439 
fxus61 kokx 030820 
afdokx 


Area forecast discussion 
National Weather Service Upton New York 
320 am EST Wednesday Dec 3 2008 


Synopsis... 
high pressure over the middle Atlantic coast moves offshore today. A 
cold front crosses the local area late Thursday afternoon into 
evening...followed by cold Canadian high pressure building over the 
region for Friday and Saturday. An Alberta clipper will pass over 
the region on Sunday...followed by high pressure building back on 
Monday. 


&& 


Near term /through tonight/... 
ridging aloft today with surface high moving off the middle Atlantic 
coast. Mostly sunny today. NAM MOS was used for highs as it was the 
coolest...thinking that we're mixing up to around 925 mb (as per 
BUFKIT forecast soundings) where the forecast temperature at this 
level during this afternoon will be around -2c. 


&& 


Short term /Thursday through Friday night/... 
fair weather tonight with some clouds filtering in during the 
overnight hours as a cold front approaches from the west. Low 
pressure associated with this front will be moving through southeast 
Canada during Thursday. Timing of frontal passage appears to be late 
in the afternoon into Thursday evening. After trending drier 
previously...the models have returned to a wetter solution with this 
front with the past couple of model runs. As the front becomes 
aligned with the middle-level flow...it takes on anafront 
characteristics with short term models showing quantitative precipitation forecast behind the front. 
Will cap probability of precipitation at chance during this period...with overall best chances 
of precipitation during Thursday afternoon and evening. As for precipitation 
type...freezing levels will be high enough to support rain showers 
for all spots during the daytime hours of Thursday. At night...snow 
may mix in...but not anticipating any problems with this as precipitation 
will be on the light side. NAM/mav MOS blend with minor adjustments 
was used for highs as FWC MOS looked a little too warm in spots. 


Weak high pressure builds in for Friday. Partly cloudy and colder 
than Thursday. Used coldest MOS guidance for highs...which was mav 
MOS. Middle level shortwave passes through during the overnight hours 
of Friday...but column looks rather dry. Will keep forecast dry for 
now...but later shifts may have to at least throw some flurries into 
the forecast. 


&& 


Long term /Saturday through Tuesday/... 
03/00z run of European model (ecmwf) and operational GFS in pretty decent agreement 
regarding the pattern in the start of the long term. 500 mb trough axis 
moves from the plains to the Great Lakes...with weak surface high 
over northeast. Will go with a partly sunny and dry day on Saturday 
with below normal temperatures. Trough axis then reaches the northeast 
Sunday afternoon/night. At the surface...a clipper approaches from 
the Great Lakes...but weakens in favor of a developing coastal low. 
European model (ecmwf) closes the 500 mb low and is stronger with this coastal low. The 
low is not prognosticated to undergo significant deepening until it is east 
of Cape Cod and heading towards the Canadian Maritimes. Will keep 
chance probability of precipitation Saturday night through Sunday night. Temperature profiles during 
this time period are cold enough for snow. 


High pressure builds in for Monday with gusty winds and temperatures below 
normal. Maybe a few flurries...but will keep the forecast dry for 
now. Next system may affect US with mixed precipitation on Tuesday 
as it approaches from the west. 


&& 


Aviation /08z Wednesday through Sunday/... 
VFR through 06z Thursday. 


Shortwave slides NE of region early this morning as high pressure 
builds from the south. Skies clearing as a result. High 
cloudiness moves over the terminals after 12z today as the ridge 
axis moves east. 


Light west-southwest flow...becoming southerly late this 
afternoon as high pressure slides offshore...strengthening along 
coastal terminals late Wednesday night ahead of approaching cold front. 


Outlook for 06z Thursday through Sunday...cold front moves 
through late Thursday night into Friday morning. Some flurries may 
accompany the front with local and brief MVFR to IFR visibilities. 
Strong and gusty northwesterly winds behind the front Friday will 
impact area terminals. Otherwise...VFR until late Saturday night 
into Sunday when a clipper system moves through the area bringing 
light snow with MVFR to IFR conditions. 


&& 


Marine... 
borderline Small Craft Advisory conditions currently. Wind gusts holding in the 20 to 
25 knots range with seas right around 5ft on the ocean. Current Small Craft Advisory on 
ocean waters expires at 16z. May be able to cancel the Small Craft Advisory early as 
conditions continue to slowly come down. 


Long period seas may be close to 5ft at times through Wednesday 
across far eastern ocean zones. 


Next event will be increasing southerly winds ahead of a cold front 
on Thursday. It will be very close to gale force gusts...so a gale 
watch may be issued later today. Sub Small Craft Advisory returns Friday into 
Saturday. 


Strong winds...possibly to gale force possible once again Sunday 
afternoon and evening behind another front. 


&& 


Hydrology... 
up to around a tenth of an inch of quantitative precipitation forecast anticipated for Thursday 
afternoon/Thursday night. Quantitative precipitation forecast forecast for Saturday night through 
Sunday night is quite uncertain...but a few tenths of an inch is 
possible. 


&& 


Okx watches/warnings/advisories... 
CT...none. 
New York...none. 
New Jersey...none. 
Marine...Small Craft Advisory for hazardous seas until 6 am EST early 
this morning for anz355. 
Small Craft Advisory for hazardous seas until 11 am EST this 
morning for anz350-353. 


&& 


$$ 
Synopsis...jc 
near term...jc 
short term...jc 
long term...jc 
aviation...bs 
marine...bs 
hydrology...jc