBY CANADA AND FAR
NORTHERN NEW ENGLAND.  THIS SUPPORTS A SURFACE LOW PRESSURE AREA AND
TRAILING COLD FRONT. THE LOW PULLS A COLD FRONT ACROSS NEW ENGLAND
EARLY TUESDAY.  THE UPPER JET WITH THIS SYSTEM ACTUALLY CROSSES
SOUTHERN NEW ENGLAND AND BRINGS FAVORABLE JET DYNAMICS. BUT MOISTURE
IS LIMITED SO EXPECT MOST SNOW/RAIN SHOWERS TO BE NORTH OF OUR
AREA...SCATTERED TO WIDELY SCATTERED SNOW SHOWERS NORTH OF THE MASS
PIKE. THE AIRMASS DRIES BEHIND THE COLD FRONT...BUT MILD AIR LINGERS
EVEN AFTER THE FRONTAL PASSAGE. THE RESULTING MIXING OF THESE TEMPS
ALOFT WOULD SUPPORT SFC MAX TEMPS OF 40S IN THE AFTERNOON.

HIGH PRESSURE BUILDS INTO THE REGION TUESDAY NIGHT WHILE THE COLD
FRONT STALLS SOUTH OF THE REGION.  FAIR WEATHER NIGHT WITH
INCREASING HIGH LEVEL CLOUDS AFTER MIDNIGHT.

WEDNESDAY-THURSDAY... WEAK HIGH PRESSURE MOVES OFFSHORE BY WEDNESDAY
MORNING. MODELS AGREE ON LOW PRESSURE DEVELOPS OVER THE CENTRAL
PLAINS TUESDAY AND TRAVELLING EAST ALONG THE STALLED FRONT TO THE
MID ATLANTIC COAST BY WEDNESDAY AFTERNOON OR EVENING. ALL MODELS
BRING THE TRACK OF THE LOW JUST SOUTH OF THE NEW ENGLAND COAST.  BUT
THERE ARE QUESTIONS ON TIMING.  THE GGEM IS FASTEST...BRINGING THE
LOW PAST NANTUCKET BY WEDNESDAY EVENING.  THE GFS IS ABOUT 4-6 HOURS
SLOWER...THE ECMWF ANOTHER 6 HOURS SLOWER WITH PASSAGE AT THE START
OF THURSDAY.

MODEL ISENTROPIC LIFT REACHES PA/NJ BY 12Z WEDNESDAY AND THEN SPREAD
NORTHEAST ACROSS NEW ENGLAND. THIS WOULD INDICATE A WEDNESDAY
MORNING START TIME. WE FORECAST INCREASING POPS AT THAT TIME.
TEMPERATURE FIELDS SUPPORT INITIAL RAIN SOUTH OF THE MASS PIKE AND
SNOW TO THE NORTH. EVENTUALLY TEMPS COOL DOWN AND ALLOW SNOW ALL
AREAS...WITH POTENTIAL FOR SEVERAL INCHES ACCUMULATION.  THE FASTEST
SOLUTION WOULD END PCPN BY THURSDAY MORNING...THE SLOWEST WOULD END
PCPN BY THURSDAY EVENING.

ONE COMPONENT...THE SHORTWAVE OVER THE NORTH PACIFIC...IS STILL FAR
FROM LAND AND WILL REMAIN SO FOR AT LEAST ANOTHER 24 HOURS.  SO
CONFIDENCE IN THE DETAILS OF THE STORM REMAIN LOW. BUT MODELS HAVE
BEEN CONSISTANT IN ADVERTISING STORMINESS FOR WEDNESDAY-
THURSDAY...SO CONFIDENCE IN POPS IS INCREASED FROM PREVIOUS
FORECASTS. WILL INDICATE HIGH-END LIKELY POPS DURING THE HEIGHT OF
THE STORM AND MAINTAINING CHANCE POPS THROUGH THURSDAY EVENING IN
RECOGNITION OF THE SLOWER ECMWF SOLUTION.

COLDER AIR IS DRAWN INTO NEW ENGLAND THURSDAY NIGHT AS THE UPPER
TROUGH AND COLD POOL MOVE OVERHEAD.  EXPECT A RETURN TO MUCH COLDER
THAN NORMAL TEMPS FOR THURSDAY NIGHT.

FRIDAY-SATURDAY... HIGH PRESSURE OVER THE REGION FRIDAY BUT WITH
COLD AIR ALOFT.  TEMPS AT 900 MB START THE DAY COLD BUT GET MILDER
BY AFTERNOON. A SHORTWAVE RACES ACROSS CANADA BRINGING INCREASING
CLOUDS ESPECIALLY TO OUR NORTHERN AREAS DURING THE AFTERNOON AND
NIGHT.  BEFORE ANY CLOUDS MOVE IN...TEMPS ALOFT WOULD SUPPORT MAX
TEMPS IN THE 30S. ON SATURDAY THE SHORTWAVE LINGERS OVER NEW ENGLAND
WITH COLDER TEMPS ALOFT DESTABILIZING THE AIRMASS.  EXPECT LOTS OF
CLOUDS AND SCATTERED SHOWERS.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

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

10 AM UPDATE...

NO CHANGES TO 12Z TAFS...VFR/DRY WEATHER ALONG WITH A MODEST NW
WIND 15-20 KT TODAY. EARLIER DISCUSSION BELOW.

