Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
334 PM EDT Wednesday Oct 1 2014
clouds will break up late this evening and tonight with a return
to 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/...
satellite and surface observations show thick cloud cover is eroding
nicely across the region at early afternoon. High pressure and upper
ridging building across the region will yield clearing skies through
Tonight...strengthening high pressure will continue to ridge into
eastern New York...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/...
on Thursday the slow moving weak middle level cutoff low will make
progress in moving off the New England coast and into the North
Atlantic. This will allow a narrow ridge over the Ohio Valley to
build north into the lower lakes with surface high pressure also
building into our region. This will bring a return to dry weather
with at least some sunshine...although lingering low level moisture
fields left from the weak system in the near term may allow a good
amount of diurnal cumulus to develop with daytime heating. 850mb
temperatures of around +11c will continue to support above normal
temperatures with highs in the middle 70s at lower elevations and lower
70s on the hills. The synoptic scale flow is weak...so expect local
lake breezes to develop during the afternoon and keep the immediate
Thursday night into Friday high pressure will drift east into New
England and the Canadian Maritimes. Deep southerly flow will
increase between the departing high and a strong trough digging into
the upper Midwest. The increasing southerly flow will allow
temperatures to rise late Thursday night into Friday morning after
an early low. Strong southerly flow will boost temperatures even
more on Friday with 850mb temperatures soaring to +14c. With some
additional warming from downslope flow this should push the lake
plains to near 80...with middle 70s common across the interior southern
tier and north country. This will be the last gasp of the warm spell
which has lasted for the better part of two weeks.
Model guidance continues the same trend from the past few runs of
slowing the trough and frontal progression later Friday into
Saturday. Latest operational models and sref mean are clustering
more tightly around the frontal timing...with the cold front not
reaching western New York until late Friday night...then moving slowly
through the Eastern Lake Ontario region on Saturday. This should
allow the bulk of Friday to be rain free even across western
New York...with showers not arriving until late in the afternoon. From the
Genesee Valley eastward the entire day should be rain free. The
slower frontal timing and downslope flow should produce a good deal
The surface cold front will be accompanied by strong dynamics aloft
as a sharp middle level trough digs into the western lakes...with
height falls and DPVA spreading downstream into our region and
supporting large scale ascent. A 120+ knot upper level jet will
rotate through the base of the trough and combine with increasingly
diffluent middle/upper level flow to support upper level divergence.
The system will capture a plume of deeper Gulf moisture...with precipitable water
rising to around 1.5 inches. Given the quality of moisture and
dynamics coming together expect a high likelihood of showers Friday
night...which will linger into much of Saturday across the Eastern
Lake Ontario region. The latest model guidance would suggest the
best juxtaposition of the strongest dynamics will occur on Saturday
over central and eastern New York where rain amounts may end up being
While rain will last through most of Saturday across the Eastern
Lake Ontario region...farther west the showers will end from west to
east early in the day. There should be a brief dry slot behind the
cold front before deeper wrap around moisture and ascent from the
base of the main middle level trough enters western New York later in the
day. This will bring a chance of a few more showers...and the
airmass will become cool enough by late afternoon or early evening
to support some lake enhancement. Ongoing cold advection will yield
high temperatures that are almost 20f cooler than highs on
Friday...with upper 50s to lower 60s across lower elevations and middle
50s across higher terrain.
Long term /Saturday night through Wednesday/...
a very deep longwave trough will remain centered over northwest
Ontario province through the long term period. Numerous shortwaves
will rotate through this trough and support a chance of showers on
most days through the period. The coolest temperatures will cross
our region on Sunday before a slow moderating trend next week.
Looking at the details...Saturday night into Sunday wrap around
moisture will slowly fade away. This should bring an end to most of
the synoptic scale showers...but cool cyclonic flow aloft will
continue to support lake effect rain showers east and northeast of
both Lake Erie and Ontario. High temperatures on Sunday will be very
cool indeed...with only middle 50s at lower elevations while some of
the hills may struggle to reach 50.
By Monday and Tuesday both the GFS and European model (ecmwf) show several middle level
shortwaves and associated weak surface waves crossing the lower
lakes region. Each of these will bring a chance of a few rain
showers along with a good deal of cloud cover. Expect highs to move
back into the lower 60s at lower elevations with middle to upper 50s
across higher terrain. This is still much cooler than recent
weather...but not far from where temperatures should be in early
Aviation /20z Wednesday through Monday/...
surface observations are indicating improving conditions for all taf
sites with VFR conditions expected through the rest of the forecast
period...the possible exception being some fog and stratus across
the southern tier.
tonight through Thursday...VFR...except for localized IFR in fog
and low stratus southern tier valley tonight/early tomorrow morning.
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 this evening 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.