Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
218 am EDT Tuesday Sep 2 2014
scattered showers and a few isolated thunderstorms will advance
eastward overnight while diminishing in intensity and coverage area
towards The Finger lakes and areas east of Lake Ontario. A cold
front will then cross the region on Tuesday with more widespread
showers and thunderstorms...some of which could produce strong gusty
winds across portions of the southern tier and Finger Lakes. In the
wake of the front...high pressure will build into the lower Great
Lakes and bring a return to drier and less humid weather Wednesday
Near term /through today/...
early this overnight regional radars still displaying line of
weakening showers stretching from Monroe County southeast to
Cattaraugus County all associated with a pre-frontal trough crossing
western New York. Northern part of line has weakened
considerably...containing just some light showers...however across
the southern tier there are still a few heavier showers with some
embedded lightning strikes. Expect this to be the trend as the night
progresses with showers/isolated thunderstorms moving through and
exiting Cattaraugus and Allegany counties before exiting to the
east...while to the north of here the line continues to all but
fizzle out as it moves through the Genesee Valley and northern
Finger Lakes region. That said...the low level jet of 30 knots at 850 hpa
should maintain at least a chance of showers across this area and
points eastward through the rest of the overnight.
Lows tonight will remain on the mild side for early September with
lows in the middle 60s to lower 70s...warmest across the lake plain.
On Tuesday...the axis of broad middle and upper level troughing will
slide east from the upper Great Lakes to the lower lakes region...
with an associated weak cold front easing eastward across the
forecast area during the course of the afternoon. In advance of this
front...a very warm and humid airmass will remain in place with
precipitable water values approaching two inches...while large-scale
lift will be on the increase owing to a combination of increasing
convergence along the front/the nose of a 30-40 knots low-middle level
jet...supporting synoptic-scale DCVA/height falls...and increasing
upper level diffluence in the right entrance region of a 120+ knot
upper level jet. Coupled with daytime heating...all of this should
result in fairly numerous showers and thunderstorms developing
along/ahead of the front as it crosses our region...for which some
likely to low-end categorical probability of precipitation will be in play.
While there will be a fair amount of wind in place aloft to keep
things moving along...given the very moist airmass there still will
be at least some threat of locally heavy rainfall on Tuesday...
especially if any stronger/heavier cells manage to train repeatedly
over a particular area. The overall severe potential is somewhat
less clear given lingering uncertainty with respect to how much
heating/destabilization will occur prior to the arrival of the
front...however with 35-45 knots Worth of 0-6 km bulk shear in
place...the potential for some stronger storms capable of attendant
strong to severe wind gusts certainly exists provided enough
instability can ultimately be realized. At this point...a rough
model consensus suggests that the greatest potential for this will
exist from interior portions of the southern tier northeastward
across The Finger lakes region...where the best instability and
large-scale dynamics will be superimposed upon each other. Not
coincidentally... this agrees quite well with spc's latest day 2
convective outlook...which portrays a slight risk of severe storms
across this particular region.
Short term /tonight through Thursday/...
the cold front will slide south and east of the forecast area
Tuesday night. Most 12z guidance has the trailing edge of showers
and thunderstorms with this front along the southeast border of the County Warning Area at
00z. Once this exits...expect dry weather late Tuesday evening which
will last through most of the week.
Surface high pressure across the Ohio Valley on Tuesday night will
gradually shift into southern New England through Thursday. This
will bring fair weather and mostly clear skies Wednesday and
Wednesday night. Temperatures will only be modestly cooler behind
the front...with mostly skies temperatures rise into the upper 70s
On Thursday...there will be a zonal flow aloft...with the jet stream
well to our north in Canada. Low pressure will lift across
Minnesota Thursday...with middle-level warm air advection forecast to
lift across our region. This may produce a stray sprinkle or shower
in northeastern portions of the County Warning Area...while the vast majority of the
region stays dry. A NAM/GFS consensus warms 850mb temperatures in
far western New York to +18c by 00z Friday. Depending on timing of
the front...highs on Thursday should rise into the lower 80s in most
Long term /Thursday night through Monday/...
high pressure will slide off the New England coast Thursday
night...meanwhile a cold front will approach from the west. This
frontal passage will be the most significant weather factor for the
long term period...with 12z guidance still differing on the fronts
timing and how much cold air will be behind it. The forecast will
follow a consensus of this guidance which is notably slower than the
12z ggem in terms of timing...and warmer than the 12z GFS with
Friday should Summer-like...with highs in the 80s. The front is
likely to move across the region Friday night...with a chance for
showers and thunderstorms Friday afternoon through Saturday. With a
nighttime passage...expect only a broken line of showers with the
front...and possibly behind it with some anafrontal precipitation.
The front will push south of the region Saturday night...with dry
weather expected on Sunday and Monday. A consensus of this guidance
drops 850mb temperatures down to +5c...which should result in
lingering lake effect clouds for at least part of the day on Sunday.
High pressure will build across the region on Monday...with a bit
more sunshine. Temperatures behind the front will be much
cooler...with highs in the upper 60s to lower 70s Sunday and Monday.
Aviation /06z Tuesday through Saturday/...
VFR flight conditions at 06z will persist for another few hours or
so...before some patches of MVFR ceilings...and southern tier IFR ceilings
form across the region just before dawn.
Pre frontal surface is now east of the kbuf/kiag/kjhw
terminals...taking showers and isolated thunderstorm activity with
it. Kjhw saw a period of MVFR ceilings with the precipitation...but
skies have now scattered out since the precipitation moved to the
east. There are some scattered showers over Lake Erie. These
are showing signs of weakening as they move onshore where air is
just a bit more stable in the wake of the passage of the trough.
However any of these showers that do hold together once onshore
could bring a brief light shower to anywhere across the Niagara
Frontier. May see a brief sprinkle or light shower at kroc through
07z with the trough as it passes through...then just some passing
clouds after that. This activity will likely diminish before
reaching the kart airfield.
On Tuesday...a weak cold front will slowly ease eastward across the
region through the course of the day. Coupled with increasing
daytime instability...expect more widespread showers and storms to
develop along and ahead of this front as it crosses the area...with
some of these potentially bringing brief periods of MVFR/IFR. A few
of these storms could even become strong to severe across interior
portions of the southern tier and Finger Lakes...where overall
instability appears as if it will be the strongest.
Tuesday night...showers and thunderstorms ending across southern and
eastern sections...with conditions mostly returning to VFR.
Wednesday and Thursday...VFR.
Friday and Saturday...a chance of showers and thunderstorms with
associated brief MVFR/IFR...otherwise VFR.
a cold front will work across the upper Great Lakes
overnight...before crossing the lower lakes region on Tuesday. In
advance of the front...southwesterly winds will increase later
tonight and Tuesday morning...particularly on on Lake Erie where
winds and waves will climb to near advisory levels. Will issue a Small Craft Advisory
for Lake Erie through midday tomorrow to account for some winds
nearing 18-20 knots overnight and through the morning hours. The
front itself will also produce a round of scattered to numerous
thunderstorms on Tuesday... a few of which could produce strong
In the wake of the frontal passage...high pressure will build across
the region Tuesday night through Thursday while bringing a return to
fair weather and lighter winds.
Marine...Small Craft Advisory until 2 PM EDT this afternoon for lez040-