Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
753 PM EDT sun Jul 5 2015
high pressure across the eastern Great Lakes region will exit off
the northeast coastline tonight. A weak low pressure system will
bring some moisture northward possibly fueling a few showers and
thunderstorms Monday afternoon and evening across western New York
and The Finger lakes. A cold front will then bring additional
showers and thunderstorms later Tuesday through early Wednesday.
Near term /through Monday/...
visible satellite imagery shows plenty of high level smoke across
our region and the entire northern tier of the central and eastern
United States for that matter. This smoke has origins in the
Canadian rockies where large and widespread fires are burning. This
smoke is very high in the atmosphere...likely at cirrus levels. It
may very well provide a red hue to the sunset this evening and to
the moon overnight.
Otherwise...high pressure across the region this evening will drift
off the New England coast overnight. Some middle/upper level moisture
will begin to build northward as southerly flow develops on the
western periphery of the departing high. This will bring a modest
increase in middle/high clouds across the southern tier. Meanwhile the
rest of the area will remain mainly clear. Temperatures will be a
little warmer than last night with ongoing airmass modification.
Expect lows in the middle 60s on the lake plains of western New York and the
middle 50s in the coolest southern tier valleys and north country.
On Monday...a weak middle level low over the Ohio Valley will open and
spread weak ascent northeastward into the lower Great Lakes. In low
levels a plume of deeper moisture will spread northward out of the
Appalachians and into western New York and The Finger lakes. Some limited
instability will develop within this area with daytime heating...
with NAM/GFS profiles suggesting 500-1000j/kg of SBCAPE. This will
produce increasing clouds from south to north and increasing rain
chances by late morning across the western southern tier...and
during the afternoon across The Finger lakes...Genesee Valley...and
Niagara Frontier. The limited instability may also produce a few
widely scattered thunderstorms. The north country will escape the
deeper moisture and hang onto more sunshine through the afternoon.
It will become warm and somewhat more humid on Monday with highs
into the middle 80s across the lower elevations. The southern tier will
be cooler with an earlier onset of clouds and showers...with upper
70s to lower 80s there.
Short term /Monday night through Tuesday night/...
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. Deep southwesterly flow ahead of
an approaching cold front will allow dew points to surge into the
upper 60s Tuesday resulting in rather muggy conditions. This
combined with clearing across western New York /between a weak wave moving
east and the approaching cold front/ will allow for better heating
and destabilization Tuesday afternoon.
A parent shortwave will track to our north and drag a cold front
across the region Tuesday evening into Wednesday morning. Guidance
continues to trend a bit faster... with 12z consensus timing
bringing a line of showers and thunderstorms by late Tuesday
afternoon/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 35 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. Also... cannot rule out an mesoscale convective system
developing over Ohio and tracking into western New York ahead of the
cold front. If the mesoscale convective system materializes... it would provide the best
opportunity to produce damaging winds across the forecast area.
However... forecast confidence in this happening are still low from
this lead time. Storm Prediction Center has our are in a marginal risk for severe
weather... which is in line with this thinking.
It is also Worth noting that both the 12z 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. BUFKIT soundings show the potential for backbuilding cells
in this moisture rich environment as well. In each case...the
potential is small and largely dependent on the timing and upstream
development of convection along this boundary.
Long term /Wednesday through Sunday/...
a trough 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 work week.
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 /00z Monday through Friday/...
VFR conditions will persist across the region tonight as high
pressure will slowly drift east across New England.
Monday...VFR conditions will remain in place through at least the
morning hours...then there will be an increasing chances for showers
and thunderstorms after 16z across the southern tier...and after 18z
for sites closer to kbuf and kroc. Some of the heavier showers will
contain brief/local MVFR and IFR...but VFR should still prevail in
most areas between the heavier showers through the afternoon.
MVFR ceilings will spread across the western southern tier and possibly
The Finger lakes region Monday night.
Tuesday...mainly VFR with a chance of showers and thunderstorms in
Tuesday night...areas of MVFR and brief IFR/gusty winds with
showers and thunderstorms likely.
Wednesday...mainly VFR with a chance of showers.
Thursday and Friday...mainly VFR.
high pressure will exit to the east tonight but will maintain light
winds and minimal waves. Monday...light southerly flow will develop
across the region as a weak low pressure system tracks northeast
towards the region. This system will bring an increasing risk for
a few showers and thunderstorms Monday afternoon.
Winds will increase some Tuesday and Tuesday night both ahead and
behind a cold front...but conditions should still remain below Small
Craft Advisory criteria. Otherwise expect flat wave action to
continue throughout the week.