FXUS61 KBOX 231014
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
515 AM EST WED DEC 23 2009
.SYNOPSIS...
DRY AND COLD WEATHER WILL GRADUALLY MODERATE THURSDAY AND FRIDAY
ALONG WITH DIMINISHING WINDS...AS HIGH PRESSURE CRESTS OVER NEW
ENGLAND. LOW PRESSURE WILL APPROACH FROM THE SOUTHWEST
SATURDAY...WHICH WILL BRING A PERIOD OF WINTRY WEATHER INLAND AND
MAINLY RAIN AND WIND ALONG THE COAST. THE LOW AND ITS PRECIPITATION
MAY DEPART THE REGION LATER SUNDAY...FOLLOWED BY COLDER AND BLUSTERY
WEATHER EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOSED UPPER LOW ALONG THE CANADIAN BORDER THIS MORNING SHIFTS
SOUTHEAST BY EVENING. CLOUDS ASSOCIATED WITH THE LOW EXTEND FROM
MAINE TO NORTHERN NEW YORK WITH LIGHT SNOW ALONG THE BORDER. AS THE
LOW TRANSLATES SOUTHEAST THESE CLOUDS SHOULD ALSO SHIFT OUR WAY.
EXTRAPOLATION OF EARLY MORNING MOVEMENT WOULD BRING THE CLOUD SHIELD
INTO SOUTHERN NH AROUND 11Z...TO THE MASS PIKE AROUND 14Z...AND TO
THE SOUTH COAST BY 18Z.
COLD POOL MOVES ACROSS ESPECIALLY THIS AFTERNOON. TIME SECTIONS SHOW
MOIST LAYER 925 MB TO 850 MB BUT WITH DRIER AIR AT SURFACE. 850-500
MB LAPSE RATES ARE AROUND 16-20C...NOT TOO IMPRESSIVE. MODEL VERTICAL
MOTION SHOWS LITTLE IN THE WAY OF LIFT. COULD BE SOME FLURRIES
ESPECIALLY OVER NH AND EASTERN MASS...BUT MOSTLY THIS LOOKS LIKE
CLOUDS AND DRY WEATHER.
EQUIVALENT 850 TEMPS FROM THE MIXED LAYER ARE IN THE -15C TO -20C
RANGE...WHICH WOULD SUPPORT MAX TEMPS MOSTLY IN THE 20S. WE USED A
BLEND OF NAM AND GFS MOS VALUES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
THE UPPER LOW MOVES EAST OUT TO SEA TONIGHT WHILE A GREAT LAKES UPPER
RIDGE BUILDS EAST. EXPECT CLEARING SKIES IN THE CT VALLEY AND OTHER
WESTERN SECTIONS. THERE MAY BE A CLEARING TREND LATER IN THE NIGHT
IN THE EAST...BUT WITH SURFACE WINDS SHIFTING FROM NORTHWEST TO
NORTHEAST BY MORNING THIS MAY RETARD THE DEPARTURE OF CLOUD COVER.
RIDGE BUILDS IN SURFACE AND ALOFT FOR THURSDAY AND FOR CHRISTMAS DAY
WITH THE SURFACE RIDGE PASSING NORTH OF NEW ENGLAND. THIS WILL BRING
OUR WINDS AROUND TO NORTHEAST OFF THE GULF OF MAINE. SO EVEN THOUGH
THE COLDEST AIR MOVES OFF WITH THE DEPARTING LOW...A COOL SURFACE
LAYER OF AIR SHOULD REMAIN. THIS AND THE EXISTING SNOWPACK WILL BE A
RESISTING INFLUENCE ON ANY LATE WEEK WARMING TREND. SKY COVER
FORECAST GRIDS LINGER IN THE 25-50 PERCENT RANGE ESPECIALLY FRIDAY IN
ANTICIPATION OF INCREASING CIRRUS. TEMPERATURES ARE AGAIN A BLEND OF
MOS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
MEDIUM RANGE MODELS STILL STRUGGLING IN HANDLING THE MOVEMENT OF
STRONG LOW PRES AND ITS ASSOCIATED CUTOFF UPPER LOW ACROSS THE
CENTRAL U.S. INTO THE GREAT LAKES...THEN ANOTHER WEAKER LOW AND
ASSOCIATED FRONT INTO NORTHEASTERN U.S. WITH THE HIGH AMPLITUDE
BLOCKING PATTERN IN PLACE...MODELS HAVE SHOWN SOME CONSISTENCY IN
SLOWING THE ARRIVAL OF THE SECOND LOW AND FRONT INTO THE REGION
UNTIL SATURDAY...THOUGH WHEN IT WILL EXIT IS STILL IN QUESTION.
