Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
234 PM EST sun Nov 29 2015
high pressure will keep dry conditions and cool but seasonable
temperatures across the region through Monday night. Then low
pressure will track across the Great Lakes on Tuesday bringing above
normal temperatures and rain. A cold front will cross the region
early Wednesday which will bring temperatures back to normal with
some rain or snow showers Wednesday and Wednesday night.
Near term /through Monday/...
lingering low-level moisture and cloud cover will remain the main
forecast challenge through this evening. The 12z buf sounding shows
a strong inversion at 900 mb which is trapping moisture beneath it.
Visible satellite shows cloud cover eroding...mainly across southern
areas where moisture from the lake is not available. However...cooler
air aloft is forecast to drop southward across Lake Ontario through
this evening...which will help re-establish cloud cover across and
south of Lake Ontario into this evening. High resolution guidance
even forecasts some light quantitative precipitation forecast south of Lake Ontario through
this evening. With moisture shallow and mostly beneath temperatures
cold enough to support dendritic snow growth this probably will only
result in clouds or possibly very light flurries or sprinkles.
Surface high pressure will drift into New England tonight which
will shift winds to the east and eventually the southeast. This
will help lift any lingering cloud cover to the north with skies
expected to clear out in nearly all area by daybreak Monday. This
will result in good radiational cooling conditions...especially
east of Lake Ontario where lows in the teens are expected.
Elsewhere should be on the cool side...with lows in mainly in the
The high across New England will continue to influence our weather
on Monday with a southeasterly flow promoting sunny skies across the
region. Temperatures will be seasonable with highs in the upper 30s
east of Lake Ontario...and in the lower 40s elsewhere.
Short term /Monday night through Tuesday night/...
Monday night the surface high will drift east into the Gulf of
Maine while the next area of low pressure and strong middle level
closed low move into the upper Midwest. Increasing warm advection
and isentropic upglide in the developing southerly flow between
the two systems will bring an increase in cloud cover from
southwest to northeast overnight. A few showers may develop across
western New York and the southern tier late. Expect early evening lows
in the low to middle 30s in most areas with middle to upper 20s across
the north country. The combination of low level warm advection and
increasing clouds will then force rising temperatures overnight.
Expect temperatures to rise above freezing several hours prior to
the onset of any showers with very little risk of any freezing
The vertically stacked low will cross the upper lakes Tuesday with
DPVA and diffluent flow aloft supporting increasing large scale
ascent across our region while an occluded front brings increasing
low level convergence during the afternoon. The increasing moisture
and ascent will bring increasing coverage of showers from southwest
to northeast through the day. 850mb temperatures surge to around +10c just
ahead of the front...and this will support highs in the middle to upper
50s across western New York despite the increasing showers.
Tuesday night the occluded front will move east across the area.
Showers during the evening will end from west to east overnight with
the passage of the frontal boundary. A well defined dry slot will
then bring a break in the rain and possibly even a period of partial
clearing overnight. Towards Wednesday morning the airmass will grow
marginally cold enough to support a Few Lake effect rain showers
northeast of the lakes.
Long term /Wednesday through Saturday/...
Wednesday a strong middle level trough will move east across the Great
Lakes region. The morning dry slot will give way to a rapid increase
in moisture and large scale ascent by early afternoon with the
approach of the middle level trough. The airmass will also grow
supportive of lake enhancement northeast of the lakes. The
combination of synoptic scale moisture and ascent along with lake
enhancement will produce numerous showers during the afternoon
northeast of the lakes...with a few showers likely even outside of
lake enhancement. Cold advection will bring falling temperatures
during the afternoon. The boundary layer will still be quite mild
with rain transitioning to a rain/wet snow mix at lower elevations
and possibly to all snow across higher terrain later in the
Wednesday night the synoptic scale moisture quickly pulls away...
with some lake effect showers of rain and wet snow lingering
southeast of the lakes overnight. Overall temperatures appear too
mild at lower elevations for any accumulation...with some minor
slushy accumulations possible across higher terrain. If Buffalo can
get through this period without measurable snow...this season will
likely shatter the record for the latest first measurable snow.
Any lingering lake effect rain and snow showers southeast of the
lakes Thursday morning will end by midday as high pressure and dry
air build into the lower lakes.
Friday and Saturday the GFS and European model (ecmwf) begin to diverge on timing
with the GFS bringing a middle level trough southward across New York and New
England Friday...while the European model (ecmwf) is much slower with the trough late
Friday night and Saturday. Regardless the system will be moisture
starved with nothing more than a few sprinkles or flurries at best.
For now have left both days dry with temperatures moderating to a
little above average.
Looking farther ahead...operational guidance and ensemble means show
a high confidence forecast for above normal temperatures to continue
through the middle of December with the upstream pattern across
the Pacific and high latitudes forcing mild Pacific air to flood
east across the nation while any cold air is locked up at very
high latitudes in northern Canada. It appears there will be little
chance for measurable snow through the middle of December.
Aviation /20z Sunday through Friday/...
patchy stratus will linger south of Lake Ontario...with visible
satellite showing stratus eroding across land but re-developing
on the lake from lake moisture and cooling air aloft. This will
result in VFR conditions at jhw...with considerable MVFR ceilings at
buf/iag/roc/Art through this evening. These will be driven by
subtle features which lowers forecast confidence in placement and
timing of this cloud cover.
High pressure will shift into New England tonight which will
eventually establish a southeast flow. This will push any lingering lake
moisture to the north and giveway to widespread VFR conditions
late tonight and Monday.
Monday night and Tuesday...rain. Mainly MVFR.
Wednesday...mainly MVFR. Rain or snow showers likely.
Thursday...mainly VFR. A chance of rain or snow showers early.
high pressure to remain in control through Monday... keeping winds
and wave minimal.
A low pressure system will then track across the Great Lakes Tuesday
into Wednesday resulting in a period of brisk southwesterly winds
ahead of the storm and west to northwest winds behind it. Small
Craft Advisory conditions will likely develop on area waters as this
weather system moves through.