Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
356 am EDT sun Jul 5 2015
high pressure will cross the eastern Great Lakes region
today...with the Holiday weekend ending with plenty of sunshine. As
this area of high pressure exits off the northeast coastline
Monday...some moisture will return northward possibly fueling a few
Monday afternoon and evening showers and thunderstorms across
western New York. A cold front will then bring additional showers
and thunderstorms later Tuesday through early Wednesday.
Near term /through tonight/...
high pressure this early Sunday
morning is camped over the eastern Great Lakes region. Aloft a ridge
of high pressure is over the Great Lakes...with a cut off low
spinning over the Tennessee Valley.
For today and tonight expect dry weather with high pressure and the
nearing upper level ridge limiting cloud cover. There will continue
to be at times a milky appearance to the sky as the effects of
wildfire smoke from western Canada and Alaska pass over the region.
Temperatures should warm to a few degrees above normal with lower
80s found Inland. Lake breeze circulations within a light synoptic
wind field will maintain 70s near the lake shorelines. Tonight as
high pressure exits towards the northeast coastline lows will drop
back into the upper 50s to lower 60s with a very light southeasterly
Short term /Monday through Tuesday night/...
high pressure will slide off the New England coast and set up a
southerly return flow which will bring a couple days of middle-Summers
heat and increasingly muggy conditions. Highs should generally be in
the 80s...with lake breezes and downsloping driving temperature
differences. A weak southerly flow should delay the lake breeze in
Buffalo Monday with warmer temperatures north of I-90 due to
downsloping. On Tuesday a stronger south-southwest flow should allow for an
earlier lake breeze and cooler temperatures across the Niagara
Frontier...while temperatures push 90 across the lower Genesee
Valley where downsloping will be in full effect. Dew points will
rise into the upper 60s Tuesday resulting in rather muggy conditions.
The vast majority of the time should be dry through Tuesday morning.
A weak upper level disturbance will pass to our south on Monday and
this may bring in moisture and a few diurnally aided showers Monday
afternoon/evening. 00z model consensus continues to show light quantitative precipitation forecast
with this...generally south and west of Rochester. Lake breezes may
provide a focus for this activity. What is left of this will move
east Monday night with the upper low.
The more significant system will come late Tuesday when a shortwave
is forecast to track to our north and push a cold front across the
region. 00z NAM/GFS/ECMWF/ggem guidance has trended a bit faster
with a consensus timing of Tuesday evening. With better model
agreement on timing and the front to provide a focus for convection
have raised probability of precipitation to likely.
Wind fields ahead of this front late Tuesday afternoon and evening
are fairly modest. Guidance generally forecasts 850mb winds
increasing to 30 to 40 kts...with limited directional shear. This is
a marginal wind field for producing widespread severe weather...but
it can result in a few bowing segments or pulse storms when ample
instability is in place. Storm Prediction Center has our are in a marginal risk...which
is in line with this thinking.
It is also Worth noting that both the 00z NAM/GFS forecast precipitable waters
over 2 inches...which is extremely moist for the area. If this
verifies...there is a potential that some storms could produce flash
flooding. In each case...the potential is small and largely
dependent on the timing and upstream development of convection along
Long term /Wednesday through Saturday/...
a trough of low pressure with a cold front will slowly exit to the
east on Wednesday with a lingering chance for showers and below
normal temperatures. After this...weak high pressure will build
across the area through Friday with below normal chances for
precipitation. Some model guidance tracks a weak area of convection
to our south Thursday and Thursday night. Otherwise...expect fairly
seasonable temperatures in the 70s to near 80 through the end of the
Looking ahead to next weekend...forecast confidence remains below
normal...as various forecast models disagree on the timing of a
shortwave that could bring increased shower/thunderstorm chances to
one of the days of the weekend. While Saturday or Sunday could see
some shower/thunderstorm activity... the weekend looks far from a
Aviation /08z Sunday through Thursday/...
VFR flight conditions
were found across the region at 06z...and these conditions will be
predominate throughout this taf package. The exception will be
across the southern tier where some valley fog may expand across the
kjhw terminal. This fog should remain thin as dewpoints remain
several degrees lower than the air temperature...with generally MVFR
visibilities within the fog.
Expect a few middle and high level clouds to start to build northward
across wny Sunday evening...with a deck of middle level clouds reaching
the southern tier by dawn Monday.
Winds will remain light and variable through the taf period with an
area of high pressure passing across the lower Great Lakes region.
Tuesday and Wednesday...mainly VFR with a chance of showers and
a weak pressure gradient will remain in place across the lower Great
Lakes today as high pressure crosses the region. This will generally
result in relatively light winds and minimal waves...with local lake
breeze circulations through the afternoon producing weak onshore
Winds will increase some Tuesday night behind a cold front...with
waves rising a foot or two on the eastern Great Lakes. Otherwise
expect flat wave action to continue through the week.