Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
1054 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 Summer-like
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/...
satellite imagery this evening indicates diminishing cloud cover
across western and north-central New York this evening with the loss
of diurnal heating. Expect the clear skies to hold throughout
tonight as surface based high pressure slides off to our east and
upper level ridging begins to move overhead. Pockets of higher
dewpoints in the upper 50s continue to be found across portions of
the southern tier...particularly near the PA border...this
evening...suggesting the potential for the development of patchy fog
across that area late tonight.
Any fog should quickly diminish Thursday morning...leading to an
abundance of sunshine on Thursday with only scattered diurnal
stratocu to contend with across the southern tier and Finger Lakes
during the afternoon. Otherwise...look for fair skies with plenty of
warm temperatures to be had courtesy of the upper level ridge that
will be moving overhead. 850mb temperatures climbing to around +13c should
easily support highs in the middle to upper 70s...with perhaps a few 80
degree reading across the Genesee Valley not out of the question.
Look for cooler readings near the lakes where light synoptic flow
should allow for the development of a fairly robust lake breeze. As
such areas within a few miles of the lakes will likely only top out
in the low to middle 60s.
Short term /Thursday night through Friday night/...
very warm air temperatures expected this period...with highs on
Friday falling several degrees from the dates record values. These
records are: Buffalo (85/1979), Rochester (89/1979), Watertown
(85/1979). No major changes to the forecast on this evenings
update with previous Disco below...
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 /03z Thursday through Monday/...
high pressure will bring clear skies to the lower Great Lakes
through the rest of tonight. Lingering low level moisture coupled
with radiational cooling across the southern tier may result in
pockets of fog with accompanying IFR/LIFR conditions late
tonight...mainly after 08z. Kjhw taf has been updated to include a
mention of vcfg accordingly. Any fog should dissipate by 14z with
diurnal heating and mixing. Otherwise..upper level ridging should
result in fair weather and widespread VFR conditions on Thursday
with just scattered stratocu around 3500ft across the southern tier and
Finger Lakes to contend with.
Outlook... Thursday night and Friday...VFR.
Friday night through
Tuesday...mainly VFR...with a chance of showers/ thunderstorms and
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.