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Area forecast discussion 
National Weather Service Taunton Massachusetts 
1115 am EST Thursday Dec 4 2008 


Synopsis... 
a cold front will cross the region this afternoon and evening. Much 
colder weather will move in on Friday and continue into Monday. A 
low pressure system may graze southern New England with a touch of 
wintry weather late Saturday night into Sunday. Another low pressure 
should arrive toward the middle of next week. 


&& 


Near term /until 6 PM this evening/... 
leading edge of clouds moving into SW New Hampshire/west Massachusetts at 15z. Also noting a 
few light showers reaching ground into Berkshire County. Radar 
showing a batch of showers from near kafn-kore-kbaf into Litchfield 
County but not seeing anything reach ground. 


Have updated zones and grids to reflect temperatures a bit warmer than 
previously forecast...mainly over western areas. Have upped the maximum 
temperatures a few degrees. Also noting good mixing with winds picking up even 
over the land. Spotter reported wind gust to 46 miles per hour at around 10 am 
in Milford Massachusetts. Also note gust to 34 knots at kmqe. Have increased the 
wind a bit as well. At this point...feel the highest winds will 
occur through 18z then should start to diminish as clouds move in. 


See main batch of showers holding together across upper Hudson 
Valley into S central New York state late this morning...so feel that 
there will be a somewhat better shot of precipitation into western areas. 
Have increased probability of precipitation to chance for S New Hampshire/north central and west Massachusetts for this 
afternoon. Still agree with previous forecast and anticipate precipitation 
to tend to break apart as it moves into central and eastern areas by 
this evening. 


Expect front to approach western areas by 6 PM or so. 


&& 


Short term /6 PM this evening through 6 PM Friday/... 
tonight... 
the brief scattered light rain showers/sprinkles should move through 
the coastal plain during the evening. Otherwise...expect skies to 
become mostly clear to partly cloudy. Much colder air will be 
ushered in behind the cold front. Low temperatures should fall into 
the 20s across most locations...with lower 30s expected in downtown 
Boston/Providence. 


Friday... 
a partly sunny but much colder day is on tap for the region. Model 
cross sections indicate a bit of high cloudiness along with the 
formation of a fair amount of diurnal cumulus clouds across the 
interior during the afternoon. Can not even rule out a passing 
flurry or two across the east slopes of the Berkshires...but not 
Worth inserting into the forecast at this point. However...the main 
story will be a return to cold weather with 850 mb temperatures 
dropping to between -10c and -12c. Highs should only reach into the 
middle to upper 30s across the interior...to the lower 40s along the 
coastal plain. 


&& 


Long term /Friday night through Wednesday/... 
04/00z NAM has much better support from the international models 
than the GFS...and was used as the basis for this forecast through 
Saturday night. GFS solution is too progressive...and possibly too 
far out to sea with its track of the secondary coastal low pressure 
Saturday night into Sunday. NAM and 04/00z GFS ensemble mean are 
closer to the coast...but still just outside the benchmark of 
40n/70w. 


Confidence in the forecast after Monday really drops due to 
significant differences in the forecast middle level flow. 04/00z 
operational GFS swings a polar vortex into the Great Lakes 
Wednesday...which looks way overdone. 04/00z European model (ecmwf) does not look to 
be much better. Decided to use a blend of the GFS and European model (ecmwf) from 
Sunday through Tuesday...then switched to the GFS ensemble mean due 
to the uncertainty. 


High pressure Friday night moves quickly into the Canadian Maritimes 
Saturday. This should set the stage for a coastal low pressure to 
develop in the Middle Atlantic States late Saturday night. Expecting a 
light snow to spread from southeast to northwest after midnight 
across most of southern New England. Rain may mix in from time to 
time across Cape Cod and the islands as the ocean is still fairly 
warm. This storm move northeast Sunday night. 


High pressure should arrive for Monday and Monday night. 


Latest MOS guidance was close to previous forecast temperatures...so 
only made some minor tweaks. 


&& 


Aviation /16z Thursday through Monday/... 
this afternoon...generally VFR conditions. Noting a few light 
showers at kore at 16z at kore and at kpsf at 15z. Not expecting 
visibility restrictions at this point. However...as main area of showers 
moves in after 18z...may see a brief MVFR ceiling/visibility restriction at a 
few spots mainly over central and western areas. 


Will see some gusts over 30 knots over coastal plain through 18z with 
good mixing in place. Note a 45 knots wind at 3kft on kbox VAD wind 
profiler. Also note some bumps on approach to kbed with low level 
mixing. Should see this cut back this afternoon as clouds move 
in...cutting down on mixing. 


Tonight...low probability of brief MVFR conditions on the coastal 
plain during the evening with a passing light rain shower/sprinkle. 
Otherwise...VFR 


Friday...VFR. 


Outlook...Friday night through Monday... 


Friday night and Saturday...VFR. Low probability of MVFR conditions 
in scattered late afternoon snow or rain showers along the coast. 


Saturday night into Sunday...periods of MVFR developing in light 
snow after midnight Saturday night into Sunday. 


Sunday night into Monday...conditions improve to VFR by morning. 
Wind gusts up to 30 knots possible late Sunday into Sunday night across 
Cape Cod and the islands. 


&& 


Marine... 
this afternoon...winds picking up with approach of cold front. Have 
kept gale gusts going for southern waters this afternoon. Note that 
buzm3 tower reported gusts to 37 knots at 15z. Also kept small crafts 
going on Boston Harbor...Narragansett Bay and the waters from 
Merrimack River to Plymouth. Note seas up to 7 feet at unh buoy well east 
of the Merrimack River. Appears low level jet will pass east of the 
waters by this evening. 


Tonight...winds will gradually turn northwest overnight behind the 
cold front. We still may see wind gusts in the low 20 knots with 
good mixing in the cold air advection pattern. Shorter fetch though 
should allow seas to slowly diminish...but we will continue to need 
headlines for our southern open waters for the remainder of the 
night. 


Friday...we should be able to remove all headlines by afternoon as 
high pressure gradually builds in from the west and left over seas 
diminish. However...20 knot wind gusts will remain possible with 
cold advection promoting good mixing over the ocean. 


Outlook...Friday night through Monday... 


Winds and seas diminish Friday night into Saturday as a high 
pressure crosses the waters. A coastal low pressure is expected to 
pass southeast of the waters Sunday. Winds and seas will increase... 
with a Small Craft Advisory likely needed by Sunday night...with 
perhaps gale force gusts across the outer waters. Winds and seas 
gradually diminish Monday as a high pressure builds across the 
waters. 


&& 


Box watches/warnings/advisories... 
CT...none. 
Massachusetts...none. 
New Hampshire...none. 
Rhode Island...none. 
Marine...Gale Warning until 3 PM EST this afternoon for anz231>235- 
237-254-255. 
Small Craft Advisory until 5 PM EST this afternoon for anz230- 
236-250. 


&& 


$$ 
Synopsis...Belk/Frank 
near term...evt 
short term...Frank/evt 
long term...Belk 
aviation...Belk/Frank/evt 
marine...Belk/Frank/evt 

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