FXUS61 KBOX 012221
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
521 PM EST TUE DEC 1 2009
.SYNOPSIS...
HIGH PRESSURE WILL BRING DRY WEATHER AND NEAR SEASONABLE TEMPERATURES
TO SOUTHERN NEW ENGLAND TONIGHT AND WEDNESDAY. STRONG LOW PRESSURE
WILL BRING HIGH WINDS AND RAIN TO THE REGION LATE WEDNESDAY NIGHT
AND THURSDAY. TEMPERATURES WILL BE AT OR BELOW NORMAL FOR FRIDAY
THROUGH THE WEEKEND. THERE IS ALSO THE CHANCE FOR SOME SNOW LATE
SATURDAY/SATURDAY NIGHT IF COASTAL LOW PRESSURE COMES CLOSE ENOUGH
TO NEW ENGLAND.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AREA OF SNOW SHOWERS REACHED INTO THE BERKSHIRES LATE THIS MORNING
AND EARLY AFTERNOON...BUT HAS SINCE DISSIPATED. STILL NOTE LAKE
EFFECT BANDS WORKING ACROSS NORTHERN NY STATE INTO VT...FAR AWAY
FROM THE REGION.
CLOUDS FROM A WEAKENING SHORT WAVE IN THE FAST UPPER WEST FLOW WILL
MOVE E AND TEND TO DISSIPATE TONIGHT AS HIGH PRESSURE BUILDS OFF THE
MID ATLC COAST...WITH SURFACE RIDGING HELPING TO CLEAR THINGS OUT.
WITH MAINLY LIGHT W-SW WINDS TONIGHT...EXPECT TEMPS TO FALL BACK TO
NEAR SEASONAL LEVELS.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
WEDNESDAY...HIGH PRES WILL SHIFT TO THE WESTERN ATLC DURING THE DAY
WHILE LOW PRES TAKES SHAPE OVER THE SOUTHEASTERN U.S. EXPECT A
PLEASANT DAY WITH SW WINDS STARTING TO PICK UP A BIT. TEMPS WILL
REBOUND TO THE UPPER 40S TO LOWER 50S AT MOST LOCATIONS. CLOUD WILL
QUICKLY INCREASE FROM SW-NE DURING THE AFTERNOON AHEAD OF THE NEXT
SYSTEM.
WEDNESDAY NIGHT...RAPIDLY INTENSIFYING LOW PRES WILL WORK ACROSS THE
APPALACHIANS...WITH THE GFS STRONGER THAN THE OTHER SHORT RANGE
MODELS. USED A BLEND OF THE PREVIOUS FORECAST ALONG WITH THE 09Z
SREF...WHICH SEEMED TO BE A GOOD BLEND OF THE 12Z OP MODEL RUNS.
RAIN WILL QUICKLY PUSH INTO THE REGION OVERNIGHT. EXCELLENT MOISTURE
CONVERGENCE WITH THIS SYSTEM WILL BRING A SLUG OF RAIN...POSSIBLY UP
TO AN INCH OF RAIN WITH LOCALLY HIGHER AMOUNTS. GOOD DYNAMICS IN
PLACE AS WELL...SO COULD SEE SCT TSTMS MAINLY NEAR OR AFTER MIDNIGHT.
THERE ARE TWO POTENTIAL PROBLEMS WITH THIS SYSTEM...THE RAPIDLY
INCREASING SOUTHERLY WINDS AND POSSIBLE COASTAL FLOODING. VERY
STRONG LOW LEVEL JET...UPWARD TO 70 KTS AT 925 HPA AND 80 KTS AT 850
HPA...WILL MOVE INTO THE REGION OVERNIGHT. WILL LIKELY SEE AT LEAST
WINDS UP TO ADVISORY LEVEL...WITH THE CHANCE OF REACHING HIGH WIND
WARNING CRITERIA MAINLY ON THE SOUTH COAST. WILL MONITOR THIS ASPECT
CLOSELY...AND COVERED IN THE HAZARDOUS WEATHER OUTLOOK. SEAS ARE
FORECAST TO BUILD QUICKLY ON THE SOUTH COAST...WHICH COULD LEAD TO
POTENTIAL OF COASTAL FLOODING MAINLY ON THE THURSDAY MORNING TIDE.
