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000
FXUS61 KBUF 211420
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1020 AM EDT Sun Apr 21 2019

.SYNOPSIS...
A slow moving cutoff low will drift from the central Appalachians
today to the Mid Atlantic coast Monday. Clouds and a few scattered
showers will linger today for much of the region before mainly dry
weather returns Monday as the system moves away from our area. Dry
weather will last through much of Tuesday before a cold front brings
another round of showers late Tuesday and Tuesday night.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today and tonight a cutoff low will drift ever so slowly from the
central Appalachians to the Mid Atlantic, with an old associated
inverted trough surface and aloft extending up into the eastern
Great Lakes. The cutoff low is steadily filling, leaving just weak
forcing for ascent across our region. Much of the focus for showers
today into this evening will be driven diurnally and by terrain and
differential heating boundaries. The latest high-res and global
guidance is in fairly good agreement in suggesting the best chance
of scattered showers will be this afternoon from the interior
Southern Tier through the Finger Lakes to the Tug Hill region. If
enough sunshine develops there could be a few slow moving convective
downpours, but this seems more likely to the south and east of our
area.

The diurnally driven showers will mostly end by early evening. The
one exception may be across portions of Lewis and Oswego counties,
where a weakly convergent surface boundary will keep a chance of
showers going tonight, and even into early Monday morning. Otherwise
most of tonight will be dry. As the cutoff low slowly weakens, there
will be little to no flow today and tonight through the lowest 15K
feet of the column. This will keep much of the low level moisture in
place, and may result in low stratus and fog becoming prevalent
again later tonight into early Monday morning.

Similar to the past few days, there will be a large range in
temperatures across the region today. Western NY will likely keep
low clouds much of the day, and will subsequently remain quite cool
with many areas only seeing highs in the upper 40s, and even low to
mid 40s right along the lakeshores. Meanwhile across Central NY into
Lewis County, there will be much less in the way of low cloud cover.
This will allow for temperatures to climb into the low to mid 60s.
Lows tonight will be in the low to mid 40s in most areas, with some
upper 30s possible in the cooler Southern Tier valleys.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
The cutoff low along the Mid-Atlantic coast will ever so slowly pull
further off shore and then lift NNE while an upper level ridge
wedges in across the lower lakes on Monday. While this occurs,
lingering moisture on the outer fringes of this slow departing low
will continue to hamper interior sections across the North Country
with a chance of a few showers. Meanwhile, with the ridge building
in aloft and high pressure at the surface expect mainly dry
conditions across Western NY with partly sunny skies developing over
the course of the day. With increasing sunshine and a warming air
mass aloft, H850T bumping up +8C to +10C, it`s expected to become
very pleasant across the forecast area with highs in the mid to
upper 60s for most locations. Although, it will be notably cooler
along the lake shores and just inland from the lakes.

Monday night, shortwave energy and a strengthening surface
reflection will track out of the Midwest towards the SOO of
Michigan. While this features tracks NE southerly flow will develop
and pick up across the lower lakes overnight. This will temper
temperatures overnight with fairly mild conditions expected with
lows only falling back into the upper 40s to lower 50s. Tuesday, the
deepening low pressure system will continue to steam ENE across Lake
Huron and then on to Ontario/Quebec Canada by late in the day. As
the low tracks into Canada it will send its trailing cold front
towards the Lower Lakes. Associated height falls with the arrival of
the pre-frontal trough and daytime insolation will likely lead to
showers and thunderstorms developing out ahead of the cold front.
With that said, forcing along the front will again likely lead to a
second round storms forming as the front crosses the eastern Great
Lakes Tuesday evening. Otherwise, it will be a warm and somewhat of
a muggy day ahead of the front as high temperatures climb into the
low/mid 70s.

Tuesday night, the low pressure to our north will continue to trek
slowly east with its trailing cold front exiting the region. Showers
and thunderstorms will come to an end from west to east, although a
few showers may linger into Wednesday across the St Lawrence valley
as the low passes by to the north. With some clearing taking place,
lows overnight will fall back into the 40s for most locations by
sunrise.

Wednesday, under NW`erly cyclonic flow a drier and cooler air mass
will advect into the lower lakes along with surface high pressure
building southeast into the region. With a cooler airmass in place
(H850T 0C to -3C), look for high temperatures to top out in the 50s
to lower 60s across the forecast area. Wednesday night with mostly
clear skies and surface high pressure moving overhead temperatures
will drop back into the low 40s across Western NY with some
readings in the 30s east of lake Ontario.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
While a progressive split flow will still be in place at the start
of this forecast period...a phasing of the branches over the
eastern third of the country is suggested by the bulk of medium
range ensemble members. Fortunately there is not enough
amplitude in the pattern to make this phasing very significant.
This should render the occasion as fairly benign with nothing more
than a complex frontal passage Friday. The weekend looks dry after
the frontal passage with strong ridging building east across the
eastern Great Lakes.  Otherwise...our region will really have little
weather to deal with while temperatures will average close to...or
just a bit above late April norms.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
Widespread IFR and LIFR CIGS will continue through this morning
across much of the area. The low stratus is developing on the cold
side of a sharp frontal zone, where a steep low level frontal
inversion is trapping abundant low level moisture. Areas of fog will
be confined to the southern tier of New York through 16z, and will
not impact any TAF sites.

The low stratus will slowly improve this afternoon, with most
locations returning to MVFR CIGS by mid afternoon. There is little
to no push to remove low level moisture today and tonight with slack
flow through the lowest 15K feet of the atmosphere, which will allow
much of the low level moisture to remain. As a result, low stratus
and fog may make a comeback tonight with IFR conditions becoming
more widespread once again after about 04Z Monday.

Outlook...

Monday...Early morning IFR in fog/stratus, otherwise VFR.
Tuesday through Thursday...Mainly VFR with a chance of showers.

&&

.MARINE...
Winds will remain very light today through Tuesday morning with
little in the way of wave action. The next period of stronger winds
will arrive later Tuesday through Wednesday as a cold front crosses
the region. Winds and waves may approach Small Craft Advisory levels
during this time frame.

&&

.EQUIPMENT...
The KBUF WSR-88D radar will be down most of this week for a
scheduled upgrade. The radar will be down beginning Monday
morning April 22, with a planned outage lasting 5 days until
Friday April 26.

During the upgrade, the transmitter will be refurbished including
the installation of new fuses and cables. Some of the components
being replaced are original to the radar, which is now over 20 years
old. The transmitter refurbishment is the second major project of
the NEXRAD Service Life Extension Program, a series of upgrades and
replacements that will keep our nation`s radars viable into the
2030`s.

This is the second project in the NEXRAD Service Life Extension
Program. The first was the installation of a new signal processor.
The last two phases of the project are the refurbishment of the
pedestal, and refurbishment of equipment shelters. All phases are
expected to be complete in 2022.

&&

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

&&

$$

SYNOPSIS...Hitchcock/TMA
NEAR TERM...Hitchcock/TMA
SHORT TERM...AR
LONG TERM...AR/RSH
AVIATION...Hitchcock/TMA
MARINE...Hitchcock/TMA
EQUIPMENT...Hitchcock