Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
352 PM EDT Wednesday may 6 2015
high pressure settling across New York state tonight will drift
off the Atlantic coastline on Thursday...where it will then remain
through the upcoming weekend. This will promote a return to dry
weather for the remainder of the work week and middle summerlike
warmth that will last through the upcoming weekend...when slowly
increasing humidity levels should also allow some scattered
showers and thunderstorms to develop.
Near term /through Thursday/...
as of middle afternoon...regional satellite imagery shows that high
pressure continues to bring clearing skies from northeast to
southwest as it builds across New York state...with the only
lingering cloud cover now found across the southern tier...which
is situated along and north of the remnant weak frontal boundary
over Pennsylvania. While a light shower will still be possible
across the southern tier late this afternoon...in general the
drying/clearing trend should continue to progress into this latter
region through early this evening. Elsewhere...expect sun-filled
skies and dry... pleasant weather to persist.
After that...the rest of the near term period will feature
surface-based high pressure remaining draped across the region
tonight...before gradually sliding off the New England coast on
Thursday...while the axis of its parent upper-level ridge slides
from the western Great Lakes to New York state. All of this should
promote fair and dry weather throughout...with the NAM/GFS
depictions of some spotty convective development across inland
sections Thursday afternoon looking to be spurious given both the
arrival of the upper level ridge axis/increasing capping
aloft...and what appears to be an overly aggressive increase in
surface dewpoints /particularly by the NAM...which is a typical
bias for that model/. In terms of cloud cover...expect mainly
clear/ mostly sunny skies to predominate...except for a potential
area of lingering low level moisture/expanding low clouds across
western New York tonight...which will then lift and transition to
diurnal cumulus as it advects eastward and strong diurnal influences
come into play during Thursday. Across the southern tier and
interior portions of The Finger lakes...there may also be enough
lingering low level moisture to allow for the development of some
patchy fog later tonight... any of which would be likely to
quickly dissipate following sunrise Thursday morning.
As for temperatures...expect nighttime lows to range from the
lower 40s across the north country to the upper 40s and lower 50s
across much of the area south of Lake Ontario tonight...with 850
mb temperatures of +10c to +13c then supporting a return to middle
summerlike highs in the upper 70s to lower 80s in most places on
Thursday. The one exception to this will be along the
lakeshores...where the weak surface pressure gradient will allow
for lake breeze circulations to develop on Thursday...which in
turn will help keep readings there significantly cooler.
Short term /Thursday night through Friday night/...
on Thursday night surface high pressure across the middle Atlantic will
ridge back into our region. This will very gradually break down as
the 500 mb ridge axis shifts east from our region to New England by
Friday night. This will bring gradually warming temperatures
aloft...which will result in a very Summer-like pattern.
The vast majority of the period will be dry due to the influence of
the ridge and a relatively dry airmass. A consensus of model
guidance continues to forecast some quantitative precipitation forecast on Friday afternoon. This
does not seem feasible on and near the lakes where a lake breeze
should stabilize things...and the extent is also misleading with any
showers activity likely to be widely scattered in nature. Based on
consensus quantitative precipitation forecast/cape inland of the lake-breeze it/S hard to completely
rule out a few afternoon instability showers along the lake breeze
boundary...so will carry slight chance probability of precipitation. Without daytime
instability as a factor...both Thursday night and Friday night
should be dry.
Perhaps the bigger weather story is that highs on Friday will be
near the warmest so far this season. Except for the immediate
lakeshores...most areas should top 80 degrees...with middle 80s a bit
further inland across the Genesee Valley and Finger Lakes regions.
Overnight lows will be mainly in the 50s Thursday night...then
warmer on Friday night due to the developing southerly flow which
will limit radiational cooling and perhaps result in some modest
Long term /Saturday through Wednesday/...
the region will get a taste of Summer this weekend...with warm
temperatures and mainly diurnally driven showers and thunderstorms.
After this...a cold front will move through early next week with a
round of more significant precipitation followed by much cooler
temperatures by mid-week.
Looking at the details...model guidance has come into better
agreement with the GFS/ECMWF/ggem all trending toward a similar
solution. It now appears likely that our region will indeed remain
in the warm sector for the weekend...with the cold front very slowly
approaching from the west as it encounters the upper level ridge
along the eastern Seaboard. The ridge is far enough away to allow
moisture to lift into the region. Showers should generally be
scattered in nature...with a bit better chance for these on Sunday
when the front is closer...and during the afternoon hours due to
diurnally enhanced instability. As advertise...temperatures will be
much above normal with highs in the 80s in most areas outside of the
The 12z runs of the GFS/ECMWF/ggem all lift a significant shortwave
across the Midwest and into the Great Lakes region on Monday. There
should be significant moister with this and decent dynamic lift so
have upped probability of precipitation to the likely category for late Monday and Monday
night when consensus timing brings this through. Then cooler air
will build in behind this on Tuesday and Wednesday. Showers should
taper off Tuesday a the shortwave exits...followed by much cooler
temperatures for Wednesday. Highs on Wednesday are expected to drop
down into the 50s. Both GFS/European model (ecmwf) clip the north country with a
shortwave on Wednesday...however confidence in this is low at this
Aviation /20z Wednesday through Monday/...
high pressure over western and north central New York late this
afternoon and tonight will slide off the New England coast on
Thursday. For the most part... this will promote a continuation of
fair VFR weather...save for some lingering lower clouds across the
western southern tier this afternoon/tonight...and possibly the
Niagara Frontier much later tonight and early Thursday. While the
majority of these will be MVFR...some IFR will be possible across
the higher terrain of the southern tier tonight. With nocturnal
cooling and some lingering low level moisture remaining in
place...some patchy IFR fog may also develop across the southern
tier and interior portions of The Finger lakes later tonight...before
dissipating after sunrise Thursday morning.
Thursday night and Friday...VFR.
Saturday through Tuesday...mainly VFR...with a chance of showers/
thunderstorms and attendant MVFR.
with a weak pressure gradient remaining in place across the lower
lakes region through the end of the work week...expect relatively
light winds and minimal waves to continue through Friday.