Forecast Discussion

Forecast Discussion for BUF NWS Office
000
FXUS61 KBUF 180232
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1032 PM EDT Tue Jul 17 2018

.SYNOPSIS...
High pressure will build across the region tonight through Friday,
which will bring comfortable temperatures and low humidity for mid-
week, followed by warmer temperatures and increasing humidity for
the end of the week. A slow-moving low pressure system will approach
this weekend bringing the next chance for unsettled weather.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
A weak secondary cold front across the region late this evening
will push south of the area overnight. This front will result
in scattered clouds and a wind shift, but it is generally too
dry for any precipitation. Dew points will fall further behind
this boundary, along with a cooler airmass with 850 mb
temperatures falling to about +8C. Northerly winds advecting in
this airmass overnight will help prevent optimal radiational
cooling, so overnight lows will be refreshing but not overly
cool, ranging from the mid 50s to the low 60s.

On Wednesday, the cool and dry airmass will make for a phenomenal
day for outdoor activities. As the boundary layer mixes out fully by
the afternoon, dew points will fall into the 40s for most, and even
into the 30s in the North Country. High temperatures will only top
out in the mid 70s, which will actually be a few degrees below
normal, something we haven`t seen much of lately. Diurnal fair
weather cumulus will be limited to western NY, mainly in the
Southern Tier where the best low-level moisture lingers.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
High pressure will drift from the central Great Lakes to the eastern
Great Lakes Wednesday night. Associated subsidence and dry air will
bring clear skies and light winds, with excellent radiational
cooling conditions. This will allow lows to drop into the low to mid
50s on the lake plains, and mid to upper 40s in the cooler Southern
Tier valleys and east of Lake Ontario. There will be valley fog
across the western Southern Tier, with some fog also possible in the
river valleys and near the larger bodies of water east of Lake
Ontario.

High pressure remains overhead Thursday with nearly full sunshine.
After a cool start, the airmass will begin to modify with 850mb
temps rising to around +11C. This will support highs in the lower
80s at lower elevations away from the immediate lakeshores, with mid
to upper 70s on the hills. The light synoptic scale winds and strong
differential heating will support lake breeze development, with
onshore winds in the afternoon keeping the lakeshores in the mid to
upper 70s.

Thursday night and Friday high pressure will drift slowly east
across New England and off the eastern seaboard. Lingering dry air
and subsidence will keep skies mainly clear Thursday night through
early Friday, with just a modest increase in thin/high cirrus. 850mb
temps rise to around +16C by afternoon as warm advection increases
behind the departing high. This will support highs in the upper 80s
to lower 90s at lower elevations, with mid 80s for higher terrain.
South to southeast winds will also prevent lake breezes in most
locations.

Friday night and Saturday a cutoff upper level low and associated
surface low will drift very slowly eastward across the western Great
Lakes. The majority of the deeper moisture and better forcing will
remain to our west through late Saturday. Marginally better moisture
and weak forcing may get close enough to the region to support a low
chance of showers and thunderstorms across the far western end of
the state later Friday night and Saturday. Otherwise the remainder
of the region will remain dry. Clouds will increase west of the
Genesee Valley Friday night and Saturday, with less cloud cover east
of Lake Ontario. Lows Friday night will be held up by a southerly
breeze, with lows in the mid to upper 60s on the lake plains, and
lower 60s in the Southern Tier valleys and east of Lake Ontario.
Highs on Saturday will reach the mid to upper 80s on the lake
plains, along with moderate humidity as dewpoints rise into the mid
60s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
A period of near to slightly above normal temperatures along
with an increased chance of showers and thunderstorms are
expected for the end of the weekend and start of the work week
as a closed upper level low tracks south of the lower Great
Lakes. Synoptic moisture associated with the closed low will be
confined to our southwest as the mid- level trough digs into the
Ohio Valley Saturday night. Showers and thunderstorms may affect
the Lake Erie region during this time however most places will
remain dry. Further east, a compact coastal low is forecast to
move north along Mid- Atlantic and southern New England coast
Saturday night. This system will likely phase with the upper
level low Sunday and Sunday night and sub- tropical moisture
will move into the Northeast. This could potentially bring a
soaking rain to the forecast area as it tracks towards Lake
Ontario Sunday. At this time, model guidance keeps the best
forcing across the North Country however, surface low pressure
associated with the closed low over the northern Ohio Valley will
promote showers and thunderstorms across Western NY. Best
chance will be during peak heating, Sunday afternoon and early
evening.

The closed low continues to spin in vicinity of Western and North-
Central NY Monday and Monday night. Showers and thunderstorms will
be possible through this period with the best chance in the
afternoon and early evening.

Highs will be near normal Sunday reaching the upper 70s to
lower 80s with low humidity. Temperatures will be a few degrees
warmer along with increased moisture Monday. Lows will
generally run in the mid to upper 60s on the lake plains, and
lower 60s across the interior.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
High pressure will build into the upper Great Lakes region
overnight. There will be a modest northerly flow behind a
secondary cold front overnight. This will limit fog development
considerably, with perhaps some patchy valley fog or stratus
across the western Southern Tier. This should mainly remain east
of KJHW.

After this, expect widespread VFR conditions on Wednesday with
scattered clouds dissipating as high pressure builds in during
the afternoon.

Outlook...
Wednesday night through Friday...VFR.
Saturday...VFR, except MVFR in showers and thunderstorms.

&&

.MARINE...
High pressure will build into the upper Great Lakes tonight,
with northerly winds increasing behind a cold front as the
pressure gradient tightens across the waters. Winds will be
strong enough support SCA conditions along the south shore of
Lake Ontario through Wednesday morning.

Winds and waves will diminish for the remainder of the week as high
pressure builds overhead, allowing for fine boating conditions. A
low pressure system looks to cross over the Eastern Great Lakes this
coming weekend with chances for showers and storms.

&&

.FIRE WEATHER...
Relative humidity will fall to around 30% on Wednesday afternoon,
and possibly well into the 20s across the North Country. Winds
will be lower on Wednesday, with gusts expected to remain less
than 20 mph across the region, precluding the need for fire
headlines.

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 2 PM EDT Wednesday for LOZ042>044.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Beach Hazards Statement from 6 AM EDT Wednesday through
     Wednesday afternoon for NYZ002>004.
MARINE...Small Craft Advisory until 2 PM EDT Wednesday for LOZ042>044.

&&

$$

SYNOPSIS...Church
NEAR TERM...Apffel/Church
SHORT TERM...Hitchcock
LONG TERM...HSK/Thomas
AVIATION...Apffel
MARINE...Apffel/Church
FIRE WEATHER...Church/Apffel

NWS BUF Office Area Forecast Discussion