Weather

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Area forecast discussion 
National Weather Service Buffalo New York 
259 am EDT Sat Oct 11 2008 


Synopsis... 
Indian Summer is in full swing across the lower Great Lakes with 
plenty of sunshine and well above average temperatures lasting right 
through the Columbus Holiday weekend. The next chance of rain will 
not arrive until at least Tuesday afternoon as a cold front 
approaches the region. A return to cooler and more seasonable 
temperatures is expected by later next week. 


&& 


Near term /through tonight/... 
high pressure centered over New York state will drift slowly to the 
east today and tonight. Expect the usual valley fog to form in the 
southern tier before daybreak...but it should burn off quickly with 
the onset of daytime heating. Otherwise...expect sunny skies with 
nothing more than a few cirrus clouds resulting from a jet streak 
passing to our north. 


The combination of abundant sunshine and 850 mb temperatures ranging 
from +10c to +14c will allow temperatures to warm into the lower 70s 
across most of the County Warning Area. The light gradient wind will also allow weak 
lake breezes to kick...especially off Lake Ontario. 


With mainly clear skies and light winds tonight...area temperatures 
will cool through the 40s again...with a few readings in the upper 
30s expected across the southern tier valleys and east of Lake 
Ontario. 


&& 


Short term /Sunday through Monday night/... 
ridging surface and aloft will continue to dominate most of the 
region Sunday and Monday. A middle level shortwave digging across 
northern New England will allow a very weak backdoor front to drop 
into the Saint Lawrence valley and eastern New York Sunday night into 
Monday. This may bring a few periods of cloudiness to the Saint 
Lawrence valley and the Eastern Lake Ontario region...possibly as 
far west as Oswego County. Otherwise the rest of the County Warning Area will bask 
in nearly full sunshine both days to wrap up the Holiday weekend. 


850mb temperatures both Sunday and Monday will range from about +15c west 
to +12c east. This should easily support upper 70s across western New York 
with full sunshine. Would not be surprised to see a few 80f readings 
in the normally warmer spots east of Buffalo and in the Genesee 
Valley. Record highs for Sunday and Monday are 81/82 at buf and 
84/83 at roc. These records will probably stand although we may get 
close on the weaker buf records. Across the north country...slightly 
cooler temperatures aloft and some cloud cover will keep temperatures down 
comparatively...but still well above average with low 70s. 


&& 


Long term /Tuesday through Friday/... 
the highly amplified meridional flow pattern across the eastern 
Pacific and noam sectors in the short term will tend to deamplify 
during the long term period with the flow becoming more zonal later 
next week...albeit with some southward push of cooler and more 
seasonable heights/temperatures. Looking deeper into the long 
term...newest 00z/11 GFS continues the trend of the 12z/10 gefs 
ensembles in suggesting the potential for some amplification during 
the 7-10 day range and perhaps some more bonifide cold air moving 
into the northeast. 


Looking at the details...the main forecast challenge revolves around 
the timing of a frontal system at midweek. Moisture channel imagery 
early this morning showing an anomalously deep closed low over the 
Great Basin. Another strong cyclone just south of the Aleutians will 
eventually make landfall in British Columbia and act as a kicker to 
eject the western Continental U.S. Low. 00z model guidance continues to show 
this system shearing northeast to James Bay by Tuesday evening... 
with a slower trend noted in most of the operational and ensemble 
guidance. Gulf inflow appears to be limited in advance of this 
system...and the bulk of the stronger large scale forcing for ascent 
is forecast to lift well north into Canada. Given the lack of strong 
dynamics and moisture...this looks to be a rather meager quantitative precipitation forecast event. 


If the 00z/11 model guidance were to verify...the precipitation chances 
would hold off until Tuesday night. Given this is still 4 days 
away...prefer not to jump completely on board with the new timing 
but rather trend the forecast in that direction to maintain good 
forecast continuity. For now pushed the start time of precipitation back to 
Tuesday afternoon...and if future model runs continue to show the 
slower timing this can be pushed back further in future forecast 
cycles. Maintained Middle Range chance probability of precipitation Tuesday night for the 
frontal passage...then low chance probability of precipitation Wednesday mainly for 
lingering morning precipitation with the frontal passage. 


Thursday into Friday forecast uncertainty increases. The bulk of the 
operational and ensemble model guidance suggests a broad/weak trough 
will begin to evolve over southeast Canada. This will likely allow 
cooler air to gradually settle across the Great Lakes and New 
England. The weakly cyclonic flow aloft combined with colder air 
crossing the Great Lakes may be enough to generate a few showers... 
thus maintained chance probability of precipitation for late next week with temperatures 
dropping back to near seasonal values. 


&& 


Aviation /07z Saturday through Wednesday/... 
high pressure centered over New York state will maintain ideal 
flying conditions through the taf period...with the bulk of the area 
experiencing unlimited ceilings/visibilities and light winds. The lone 
exception to this will be in the southern tier valleys early this 
morning where the usual valley fog will form and produce localized 
reductions to IFR. However...because the dewpoints are lower early 
this morning...the valley fog may burn off a little sooner than it 
did Friday morning. 


Outlook... 
Sunday through Wednesday...generally VFR...except for typical late 
night/early morning valley fog in the southern tier. 


&& 


Marine... 
very quiet through the Holiday weekend with winds generally less 
than 10 knots and flat wave action. With abundant sunshine and warm 
temperatures combined with light surface winds...expect to See Lake 
generated winds each of the next 3 days with onshore lake breezes 
during the afternoon and offshore land breezes later at night and 
early morning. This is more reminiscent of springtime than middle fall. 


&& 


Buf watches/warnings/advisories... 
New York...none. 
Marine...none. 


&& 


$$ 


Synopsis...Hitchcock 
near term...tjp 
short term...Hitchcock 
long term...Hitchcock 
aviation...tjp 
marine...Hitchcock 

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