Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
154 am EDT Wednesday Jul 30 2014
a cool airmass will remain in place tonight with the chance for lake
enhanced showers east of Lake Erie. A surface trough will cross New
York Wednesday bringing another round of showers to the area. The
cool pattern along with chances for showers will last through much
of the week as an upper level low lingers over the Great Lakes.
Warmer air will return by the weekend but a lingering trough aloft
will result in the continued chance for showers and thunderstorms.
Near term /through today/...
clouds continue to spread eastward across western New York early this
morning with scattered showers and isolated thunderstorms over Lake
Erie and far western New York. This is occurring just ahead of an
approaching trough. Expect a slow eastward movement with showers
falling apart as they move further inland. As the trough axis moves
closer...expect southwesterly flow to become better
aligned...allowing for lake enhanced showers to develop after late.
Lows will run in the 50s with coolest spots being found in the
southern tier and the Tug Hill.
Lake-enhanced showers are expected to persist into the morning hours
as we move into Wednesday...however they should give way to more
widespread...diurnal instability-driven rain showers on Wednesday
afternoon as an upper level shortwave transits the region.
This...along with the chilly airmass associated with the
aforementioned middle/upper level troughing will keep conditions cloudy
and cool throughout the day with highs expected to barely breach the
70 degree mark. Higher elevations of the southern tier will likely
remain in the 60s.
Short term /tonight through Friday night/...
an anomalously deep longwave trough will dominate the northeast
quarter of the nation through the short term period. A series of
lower amplitude shortwaves will rotate across the Great Lakes within
the mean longwave trough and provide several periods of enhanced
large scale ascent and moisture. The airmass is also cool enough to
support lake enhanced rain at times.
The airmass will be cool enough to support a lake response Wednesday
night and Thursday...with showers tending to focus over and east of
the lakes again. There may be enough instability left for a few
isolated thunderstorms Thursday afternoon. Finally Thursday night
the longwave trough will begin to pull out into Quebec...allowing
for some drying to take place across the lower lakes. Expect most
locations to be dry Thursday night with partial clearing. The
longwave trough over the east will finally pull away enough into
Quebec on Friday to bring a brief return to mainly dry weather.
Temperatures will continue to run below average through the period.
Highs on Thursday will be in the 70s and near seasonal averages on
Friday. Overnight lows will be cool...but cloud cover will limit
radiational cooling potential. Expect lows in the middle to upper 50s
on the lake plains and lower 50s inland.
Long term /Saturday through Tuesday/...
the broad longwave trough encompassing over 2/3 of the eastern
United States will slightly deepen and sharpen as a fairly strong
wave drops through the backside of this trough at the beginning of
this period. As this wave begins to round the base of the upper
trough increasing southerly flow and moisture will advect northward
along the East Coast and up The Spine of the Appalachians. This will
likely lead to an increasing threat of afternoon showers and
thunderstorms Saturday and to a lesser extent into Sunday.
Beyond Sunday...a great deal of model differences arise regarding
the timing of next system. The European model (ecmwf) continues to be a bit more
progressive with a Monday night and Tuesday time frame with a
frontal passage...right now leaning towards the faster solution with
another round of showers and thunderstorms with the front.
Temperatures overall will hover right around climatology through this
entire period with highs in the upper 70s to near 80f.
Aviation /06z Wednesday through Sunday/...
-shra pushing into far western New York at this time are accompanied by
VFR ceilings. Expect -shra to continue east across western New York but
falling apart with time. The arrival cooler air aloft and
better-aligned SW flow are expected to result in the development of
lake enhanced showers NE of the lakes towards 12z...however
conditions are expected to remain VFR...though brief periods of MVFR
may be possible should any heavier showers develop. In
addition...given model projections of lake-induced instability...a
few rumbles of thunder may also be possible.
Lake-enhanced -shra should begin to dissipate Wednesday morning...however
with the upper level trough settling in across the lower Great
Lakes...widespread diurnally driven -shra are expected to develop by
the afternoon. Again prevailing conditions are expected to remain
Wednesday night and Thursday...VFR/MVFR with scattered showers.
Saturday and Sunday...mainly VFR with chance showers and
upper level low will keep cool temperatures aloft across the Great
Lakes through much of the week. This will bring a chance waterspouts
tonight through Thursday for both lakes along with chances of lake
enhanced showers each night. Winds and waves will remain below Small
Craft Advisory levels.