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000
FXUS61 KBUF 221024
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
624 AM EDT Mon Apr 22 2019

.SYNOPSIS...
High pressure will build into the eastern Great Lakes today and
bring a return to dry weather and warmer temperatures. Dry weather
will last through Tuesday morning before a cold front crosses the
region and brings showers and possibly a few thunderstorms to the
area Tuesday afternoon and evening. High pressure will build back
into the eastern Great Lakes Wednesday with a return to mainly dry
weather.

&&

.NEAR TERM /THROUGH TONIGHT/...
IR satellite imagery showing low stratus has expanded and become
widespread across the entire area. Overcast skies will continue
through midday with a shallow layer of low level moisture trapped
beneath a steep inversion. Expect increasing amounts of sunshine
this the afternoon after diurnal warming erases the low level
inversion and mixes out the field of low level moisture.
Temperatures will run just a little above average, with low 60s in
most locations. It will be cooler along the lakeshores, especially
the south shore of Lake Ontario where a northeast breeze will
develop.

High pressure will remain in place tonight. This will bring a
continuation of dry weather, with mainly clear to partly cloudy
skies as a few patches of mid/high clouds cross the region. Lows
will be in the upper 40s across Western NY, and low to mid 40s east
of Lake Ontario.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Ridging at all levels will be found over the eastern Great Lakes
early Tuesday. However, over the course of the day the upper level
ridge axis will shift east in advance of an approaching shortwave
trough which will introduce a round of showers and thunderstorms to
the eastern Great Lakes late in the day. With that said, a vast
majority of the day should be dry and on the mild side with
temperatures approaching the mid 70s, except near the influence of
the cold lakes. Speaking of which, Lake Erie still has a fair amount
of ice on the eastern end of the lake with water temperatures still
running in the 30s. Lake Ontario isn`t much different temperature
wise both of which will likely play a role in quelling convection.
Regarding convection, low pressure over the SOO of Michigan will
continue to track ENE into Canada nearing the boarder of
Ontario/Quebec with the cold front just to our west by late in the
afternoon. Associated height falls with the pre-frontal trough,
along with moisture advecting into the lower lakes (PW values of
around an inch, not overly impressive), and favorable jet dynamics
over New York State (left exit region of a 90-100 knot H250 jet)
will allow for showers and scattered thunderstorms to develop just
ahead of the cold front. Although, as mentioned above the cold lake
temperatures this time of year will act as a barrier to any upstream
convection. It`s likely that the initial round of storms with the
pre-frontal trough will be sparse in coverage and then likely
develop or redevelop fairly far inland from both lakes as a healthy
SW`erly flow off the lakes will be present. Behind the pre-frontal
trough the cold front will quickly approach the lower lakes, forcing
along the front will most likely lead to a better chance for showers
or a thunderstorm as it crosses Western and then North Central NY.
Although, areal coverage at this point still doesn`t look to be all
that impressive and lacking significant instability with only 300-
500 J/kg available per latest HIres guidance. Have kept POPs at
current levels with some uncertainty in regards to expected
areal coverage for showers and thunderstorms.

Tuesday night, the deepening low pressure system will continue to
slowly track east passing by to the north of the lower lakes as it
head towards New England. Cyclonic WNW`erly flow around this feature
will advect a drier and much cooler air mass into the eastern Great
Lakes behind its front. As this occurs showers will end from west to
east across most of the region overnight. Although, a few showers
will linger across the North Country as wrap around moisture works
across this region and impacts upslope locations as the low slowly
pulls away Wednesday.

Wednesday, in the wake of the departing surface low high pressure at
all levels will begin to build into the eastern Great Lakes. Look
for gradual clearing as subsidence takes hold with mostly sunny
skies enveloping the forecast area. With a cooler air mass in place
(H850T hovering near 0C or just below) look for highs 10-15F degrees
cooler areawide with 50s to low 60s across the lower lakes. Surface
high pressure will continue to influence the lower lakes Wednesday
night as it track east passing by to our south through PA/MD. Good
radiational cooling will take place under clear skies and light
surface winds resulting in temperatures falling back into 30s to low
40s.

Thursday, surface high pressure exit off the Mid-Atlantic coast in
advance of the next upstream system plunging southeast across the
upper Great Lakes. However, the surface high will maintain one more
day of dry conditions and warming temperatures as return southerly
flow develops across the region. After a chilly start look for
temperatures to rebound into the low to mid 60s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
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. Although cooler, the
first half of the weekend looks pleasant as brief ridging builds in
at all levels Saturday. With a cooler airmass in place, high
temperatures will run a few degrees below normal with 50s to lower
60s. The next system, with Pacific NW origins, heads east with
increasing chances for showers Saturday night into Sunday. Although,
at this point there is a fair amount of track and timing difference
amongst the different guidance packages.

&&

.AVIATION /10Z MONDAY THROUGH FRIDAY/...
Widespread stratus with MVFR CIGS will continue through midday as
low level moisture remains trapped beneath a steep inversion. The
low stratus will mix out during the early afternoon as diurnal
warming erases the low level inversion. This will bring a return to
VFR areawide for the afternoon. High pressure will drift east of the
area tonight with a continuation of dry weather and VFR conditions
as a few patches of mid/high clouds cross the region.

Outlook...

Tuesday...VFR in the morning, then VFR/MVFR with showers and a
chance of thunderstorms in the afternoon and evening.
Wednesday...Mainly VFR. A chance of showers east of Lake Ontario.
Thursday...Mainly VFR. A chance of showers late.
Friday...VFR/MVFR with a chance of showers.

&&

.MARINE...
High pressure will build across the eastern Great Lakes today and
then drift east tonight, with light winds and flat wave action
through Tuesday morning. A cold front will then cross the region
Tuesday afternoon and evening. Southwest winds will increase Tuesday
ahead of this system, then become west behind the front Tuesday
night and Wednesday. This will likely produce a period of Small
Craft Advisory conditions on the lakes, with the strongest winds on
Lake Ontario.

&&

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