NOTED THAT THE ECMWF...WHICH HAD BEEN ON THE SLOWER SIDE OF THE
SOLUTION ENVELOPE...HAS COME IN A BIT FASTER ON ITS 00Z OP RUN.
LEANED TOWARD A BLEND OF THE EC AND GFS ENSEMBLES FOR THIS PORTION
OF THE FORECAST. TOUGH TO CALL HOW THE SENSIBLE WEATHER WILL RESOLVE
BEYOND MONDAY...AS ALL IS DEPENDENT UPON THE EXIT OF THE LOW AND
FRONT.
FRIDAY NIGHT...LOOKS LIKE IT WILL REMAIN DRY ON CHRISTMAS
NIGHT...THOUGH CLOUDS CURRENTLY FORECAST TO INCREASE. HAVE LOWERED
TEMPS A BIT FROM PREVIOUS FORECAST CONSIDERING THAT PRECIP WILL HOLD
OFF...ESPECIALLY WELL INLAND.
SATURDAY-SUNDAY...HAVE BROUGHT PRECIP INTO THE REGION FROM W-E
DURING THE DAY SATURDAY. BIG QUESTION BEYOND THE MOVEMENT OF THE LOW
AND FRONT WILL BE HOW QUICKLY THE COLD TEMPS SCOUR OUT WELL INLAND.
PRECIP MAY START OFF AS A WINTRY MIXTURE ACROSS THE COLDER VALLEYS
OF S NH/N CENTRAL MA...BUT SHOULD CHANGE OVER.
HEAVIEST PRECIP DUE TO PUSH IN SATURDAY NIGHT...WITH RAIN FALLING
HEAVILY AT TIMES ACROSS E MA INTO RI/NE CT. THIS COULD PRODUCE URBAN
AND POOR DRAINAGE FLOODING...ESPECIALLY SINCE THIS WILL FALL IN
THOSE AREAS THAT RECEIVED THE HEAVIEST SNOWFALL SEVERAL DAYS AGO.
HOWEVER...THE BIGGER PROBLEM WOULD BE WELL INLAND /S NH AND N
CENTRAL AND W MA/ WHERE TEMPS WILL BE CRITICAL...WHICH COULD MEAN A
MIX BACK TO FREEZING RAIN AND/OR SLEET. DO NOTE THAT WINDS WILL
SHIFT TO E-SE AND WILL INCREASE...WHICH MAY HELP IN MIXING THE LOW
LEVELS AND HOLDING TEMPS UP. WILL NEED TO BE MONITORED VERY
CLOSELY...ESPECIALLY IF THE WINDS DO NOT MIX AND TEMPS DROP. HAVE
CONTINUED WITH CATEGORICAL POPS.
HAVE CONTINUED WITH LIKELY POPS FOR MOST AREAS INTO SUNDAY MORNING.
CURRENT TIMING SUGGESTS THAT THE PRECIP WILL TAPER OFF FROM SW-NE BY
MIDDAY ACROSS N CT/SW MA...BUT MAY LINGER ACROSS S NH/E MA THROUGH
THE DAY. AGAIN...COULD STILL SEE MIXED PRECIP ACROSS INLAND AREAS
THAT SHOULD CHANGE BACK TO RAIN BEFORE ENDING. HAVE ENDED ALL PRECIP
EARLY SUNDAY NIGHT FOR NOW.
