213 
fxus61 kbgm 211136 
afdbgm 


Area forecast discussion 
National Weather Service Binghamton New York 
636 am EST Sat Nov 21 2009 


Synopsis... 
a moist northwesterly flow of air will keep our skies cloudy today 
with high temperatures either side of 50. By the 2nd half of the 
weekend an area of high pressure now located over the Ohio Valley 
will build overhead helping to clear out the clouds making for a 
very bright end to the weekend. 


&& 


Near term /through tonight/... 
as of 250 am...mostly cloudy skies continue across the area at the 
moment with dry weather. Despite a northwest flow over the lakes 
with 850 temperatures around +2c/3c we are just not cold enough for lake 
effect activity. A shortwave that is now moving through lower 
Michigan into southern Ontario will track east this morning. Given 
that radar imagery to our west shows nothing I am not expecting 
any precipitation today. For the rest of today our area will be 
stuck with a very shallow layer of strato-cumulus based on both the NAM 
and GFS. Both models show greater than 90% relative humidity from just above the 
surface up through about 3kft. It certainly is a very shallow 
layer as you don't have to go much above that to find an absence 
of moisture. While a peek or two of sun is possible late in the 
day almost anywhere this seems to be about the extent of any hope 
for sun. The lone exception may be across the far southeast where 
climatology favors a slightly better chance for a few sunny 
breaks. 925 temperatures around 2/3 c support highs near 50...with 
slightly warmer 925s near kelm supporting highs in that area 
closer to 53. 


The often moisture laden NAM keeps in moisture through tonight 
while the GFS seems to have a better idea by thinning out the deck 
of clouds gradually. The key word tonight will be gradually as 
even the more optimistic GFS does not show drying below the 
inversion until after 06z. 


&& 


Short term /Sunday through Monday night/... 
as of 250 am...Sunday will be the pay off day of the weekend with a 
surface high pressure system building right overhead. Any 
lingering clouds from the overnight will quickly be a distant 
memory with a sun filled day. While abundant sunshine is expected 
both the NAM and GFS show US barely mixing to 925 mb and with hp 
in control winds will be very light. Adding to the temperature forecast 
problem Sunday is the fact that the GFS and NAM are about 3c apart 
on 925 mb temperature forecasts. The GFS with 925s around 5 or 6 is 
suggestive of highs in the middle 50s while the NAM is closer to 
50 again with 925s around 3. I split the difference for now but my 
gut says despite the sunshine the cooler met guidance will be more 
accurate given the limited mixing potential (light winds, low 
inversion). 


Forecast problems begin by Monday as the models are having trouble 
trying to resolve the 500 trough now over southeast Texas. The GFS 
seems to be the outlier in bringing in moisture on 
Monday...by keeping the 500 trough much stronger. The other 
models...especially the Gem and NAM keep the 500 trough more of an 
open wave and focus more on the potential coastal development off 
the Delaware-Maryland-Virginia. This would keep the bulk of the moisture to our 
east through Monday evening. A blend between the NAM and Gem was 
used with some showers possible late in the day from nepa up 
through the Catskills. The new Euro is in and seems to be a 
compromise between the GFS Camp and the Gem/NAM keep by keeping 
the wave more open (like the NAM/Gem models) but still showing 
some moisture in our area. Overall the idea remains the 
same...best chances for moisture will be the farther south/east 
you go. 


&& 


Long term /Tuesday through Friday/... 
updated as of 101 am...no appreciable changes to the forecast this 
period. 


Model consensus still indicates that the majority of the rainfall 
with the surface wave off the East Coast on Tuesday will stay 
east of the forecast area...so only slight chance probabilities 
look good from this Vantage Point. 


The start of the Holiday period from Wednesday through Friday 
still carries plenty of forecast uncertainty at this time. 
Overall...longer range guidance is leaning towards a slower onset 
of precipitation (more like on Thanksgiving day or Thanksgiving 
night)...with Wednesday mainly dry. The GFS...however...is much 
faster in carrying energy eastward into our neck of the Woods by 
Wednesday...with showers beginning at that point. Given all the 
model discrepancies...won't tinker much with our going 
forecast...which does mention at least a low chance of showers on 
Wednesday. One well agreed upon scenario is that Wednesday and 
Thanksgiving day will continue to feature mild temperatures. 


By Friday...it appears that colder air will begin to filter 
in...as a storm system winds up offshore. This would likely 
result in some lake response...with a good shot of rain and snow 
showers. 


&& 


Aviation /12z Saturday through Wednesday/... 
for ksyr...krme...kith...and kbgm...MVFR ceiling restrictions 
anticipated for most of the day. Late this afternoon and early 
evening...clearing skies anticipated...with a return to VFR at 
that point. 


West to northwest winds 5-10 knots today...turning light and 
variable after sunset. 


At kelm...after a period of MVFR ceilings this morning...cloud bases 
should lift enough to allow a return to VFR this afternoon and 
evening. IFR conditions in fog could develop towards daybreak Sunday. 


West to northwest winds 5-10 knots today...turning light and 
variable after sunset. 


For kavp...mainly VFR expected through 12z Sunday. A very brief period 
of MVFR ceilings possible early this morning. 


Northwest winds 5-10 knots today...will turn light overnight. 


Outlook... 


Sat night...some MVFR ceilings possible. 
Sun/Sun night...VFR. 
Monday/Monday night...MVFR possible in showers. 
Tuesday/Wednesday...VFR. 


&& 


Bgm watches/warnings/advisories... 
PA...none. 
New York...none. 


&& 


$$ 
Synopsis...emh 
near term...emh 
short term...emh 
long term...mlj/rrm 
aviation...mlj