Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 290552

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

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.


Low pressure will continue to move off the Jersey coast while
high pressure centered near Hudson Bay ridges southward across
Ontario province and into our region overnight. 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 morning. Some patchy areas of fog/drizzle
may linger of the higher terrain on the upslope northerly flow until
before sunrise across the northern Finger Lakes and Southern Tier,
but will clear quickly as the drier air builds in toward sunrise.

The lingering clouds will keep most of western NY and the Finger
Lakes just above freezing. Slightly colder air and perhaps a few
breaks in the clouds will allow temperatures to drop into the upper
20s to lower 30s south and east of Lake Ontario where clearing
develops earlier in the night.

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.


While dry pleasant weather will be featured at the start of this
period...a closed low currently over the Desert Southwest will play
a big role in supplying our region with another soaking rain during
the latter portion of the week. As a side note...this same system
will be directly responsible for widespread severe weather across
Texas and the Lower Mississippi Valley in the days leading up to our
rain event. The details...

Expansive high pressure centered over northern Quebec will nose to
the south across our forecast area Wednesday night. This will
produce fair chilly weather across our region with nothing more than
some cirrus obscuring an otherwise star filled sky. Temperatures
will be very close to typical late March levels...with lows ranging
from the low to mid 20s across the North Country to between 25 and
30 elsewhere.

The axis of a mid level ridge will pass overhead on Thursday...while
a closed low over the central Plains will open up and move east.
This will push an area of strong warm advection to the northeast...
where a tightening H925-70 baroclinic zone will make its way to the
Lower Great Lakes. Warmer and increasingly more moist air will push
up and over this burgeoning warm that some rain showers
will become possible over the western counties during the afternoon.
Otherwise...lowering and thickening clouds can be expected over our
region during the course of Thursday with temperatures climbing to
between 50 (Srn Tier) and the mid 40s (North Country).

The aforementioned mid level low will move across the Lower Ohio
Valley Thursday night while attempting to phase with northern stream
energy over the Upper Great Lakes. A 40 kt low level jet ahead of
these mid level features will pump increasing moisture across our
region...with a wide open connection to the GOMEX encouraging PWAT
values to climb to around an inch (wrn counties). The low level jet
will push the moisture rich low level air up and over a fairly
strong warm frontal boundary...producing several hours of steady and
occasionally heavy rain across our region. The rain could start off
as wet snow or a mix of rain and snow across parts of the eastern
Lake Ontario region...and in particular across Lewis County. At
first glance of the synoptic pattern (and strength of warm
front)...would think that there would be the potential for a
thunderstorm or two. Model soundings do not suggest steep enough
lapse rates aloft without significant elevated CAPE...
will keep the mention of thunder out of the package. Have raised pops
to 90 over the western counties and to likely over the North

On Friday...the tight baroclinic zone will push north across Lake
Ontario and the North Country. While this is where the steadiest...
most widespread rain will be found...rain and drizzle will stay in
place across the western counties in the vcnty of a stacked trough.
Will use cat pops across all of the forecast area. Any mixed pcpn at
the start of the day over the North Country will change to just rain
by late morning.

The complex system responsible for the all of the unsettled weather
will push to our east 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 sfc trough...which will be aligned over the Genesee
Valley for the first half of the night. Again...some of this pcpn
could change to a wintry mix late.


There is high confidence that this will be a relatively mild 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 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.


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.


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


Light northerly winds will increase 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.





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