FXUS61 KBOX 260014
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
714 PM EST WED NOV 25 2009
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN ACROSS NEW ENGLAND TONIGHT AND
THURSDAY. HOWEVER CLOUDS...DRIZZLE AND FOG WILL PERSIST. LOW
PRESSURE WILL RAPIDLY DEVELOP THURSDAY NIGHT SOUTHEAST OF NANTUCKET.
THE LOW WILL INTENSIFY AS IT PASSES NEAR NANTUCKET EARLY
FRIDAY...THEN MOVE NORTHEAST THROUGH THE MARITIMES FRIDAY NIGHT AND
SATURDAY BRINGING STRONG NORTHWEST WINDS. HIGH PRESSURE WILL THEN
BRING DRIER WEATHER FROM SATURDAY AFTERNOON INTO SUNDAY. MILD BUT
SHOWERY WEATHER RETURNS EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
DREARY WEATHER CONTINUES TONIGHT AS WEAK HIGH PRES REMAINS
ENTRENCHED ACROSS NEW ENGLAND. THIS WILL PROMOTE ABUNDANT LOW LEVEL
MOISTURE REMAINING TRAPPED BENEATH INVERSION ALONG WITH AREAS OF
DRIZZLE AND FOG. PATCHY DENSE FOG IS POSSIBLE ESPECIALLY ACROSS
EASTERN MA AND THE HIGHER TERRAIN. ALTHOUGH LIKELY NOT WIDESPREAD TO
WARRANT A DENSE FOG ADVISORY.
SHORTWAVE OVER THE EASTERN GREAT LAKES IS CAUSING A LINE OF SHOWERS
THAT ENTERED WESTERN NEW ENGLAND IN THE EVENING. QPF IS JUST A FEW
HUNDREDTHS...IF THAT. THE SHORTWAVE IS MOVING NORTHEAST AND WILL
MOVE DOWN THE ST LAWRENCE VALLEY. EXPECT THE SHOWERS TO MAINLY STAY
NORTH AND WEST OF BOSTON. THE EVENING FORECAST WAS ADJUSTED FOR
LIKELY POPS FOLLOWING THIS FEATURE NORTHEASTWARD THROUGH 10 PM AND
CHANCE POPS THROUGH MIDNIGHT.
NOT MUCH TEMPERATURE CHANGE TONIGHT GIVEN OVERCAST CONDITIONS AND
ABSENCE OF ANY THERMAL ADVECTION. USED A BLEND OF THE COOLER METNAM
AND WARMER GFS MOS. OVERALL...TEMPS WILL BE WARMER THAN NORMAL.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
THU...
MODELS IN GOOD AGREEMENT HERE WITH WEAK SURFACE RIDGE REMAINING
ACROSS THE REGION. THIS WILL LIKELY KEEP THE LOW LEVEL INVERSION IN
TACT. IN ADDITION...THE LACK OF ANY SURFACE GRADIENT WILL PRECLUDE
LOW LEVEL MOISTURE FROM BEING SCOURED OUT. RH TIME SECTIONS FROM
BOTH THE NAM AND GFS INDICATE LOTS OF LOW CLOUDS. THERE COULD BE
SOME BREAKS OF SUNSHINE BUT GIVEN THE REASONS ABOVE COMBINED WITH
THE LOW SUN ANGLE...THINK CLOUDS WILL DOMINATE. HOWEVER ANY FOG AND
DRIZZLE SHOULD BE CONSIDERABLY LESS IN COVERAGE THAN TODAY.
AS FOR TEMPS...BLENDED THE COOLER METNAM WITH THE WARMER GFS MOS
GIVEN THE ABUNDANT CLOUD COVER.
THU NIGHT...
SIGNIFICANT TROF AMPLIFICATION ACROSS THE EASTERN GREAT LAKES AS
NORTHERN STREAM SHORT WAVES MERGE FORMING A CLOSED MID LEVEL LOW
OVER PA BY 12Z FRIDAY. THIS INDUCES THE BEGINNING OF SIGNIFICANT
CYCLOGENESIS EAST OF NANTUCKET LATE THU NIGHT. LOOKS LIKE WARM
ADVECTION RAINS WILL OVERSPREAD THE REGION FROM SOUTH OF NORTH
DURING THE EVENING HOURS WITH RAIN BECOMING WIDESPREAD BY MIDNIGHT.