EXPECT TEMPS TO INCREASE THROUGH THE NIGHT...APPROACHING 60 DEGREES
OR HIGHER BY SUNRISE WITH THE STRONG WARM AIR ADVECTION AHEAD OF THE
APPROACHING COLD FRONT.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
THE 12Z MODEL CYCLE BROUGHT A RANGE OF SOLUTIONS FOR THE TRACK OF THE
THURSDAY STORM. THE RANGE WAS FROM NEAR HAMILTON ONTARIO IN THE WEST
TO NEAR BENNINGTON VT IN THE EAST. THE BULK OF TRACKS BROUGHT THE LOW
THROUGH CENTRAL NY. OUR FORECAST IS BASED ON THIS CENTRAL TRACK WITH
A PREFERENCE FOR THE ECMWF. RAIN AND WIND FROM THIS SYSTEM WILL BE AT
MAXIMUM AROUND 12Z THURSDAY AND THEN DIMINISH DURING THE MORNING FROM
SOUTH TO NORTH AS THE LOW MOVES UP ALONG THE CANADIAN BORDER. THIS
STORM WILL BRING THREE MAIN CONCERNS TO SOUTHERN NEW ENGLAND.
FIRST CONCERN...WIND. THE LOW IS FORECAST TO EXPRESS 4 MB/HOUR
PRESSURE FALLS AS IT PASSES US FOLLOWED BY 2-3 MB/HOUR PRESSURE RISES
DURING THE REST OF THURSDAY. THIS WILL MEAN A TIGHT PRESSURE GRADIENT
AROUND THE CENTER. ALSO...MODEL FORECASTS AGREE ON A STRONG SOUTH TO
SOUTHWEST JET AT 12Z THURSDAY WITH 65-70 KNOTS AT 950 MB AND 75 TO 85
KNOTS AT 850 MB. MOST OF THIS IS FOCUSSED OVER RI AND SOUTHEAST
MASS...EXPECT THE STRONGEST WIND POTENTIAL IN THIS AREA WITH A
SECONDARY CONCERN OVER THE HIGHER ELEVATIONS OF THE CENTRAL HILLS AND
BERKSHIRES.
THIS SHOULD BE MORE THAN ENOUGH TO SUPPORT WIND ADVISORY CRITERIA
THROUGH MUCH OF THURSDAY. IF MIXING IS A LITTLE DEEPER AND REACH
THOSE 850 MB WINDS...THEN WIND GUSTS OF 50 KNOTS OR HIGHER WOULD BE
REASONABLE. BOTTOM LINE...EXPECT A WIND HEADLINE WITH THIS SYSTEM
WITH POTENTIAL FOR A HIGH WIND WARNING IF EVERYTHING COMES TOGETHER.
WIND ADVISORY CATEGORY WINDS CAN CAUSE SCATTERED POWER OUTAGES AND
FALLING TREE LIMBS. HIGH WIND WARNING CATEGORY WINDS BRING THE
POTENTIAL FOR MORE WIDESPREAD POWER OUTAGES AND DOWNED TREES.
SECOND CONCERN...COASTAL FLOOD POTENTIAL
THE MONTHLY ASTRONOMICAL TIDE CYCLE PEAKS ON THURSDAY MORNING. THE
STRONGEST WINDS WITH THIS STORM WILL OCCUR ABOUT THE SAME TIME. WITH
WINDS EXPECTED FROM THE SOUTH AND SOUTHWEST...THIS WOULD PUSH THE
COASTAL WATERS UP AGAINST THE RI AND SOUTH MASSACHUSETTS COASTS.
