Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Buffalo New York
438 am EDT Sat Jun 24 2017
a cold front will cross the forecast area this morning, with showers
tapering off from west to east. Temperatures will run cooler than
average this weekend, as upper level troughing moves across the
region. The cooler temperatures will be accompanied by showers at
times, particularly on Sunday and Monday, as a series of upper level
disturbances moving through the trough cross the area. The trough
will move east by Wednesday, with warmer temperatures expected by
Near term /through tonight/...
a cold frontal boundary continues to advance east across the
forecast area this morning, and the bulk of western New York has
finally dried out behind the front, though a final line of
showers continues to track east across The Finger lakes and
portions of the north country. These showers will taper off from
west to east over the next several hours, with clearing skies
from the west as Post-frontal subsidence takes over.
Increasing sunshine this morning will give way to increasing clouds
this afternoon, as upper level troughing moves into the area.
Cooling temperatures aloft, along with diurnal heating will allow
for the development of widespread cu during the afternoon, with a
few showers and isolated thunderstorms possible along the lake
breeze boundary south of Lake Ontario as well as the Boston Hills.
With cooler air advecting into the region, temperatures this
afternoon will top out in the low to mid 70s across most locales,
with a few spots in the typically warmer Genesee Valley climbing
into the upper 70s.
Any convective activity will come to an end during the evening
hours, with the loss of diurnal heating, leaving quiet and cool
night across the area. The cooler temperatures aloft, combined with
diminished cloud cover will translate to cooler readings than we have
seen at night of late, with lows dipping into the upper 50s along
the lake plains, with mid 50s across the higher elevations inland.
Short term /Sunday through Monday night/...
Saturday night...the upper level pattern will feature a longwave
trough centered over the Great Lakes region with an upstream
intermountain ridge. At the surface...a weak ridge will be in
place. Thus any leftover scattered evening convection on lake
breezes, primarily S of Lake Ontario, should quickly dissipate
during the evening with a dry and cool remainder of the night - low
should be mostly in the 50s.
Sunday and Sunday night...Sunday should start out nice, but expect
the eventual development of scattered to possibly numerous showers
and thunderstorms developing on lake breeze boundaries. Additional
development may form along a weak cold front moving southeast into wny
during the afternoon. Similar to Saturday night, expect convection
to dissipate fairly quickly with the loss of daytime heating.
Monday...the upstream cold pool aloft corresponding to the upper
level trough will pass overhead. Strong insolation and resultant
mixing, together with plenty of moisture and cool air aloft without
any signs of a cap will result in fairly quick development of
showers and some thunderstorms, although cape values will be
unimpressive with a skinny profile seen in point forecast soundings.
Still, with a freezing level somewhere near 8000-10000ft, cells
could easily support small hail. As noted earlier, there may
even be a hint of a lake response with a dry adiabatic lapse
rates over the 65-70+f waters. Once again, expect showers to be
on the decrease during the evening with little or no showers
Long term /Tuesday through Friday/...
Tuesday a final upper level shortwave will round a longwave trough
over the northeast, bringing additional chances for showers and
thunderstorms through the day.
The upper level trough will push eastward Tuesday night and
Wednesday, with just a small chance for a lingering shower across
the north country. Surface high pressure will drift across the
eastern US, south of our region Wednesday, providing for some
clearing skies. Southerly winds behind this surface high Thursday
will bring increasing temperatures, along with an increase in
humidity levels. A shortwave rippling across the northern US may
trigger a few showers and thunderstorms later Thursday and Friday,
though timing at this point remains a bit uncertain.
Temperatures under the upper level trough Tuesday and Wednesday will
remain below normal. Southerly winds Thursday and Friday should push
temperatures into the upper 70s to lower 80s across the region.
Aviation /09z Saturday through Wednesday/...
a final round of showers associated with a cold frontal boundary are
moving across The Finger lakes early this morning. Brief
periods of MVFR will accompany the showers, with improving
conditions to VFR to the west of the front. Moisture pooling
ahead of the front continues to generate IFR/LIFR conditions
across the north country. Expect these conditions to last a few
more hours before the front moves through, once again with
improving conditions behind the front.
While the entire forecast area can expect improvement to VFR on
Saturday, upper level troughing settling across the area will allow
for the development of isolated scattered -shra, with a few -tsra
also possible, with convection focusing on lake breeze boundaries,
and largely sparing kbuf/kart.
Sunday through Tuesday...mainly VFR with scattered to
numerous showers and thunderstorms...mainly in the afternoons.
Thursday...VFR/MVFR with a chance of showers and thunderstorms.
westerly flow developing in the wake of a cold front crossing the
area will generate a moderate chop across the eastern ends of the
lakes, with waves building to 3 feet by this afternoon. Waves will
rise higher on Sunday, particularly on the eastern half of Lake
Erie, as winds strengthen further as a strong upper level
disturbance moves through, and small craft advisories will likely be
needed on both lakes for Sunday afternoon into Sunday night. After a
brief respite Monday morning, another passing upper level
disturbance will likely bring another period of Small Craft Advisory
conditions to Lake Erie Monday night.