Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
932 PM EDT Wednesday Oct 1 2014
low clouds and fog are likely tonight. High pressure will bring a
dry and mild weather for Thursday. A strong cold front is then
expected to cross the region late Friday and Friday night...
bringing a greater likelihood of showers followed by much cooler
temperatures for the upcoming weekend.
Near term /through Thursday/...
strengthening high pressure will continue to ridge into eastern New
York tonight...while a narrow upper level ridge starts to build
across the lower Great Lakes. Drier air associated with these
features will bring about a general clearing trend across the
area. There will be a buildup of low clouds and patchy fog over
western third of Lake Ontario basin...but should be held to the
Canadian side of the lake as winds veer to southerly across
western New York. Lows tonight will be in the low to middle 50s.
On Thursday...the main axis of the high pressure ridge will slide a
little to the east of the region...with a return flow of southerly
winds helping to boost temperatures to the lower to middle 70s across the
region. Although there will be slightly drier surface conditions on
Wednesday...expect a buildup of stratocu and cumulus during the
afternoon across the inland areas and away from the stabilizing
effect of the lakes.
Short term /Thursday night through Saturday night/...
a significant pattern change will be underway moving into the coming
weekend as a longwave trough becomes established across the Great
Lakes...ushering in an extended period of cool and unsettled weather
across western and north-central New York. This breakdown will not
occur until later on Friday however. In the meantime...the forecast
area should remain dry Thursday night through much of Friday as a narrow
upper level ridge...a reflection of the deep trough just
upstream...slides overhead. With increasing cloud
cover...downsloping southerly winds and associated warm air
advection...particularly across far western New York...temperatures
will be quite mild Thursday night with lows in the middle to upper 50s
with areas along Lake Erie and in the Buffalo metropolitan remaining in the
Warm advection and gusty southerly winds will continue on Friday
with widespread gusts of 20-30mph possible ahead of an approaching
cold front. Downsloping ahead of this front should allow for a
decent amount of sunshine to break out and aid in pushing
temperatures into the upper 70s along the lake plains with low to
middle 70s farther inland.
Precipitation will move into far western New York Friday night as a
powerful 100+kt jet streak diving across the Great Plains
strengthens and digs a deep upper level trough across the western
Great Lakes...in turn pushing a strong cold front into the lower
Great Lakes. While a few showers may develop ahead of the front
across far western New York Friday evening in association with a
lead shortwave moving across the area...persistent downsloping ahead
of the front will keep this potential limited to only a chance
initially. The greatest likelihood for rain will be found along and
behind the cold front as it moves into western New York later Friday
night and crosses central New York on Saturday. Here low level
convergence/upper level divergence and DPVA aloft will be
maximized...leading to widespread rainfall averaging a quarter to a
half inch across the forecast area.
Rainfall will taper off from west to east as Post-frontal subsidence
takes over and dries things out across western New York as we move
through Saturday morning and into Saturday afternoon. This drying
trend will work its way east through Saturday afternoon...with the
north country likely drying out by Saturday evening. Temperatures
will also drop substantially behind the cold front as the upper
level trough and associated cold advection takes hold across the
region with surface temperatures struggling to get out of the 50s on
As we move into Saturday night...wraparound moisture coincident with
increasingly cold temperatures aloft will work its way across the
lower Great Lakes. This will set the stage for the development of
lake effect precipitation across the lower Great Lakes. While
initial development may be stunted by the presence of a decent
amount of vertical shear Saturday evening...winds become better
aligned overnight Saturday night as the main shortwave driving the
upper trough lifts across northern New England and upper level flow
becomes better aligned in a westerly direction. With 850mb temperatures
falling to around 0c and Lake Erie a comparatively balmy
+19c...lake-induced instability will be substantial with convective available potential energy
potentially cracking 1500j/kg and equilibrium levels approaching
25kft. Given this...will include a chance for thunder. In
addition...given how cold temperatures aloft will be...graupel will
be possible in heavier showers as well as waterspouts on the lakes.
This scenario will be a little slower to evolve on Lake Ontario
owing to it's closer position to the exiting shortwave and
associated shear. The cold air advecting into the region will drop
temperatures in the lower 40s near the lakes with upper 30s possible
across higher elevations inland from the lakes.
Long term /Sunday through Wednesday/...
lake effect showers will likely taper off during the morning on
Sunday as diurnal effects disrupt any lingering bands...however a
chance of showers will persist through much of Sunday as a shortwave
tracks across the lower Great Lakes. In fact the weather through the
middle of next week will continue to be generally cloudy with
periods of showers as a parade of shortwaves rotate around the base
of the longwave trough becoming established over the Great Lakes and
across the region. Temperatures will remain on the cool side with
highs in the 50s Sunday and upper 30s to lower 40s Sunday night.
There will be some moderation Monday into Tuesday as Pacific air
invades the northern tier of the country.
Aviation /02z Thursday through Monday/...
stratus deck impacting kiag and kbuf this evening will likely expand
and impact most taf sites overnight...perhaps kart will be the only
site remaining VFR. Fog will develop in the southern tier valleys
with possible impacts at kjhw after 07z. Stratus fog may hold in
for the better part of Thursday morning...before mixing out to
VFR conditions by afternoon.
Friday...VFR lowering to MVFR with showers becoming likely.
Saturday through Monday...VFR/MVFR with a chance of showers.
high pressure building across the lower lakes will yield lowering
winds and waves through Thursday.
Late in the week...a strong area of low pressure is expected to lift
across the Great Lakes region on Friday...while swinging a strong
trailing cold front across the lower lakes. The tightening pressure
gradient associated with the low will lead to a period of stronger
winds...with advisory-level winds and waves becoming possible.