NARRAGANSETT BAY AND BUZZARDS BAY WOULD...BY THEIR SHAPE...BE
ESPECIALLY AT RISK. THE POTENTIAL EXISTS FOR A 2 FOOT OR HIGHER STORM
SURGE ALONG THE SOUTH COAST. THIS SURGE...IF REALIZED...WOULD BRING A
RISK OF MODERATE COASTAL FLOODING TO THE SOUTH COAST AND ITS BAYS.
MODERATE COASTAL FLOODING MEANS THAT THERE IS THE POTENTIAL FOR
STRUCTURAL DAMAGE TO VULNERABLE AREAS. A COASTAL FLOOD WATCH MAY BE
NEEDED IN SUBSEQUENT FORECAST PACKAGES.
THIRD CONCERN...HEAVY DOWNPOURS
PRECIPITABLE WATER VALUES OF 1.5 INCHES ARE EXPECTED WITH THIS
STORM...ESPECIALLY ACROSS RI AND SOUTHEAST MASS. THIS WILL BE COUPLED
WITH STRONG JET FORCING AS WE WILL BE UNDER THE LEFT EXIT REGION OF A
130 KNOT JET AT 12Z THURSDAY. FORTUNATELY THE SYSTEM WILL BE MOVING FAST
WHICH SHOULD LIMIT THE WINDOW FOR RAINFALL. EVEN SO...AMOUNTS OF 1 TO
2 INCHES ARE POSSIBLE WITH THIS STORM...WITH RAIN TAPERING OFF BY
MIDDAY THURSDAY. NO SIGNIFICANT SMALL STREAM OR RIVER FLOODING IS
EXPECTED...BUT WE WILL LIKELY SEE TYPICAL URBAN AND POOR DRAINAGE
STREET FLOODING.
HIGH PRESSURE BRINGS A DRIER BUT COLDER BREAK FOR FRIDAY.
UPPER TROF DIGGING INTO THE PLAINS FRIDAY INDUCES A COASTAL LOW ALONG
THE SOUTHEAST USA COAST FRIDAY NIGHT. THIS LOW THEN MOVES NORTHEAST
SATURDAY. MODELS AGREE ON THE LOW FORMING. THE QUESTION IS...HOW
CLOSE TO NEW ENGLAND DOES IT COME? THE 12Z CYCLE KEEPS THE LOW WELL
OUTSIDE THE 40N/70W BENCHMARK. BUT THE DIGGING OF THE UPPER TROF HAS
THE POTENTIAL TO PULL THE SURFACE LOW FARTHER WEST. LOW CONFIDENCE IN
THE STORM TRACK AT THIS TIME...WITH POTENTIAL FOR IT TO MOVE CLOSER.
SO WE WILL CONTINUE TO FORECAST CHANCE POPS FOR SATURDAY.
TEMPERATURE PROFILES SUPPORT PTYPE OF SNOW EXPECIALLY AWAY FROM THE
COAST.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
TONIGHT AND WEDNESDAY...VFR. CIGS WILL START TO LOWER TO AROUND 5KFT
DURING WEDNESDAY AFTERNOON ACROSS N CT/RI...QUICKLY PUSHING ACROSS
THE REMAINDER OF THE REGION.
WEDNESDAY NIGHT...GENERAL MVFR-IFR CIGS/VSBYS WITH AREAS LIFR IN
LOCALLY HEAVY RAINFALL AND AREAS OF FOG. SCT TSTMS POSSIBLE NEAR OR
AFTER MIDNIGHT. S-SW WIND GUSTS UP TO 45 KNOTS POSSIBLE.
OUTLOOK /THURSDAY THROUGH SATURDAY/...
THURSDAY...IFR CONDITIONS THURSDAY MORNING IN HEAVY RAIN...STRONG
SOUTH TO SOUTHWEST WIND GUSTS TO 45 KT...ALONG WITH SCATTERED
THUNDERSTORMS. LOW LEVEL WIND SHEAR POSSIBLE ESPECIALLY AT BOS-PVD-
FMH-HYA-ACK. CONDITIONS IMPROVING FROM SW-NE DURING THE AFTERNOON.
