Forecast Discussion for BUF NWS Office
000
FXUS61 KBUF 151447
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1047 AM EDT Mon Oct 15 2018

.SYNOPSIS...
A cold front will shift across the lower Great Lakes region today
with widespread rain showers and gusty winds. A cool and windy
airmass will settle over our region behind the front with below
normal temperatures returning Tuesday through the remainder of the
week. Another cold front will bring chances for rain showers
Wednesday turning cold enough perhaps for some wet snow across
higher elevations Wednesday night.

&&

.NEAR TERM /THROUGH TONIGHT/...
The surface map shows an elongated frontal zone extending from low
pressure north of Lake Huron to the south across the Midwest and
into the lower Mississippi River Valley. A warm front and leading
edge of an airmass with deeper moisture extends from about the
southern end of Lake Huron arcing east across Lake Erie into WNY and
western PA. The surface low resides in divergent 500mb flow across
the Great Lakes to the east of a cut off low over northern
Minnesota. The divergent flow will support continued deepening of
the low today as it shifts northeast into central Quebec. A
southwesterly low let jet is ramping up behind the warm front this
morning which is supporting some leading scattered rain showers
north of the warm front, extending from Lake Ontario southeast
across CNY. These leading warm advection showers will move
northeast across north-central NY through the morning hours with
only some isolated showers possible within the narrow warm
sector ahead of the approaching cold front.

Chance POPs are in play across WNY and the Finger Lakes this morning
with downslope flow and limited synoptic lift within the warm
sector. The cold front should pass east across western and north-
central New York near midday. Expect numerous to widespread rain
showers through at least early afternoon along the cold front,
before precip coverage trends down during the late afternoon with
incoming drier air behind the cold front. Winds will become quite
gusty behind the front topping out just below Wind Advisory
criteria, sustained 15-20 with gusts 35-40 mph. Daytime high
temperatures should be met around midday before sliding down during
the afternoon in developing cold air advection. Look for upper 50s
to lower 60s in most spots the sliding back toward 50 by sunset.

Tonight, cold air advection will continue behind the cold front.
850mb temperatures will fall to around -4C overnight. Although
moisture will diminish behind the cold front, mesoscale models and
BUFKIT profiles support development of some lake enhanced/effect
rain showers east of the lakes. The fetch is better across Lake
Ontario where these showers will persist into Tuesday morning. Off
Lake Erie, westerly winds over the smaller fetch of the lake and
lack of deeper moisture will result in a much more muted response
with only isolated to scattered rain showers through mainly the
evening hours. Winds will remain quite gusty with some sites seeing
gusts to around 45 mph as the 500mb trough axis shifts across our
region. Winds will slacken toward Tuesday morning. Low temperatures
will fall into the upper 30s to low 40s. Higher elevations will
likely see mid 30s.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Tuesday high pressure will build into the Ohio Valley, while the
next mid level trough and associated cold front advance through the
Upper Great Lakes. The airmass will be quite dry ahead of this next
cold front, but there may still be just enough boundary layer
moisture and lake induced instability left to support a few
scattered lake effect rain showers. Off Lake Erie, any scattered
showers that do develop would move from the lakeshore of Chautauqua
County in the morning to near Buffalo by midday as boundary layer
flow backs to the southwest. Off Lake Ontario, any scattered showers
would move from Oswego County in the morning to near Watertown by
afternoon. Otherwise the rest of the area will be dry, with some
sunshine away from the lake effect clouds. Highs will reach the
lower 50s at lower elevations, and mid to upper 40s across higher
terrain. It will be another windy day, with gusts of 30-40 mph in
the afternoon in the typical areas northeast of Lakes Erie and
Ontario, and 20-30 mph farther inland.

Tuesday night the next cold front will cross our region, with an
increase in clouds and possibly a few scattered showers outside of
lake effect areas. The front will bring a notable increase in
moisture and supporting ascent, as well as the start of colder
temperatures aloft. This will allow lake effect rain to increase in
coverage through the evening. Off Lake Erie this will initially
develop from near Buffalo to Batavia, then settle south into the
western Southern Tier overnight as boundary layer flow veers behind
the cold front. Ongoing synoptic scale support and strong boundary
layer flow will allow lake effect showers to push well inland, even
reaching the western Finger Lakes overnight. Off Lake Ontario, lake
effect rain will increase near Watertown in the evening, then settle
south across the Tug Hill region overnight. The rain may become
moderate to heavy at times especially off Lake Ontario, but a steady
southward shift in band placement will prevent high rain amounts at
any one location. Lows will be in the lower 40s in most locations,
with some upper 30s across higher terrain. It will remain quite
windy overnight, especially along the lakeshores where winds will
continue to gust in the 30-40 mph range.

