FXUS61 KBOX 150000
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
700 PM EST MON DEC 14 2009
.SYNOPSIS...
LOW PRESSURE TRACKING ACROSS NORTHERN NEW ENGLAND WILL PUSH A STRONG
COLD FRONT THROUGH THE REGION LATE TUESDAY AND TUESDAY EVENING.
BLUSTERY AND COLD CONDITIONS WILL FOLLOW FOR WEDNESDAY AND THURSDAY
WITH BELOW NORMAL COLD PERSISTING THROUGH THE WEEKEND. A COASTAL
STORM MAY THREATEN SOUTHERN NEW ENGLAND SOMETIME LATE IN THE WEEKEND
BUT THERE IS STILL MUCH UNCERTAINTY.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
LOW PRESSURE IN THE GREAT LAKES WILL MOVE THROUGH NEW YORK STATE AND
APPROACH NORTHERN NEW ENGLAND BY TUESDAY MORNING. THIS PUTS
SOUTHERN NEW ENGLAND IN THE WARM SECTOR OF THIS SYSTEM. MOISTURE IS
LACKING WITH THIS SYSTEM SO WILL LIKELY JUST SEE A DRY NIGHT WITH
PLENTY OF CLOUD COVER. THERE IS A SLIGHT CHANCE OF PRECIP ACROSS
NORTHWESTERN MASS AND SOUTHWESTERN NH. IF PRECIPITATION OCCURS...
TEMPERATURE PROFILES INDICATE PTYPE MOST LIKELY WOULD BE RAIN...WITH
POCKETS OF FZRA POSSIBLE IN COLDER VALLEYS...BUT THIS IS A LOW
PROBABILITY.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
AN UPPER LEVEL TROUGH APPROACHES SOUTHERN NEW ENGLAND TUESDAY...
MOVING THROUGH THE AREA TUESDAY NIGHT. ASSOCIATED LOW PRESSURE WILL
MOVE ACROSS NORTHERN NEW ENGLAND TUESDAY...PULLING A COLD FRONT
ACROSS THE AREA LATE TUESDAY AFTERNOON. PRIOR TO THIS OCCURRING...
TEMPERATURES WILL WARM INTO THE UPPER 30S TO MID 40S. ANY REMAINING
PRECIPITATION FROM TONIGHT WILL CHANGE TO RAIN AND THEN COME TO AN
END FAIRLY QUICKLY BY MIDDAY TUESDAY. STRONG COLD AIR ADVECTION
BEHIND THE FRONT WILL USHER IN MUCH COLDER...DRIER AIR. THERE ARE
SOME MINOR TIMING DIFFERENCES AMONGST THE MODELS AS TO HOW QUICKLY
THE COLD AIR WILL MOVE IN WITH THE 00Z ECMWF THE FASTEST...THE 12Z
NAM THE SLOWEST AND THE 12Z GFS IN BETWEEN. THE MAJORITY OF THE
GEFS MEMBERS ARE MORE COMPARABLE TO THE ECMWF...SO WILL GO WITH THE
QUICKER ADVANCE OF COLD AIR.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
MEDIUM RANGE GUIDANCE IN AGREEMENT THAT HIGH LATITUDE BLOCKING NEAR
GREENLAND WILL RESULT IN POLAR VORTEX INVOF CANADIAN MARITIMES FOR
MUCH OF THE PERIOD POSSIBLY RETROGRADING LATE IN THE PERIOD. BELOW
NORMAL HEIGHTS AND NW FLOW WILL BRING MAINLY DRY AND COLD CONDITIONS
THROUGH THE PERIOD. HOWEVER BY LATE IN THE WEEKEND...SHORTWAVE
ENERGY UNDERCUTTING THIS VORTEX WILL LIKELY RESULT IN A DEVELOPING
COASTAL STORM OFFSHORE BUT IT IS UNCERTAIN HOW CLOSE THIS STORM GETS
TO NEW ENG.
WED THROUGH THU...SNE WILL BE SANDWICHWED BETWEEN SFC LOW IN THE
MARITIMES AND HIGH PRES IN THE OHIO VALLEY. STRONG GRADIENT AND CAA
WILL RESULT IN WINDY AND COLD CONDITIONS AS 850 MB TEMPS AROUND -14
TO -16C. UNCERCUT MEX GUIDANCE FOR MAX TEMPS BOTH DAYS BUT WENT
CLOSE TO GUIDANCE FOR THE MINS AS WINDS DO NOT DROP OFF. MAX TEMPS
AVERAGING ABOUT 10 DEGREES BELOW NORMAL. NW FLOW WILL KEEP ANY
OCEAN EFFECT SNOW SHOWERS OFFSHORE BUT SOME CLOUDS MAY FLIRT WITH
OUTER CAPE AT TIMES. OTHERWISE...MOCLEAR TO PARTLY CLOUDY SKIES
EXPECTEDD.