THURSDAY NIGHT AND FRIDAY...MAINLY VFR CONDITIONS EXPECTED.
SATURDAY...LOW CONFIDENCE BUT MVFR-IFR CONDITIONS ARE POSSIBLE IN A
PERIOD OF SNOW.
SUNDAY...VFR.
&&
.MARINE...
TONIGHT...SMALL CRAFT CONTINUES INTO THE EVENING MAINLY FOR LEFTOVER
5 FOOT SEAS.
WEDNESDAY...HIGH PRES PUSHES E OF THE WATERS...WITH LIGHT W-SW WINDS
AND SEAS BELOW 5 FEET.
WEDNESDAY NIGHT...HAVE ISSUED A GALE WATCH FOR RAPIDLY INCREASING
S-SW WINDS...GUSTING UP TO 40-45 KTS LATE. SEAS QUICKLY BUILD...UP
TO 9-13 FEET BY SUNRISE THURSDAY.
OUTLOOK /THURSDAY THROUGH SATURDAY/...
THURSDAY...A PERIOD OF SOUTHERLY GALE FORCE WINDS ARE EXPECTED ALONG
WITH RAPIDLY BUILDING SEAS TO BETWEEN 10 AND 15 FEET OVER THE
SOUTHERN OUTER-WATERS. THERE IS A LOW PROBABILITY OF STORM FORCE
WIND GUSTS FOR AN HOUR OR TWO.
FRIDAY...WINDS SHOULD DIMINISH BELOW SCA CRITERIA BUT SEAS WILL
REMAIN ABOVE SCA THRESHOLDS ACROSS THE SOUTHERN OUTER-WATERS.
SATURDAY...THE POTENTIAL EXISTS FOR GALE FORCE NORTHEAST WINDS
AS LOW PRESSURE DEVELOPS OFF THE COAST. CONFIDENCE IS LOW TO MEDIUM
AT THIS TIME AS TO HOW FAR OFFSHORE THE STORM MIGHT BE.
SUNDAY...WIND DIMINISH TO SMALL CRAFT STRENGTH...WITH LINGERING ROUGH
SEAS.
&&
.CLIMATE...
BOSTON/S LOGAN AIRPORT HAS NOT FALLEN TO THE FREEZING MARK SO FAR
THIS SEASON. THE RECORD LATEST IN THE SEASON THAT BOSTON HAS
RECORDED ITS FIRST 32F WAS DEC 2ND 1975. AVERAGE FIRST DATE OF 32 IN
BOSTON IS AROUND NOVEMBER 4TH. OVERNIGHT LOWS TONIGHT AND WEDNESDAY
NIGHT FORECASTED TO REMAIN ABOVE FREEZING.
NOVEMBER 2009 WAS TOP 10 WARMEST AT OUR 4 CLIMATE SITES. BELOW ARE
PRELIMINARY NOVEMBER TEMPERATURE AVERAGES AND DEPARTURES FOR THE
MONTH.
BOS 48.8...PLUS 3.9...RANKED NUMBER 6.
BDL 46.4...PLUS 4.6...RANKED NUMBER 6.
PVD 48.9...PLUS 5.1...RANKED NUMBER 3.
ORH 44.5...PLUS 4.9...RANKED NUMBER 5.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY AFTERNOON
FOR ANZ231>235-237-250-254>256.
GALE WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
AFTERNOON FOR ANZ230-236-251.
SMALL CRAFT ADVISORY UNTIL 9 PM EST THIS EVENING FOR ANZ254-
255.
&&
$$
SYNOPSIS...WTB
NEAR TERM...EVT
SHORT TERM...EVT
LONG TERM...WTB
AVIATION...WTB/EVT
MARINE...WTB/EVT
CLIMATE...