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

TODAY...VFR/DRY WEATHER AND A MODEST NNW WIND. CLOUD SHIELD ALONG
THE SOUTH COAST OF MA AND RI SHOULD MOVE OFFSHORE THIS MORNING.

TONIGHT INTO MONDAY...VFR TO START BEFORE DROPPING TO MVFR FROM
NW TO SE DUE TO SCATTERED SNOW SHOWERS. LITTLE IF ANY
ACCUMULATION EXPECTED.

KBOS TERMINAL...HIGH CONFIDENCE IN TAF.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF.

OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...

MONDAY NIGHT-TUESDAY...MODERATE CONFIDENCE. VFR.

WEDNESDAY-THURSDAY...LOW CONFIDENCE. CONDITIONS LOWERING TO IFR IN
SNOW AND RAIN DURING WEDNESDAY...CONTINUING INTO AT LEAST THURSDAY
MORNING.  WINDS INCREASE FROM THE NORTHEAST LATE WEDNESDAY AND
WEDNESDAY NIGHT WITH SPEEDS WITH SFC GUSTS TO 30 KNOTS ALONG THE
COAST. LOW LEVEL NORTHEAST JET OF 50-60 KNOTS IS POSSIBLE WEDNESDAY
NIGHT...WHICH WOULD SET UP A PERIOD OF LOW LEVEL WIND SHEAR DURING
THE STORM ESPECIALLY ACROSS THE COASTAL PLAIN. WINDS SHIFT TO
NORTHWEST THURSDAY. FORECAST WINDS AT 3000-5000 FEET ARE 30-40
KNOTS...SOME OR ALL OF WHICH COULD BE BROUGHT TO THE SURFACE IN
GUSTS. AS THIS IS A DAY 5 FORECAST...FOR NOW WE ARE TAKING A MORE
CONSERVATIVE APPROACH WHICH IS CLOSER TO MODEL VALUES OF 18-25 KNOTS.

CONDITIONS SHOULD IMPROVE TO VFR THURSDAY NIGHT.
-- End Changed Discussion --

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

THROUGH MONDAY...HIGH CONFIDENCE.

TODAY...NW WIND WILL DEVELOP GUSTS 15-20 KT. THIS COMBINED WITH
LINGERING SE SWELL WILL ALLOW FOR SEAS TO REMAIN ABOVE 5FT ESP
ACROSS THE EASTERN WATERS. SCA CONTINUES ON MOST OF THE WATERS.

TONIGHT AND MON...SE SWELLS LINGERS AND NW WINDS EASE AND SHIFT
TO SW MON. VSBY MAY LOWER 3-5 MILES IN MORE WIDESPREAD SNOW
SHOWERS BY MONDAY MORNING.

OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...

MONDAY NIGHT-TUESDAY... MODERATE CONFIDENCE.
WINDS REMAIN BELOW 25 KNOTS. SEAS START MONDAY NIGHT BELOW 5
FEET...BUT BUILD TO 5-6 FEET ON THE OUTER WATERS BY TUESDAY.

WEDNESDAY-THURSDAY...LOW CONFIDENCE.
LOW PRESSURE MOVES OUT OF THE PLAINS AND ACROSS THE MID ATLANTIC
COAST...THEN PASSES SOUTH OF NEW ENGLAND. MUCH UNCERTAINTY REMAINS
IN THE PROJECTED TRACK OF THE LOW PRESSURE CENTER. EXPECT
INCREASING NORTHEAST WINDS WEDNESDAY WITH HIGH CONFIDENCE SPEEDS
NORTH OF THE TRACK WILL REACH 30 KNOTS AND LOW CONFIDENCE IN
NORTHEAST GALES WEDNESDAY NIGHT REACHING 40-45 KNOTS. SEAS WILL
BUILD WEDNESDAY NIGHT AND THURSDAY...REACHING 10-14 FEET EAST OF
MASSACHUSETTS AND 5-8 FEET SOUTH OF THE ISLANDS AND RI COAST.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 2 AM EDT MONDAY
     FOR ANZ250-254.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL NOON EDT TODAY
     FOR ANZ255-256.
-- End Changed Discussion --

&&

$$
SYNOPSIS...WTB/DUNTEN
NEAR TERM...WTB/NOCERA/DUNTEN
SHORT TERM...DUNTEN
LONG TERM...WTB
AVIATION...WTB/NOCERA/DUNTEN
MARINE...WTB/DUNTEN