THERMAL PROFILES AND SOUNDINGS SUGGEST COLUMN IS WARM ENOUGH TO
SUPPORT ALL RAIN ACROSS THE ENTIRE REGION. THERE IS A LOW PROB OF
THUNDER TOWARD MORNING AS SIGNIFICANT HEIGHT FALLS YIELDS STEEPENING
MID LEVEL LAPSE RATES. ALTHOUGH DID NOT INCLUDE THUNDER IN THE
FORECAST YET GIVEN THE TIME RANGE AND LOW PROBABILITY.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AGREEMENT AMONG THE MODELS THAT LOW PRESSURE MOVES PAST NANTUCKET
FRIDAY AND INTO THE MARITIMES FOR SATURDAY. SOME DIFFERENCES IN
TIMING THE END OF PRECIPITATION FRIDAY. WITH A CLOSED UPPER LOW AND
ITS COLD POOL MOVING OVERHEAD AT THE TIME...WE WILL NOT BE TOO QUICK
TO END IT. RATHER WE WILL START WITH CATEGORICAL POPS AND WIND DOWN
FROM SOUTH TO NORTH DURING THE AFTERNOON AND EVENING.
COLDER AIR MOVING IN CHANGES THE PROFILES ENOUGH TO CHANGE LINGERING
SHOWERS OVER TO SNOW SHOWERS IN THE NORTHWEST...MOSTLY THE HIGHER
ELEVATIONS. SUFFICIENT MOISTURE TO SUPPORT AN INCH OR TWO OF SNOW IN
THOSE AREAS FRIDAY NIGHT.
SURFACE PRESSURES FALL AS THE LOW PASSES US FRIDAY. THIS TIGHTENS
THE PRESSURE GRADIENT AND SHOULD BRING INCREASING WINDS FRIDAY
AFTERNOON AND NIGHT. THE COLDER AIR TRAILING THE LOW ALSO ENHANCES
MIXING OF STRONGER WINDS FROM ALOFT. THE GFS SHOWS A POTENTIAL FOR
WEST WIND GUSTS AROUND 45 KNOTS WHILE THE NAM FAVORS GUST POTENTIAL
FOR 35 TO 40 KNOTS. WE MAY NEED TO CONSIDER A WIND ADVISORY...MAINLY
FOR THE CAPE AND ISLANDS AND SOUTH COAST BUT POTENTIALLY FOR HIGHER
ELEVATIONS INLAND.
UPPER TROF OVER MAINE AND GULF OF MAINE SATURDAY MORNING...SHOULD
REMAIN SUFFICIENTLY MOIST AND UNSTABLE TO KEEP SCATTERED RAIN/SNOW
SHOWERS DURING THE MORNING. THE LOW MOVES OFF INTO THE MARITIMES
AFTERNOON WHICH SHOULD ALLOW CLEARING AND AN END TO ANY SHOWERS.
HIGH PRESSURE BRINGS GENERAL CLEARING/DRY WEATHER FOR SUNDAY.
LOW COMING OUT OF THE MIDWEST/GREAT LAKES AREA WILL PUSH CLOUDS OUR
WAY MONDAY. MODELS DISAGREE ON TIMING OF THE SUBSEQUENT COLD FRONT
PASSAGE WITH THE GFS AND GLOBAL SAYING MONDAY NIGHT WHILE THE ECMWF
SAYS TUESDAY. WE WILL GO WITH THE GFS/GLOBAL CONSENSUS FOR NOW WITH
CHANCE POPS MONDAY AFTERNOON AND NIGHT AND DRY WEATHER TUESDAY.
WEDNESDAY WEATHER STILL UNCERTAIN WITH DIFFERENCES BETWEEN THE
OPERATIONAL MODELS AND THEIR ENSEMBLES. WE WILL START WITH CHANCE
POPS CONNECTED WITH LOW PRESSURE MOVING UP FROM THE SOUTHEAST
USA...BUT WITH LOW CONFIDENCE AT THIS TIME.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
00Z TAFS REFLECT IFR/LIFR CONDITIONS INTO THU MORNING.
CONTINUED HIGH CONFIDENCE ON LOW CIGS/VSBYS THROUGH THIS NIGHT.
EXPECT CIGS AND VSBYS TO LOWER SOMEWHAT THROUGH SUNRISE WITH MOST
PLACES BELOW 1000 FEET/1 MILE FOR AT LEAST A PART OF THE NIGHT.
THEREFORE WIDESPREAD IFR/LIFR 00Z- 12Z THU.
