Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 220231

Area Forecast Discussion
National Weather Service Buffalo NY
1031 PM EDT Sun Apr 21 2019

A slow moving cutoff low will drift from the central Appalachians
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.


An upper level cutoff low will drift ever so slowly from the
central Appalachians to the Mid Atlantic overnight, while a
ridge over the plains and upper Great Lakes region slowly moves
in with a corresponding area of surface high pressure. This will
result in dry weather overnight but with still plenty of low
level moisture through the lowest 15K feet of the column
together with minimal flow. This will keep much of the low
level moisture in place, and may result in low stratus and fog
becoming prevalent again late tonight into early Monday

Lows tonight will be in the low to mid 40s in most areas, with
some upper 30s possible in the cooler Southern Tier valleys.


Monday night our region will be situated in between an upper
level low just off the New England coastline and a mid-level
trough/associated surface low developing into the Upper Great
Lakes...and therefore under the influence of compensating ridging
and large-scale subsidence at all levels. This will translate
into a dry and tranquil night for all...with lows mostly in the
mid to upper 40s.

On Tuesday the aforementioned wave of low pressure will slowly
deepen as it makes its way northeastward across Lake Huron to the
Ontario-Quebec border. In the process it should pivot an initial
prefrontal trough to about our western doorstep by about mid-
afternoon...with its trailing cold front quickly following and
reaching roughly this same position by about sunset. Out ahead
of these features...our area should remain mostly dry through
midday or early afternoon...before the approaching boundaries
and increasing height falls/DCVA aloft bring about an increasing
likelihood of showers from northwest to southeast through the
rest of the daylight hours. While it remains to be seen whether
there will actually be one or multiple distinct bands of showers
given the rapidly increasing forcing aloft and the relatively close
proximity of the prefrontal trough to the trailing cold front...
the increasingly favorable dynamics and moisture accompanying
these features certainly continues to warrant categorical PoPs.

In addition to the showers...the combination of warm advection
and daytime insolation/heating out ahead of this system will also
help yield sufficient instability both at the surface and aloft to
support some scattered thunderstorms as well...with the greatest
potential for these found across areas south of Lake Ontario. As
for temps...850 mb readings surging to between +10c and +12c and
an increasing southerly to southwesterly flow will help lead to
highs in the lower to mid 70s in most places...with some upper 70s
possible across interior portions of the Finger Lakes. Given the
orientation of the low level flow...any lake cooling should be
largely confined to areas northeast of Lake Erie and the far
westernmost portions of Jefferson county.

Tuesday evening the surface low will make its way across southern
Quebec while sweeping its cold front across our region...with
the combination of the frontal passage and quality forcing aloft
generating fairly widespread showers along with some scattered
thunderstorms. In the wake of the air advection and
strong drying/subsidence will then lead to quickly diminishing
shower chances through the rest of the night...followed by largely
dry conditions on Wednesday. The only possible exception to the
latter will lie across the North Country...where the closer proximity
to a closed low passing across Quebec could keep a few scattered
light showers going into Wednesday morning. Otherwise the cool
air advection regime will help to drive temperatures back down
to around or a little below seasonal normals by Wednesday...when
highs should mostly range in the mid to upper 50s.

After that...the remainder of this period should be quiet and dry
as high pressure crests across our region Wednesday night...with
this feature then only slowly departing to our east on Thursday
while helping to keep a pair of modest approaching upstream systems
at bay. Temperature-wise...Wednesday night will be a chilly night
under the surface ridge with lows dipping into the mid to upper
30s in most places...with warm air advection on its backside then
allowing readings to largely recover into the 60s on Thursday.


A low amplitude pattern wavering over the northern tier of the
country will make up the northern branch of a split flow that will
be found across the Lower 48 throughout this period. As such...we
can anticipate that temperatures for our forecast area will average
within a couple degrees of normal. This will also keep our region
from experiencing any significant weather outside of a complex
frontal passage late Thursday night and Friday.


MVFR CIGS will gradually lower to IFR over portions of WNY and
CNY overnight as surface high pressure moves overhead while low
level moisture is trapped under a developing inversion. Fog is
again a possibility, particularly near the lake shores.


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


Winds will remain very light 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.


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

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.





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