Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 170140
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
940 PM EDT Wed Aug 16 2017

.SYNOPSIS...
High pressure will provide our region with fantastic weather
through the first half of Thursday. A warm front will then
stubbornly push north across our area late Thursday and Thursday
night...with increasingly widespread showers and thunderstorms
marking its progress. This will be followed by a cold front and
more thunderstorm activity on Friday.

&&

.NEAR TERM /THROUGH THURSDAY/...
High pressure across the region will slowly drift to our east
overnight, resulting in mainly clear skies and light winds.
Good radiational cooling conditions will allow temperatures to
fall into the 50s in most areas, with upper 40s across the
foothills of the `Dacks` in Lewis County. Fog will be less
widespread than last night, but still will develop across the
Southern Tier overnight, especially in the river valleys and
open fields.

On Thursday...pleasant conditions during the morning will gradually
give way to increasing clouds as a warm front will approach the
region. Cloud cover will lower and thicken from the southwest
during the day. There could even be some showers and
thunderstorms over the far western counties by the end of the
day...with the unsettled weather further blossoming after
dinnertime. Otherwise...it will be warm with a return of more
humid conditions. Max temps will generally be in the low to mid
80s.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
A warm front will continue to lift north across the region Thursday
night. The associated showers/thunderstorm have a ample supply of
moisture with PW of 1.5 to 2.0" thus locally heavy downpours are
possible. Expect a warm muggy night Thursday night with
temperatures in the mid to upper 60s.

The showers/tstms continue into Friday ahead of and along an
approaching cold front. While most of the convection not expected to
be severe, increasing shear could be just enough to allow some of
the stronger storms to produce damaging wind gusts. SPC continues to
outline much of the region in its Day 3 outlook.  Look for max temps
in the upper 70s to low 80s.

Weak surface ridging builds across the CWA in the wake of the cold
front with drying slowly taking place with lingering showers
tapering off from west to east Friday night. It will be a few
degrees cooler with lows dropping into the low to mid 60s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
On Saturday...the guidance suite is in pretty good agreement that
the surface low responsible for the unsettled conditions of the
previous couple of days will bodily lift northeastward across
northern Quebec Province...while its rather sharp parent upper level
trough digs across the Central/Lower Great Lakes. The westerly upslope
flow in the wake of the surface low and its trailing cold front will
probably lead to some scattered morning showers across the North
Country...with more general lower-end shower chances then arriving
during the afternoon in concert with diurnal heating and the arrival
of the upper level trough/cooler air aloft. Otherwise less humid
conditions and seasonable temperatures will prevail...with afternoon
highs mostly in the mid to upper 70s and dewpoints largely running
in the lower 60s. Saturday night any showers should largely fade out
with the loss of heating and diurnally-driven instability...while
continued gradual cool/dry air advection allows overnight lows to
drop back to more comfortable levels in the upper 50s to lower 60s.

After that...Sunday and Monday both look to feature quiet and dry
weather as sprawling surface-based ridging builds into our region
from the Ohio Valley on Sunday...then only slowly drifts eastward and
off the Delmarva coastline on Monday. With plenty of attendant dry
air also in place...this will allow for mostly sunny/mainly clear
skies...thereby resulting in near ideal sky conditions for viewing
of Monday`s solar eclipse. Otherwise slow but steady warming of our
airmass will allow daytime highs to climb back into the upper 70s and
lower 80s on Sunday and into the mid 80s in many places on Monday...
while dewpoints remain at tolerable levels (around 60 on Sunday and
in the lower 60s on Monday).

As we progress deeper into the new work week...our weather still
looks to turn more unsettled again for later Tuesday and especially
Tuesday night...when the medium range guidance suggests that the next
upper level trough and associated cold front will move across our
region. Have continued to advertise broadbrush chance PoPs to cover
the passage of these features...with our area then drying out from
northwest to southeast on Wednesday following the frontal passage.
With warmer and more humid air continuing to advect into our region
out ahead of this system...expect highs on Tuesday to surge all the
way into the mid to upper 80s while dewpoints climb back into the
mid 60s...which will make for a rather uncomfortable day. Following
the passage of the cold front...cooler and less humid air will then
spread back into our region on Wednesday...when daytime highs will
retreat back into the mid and upper 70s.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
High pressure across the region will slowly drift east resulting
in fair weather and largely VFR conditions which will last well
into Thursday. Expect valley fog to again develop in the
Southern Tier Valleys, with a period of IFR or lower conditions
at JHW.

Clouds will increase during the day on Thursday as a warm front
lifts toward the region from the southwest. This will result in
increasing chances for showers and possibly a thunderstorm
mid to late afternoon onward in western portions (BUF/IAG/ROC).

Outlook...
Thursday night...VFR deteriorating to IFR/MVFR in increasing
coverage of showers and thunderstorms.
Friday...MVFR improving to VFR with showers and thunderstorms
exiting during the midday and afternoon.
Mainly VFR with a chance of showers and thunderstorms.
Saturday into Monday...Mainly VFR.

&&

.MARINE...
High pressure drifting across the Lower Great Lakes overnight
will keep light winds and minimal waves in place through the
first half Thursday.

As the high pressure exits across New England...a warm front will
approach the region Thursday afternoon. This will set up a light
southeasterly flow with negligible waves remaining in place.

Showers and thunderstorms associated with the warm front will
increase in coverage later Thursday afternoon and particularly
Thursday night. Mariners should be wary of the deteriorating
conditions...as some of the thunderstorms may warrant special marine
warnings.

The showers and thunderstorms will persist across the Lower Great
Lakes through at least the first half of Friday when a cold front
will push across the region. These storms could again be rather
strong...especially on the eastern half of Lake Ontario and in the
St Lawrence Valley.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...RSH
NEAR TERM...APFFEL/RSH
SHORT TERM...LEVAN
LONG TERM...JJR
AVIATION...APFFEL
MARINE...CHURCH/RSH



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