258
FXUS61 KBUF 211017
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
617 AM EDT Sat Sep 21 2024

.SYNOPSIS...
An upper level disturbance will cross the area today, producing
scattered showers and a few isolated thunderstorms, mainly this
afternoon and early evening across Western NY, the Genesee Valley,
and Finger Lakes. A narrow ridge of high pressure will then bring a
return to dry weather Sunday. The weather will then turn unsettled,
as a cold front moves into the area Monday and stalls out, with
several areas of low pressure moving northeast along it through the
course of next week, with numerous rounds of showers and a few
thunderstorms.

&&

.NEAR TERM /THROUGH SUNDAY/...
IR satellite imagery showing areas of high clouds drifting across
the eastern Great Lakes early this morning. A few scattered showers
are upstream across Lake Erie, northwest PA, and southern Ontario.
These are moving slowly east, and the first of the scattered showers
will start to arrive in far Western NY by mid to late morning.

A mid level shortwave will move southeast across the eastern Great
Lakes this afternoon and evening. DPVA and height falls ahead of the
shortwave combined with frontogenesis along a NNW-SSE oriented
thermal gradient will bring an increase in large scale forcing
today. Modest diurnal instability will develop this afternoon and
combine with the synoptic scale forcing to produce scattered showers
and a few spotty thunderstorms. Expect the best coverage to be for a
few hours late afternoon and early evening across the Genesee Valley
and western Finger Lakes. The eastern extent of the scattered
showers will reach the Finger Lakes late afternoon and evening, with
mainly dry weather prevailing east of Lake Ontario.

Tonight, the evening showers and a few thunderstorms will taper off
this evening, with any lingering spotty light showers ending by
daybreak Sunday. Expect partial clearing and light winds overnight,
which will promote areas of fog, especially across the Southern Tier
and Finger Lakes, and in any areas which receive rainfall this
afternoon and evening.

Sunday, morning fog and low stratus across the Southern Tier and
Finger Lakes will burn off by mid to late morning, leaving a mix of
sun and clouds for the rest of the day with dry weather prevailing
as a narrow ridge builds into the eastern Great Lakes.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
A well defined closed low over the desert Southwest this early
morning will open up with a piece of energy transversing the Plains,
and phasing with a northern branch jet to bring enhanced synoptic
lift for the formation of showers late Sunday night and through
Monday. Deeper moisture will be near the surface low along a stalled
frontal boundary...with this low just to north of Lake Erie. This
will allow for rainfall amounts Monday and Monday night for most
areas to remain a third of an inch or less...with heavier rain just
to our west and north.

With this low remaining to our west, surface winds will generally
remain south to southeast, with the downslope regions near Lake
Erie/Thruway and along the southern Lake Ontario shoreline likely to
top the 70 degree mark Monday, while cloud cover over higher terrain
will keep the interior higher terrain of WNY and the Tug Hill in the
lower to mid 60s.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Pattern this period will feature unsettled weather throughout. Aloft
a 250/300 hPa southern branch of the jet stream will lift northward
towards the Ohio Valley, while a northern branch jet within a
developing long wave trough will be dropping over the Prairies of
Canada and into the Northern Plains. In an amplifying pattern, these
jets will help to close the upper level trough over the
Plains/Midwest region, which will linger unsettle weather through
the remainder of this period. Where this closure occurs is still
with great uncertainty among the models, increasing further the
uncertainty in the weather towards the end of this period.

Will carry chance to likely PoPs each day through this period.
Wettest period may end up being Tuesday night into Wednesday as a
stronger LLJ of 30 - 35 knots, and surface warm front moves across
the region. Marginal instability will allow for a risk of thunder
through Thursday, though none of the days is overly convincing for
thunder chances.

Cloud cover and showers will keep daytime highs close to normal,
while these same clouds will hold overnight lows above normal
through the period.

&&

.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
A mid level shortwave will cross the eastern Great Lakes today,
bringing with it a period of cloudiness with VFR bases and scattered
showers. The scattered showers will start to enter Western NY by mid
to late morning, then reach as far eastward as the Finger Lakes
later this afternoon before tapering off and ending tonight.
Overall, coverage of the rain showers will stay scattered to widely
scattered, with the best chance of a more organized cluster of
showers across the Genesee Valley and Southern Tier for a few hours
late afternoon/early evening. There may be a few isolated
thunderstorms as well in this area later this afternoon. Given the
expected scattered nature of showers, and even more sparse coverage
of thunder, used VCSH in the TAFs for now.

Tonight, any remaining showers will taper off and end, and skies
will partially clear. The light winds and clearing skies will allow
areas of IFR fog and low stratus to develop, especially across the
Southern Tier and Finger Lakes valleys and in any locations that
receive rainfall today. KJHW is the most likely terminal to
experience fog and IFR overnight through Sunday morning.

Outlook...

Sunday...Patchy IFR fog and low stratus through mid morning, then
mainly VFR.
Monday through Wednesday...VFR/MVFR with showers likely and a chance
of thunderstorms at times.

&&

.MARINE...
East to southeast winds will continue through the weekend on the
lower Great Lakes, directing most of the moderate chop into the
middle of the lakes and Canadian waters.

Low pressure and a cold front will approach from the west late
Sunday night and Monday, with increasing south to southeast winds on
both lakes. This wind direction will once again keep the greater
wave action well offshore and in Canadian waters.

&&

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

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Hitchcock
SHORT TERM...Thomas
LONG TERM...Thomas
AVIATION...Hitchcock
MARINE...Hitchcock