MIXING ALGORITHM SHOWS POTENTIAL FOR GUSTS AROUND 35 KT WED WITH LOW
PROB OF SUSTAINED WIND ADVSY CRITERIA FOR CAPE/ACK. IT WILL REMAIN
BLUSTERY NEAR THE COAST AND HIGH TERRAIN WED NIGHT...AND WIND GUSTS
STILL NEAR 30 KT THU. SUBZERO WIND CHILLS IN THE HIGH TERRAIN WED
NIGHT AND THU NIGHT.
FRI...GRADIENT RELAXES AS HIGH PRES BUILDS IN FROM THE WEST SO
EXPECT DIMINISHING WIND. BUT STILL COLD AS 850 TEMPS FROM GEFS MEAN
AND EC RUNNING -12 TO -14C.
UNCERTAINTY INCREASES THIS WEEKEND AS COASTAL STORM FORECAST TO
DEVELOP OFF THE COAST. THERE IS CONSIDERABLE SPREAD AMONG OP
MODELS AND ENSEMBLE MEMBERS WITH TIMING...TRACK AND INTENSITY OF
THIS STORM SO FORECAST CONFIDENCE IS LOW. GGEM HAS BIG STORM HERE
SAT AND SAT NIGHT WHILE EC IS A MISS. GFS/UKMET IN BETWEEN AND
SLOWER. WE FOLLOWED HPC GUIDANCE WHICH SUGGEST STORM TRACK JUST SE
OF BENCHMARK SUN NIGHT SO HAVE LOW CHC POPS SUN/SUN NIGHT...EXCEPT
DRY FOR NOW NW ZONES.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
TONIGHT...MVFR CIGS HAVE DEVELOPED IN THE COASTAL PLAIN EARLY THIS
EVENING AND EXPECT THESE CONDITIONS TO PERSIST BASED ON RH TIME
SECTIONS WHICH INDICATE INCREASING LOW LEVEL MOISTURE. CIGS
GRADUALLY LOWERING TO MVFR ELSEWHERE WITH LOW PROB OF IFR CIGS
DEVELOPING LATE. PATCHY FOG WITH MVFR/IFR VSBYS POSSIBLE...MAINLY W
OF ORH-MHT SO DID NOT INCLUDE IN TERMINALS.
TUE...MVFR/IFR CIGS IN THE MORNING...THEN IMPROVING TO VFR DURING
AFTERNOON AND EVENING AFTER FROPA. LOW PROB OF A BRIEF SHOWER.
TUE NIGHT...VFR. NW WINDS GUSTING TO 30 KTS LATE.
KBOS...MAINLY MVFR CIGS AROUND 2-3K FT THIS EVENING ALTHOUGH CLOUDS
MAY SCATTER OUT TEMPORARILY THROUGH 06Z. A PERIOD OF IFR CIGS
DEVELOPING LATE TONIGHT OR TUE MORNING BEFORE IMPROVING TO VFR LATE
TUE/TUE EVENING.
OUTLOOK /WEDNESDAY THROUGH SATURDAY/...
WEDNESDAY AND THURSDAY...VFR. NW WINDS GUSTING TO 30 TO 35 KT WITH
SOME MECHANICAL TURBULENCE.
FRIDAY AND SATURDAY...VFR.
&&
.MARINE...
SCA IN EFFECT FOR THE OUTER WATERS THROUGH TONIGHT FOR LINGERING
ROUGH SEAS. SEAS SHOULD DIMINISH BELOW 5 FEET BY EARLY TUESDAY
MORNING AS HIGH PRESSURE MOVES OVER THE WATERS. LIGHT WINDS FROM
THE SOUTH/SOUTHWEST AS LOW PRES MOVES FROM THE GREAT LAKES ACROSS
NORTHERN NEW ENGLAND TUESDAY. SCA TUESDAY NIGHT LIKELY BUILDING TO
W/NW GALES BY DAYBREAK IN COLD ADVECTION.
OUTLOOK /WEDNESDAY THROUGH SATURDAY/...
WED AND WED NIGHT...HIGH PROB OF NW GALES WITH GUSTS TO 35 TO 40
KT...STRONGEST EASTERN WATERS
THU...GALES STILL LIKELY EASTERN WATERS BUT WIND GUSTS PROBABLY
DIMINISING TO 30 KT ELSEWHERE.
FRI...SCA WINDS IN THE MORNING THEN DIMINISHING.
SAT...WINDS AND SEAS BELOW SCA.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...GALE WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON
FOR ANZ230>237-250-251-254>256.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL MIDNIGHT EST
TONIGHT FOR ANZ254>256.
&&
$$
SYNOPSIS...KJC
NEAR TERM...RLG
SHORT TERM...RLG
LONG TERM...KJC
AVIATION...KJC/RLG
MARINE...KJC/RLG