Wednesday the mid level trough will cross the eastern Great Lakes,
allowing a cooler airmass to pour into the region. Boundary layer
flow will continue to veer from westerly to northwesterly, keeping
lake effect rain bands mobile. Off Lake Erie, the veering winds will
force lake effect rain to weaken as the fetch shortens, evolving
into an upslope scenario for the Chautauqua Ridge with some upstream
connection to Lake Huron possible at times. Off Lake Ontario, a
healthy band in the morning across Oswego County and the southern
Tug Hill will settle into Wayne/Northern Cayuga counties through the
day, with model guidance continuing to hint at a good upstream
connection to Georgian Bay. The western extent of the band will also
likely move onshore from Niagara to Monroe counties as well. Outside
of these main lake effect areas, a few scattered showers will still
occur from the mid level trough and meandering bands of Lake Huron
showers. Highs will range from the upper 40s along the lakeshores to
the lower 40s across higher terrain.

Wednesday night northwest flow lake effect will continue as the
coldest air aloft settles across the region. The overall airmass
will begin to dry out, which should bring an end to any scattered
showers outside of the main lake effect areas during the evening.
The best lake effect band should be off Lake Ontario overnight with
a favorable connection to Georgian Bay likely. Most of the lake
effect will focus from near Rochester into the Finger Lakes. Off
Lake Erie, northwest upslope flow will continue to generate a few
showers across the western Southern Tier. Ongoing cold advection
will allow rain to mix with and change to snow overnight across
higher terrain. On the lake plains, model point soundings show
precipitation staying all rain, however past experience suggests the
forecast 850mb temps of -8C should support at least wet snow mixing
in on the lake plains. There could be a minor coating of
accumulation in a few spots across higher terrain and in the most
dominant Lake Ontario band.

A few lake effect rain/snow showers will persist into Thursday
morning southeast of the lakes, especially off Lake Ontario. Mid
level warm advection rapidly overspreads the area by afternoon,
which will crash inversion heights and bring an end to the lake
effect. Lake effect clouds will give way to some clearing later in
the day. High temperatures will only be in the 40s again, with some
upper 30s for the higher terrain east of Lake Ontario.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
The overall pattern will remain cold in the Great Lakes and New
England over the next week to 10 days with a longwave trough
position well established across eastern North America. There will
be some day to day modulation, with a few brief warm-ups between
fresh batches of cold air.

Thursday night and Friday will be one of these warm-ups, as the
trough reloads across the northern Plains allowing warm advection to
briefly spread across the eastern Great Lakes. Highs will reach the
mid to upper 50s Friday, with some lower 60s possible in the Genesee
Valley. A ridge surface and aloft will provide a stretch of dry
weather to end the week.

The digging upstream trough will approach the area Friday night and
then cross Saturday, along with an associated cold front. This will
bring increasing chances of showers, with some lake enhancement
possible Saturday east and southeast of the lakes as the mid level
trough and associated cold air aloft enter the region. Another surge
of cooler air will arrive Saturday night and Sunday, with northwest
flow lake effect producing some rain and snow showers. Highs will
be in the 40s again by Sunday.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
Cigs have lowered to MVFR with IFR at KJHW as a warm front lifts
northeast across WNY. KROC/KART are VFR but will fall this morning
with increasing moisture. Some limited showers are showing along the
warm frontal boundary but a second more widespread round is expected
late morning into around midday along a passing cold front.

Behind the cold front winds will become gusty from mid afternoon
through at least the first half of tonight along with showers
diminishing over most areas with only the areas east of the lakes
seeing a slower diminishing tread with some contribution for lake
enhancement. When showers diminish, cigs will lift back to VFR except
again in areas with lake enhancement east of Lakes Erie and Ontario.
The southwest to west winds will occasionally gust towards 30-35
knots behind the cold front.

Outlook...

Tuesday...Mainly VFR with a chance for rain showers late.

Wednesday...VFR/MVFR with a chance of rain showers.

Thursday and Friday...Mainly VFR.

&&

.MARINE...
A cold front will pass across the lower Great Lakes today, with
showers and southwest winds ahead of the front increasing then
remaining gusty from the west through tonight. Small craft
advisories have been raised for Lake Erie and the Niagara and Saint
Lawrence Rivers to account for these higher winds and lake waves.

Strong cold air advection and deepening surface low tracking well to
the north of Lake Ontario tonight will support winds increasing
further on Lake Ontario with Gales expected from late this afternoon
through the first half of tonight.

Westerly winds will subside below Gales on Tuesday but will likely
support lingering Small Craft Advisory conditons on the eastern
Great Lakes through much of this week. Small craft advisory
conditions will persist on Lake Erie at least through Wednesday
night and will run the current SCA through this time period.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 11 PM EDT this evening for LEZ020.
         Small Craft Advisory until 8 AM EDT Thursday for LEZ040-
         041.
         Small Craft Advisory until 11 PM EDT this evening for
         LOZ030.
         Gale Warning from 4 PM this afternoon to 5 AM EDT Tuesday
         for LOZ042>045-062>065.
         Small Craft Advisory from 5 PM this afternoon to 2 AM
         EDT Tuesday for SLZ022-024.

&&

$$

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

NWS BUF Office Area Forecast Discussion