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fxus61 kaly 221142 
afdaly 


Area forecast discussion 
National Weather Service Albany New York 
640 am EST Sat Nov 22 2008 


Synopsis... 
the cold weather pattern across the region will continue through the 
weekend...with some moderation to near normal temperatures early 
next week. Snow shower activity will continue downwind of Lake 
Ontario...with the heaviest activity over central New York. 


&& 


Near term /through Sunday/... 
main weather features will be the unseasonably cold air...and lake 
effect snow showers. Only scattered lake effect snow showers 
expected over our forecast area today and tonight because lake 
effect snow bands aligned in about a 320 degree orientation. This 
keeps most of the activity to the west of the kaly forecast area... 
and it also has a tendency to produce a multi-banded lake response. 


Moisture rotating around the rapidly developing low pressure system 
off the New England coast may bring some flurries or snow showers to 
the rest of the region this morning and have included the slight 
chance of flurries or snow showers in all other zones. 


On Sunday the lake effect snow band will be shifting northward... 
into a 260-270 degree alignment...by the end of the day. 


Temperature wise expect temperatures 10 to 15 degrees below normal today 
and tonight...with a brisk wind making it feel even colder. Highs 
today will be in the upper teens to lowers 30s...and lows tonight 
will be in the single numbers and teens. Northwest winds of 15 to 25 
miles per hour with gust to 30 to 35 miles per hour will make it feel much colder. The 
winds will subside somewhat tonight...into the 10 to 20 miles per hour range. 


A slight moderation on Sunday as temperatures reach the upper 20 top upper 
30s. Winds will become westerly at 10 to 25 miles per hour. 


&& 


Short term /Sunday night and Monday/... 
the moderation in temperatures will continue during this period and lake 
effect will no longer be an issue. A warm front may produce some 
light snow showers across the Adirondack and Mohawk Valley zones 
during this period...otherwise the forecast will be dry for the rest 
of the forecast area. By late in the day on Monday have introduced a 
low chance of light snow or light rain as the next system 
approaches. 


Lows Sunday night will be between 15 and 25...and the highs Monday 
in the middle 30s to middle 40s. 


&& 


Long term /Monday night through Friday/... 
on Monday night the 500 hpa cutoff low over Michigan drops 
south across the Great Lakes into central PA...as the associated 
surface low moves into the lower Hudson Valley and deepens. The 
GFS and European model (ecmwf) models only differ slightly on the pattern of the 
500 trough and cutoff but as time GOES on the GFS keeps the upper 
low farther south than the ecm. On the surface the GFS moves 
the low center farther east while the European model (ecmwf) holds it back some 
but the two come closer together Tuesday evening although the 
GFS deepens it considerably more. Both models keep the low in 
the general vicinity through at least Wednesday but the GFS is 
particularly depressing in keeping the low over the region 
through the Thanksgiving Holiday and only then slowly moving 
it east in time for the shoppers on black Friday. Of particular 
interest is the temperature profile of the lower layers on Monday 
night and Tuesday with a low level flow out of the south off the 
still relatively warm ocean...after all...synoptically 
speaking...the Gulf Stream isn/T all that far away. The 925 hpa 
temperature at Albany reaches zero(c) Monday evening and stays 
close to the borderline until the cold air sweeps in from 
the west to the south...meanwhile the warmer air nudges into 
the central Adirondacks from off the Gulf of Maine by midday 
Tuesday...before the cold air from the north and west overspreads 
the entire forecast area. This all suggests a rather messy mix 
of rain and snow for the event. Total precipitation accumulations are 
not as high as I would tend to believe from such a storm with 
0.50-0.75 in the European model (ecmwf)...and 0.5 to 1.5 in the GFS...and a paltry 
0.25 to 0.75 with the NAM. I would be more inclined to think 
around a inch liquid...give or take...with the obvious variations 
due to terrain...which could pile up seven plus inches of snow 
up north with a few inches of snow...then rain...than a couple 
inches more to finish it off farther south. And the model and HPC 
analysis suggests that at best the weather will be unsettled... 
if not downright nasty...for both the Thanksgiving Holiday and 
the day before...when many people travel for the Holiday. The 
cutoff low lifts north into Canada...as high pressure over the 
southern states wedges north...for black Friday...suggesting 
that perhaps the weather might not be too bad for those who are 
planning to get that shopping done. 


It appears the MOS temperatures for Tuesday morning lows are 
too cold...with warm air pouring into the region...so we have 
bumped them up a few degrees. Also it looks like the low will 
occur around midnight...with temperatures rising during the 
night. Aside from that...stayed pretty close to gmos guidance. 


&& 


Aviation /12z Saturday through Wednesday/... 
VFR flight conditions will predominate across the region through 
this evening...with lots of clouds across the area except for 
the middle Hudson region of New York and New England south of the Mass 
Pike. A large area of low clouds was being brought around the 
north side of the low in the Canadian Maritimes and northerly 
low level winds were bringing it down the Champlain Valley 
into the region while a second band of clouds was lake effect 
from off lakes Huron...Ontario...and Erie. At times there was 
a narrow band of relatively clear air between them while at 
other times the two bands merged just west of the Albany area. 
Some areas of MVFR ceilings may be expected over the higher terrain 
of the Adirondacks and Catskills throughout the day today... 
but for the most part ceilings over the Hudson and Mohawk valleys 
should remain above VFR mins. We have added a wind shear group 
for the Albany taf based on both speed and direction shear 
until the winds mix down later this morning...along with the 
directional shear caused by the terrain and funneling down 
the Mohawk Valley. Bands of lake effect clouds and snow showers 
extended from the southeast corner of Lake Ontario toward the 
Delaware Water Gap well west of the Hudson Valley...but these 
bands may shift northward later today and possibly extend far 
enough east to reach the Albany area this afternoon...so we have 
included a vicinity group /vcsh/ in the Albany taf. The other 
Hudson Valley taf sites should not be affected as kgfl will be 
north of the band and downsloping will likely diminish most... 
if not all of...the snow showers that head toward kpou. 


Winds in the predawn hours will generally be west/northwest less 
than 10 knots. They will increase and become gusty shortly after 
the sun rises...and by midday the wind is likely to exceed 20kts 
at kalb at times. Broken to overcast clouds will stream down from 
the lake in the band...but north and south of the band only a few 
low clouds are likely under some middle/high level clouds. Local 
terrain effects may include low level shear and funneling. 


Outlook... 
tonight-Mon...VFR...no sig weather. 
Monday nght...MVFR/IFR...chc -sn/-ra. 
Tue-Wed...IFR..chc -sn/-ra. 


&& 


Hydrology... 
no hydrology problems through Monday as it will remain mainly dry 
with any precipitation falling as light snow showers. 


A complex storm will likely bring significant precipitation to the 
region Tuesday...possibly continuing into Thanksgiving day. The 
latest round suggests that snow will predominate over the higher 
terrain north and west...with a mixture of snow and rain farther 
south. At this point...it does not look like flooding will be a 
problem aside from paved areas where drainage may be blocked by 
piles of snow or debris. However a potential exists that the 
storm could bring more rain than currently expected. 


For details on the rivers...please visit the advanced hydrologic 
prediction service /ahps/ graphs on our website. 


&& 


Aly watches/warnings/advisories... 
CT...none. 
New York...none. 
Massachusetts...none. 
Vermont...none. 


&& 


$$ 


Synopsis...gjm 
near term...gjm 
short term...gjm 
long term...rck 
aviation...rck 
hydrology...rck 

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