Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 200836

Area Forecast Discussion
National Weather Service Buffalo NY
436 AM EDT Sun May 20 2018

Rain showers will taper off early Sunday behind a cold front. Clouds
will be slow to erode today, with sunshine returning early across
the North Country, and later across Western New York. This sunshine
will spell a slightly warmer day today than yesterday across the
North Country, while areas south of Lake Ontario will be cooler
today behind the cold front.


A cold front has entered the Saint Lawrence Valley and western
portions of WNY this early morning and is moving eastward across the
forecast area. Ahead of the front rain showers are scattered to
numerous...with just a few isolated showers behind the front. Shower
activity will end from west to east through the morning hours as the
cold front passes through, though lingering low level moisture and
northwest upslope flow will likely maintain plenty of clouds south
of Lake Ontario through at least early afternoon, and possibly into
the evening hours closer to the state line. This lingering low level
moisture coupled with some cooling behind the front will promote
patches of fog to form across a good portion of the CWA this

East of Lake Ontario clouds will clear through late morning,
allowing for a mostly sunny afternoon. High temperatures this
afternoon will largely fall within the mid 60s for the
forecast region.

Surface high pressure currently across the western Great Lakes will
push eastward today and tonight, promoting a period of fair weather
with clearing skies tonight and light winds. This surface high,
combined with confluence aloft will hold showers and thunderstorms
well to our south through the night. Temperatures will quickly fall
this evening...dropping to around 40F across inland portions of the
North Country, and 40s elsewhere.


High pressure will slide across the region while weakening Monday,
providing for dry weather to kick off the work week. A weak wave
will then approach the eastern Great Lakes later Monday and cross
the region through Tuesday. Cloud cover will increase from southwest
to northeast ahead of this wave Monday, but any rain will hold off
until Monday evening through Tuesday. There is still some
differences in timing and location among model guidance, but in
general the chance for precipitation is greatest across the Southern
Tier and less further to the north. Despite model agreement keep
Pops in the chance-likely range due to the convective nature of the
precipitation. Some surface based instability develops on Tuesday,
which carries the risk of some thunderstorms. The wave will depart
to our east later Tuesday with a clearing and drying out trend
Tuesday night through Wednesday.

Temperatures will be slightly above normal during the period with
daytime highs mainly in the 70s, except slightly cooler near the
immediate lakeshore due to the lake breeze. Lows will be in the 50s.


High pressure will dominate the eastern Great Lakes for the second
half of the work week, bringing dry weather and a gradual warming
trend. Temperatures will average above normal, with daytime highs
warming from the 70s on Thursday to the upper 70s to mid 80s on

A slow moving trough is then set to impinge upon the Great Lakes
region as we move into the weekend, with several global models also
showing some poleward advection of tropical moisture into the region
ahead of the trough. Thus there is some potential for heavy rainfall
next weekend and into early next week, although there are plenty of
details that still need to be resolved.


For the 06Z TAFS a cold front will pass across the region through
the first 6 hours, with scattered to numerous rain showers.
Visibilities within the showers should remain MVFR or greater.
Behind the front widespread IFR or lower ceilings are expected as
low level moisture remains abundant...with some areas of fog likely
across the So. Tier...including the KJHW terminal.

Shortly after 12Z rain showers will be ending across the North
Country, including the KART airfield...with flight conditions slowly
improving back to VFR. Expect these VFR flight conditions to persist
through Sunday night for all areas save for the SO. Tier where some
areas of fog with IFR flight conditions are likely.



Tuesday...VFR/MVFR with a chance of showers and thunderstorms.

Wednesday and Thursday...VFR.


Behind a cold front waves will increase some on the lakes, but
likely remain just below small craft thresholds. Surface high
pressure will then build eastward across the Lower Lakes tonight
through Monday night with light winds and minimal waves. This
surface high pressure will be reinforced mid-week...maintaining a
prolonged period of light winds and minimal waves on the lakes
through the end of the week.





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