SHOULD SEE GRADUAL IMPROVEMENT THU MORNING...ESPECIALLY KBAF KBDL
KMHT KPVD. IT MAY TAKE UNTIL THU AFTERNOON FOR CIGS TO LIFT TO MVFR
KBOS TO KACK. CIGS SHOULD IMPROVE TO VFR THU AFTERNOON NEAR CT RIVER
VALLEY /KBDL/.
KBOS...CIGS/VSBYS EXPECTED TO LOWER SLIGHTLY THROUGH 03Z. LIGHT
WINDS WILL KEEP CIGS AOB OVC005 AND VSBYS AOB 1SM. CONDITIONS NOT
EXPECTED TO IMPROVE SIGNIFICANTLY UNTIL SUNRISE.
OUTLOOK /FRIDAY THROUGH MONDAY/...
FRIDAY...WIDESPREAD IFR CIGS AND VSBYS IN RAIN AND FOG. FLIGHT
CONDITIONS IMPROVING TO MVFR IN THE AFTERNOON.
FRIDAY NIGHT AND SATURDAY...MVFR CONDITIONS IMPROVE TO VFR. STRONG
SURFACE WINDS WITH W WIND GUSTS 35-40 KT AND ASSOCIATED MECHANICAL
TURBULENCE. WINDS DIMINISH LATE SATURDAY/SATURDAY NIGHT.
SUNDAY AND MONDAY...VFR.
&&
.MARINE...
TONIGHT...
PATCHY DENSE FOG WILL REDUCE VSBY TO LESS THAN A 1/2 MILE AT TIMES
ESPECIALLY ACROSS EASTERN MA WATERS. ALSO...HAZARDOUS SEAS WITH EAST
SWELLS OF 5-7 FT EVERY 10 SECONDS ACROSS THE OCEAN WATERS.
THURSDAY...
VSBY SHOULD IMPROVE ESPECIALLY BY MIDDAY. EAST SWELLS WILL SUBSIDE
AS WELL. WINDS WILL BE LIGHT AND VARIABLE.
THURSDAY NIGHT...
LOW PRES DEVELOPS SOUTHEAST OF NANTUCKET TOWARD MORNING. VSBY WILL
LOWER IN RAIN. LOW PROB OF AN EASTERLY GALE TOWARD DAYBREAK FRI
ACROSS THE EASTERN MA WATERS. MORE LIKELY SCENARIO WILL BE FOR EAST
WINDS 20-30 KT...LESS WIND ALONG THE SOUTH COAST OF NEW ENGLAND.
OUTLOOK /FRIDAY THROUGH MONDAY/...
FRIDAY...WINDS SHIFT TO WEST AND INCREASE IN THE AFTERNOON.
FRIDAY NIGHT AND SATURDAY...WEST WINDS STRENGTHEN TO GALE FORCE
BEHIND THE DEPARTING LOW. GUSTS TO 40 KT POSSIBLE.
SATURDAY NIGHT-SUNDAY...DIMINISHING WEST WINDS WITH LINGERING SEAS
AND WIND GUSTS AT SCA LEVELS...ESPECIALLY ON THE OUTER WATERS.
MONDAY...LINGERING ROUGH SEAS ON THE OUTER WATERS.
PERSISTENT ONSHORE FLOW AND 6 TO 8 FOOT EAST SWELLS COULD LEAD TO
MINOR BEACH EROSION ACROSS THE EASTERN MASSACHUSETTS COAST EARLY
FRIDAY. WE COULD SEE A SURGE OF 1.0 TO 1.5 FT DURING THE TIMES OF
HIGH TIDE FRIDAY BUT ASTRONOMICAL TIDES ARE QUITE LOW.
&&
.CLIMATE...
IT IS INTERESTING TO NOTE THAT BOSTON/S LOGAN AIRPORT HAS NOT GOTTEN
DOWN TO THE FREEZING MARK SO FAR THIS SEASON. THE LATEST IN THE
SEASON THAT BOS HAS GONE WITHOUT HITTING 32F WAS DEC 2ND 1975. IT/S
POSSIBLE WE BREAK THAT RECORD...BUT IT WILL BE CLOSE SUNDAY
NIGHT...AND NOT COMPLETELY OUT OF THE QUESTION SATURDAY NIGHT...BUT
LOWER PROBABILITY THEN.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 AM EST
THURSDAY FOR ANZ250-251-254>256.
&&
$$
SYNOPSIS...WTB/NOCERA
NEAR TERM...WTB/NOCERA
SHORT TERM...NOCERA
LONG TERM...WTB
AVIATION...WTB/NOCERA/JWD
MARINE...WTB/NOCERA
CLIMATE...
