Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 170242

Area Forecast Discussion
National Weather Service Buffalo NY
1042 PM EDT Sun May 16 2021

High pressure extending from the Northeast to the eastern Great
Lakes will provide an extended period of warm and mainly dry weather
which will last well into next weekend.


Surface high pressure is over much of the East Coast with dry
weather overhead overnight.  Some fog will be possible in the
Southern Tier valleys.

Upstream ridge axis amplifies over the upper Midwest and upper Great
Lakes Monday, keeping the Northeast in a weak northwest flow.
Weak impulse moving through the flow aloft will combine with
diurnal heating and lake breeze/terrain boundaries to bring the
potential for a few showers during the afternoon well inland
from the lakes, although coverage appears like it even more
dispersed when compared to Sunday afternoon. Diurnal showers
will end by Monday evening, but a shortwave trough will pass by
to the north. This may bring a few showers to the North Country
Monday night.


Strong ridging both surface and aloft will build across the area
Tuesday through Wednesday. Robust subsidence and dry air associated
with these features should provide a completely dry forecast for the
Tuesday through Wednesday timeframe, even eliminating most, if not
all chances for any diurnally driven convection during the
afternoons on both days. A weak mid level shortwave will rotate
north through the central Great Lakes during the first half of
Wednesday night, then east into southeastern Ontario Province. This
should keep most any shower activity to the west and north of our
forecast area, however can`t rule out a stray shower north of Lake
Ontario into the Saint Lawrence Valley overnight.

The airmass will continue to warm each day. Highs Tuesday will
mainly be in the low to mid 70s, with some upper 70s found in the
traditionally warmer areas. Slight cooler temperatures will be found
near the lakeshores. Increasing heights and subsidence Wednesday
owed to the ridge axis centering itself nearly overhead will help
boost temperatures into the low 80s across lower elevations south of
Lake Ontario. Otherwise, expect mid to upper 70s elsewhere away from
any lake influences.


A strong ridge of high pressure will build over our region this
period...with heights peaking Thursday-Friday around 588 dm across
SW NYS. This should keep our region generally rain free with above
normal temperatures, until later Friday Night and Saturday when
falling heights due to a shortwave cresting the ridge, and increased
moisture and instability brings chances for showers and
thunderstorms. Another shortwave in northwest flow could bring
additional chances for showers and thunderstorms on Sunday.


High pressure will maintain mainly VFR flight conditions and
light winds though tonight. Localized flight restrictions
will be possible in the Southern Tier valley due to fog or low
clouds late.

Winds will generally be light, outside of a weak lake breezes Monday
afternoon. A few showers will be possible Monday afternoon well
inland from the lakes.


Monday night through Thursday...VFR.
Friday...Mainly VFR. A chance of showers and thunderstorms.


High pressure over the eastern Great Lakes will keep a weak
gradient in place resulting in light and variable winds through
at least early next week. Expect a brief uptick in winds during
the afternoon hours due to lake breeze circulations.





NEAR TERM...Apffel/TMA/Zaff
LONG TERM...Thomas
MARINE...Apffel/TMA is the U.S. government's official web portal to all federal, state and local government web resources and services.