Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
614 PM EDT Wednesday Aug 27 2014
cooler air will move in following the passage of a cold front...with
a return to below normal temperatures through Thursday before
temperatures warm to near normal by the end of the week. The next
opportunity for precipitation will arrive for the Labor Day
weekend...when a complex frontal system will slowly push across
Near term /through Thursday/...
an upper level trough axis passing north of Lake Ontario early
this evening will spark a few showers or sprinkles early this
evening. This will mainly be confined east and southeast of Lake
Ontario...with dry weather elsewhere.
The center of surface high pressure will move east over the upper
Great Lakes tonight. A northerly component to the flow on the
east side of the high will allow cooler air from Canada to pour
south into the area. Expect clear to partly cloudy skies for most
of the region...with some extra lake clouds late tonight.
Temperatures will be much cooler with lows generally in the low to
middle 50s...some 5 degrees or so below normal.
850mb temperatures will average +7c which is cool enough to elicit a lake
effect response in cloudiness to the south and southeast of Lake
Ontario. Expect partly to mostly clear skies across the rest of the
forecast area. The sunnier skies will not be enough to offset the
cool air advection throughout the day...thus high temperatures will be in
upper 60s to the lower 70s across the forecast area.
Short term /Thursday night through Saturday night/...
it will be a warm...but mainly dry start to the period as an upper
level ridge crests over the lower Great Lakes. After a cool dry
night Thursday night...temperatures will begin to warm back into
the middle 70s on Friday as the ridge moves overhead and a warm front
approaches the forecast area. The warm-up will begin in earnest
Friday night and Saturday as the warm front lifts north across the
region with temperatures climbing well into the 80s on Saturday.
Any showers and thunderstorms associated with the warm front
should stay largely to our north and west around the edge of the
upper level ridge...though there is a slight chance of a few
showers spilling over the top of the ridge and into the Saint
Lawrence valley late Friday night.
The chance for showers and thunderstorms will increase Saturday
afternoon and evening as the axis of the upper level ridge moves off
to the east and lapse rates aloft steepen...however coverage should
be scattered in nature as any triggers will be largely mesoscale in
Long term /Sunday through Wednesday/...
the highest chances for rainfall this weekend across western and
north-central New York will fall on Sunday when a surface low
tracking across southeastern Ontario tracks across the Saint
Lawrence valley and into northern New England. This will introduce
deeper moisture along with synoptic scale low level convergence to
the lower Great Lakes...allowing for more widespread shower and
thunderstorm development. Warm and moist air will remain in place
on Monday as another weak warm front lifts north across the region
ahead of cold front tied to a much deeper surface cyclone over
northern Ontario. This cold front is currently expected to swing
across the region Tuesday...likely bringing a more extensive round
of showers and thunderstorms.
Temperatures during the period will continue to run a few degrees
above average with plenty of lingering moisture with 60+ degree
dewpoints making it feel quite humid. The passage of the cold front
Tuesday/Tuesday night should reintroduce cooler and drier air by
Aviation /22z Wednesday through Monday/...
VFR conditions are in place across most of the region...with the
majority of clouds middle level at taf sites. Expect VFR conditions
to continue this evening as skies should become clear to partly
cloudy. Later tonight...temperatures aloft will become just cool enough on
a northwest flow to produce some lake clouds...which may bring
some low VFR/MVFR ceilings to the region...especially in upslope
areas such as roc.
Thursday night through Friday night...VFR except for typical
southern tier valley fog with local IFR late Thursday night into
early Friday morning.
Saturday through Sunday...mainly VFR with chance of showers.
Monday...VFR/MVFR in scattered showers and thunderstorms.
west northwesterly winds following the passage of a cold front will
increase winds to around 15 knots on Lake Ontario. These longer
fetch with the west northwest winds will eventually raise wave
heights on Lake Ontario with conditions expected to fall just shy
of Small Craft Advisory criteria across the central and Eastern
Lake Ontario waters late this evening into early Thursday morning.
Waves will likely remain just around 2 feet or less on Lake Erie
with the perpendicular wind flow. Winds and waves will lessen as
the pressure gradient relaxes during Thursday.