Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 222109

Area Forecast Discussion
National Weather Service Buffalo NY
509 PM EDT Sun Apr 22 2018

High pressure will slowly drift east across the area through Monday
and provide plenty of sunshine each day and much warmer
temperatures. Low pressure moving from the Ohio Valley to New
England will then bring rain showers to the region from late Tuesday
through Wednesday.


Visible satellite imagery shows clear skies across the region early
this afternoon. Surface high pressure across the Great Lakes will
slowly drift east off the New England coast through Monday. With a
very dry airmass and subsidence expect full sunshine today and clear
skies tonight.

A weak northerly flow will remain in place today, with airmass
modification warming 850mb temps to around 0C. This will support
highs in the upper 50s to lower 60s at lower elevations away
from lake influences, with mid 50s for higher terrain. The weak
gradient northerly flow will be enhanced by lake breeze
circulations this afternoon, keeping the south shores of Lake
Ontario and Lake Erie in the mid to upper 40s.

Expect another good radiational cooling night tonight with clear
skies and light winds. Lows will be in the 30s in most locations,
with 20s east of Lake Ontario.

A weak southerly return flow will develop on Monday, and this along
with a warmer air mass will result in even warmer temperatures.
Expect highs to be mainly in the 60s on Monday, with a few spots
making a run at 70. It will continue to be cooler along the
lakeshores, but the southerly gradient flow will limit the lake
breeze to the immediate shoreline.


High pressure will continue to move off the New England coast Monday
night. An upper level trough will slowly move northeastward
along the Ohio River Valley Monday night and Tuesday. A
southerly flow will maintain mild temperatures through this time
while moisture advection increases. Rain showers will begin to
move into Western NY Tuesday. With little upper-level support,
showers should be light going into Tuesday evening.

A fast moving shortwave trough from the western Great Lakes will
phase with the upper level low and low pressure will rapidly deepen
off the Mid-Atlantic coast by Wednesday afternoon. Enhanced synoptic
lift and a strengthening easterly jet will likely produce heavier
rain showers across the eastern Great Lakes Wednesday afternoon into
Wednesday night. Rainfall amounts through Wednesday will range from
three tenths of an inch across the Southern Tier to three quarters
of an inch across portions of the North Country.

Temperatures remain mild through Wednesday night as no airmass
change is expected. Clouds, moisture and a southerly flow
inhibit day time highs some and will keep low temperatures


Periods of showers will continue through Saturday evening before a
break in the weather for late Saturday into the mid-day period on
Sunday. Disagreement still between the models with timing of the
rain for the time between Thursday and Saturday evening.

GFS brings a break in the weather for Thursday morning through
Friday afternoon after the system on Wednesday moves out of the area
and an area of high pressure over the Ohio Valley moves east to the
mid-Atlantic Coast. The ECMWF timing for this break in the
rain/showers comes more during the overnight Thursday through early
Saturday morning period. Both models bring another system similar to
the one that is expected on Wednesday into the region but slightly
more south and west for Friday and Saturday with timing
discrepancies still between the two models.

The GFS has this system a little stronger then the mid-week system.
An area of low pressure over the southeast U.S. will deepen as its
associated upper level trough phases with an approaching upper level
trough diving southeast out of the Ohio Valley toward the southeast
coast. The phasing of the two upper level troughs will help to
strengthen the system as it moves north along the coast and inland
over the Hudson Valley before moving into Quebec and exiting the
region. GFS timing precipitation from Friday afternoon through
Saturday afternoon with some leftover showers/drizzle to follow
through Saturday evening.

The ECMWF has a similar upper level scenario, but doesn`t form as
strong of a coastal low. Instead the ECMWF has a second synoptic
system form over the northern Great Lakes and Quebec, as the two
pieces of upper level energy are a bit to far apart to phase as much
as the GFS solution. A cold front associated with the northern
system will move through the WNY and North Country on Saturday. With
this ECMWF scenario the precipitation would be less than the GFS and
the rain would be much shorter in duration moving through Saturday
morning through the early evening.

Temperatures during this period will cool to below normal with most
areas in the 50s during this four day stretch.


VFR conditions will prevail this through Monday with strong high
pressure bringing SKC.


Monday night...VFR.
Tuesday...VFR with a chance of afternoon showers.
Tuesday night and Wednesday...Areas of MVFR with showers
Thursday and Friday...VFR/MVFR. A chance of showers.


High pressure across the Great Lakes this afternoon will move
off the southern New England coast on Monday. This will support
light winds and flat wave action on Lakes Erie and Ontario
through Monday. Local lake breeze circulations will develop each
afternoon with onshore winds along most lakeshores.





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