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000
FXUS61 KBUF 231557
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1157 AM EDT Sun Sep 23 2018

.SYNOPSIS...
An area of high pressure will maintain fair weather and seasonably
cool temperatures through the remainder of the weekend. Temperatures
will climb back above normal Monday and through mid-week. A storm
system will bring the next chance for rain showers Monday night,
with unsettled weather remaining through Wednesday night.

&&

.NEAR TERM /THROUGH TONIGHT/...
Surface high pressure will edge towards New England this
afternoon, with fair weather, plenty of sunshine and temperatures
warming back into the 60s.

Tonight will not be as cold as this morning as the main pool of
cold air aloft is displaced eastward, and a light easterly flow
begins with the departure of the surface high. Skies tonight
will again be mainly clear.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
Our first rain of astronomical fall is expected to arrive during the
first half of this week although temperatures will run 5 to 10
degrees above normal. Monday into Monday night a surface high will
shift from central Quebec east to center over the Canadian
Maritimes. In this process, winds across New York will increase and
further veer from southeast to south by daybreak Tuesday. Warm air
advection and moisture transport will increase with a warm front
lifting across the upper Great Lakes by Tuesday morning. While
Monday morning will remain dry, enhanced synoptic moisture will
support chance POPs across WNY by Monday afternoon with likely to
categorical POPs for rain showers Monday night. The warm air
advection will push temperatures back above normal for Monday with
highs in upper 60s to lower 70s. Lows Monday night will run a bit
more milder than recent nights with cloud cover and showers.

The flavor of Tuesday and Wednesday will be warm and showery with a
chance for some thunderstorms depending on available instability.
Western and north-central NY will be within the warm sector of low
pressure well to our north crossing northern Quebec Tuesday. The
lack of a surface front crossing our region during this time should
result in scattered to at times widespread rain showers ahead of a
cold front into Tuesday night. Instability per 00z GFS SBCAPE looks
weak with less than 500 J/kg but bulk wind shear of 35-45knots
during this time could support some isolated to scattered storms
perhaps reaching severe levels. SPC has included our forecast area
in a Day 3 Marginal Risk largely due to available wind shear.

00z model consensus is to push the surface cold front across the
eastern Great Lakes Wednesday with high pressure then building
across our region in its wake Wednesday night. PWAT anomaly of +2
top +3 shows atmospheric moisture will be above normal especially
Tuesday night and Wednesday where showers and storms would likely
bring heavy downpours. SBCAPE forecast by 00z GFS climbs a bit
higher Wednesday with perhaps some pockets reaching near or above
1000 j/kg ahead of the cold front while bulk shear may reach near 50
kts. This has lead to a Day 4 (Wednesday) severe weather outlook
across New York state. Forecast QPF through 00z Wednesday is around
one-half inch but factoring in heavy rain possible through Tuesday
night the WPC 1-3 Day QPF is one to one and one-half inches.

As mentioned above temps will run above normal with highs generally
in the low to mid 70s Tuesday and Wednesday. Lows dipping into the
50s Monday night but then not fall below the 60s Tuesday night. A
cold and dry air mass arriving from Canada Wednesday night will help
temps to slip back into the low 50s for most.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
Generally benign weather can be expected across our region during
this period...as a deamplifying longwave trough over the center of
the country will evolve into a pseudo zonal flow with the main H25
jet aligned from the high plains to the St Lawrence Valley. This
will support temperatures that will average close to normal
throughout the period.

In the wake of a cold front...high pressure will make its way across
the Lower Great Lakes to New England on Thursday. This will result
in cooler weather than the days leading up to this point...as H85
temps in the vcnty of 6c will only support afternoon highs in the
upper 60s. Otherwise it will be a pleasant day that will feature a
fair amount of sunshine.

A stacked storm system tracking just northwest of Lake Superior
looks to push an occluding frontal system across the lower Great
Lakes Thursday night. A triple point along this occlusion will be
found in the vcnty of Georgian Bay or southern Ontario. This feature
will serve as the pivot for an advancing weak warm front that will
do little more than to increase some high and mid level clouds over
our forecast area with a slight chance of some showers.

As the parent storm system moves to near James Bay on Friday...its
negatively tilted mid level support will push a cold front across
our region. While this may lead to scattered showers...the majority
of the day will be rain free.

Colder air in the wake of the front will overspread the Lower Great
Lakes Friday night...while a very broad...low amplitude trough will
become situated across the eastern half of Canada. H85 temps in the
lower single digits c will certainly support some instability over
the lakes...but will there be enough synoptic moisture to allow for
a legitimate lake response? From this long range vantage point...it
appears that low and mid level moisture will be limited...but the
confidence is not high enough to rule out some nuisance showers.
This will mainly be the case for sites east of Lake Ontario in the
vcnty of the Tug Hill. Otherwise...an uneventful night is expected.

On Saturday, high pressure stretching from the oil fields of western
Canada to the Mid Atlantic region should encourage fair dry weather
over our region although the 00z GFS is showing another cold front
passage across the Great Lakes. It should be relatively cool though
as H85 temps in the lower single digits c will only support
afternoon highs in the low to mid 60s.

&&

.AVIATION /16Z SUNDAY THROUGH THURSDAY/...
Widespread VFR conditions are expected this afternoon and early
tonight. Winds will remain light as surface high pressure
remains near the region.

High clouds will begin to increase late tonight and will likely
restrict any fog to the immediate river valleys of southern New
York, with KJHW likely to remain VFR through the night.

Outlook...

Monday...VFR. Showers likely late Monday night.
Tuesday and Wednesday...Areas of MVFR (IFR possible in So. Tier)
with showers likely.
Thursday...Mainly VFR.

&&

.MARINE...
Area of high pressure was over the eastern Great Lakes early
this afternoon, with light winds and minimal waves on the
lakes. These light winds and low wave heights will continue
through the first half of tonight.

As the surface high moves eastward late tonight and into Monday
an easterly flow will increase on the Lakes, with possible
small craft conditions late tonight in Monday.

Ahead of a cold front slowly marching eastward towards the eastern
Great Lakes a southerly flow will begin to increase later Monday
through Wednesday, with a likely bring another round of small craft
conditions on the lakes.

&&

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

&&

$$

SYNOPSIS...Thomas/TMA
NEAR TERM...Thomas/TMA
SHORT TERM...Smith
LONG TERM...RSH/Smith
AVIATION...Thomas/TMA
MARINE...Thomas/TMA