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fxus61 kaly 220259 
afdaly 


Area forecast discussion 
National Weather Service Albany New York 
959 PM EST Friday Nov 21 2008 


Synopsis... 
the cold weather pattern across the region will continue 
through the weekend...with some moderation to near normal 
temperatures early next week. An upper level disturbance will 
produce isolated to scattered snow showers across the region 
tonight...with more widespread and heavier snow shower activity 
downwind of Lake Ontario. 


&& 


Near term /through Saturday/... 
quick update just for cosmetic purposes. Lake effect snow band has 
gotten a little better organized over Schoharie County. Have issued 
nowcasts for it and probability of precipitation are there for tonight. It is broken 
up...not continuous so we are not expected too much accumulation. 


Otherwise...cold and clear to partly cloudy with temperatures 
tumbling to the teens...except single numbers across the 
Adirondacks. An occasional breeze will drop wind chills close to 
zero degrees at times. 


Highs Saturday will range from around 20 in the Adirondacks...to the 
lower 30s in the middle Hudson Valley. Wind chills will remain mostly 
in the teens. 


&& 


Short term /Saturday night through Monday/... 
Lake effect activity however will actually increase Saturday 
night in the western Mohawk Valley as the flow becomes aligned 
with the Mohawk Valley. Thus have put high chance probability of precipitation in the 
forecast for this region. 


Lows Saturday night will be in the teens once again with some single 
number readings across the higher terrain. 


Lake effect snow showers on Sunday will slowly transition from a 
290 or 300 degree orientation late Saturday night...to a 260 to 
270 degree orientation Sunday afternoon. The intensity of the snow 
band is expected to decrease as the flow becomes more 
anticyclonic and instability decreases somewhat by late Sunday 
afternoon. 


On Sunday highs will be warmer as winds switch to southwest as 
the center of a large surface high pressure system moves off the 
the middle Atlantic coast. The highs Sunday will be in the upper 20s 
to upper 30s. 


Sunday night looks quiet as flow briefly becomes anticyclonic 
which should bring an end to any lake activity although middle and 
high clouds will start to increase ahead of clipper type system 
for Monday...thus lows will be higher compared to recent nights 
with lows in the 20s. 


Expect that much of Monday will be dry...but due to uncertainty 
with timing will gradually increase probability of precipitation during the afternoon to 
slight chance east and chance west. Temperatures will be milder on 
Monday with highs near normal and if precipitation arrives during the 
afternoon ptype would likely be rain far southeast with a mixture 
of snow and rain central sections and snow north. 


&& 


Long term /Monday night through Friday/... 
the extended period begins with low pressure moving into western New 
York from the Great Lakes. The GFS is a little faster than the 
European model (ecmwf) in moving the quantitative precipitation forecast in...but the European model (ecmwf) provides greater qpfs... 
despite the fact that the 12z run of the GFS indicates explosive 
development of the low which becomes a translation to a developing 
coastal system...which then cuts off and meanders around southern 
New York/New England through Wednesday. The GFS also draws in much 
warmer air up through 850 mb...leaving only the Catskills to the 
Adirondacks in good shape for significant snowfall as it appears 
right now. The European model (ecmwf) hangs back for longer before the energy is 
drawn into the coastal system much later in the game...Thu/Fri. 
Have gone somewhere in between the GFS and European model (ecmwf) solutions because 
the greater persistence of the GFS low compared to the 12z Thursday 
run...and the much further west cutting off of the European model (ecmwf) low since 
its 12z run...both point to low confidence and continued uncertainty 
concerning the outcome of this event given either model. But right 
now both models draw in above zero air through 850...with the GFS 
taking it a little further in to the west. Once the surface low 
lifts north by late Wednesday...some dry slotting should occur across the 
southern portion of the County Warning Area... and a persistent westerly flow 
through the vertical sets up...with the western Adirondacks in play 
for some lake effect snow showers late Wednesday and Thursday. The lake effect 
could be more extensive in coverage as indicated by both the GFS and 
European model (ecmwf)... but for now...with the vertical profile appearing to take 
shape... have included just slight chance for the remainder of the County Warning Area. 
It now looks as though Friday will be the best day of the work 
week...not Thanksgiving as was thought yesterday. Although plenty 
of cloudiness will linger behind the slowly departing low...some sun 
is likely. 


Surface temperatures will warm to a little above freezing on Tuesday. The cold 
front associated with the low...while possibly not extending north 
into our County Warning Area...will be well to the east by then. The more 
significant warming occurs aloft. Surface temperatures Tuesday night drop again 
below freezing...but the close proximity of the low and the 
enhancing wraparound as the low cuts off will help warm the temperatures 
above freezing at most locations again on Wednesday. By Thursday...there is no 
more cold air pouring in...so daytime highs Thursday and Friday should have 
no problem bouncing back into the 30s. 


&& 


Aviation /00z Saturday through Wednesday/... 
VFR conditions through Saturday. Some scattered to occasionally 
broken clouds tonight. Any significant snow showers should remain 
well west of the metar sites. The wind will become gusty by midday 
Saturday with the northwest to north wind possibly exceeding 20kts at kalb at 
times. Clouds will become a bit more broken at kalb/kgfl. 






Outlook... 
Sat nght-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. After 
that...all bets are off. 


A complex coastal storm will likely bring significant precipitation 
to the region Tuesday...possibly continuing into Thanksgiving day. 
The question is whether the precipitation will be primarily rain... 
snow or a mix. 


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. 


&& 


$$ 
Near term...hwjiv 
aviation...hwjiv 
hydrology...hwjiv 

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