Forecast Discussion for BUF NWS Office
000
FXUS61 KBUF 271824
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
224 PM EDT Thu Jul 27 2017

.SYNOPSIS...
A cold front with a few showers will slide across the region this
evening, to be followed by temporarily clearing skies. A cool
northerly flow will develop a wealth of low clouds across the region
later tonight, with these clouds hanging around through the morning
hours of Saturday. High pressure following this cold front will
bring dry conditions tonight and through the weekend.

&&

.NEAR TERM /THROUGH FRIDAY/...
A cold front will drop across the region this evening...with a few
showers and isolated thunderstorms...mainly across far SW NYS, and
then across the North Country...where both areas will be closer to
better upper level lift associated with passing shortwaves.

Skies will clear behind the front later this afternoon and evening,
however there will remain a fair amount of low level moisture, that
when a cool northerly flow (850 hPa temperatures around 10C)
develops after midnight it will likely bring a good amount of low
level clouds...both south of Lake Ontario and also across the
upslope areas of the Tug Hill.

Surface high pressure will push towards the region tonight and
tomorrow...and while this feature will bring fair weather it will
bring a developing inversion...such that overnight cloudiness may
linger through at least the morning hours of Friday.

Temperatures tonight will drop down into the upper 50s to mid 60s,
while tomorrow under the cool air advection, highs will only recover
back to the lower 70s.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
An upper level trough near Northern MN should have closed off and be
somewhere near Eastern OH/Western PA Friday Night into Saturday.
This scenario paints a rather dreary picture for areas south of NYS,
but results in weak subsidence overhead.  Surface high pressure
underneath a longwave ridge upstream should therefore be the
dominant feature for the weekend. The ridge will remain just
upstream, with NE flow over the region through the weekend.

The result should be dry weather for the entire region.  The only
concern would be along the PA border/Southern Tier, where some
moisture could sneak north across the border if the low ends up a
little north of most models.  Otherwise, the main impact will be
mostly opaque high cirrus over the region mainly on Saturday. Sunday
looks better for sunshine and resulting higher temperatures closer
to normal - near upper 70s to near 80, while Saturday`s highs will
be ~5F lower.  Overnight, there may be some patchy valley fog Friday
night and Saturday night, but high clouds should prevent strong
radiational cooling. Clearing skies Sunday night may result in
typical inland river valley fog.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The aforementioned low will continue to fill as it slowly tracks
northeast along the northeastern coast before moving out in to the
North Atlantic by the middle of the week. Meanwhile, a broad surface
high encompassing much of the central U.S. will make inroads into
the lower Great Lakes in the wake of the departing low, keeping
conditions dry at least on Monday. Guidance is indicating a
potential for a few showers on Tuesday as a weak shortwave works its
way around the upper level ridge to our west. A stronger wave and
associated cold front has a somewhat better potential to bring
rainfall to the region in the Wednesday to Thursday timeframe.

Regarding temperatures, the retreat of the weakening upper level
trough and encroaching upper level ridging from the west will lead
to somewhat of a warm-up across the lower Great Lakes next week, as
warmer air advects into the region. Temperatures will rise back into
the upper 70s to around 80 on Monday, with readings a couple of
degrees warmer Tuesday. Warmer air surging across the region in
advance of the aforementioned cold front should push readings back
into the low to mid 80s by Wednesday. Low temperatures will follow
suit, with upper 50s to mid 60s Monday night giving way to mid to
upper 60s by Wednesday night.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
For the 18Z TAFS a cold front with low end VFR/MVFR CIGS and
producing a swath of rain showers will cross the region through
about 18Z. The greatest chances for a shower at a TAF site will be
KJHW where a few showers may drift across the airfield from Lake
Erie.

Surface high pressure behind the cold front will build towards the
region tonight, and with lingering low level moisture there will be
concern for developing poorer flight conditions through the night.
If sufficient clear occurs across the So. Tier there likely will be
fog formation...that will bring IFR or lower visibilities to KJHW.

In addition a cool north to northeasterly flow will form and bring
low clouds (MVFR flight range) across TAF sites around 06Z...with
these clouds lingering through much of the remainder of the TAF
cycle. There will be some improvement to the CIGS through the day
tomorrow...with flight conditions returning to VFR by the close of
the TAF cycle as the clouds begin to thin.

Outlook...

Friday afternoon through Tuesday...Mainly VFR. A slight chance of
showers and thunderstorms Tuesday.

&&

.MARINE...
A cold front will drop across the eastern Great Lakes this evening.
Westerly winds ahead of the front will veer to north to
northeasterly late this evening and remain at this direction through
Saturday morning. These winds will increase to around 20 knots later
tonight and again Friday night, while producing waves around 4 feet
on the western and central waters of Lake Ontario. This will yield a
small craft advisory for western Lake Ontario Friday morning.

Winds appear to have enough of an easterly component near the
Niagara River such that a SCA will not be needed here.

On Lake Erie winds will yield the highest waves on the western
waters of the lake, with waves less than four feet from the state
line northward.

Later Saturday and then through the weekend high pressure over the
Eastern Great Lakes will bring fine boating conditions continuing
through the weekend as high pressure slowly passes by.

&&

.TIDES/COASTAL FLOODING...
An intensifying storm system over the Middle Atlantic states
Friday-Saturday will combine with high pressure over the Upper
Great Lakes to produce a prolonged period of fresh
northeasterlies on Lake Ontario from late tonight through
Friday. While winds and waves may temporarily subside late
Friday...winds are forecast to become northerly and increase
during the first half of Friday night. The risk remains that
waves could build to levels that may produce additional erosion
and flooding along much of the south shore of the lake. A
lakeshore flood watch continues from Niagara county to Wayne
county to cover this heightened risk.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Lakeshore Flood Watch from Friday morning through late Friday
     night for NYZ001>004.
MARINE...Small Craft Advisory from 5 AM to 2 PM EDT Friday for LOZ042-
         043.

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...THOMAS
SHORT TERM...ZAFF
LONG TERM...WOOD
AVIATION...THOMAS
MARINE...THOMAS
TIDES/COASTAL FLOODING...RSH/THOMAS

NWS BUF Office Area Forecast Discussion