Area Forecast Discussion
Issued by NWS Buffalo, NY

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202
FXUS61 KBUF 290816
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
416 AM EDT Wed Mar 29 2017

.SYNOPSIS...
High pressure will build across the Great Lakes today bringing
clearing skies and seasonable temperatures. Our next storm system
will bring rain later Thursday into Friday. Temperatures will run
near to slightly above normal through Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure will build in across the Great Lakes today bringing
drier air and seasonal temperatures. IR satellite imagery reveals
cloud cover eroding from north to south across Lake Ontario, expect
this clearing trend to continue across western and north central NY
through the morning. Some patchy areas of fog may linger on the
higher terrain of the Southern Tier and Northern Finger Lakes in the
upslope northerly flow. This lingering cloud cover and high
elevation fog will clear quickly as the drier air builds in toward
sunrise.

During the day today, surface ridging will continue to build over
western and central New York. Colder, but much drier, air will spill
across Lake Ontario, with 850 mb temps falling from around 0C now to
about -8C by 15Z. This should result in a very modest lake response,
given the dry airmass, and thus this should result in a diurnal
cumulus field south of Lake Ontario and across the northern Finger
Lakes. Outside of this area, it will be mostly sunny. Temperatures
will be seasonable with highs in the 40s.

Tonight high pressure will settle across the region with mostly
clear skies and light winds resulting in decent radiational cooling
conditions. Low temperatures will drop below freezing for most
locations, with the coldest readings in the mid 20s in the North
Country.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Expansive high pressure centered over northern Quebec Thursday
morning will move slowly but steadily eastward, allowing low
pressure to eject from the central plains. Mid and upper level
moisture and lift increases along a boundary that extends well out
ahead of the system. Model soundings point to a dry sub 700 mb layer
which will persist into Thursday afternoon. This should help to
delay the onset of precipitation until mid to late afternoon over the
western counties. Otherwise, lowering and thickening clouds can be
expected over our region during the course of Thursday with
temperatures climbing to near 50 degrees in the west and the mid 40s
for the North Country.

Increasing isentropic ascent and strong northward moisture transport
Thursday night will overcome in-place dry air across the area from
southwest to northeast. Thus, a steady increase in precipitation
with the steadiest/most widespread precipitation arriving during the
late evening/overnight hours and continuing through at least Friday
morning. Model soundings do not suggest steep enough lapse rates
aloft, so without significant elevated CAPE, will continue to keep
the mention of thunder out of the forecast.

For the most part precipitation type should not be an issue, with
most expected to fall as rain as a lack of true cold air helping to
sufficiently warm boundary layer temperatures. However, the
expectation could be across the North country as marginal thermal
profiles could allow for a brief period of mixed precipitation late
Thursday night/early Friday morning.

The complex system responsible for the all of the unsettled weather
will push to our east by Friday night. While the bulk of the
associated lift and mid level moisture will be removed, there will
still be the chance for some leftover showers, especially along and
east of the axis of the surface trough, which will be aligned over
the Genesee Valley for the first half of the night. Some of the
lingering precipitation could change to a wintry mix late.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
There is high confidence that this will be a relatively mild
period...as a progressive ridge will make its way across the eastern
half of the country. This ridge will also keep the bulk of the
period rainfree. The tranquil weather will come to an end though by
Monday night and Tuesday...as the next southern stream system will
lift northeast out of the Lower Mississippi Valley. The details...

A storm system exiting off the East Coast will support some leftover
nuisance showers across the region Saturday morning. In its wake...
expansive high pressure centered over Hudson Bay will build south
across the Lower Great Lakes Saturday afternoon through Monday. This
will promote fair dry weather. While high temperatures will
generally be in the 40s on Saturday...the mercury will climb into
the 50s for Sunday and Monday.

Monday night and Tuesday...low pressure over the Lower Mississippi
Valley is forecast to push north towards the Lower Great Lakes. Most
of the ensemble members of the GEFS along with the operational
ECMWF track the broad low to our west within a negatively tilted
trough...which will once again set up a scenario where we experience
another round of rain.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
A stratus deck across the region will erode from north to south
during the early morning hours, with clearing already reaching near
KART and the south Lake Ontario shoreline from KIAG to KROC. This
clearing will continue to progress southward before sunrise, with
station becoming VFR. KJHW will see IFR conditions persist for a few
more hours, with the linger moist upslope flow, but will see
improvement to MVFR and perhaps even VFR by around sunrise.

Expect a scattered cumulus deck around 3kft to 5kft to redevelop
south of Lake Ontario between 12 to 15Z and persist through the
afternoon as colder, but very dry, air spills across Lake Ontario.

Outlook...

Tonight and Thursday...VFR.
Thursday night into Saturday...MVFR/IFR with occasional rain showers.
Sunday...some improvement to VFR possible.

&&

.MARINE...
Light northerly winds will persist today as strong Canadian high
pressure builds across the Great Lakes...however winds and waves are
expected to remain below advisory levels. Winds will turn easterly
Thursday and Friday as our next storm system passes south of the
Great Lakes. Winds will approach 15-20 knots but higher waves should
remain in Canadian waters.

&&

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

&&

$$

SYNOPSIS...CHURCH
NEAR TERM...CHURCH
SHORT TERM...TMA
LONG TERM...RSH
AVIATION...CHURCH
MARINE...CHURCH



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