MONDAY-TUESDAY...WILL CONTINUE WITH A DRY BUT COLD FORECAST FOR
NOW...BUT ALL DEPENDS UPON HOW FAST THE WEEKEND SYSTEM MOVES OUT DUE
TO BLOCKING UPPER LEVEL PATTERN. HAVE LOW CONFIDENCE WITH THIS
PORTION OF THE FORECAST.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
TODAY AND TONIGHT...
VFR CONDITIONS WITH CIGS EXPECTED AT 4K TO 5K FEET. THERE ARE 2K TO
3K FOOT CIGS IN THE MOUNTAINS AND NEAR OTTAWA CANADA...BUT THESE
SHOULD STAY NORTH OF OUR AREA. HIGH CONFIDENCE IN CIGS
DEVELOPING...MEDIUM CONFIDENCE THAT CONDITIONS REMAIN VFR. FLURRIES
POSSIBLE THIS AFTERNOON THROUGH EARLY TONIGHT MAINLY MHT-BOS-FMH-
HYA-ACK.
THURSDAY...VFR. WINDS BECOMING NORTHEAST BUT REMAINING BELOW 15
KNOTS.
CHRISTMAS DAY...VFR WITH INCREASING CIRRUS AT 25K FEET.
OUTLOOK...FRIDAY NIGHT THROUGH SUNDAY...
FRIDAY NIGHT...VFR CIGS.
SATURDAY...VFR TO START...LOWERING TO MVFR OR IFR FROM W-E AS RAIN
OR MIXED PRECIPITATION PUSHES E. LOW CONFIDENCE ON TIMING.
SATURDAY NIGHT AND SUNDAY...IFR CIGS AND MVFR-IFR VSBYS LIKELY WITH
RAIN OR MIXED PRECIPITATION. LOW CONFIDENCE ON TIMING.
&&
.MARINE...
TODAY...
NORTHWEST WINDS 20 TO 25 KNOTS SLOWLY DIMINISHING. SMALL CRAFT
ADVISORY WILL CONTINUE TO MOST OF OUR WATERS. BOSTON HARBOR AND
NARRAGANSETT BAY WILL GUST NEAR 20 KNOTS BUT SHOULD REMAIN BELOW
SMALL CRAFT LEVELS.
TONIGHT...
HIGH PRESSURE BUILDS NORTH OF NEW ENGLAND. THIS WILL BRING WINDS
AROUND TO NORTH OVERNIGHT. FREEZING SPRAY POSSIBLE.
THURSDAY...WINDS INCREASE TO 20-30 KNOTS OVER MOST OF THE WATERS
ESPECIALLY THURSDAY MORNING. THIS BRINGS SEAS UP TO 5-10 FEET
ESPECIALLY EAST OF CAPE COD. WINDS AND SEAS DIMINISH BY THURSDAY
NIGHT.
CHRISTMAS DAY...LIGHT NORTHEAST TO EAST WINDS. SEAS ON MASSACHUSETTS
BAY AND THE OUTER WATERS WILL REMAIN AT 5 FEET OR HIGHER SO SMALL
CRAFT ADVISORIES WILL LINGER OVER THOSE WATERS.
OUTLOOK...FRIDAY NIGHT THROUGH SUNDAY...
FRIDAY NIGHT...SMALL CRAFT WINDS AND SEAS CONTINUE.
SATURDAY-SUNDAY...E-SE WINDS INCREASE TO GALE FORCE MAINLY OVER THE
OUTER WATERS WITH GUSTS UP TO 40 KT POSSIBLE. SEAS MAY BUILD UP TO
10-12 FT...HIGHEST ON THE SOUTHERN OUTER WATERS. WINDS SHIFT TO W
AND DIMINISH TO SMALL CRAFT LATER SUNDAY.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
ANZ231>235-251.
SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR ANZ237-250-
254>256.
&&
$$
SYNOPSIS...WTB/EVT
NEAR TERM...WTB
SHORT TERM...WTB
LONG TERM...EVT
AVIATION...WTB/EVT
MARINE...WTB/EVT
