Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 240559

Area Forecast Discussion
National Weather Service Buffalo NY
159 AM EDT Mon Apr 24 2017

A sprawling area of high pressure across the Great Lakes will
continue to provide for fair weather through Monday evening. A slow
moving area of low pressure moving up the Eastern Seaboard will then
spread showers across our region Monday night into Tuesday. It will
become almost summer like by mid week as the mercury will soar into
the 80s for most areas away from the lakes.


A weak cool frontal boundary will wash out across the western
counties of New York overnight...while the bulk of its associated
moisture will remain north of the region. This will leave star
filled skies across the region through daybreak with temperatures
once again falling into the mid and upper 30s.

After daybreak...expansive high pressure centered over the western
shore of Hudson Bay will extend to the southeast across the St
Lawrence Valley and New England. This will keep our skies mainly
cloud free and will set the stage for a beautiful afternoon. H85
temps warming to between 6 to 8c will combine with the wealth of
sunshine to support max temps in the lower 70s f across much of the
Southern Tier...while readings will generally be in the low to mid
60s elsewhere. The coolest area this afternoon will be across the
counties that border the south shore of Lake Ontario. In these
areas...a persistent northeast wind will keep temperatures from
climbing out of the 50s.


Monday night should start off dry with the region under the
influence of weak ridging. This ridge will start to break down late
in the night when a weak closed low across the mid-Atlantic nudges a
bit closer to the area. A modest 40kt LLJ will increase the 850mb
flow and transport Atlantic moisture into the area. Model consensus
develops showers along this boundary late Monday night. Showers
should become more widespread Tuesday morning, then diminish as the
as the axis of the LLJ lifts north of the area Tuesday afternoon.
These showers should taper off south of Lake Ontario by late
afternoon, while lingering into Tuesday evening east of Lake
Ontario. Despite likely PoPs in many areas, showers only last a
couple hours so Tuesday will be far from a washout.

Temperatures will be seasonably cool Monday night, with lows mainly
in the lower to mid 40s. Highs Tuesday will generally be in the
upper 50s to lower 60s, with mid 60s across the lake plains west of
Buffalo where downsloping and a partial clearing will help warm
things a bit.

The region will be in between the weakening coastal low and an
approaching trough late Tuesday night through Wednesday night. This
will keep Western New York dry, with mid-level riding supporting
a clearing trend Wednesday afternoon and night.

Despite some differences in guidance, there is little doubt that
temperatures will be above normal Wednesday. Expect highs in the
70s, with a weak southeast flow and associated downsloping bringing
the warmest temperatures to the lake plains. This also will help
limit the inland extent of the lake breeze and keep cooler
afternoon temperatures very close to the lakeshores. Given model
differences the forecast sticks close to model consensus, but does
enhance downslope influences where are likely to be missed by lower
resolution guidance.


Thursday will likely have a summer feel to the day as a narrow 500
hPa ridge extends northward, between a cut-off low off the SE New
England coastline, and digging trough across the Midwest. Much of
Thursday will be dry, but as this upstream trough, with moisture
pooling ahead of a cold front nears, showers and thunderstorms will
start to blossom through the afternoon and evening hours. Activity
at first will likely be along lake breeze boundaries across WNY,
then as the cold front crosses Thursday night, there will be chances
for storms everywhere. A southerly wind will bring 850 hPa
temperatures spiking towards +15 to +18C across the region and this
should bring a very warm day to the region, with most areas reaching
into the 80s.

It will then turn cooler, and less humid later Thursday night and
into Friday behind the cold front. Some lingering moisture towards
the SE region of the forecast area may allow for an afternoon
showers or thunderstorm, but the bulk of Friday appears to be dry.

Another storm system, with a warm frontal boundary nearing the
region next weekend will bring the next threat of rain. There will
be chances for showers and thunderstorms both days with the frontal
boundary nearby. Temperatures both weekend days will likely average
above seasonal normals.


High pressure centered near Hudson Bay will extend to the south
across New England this afternoon...and this will allow for another
beautiful day for flying with nearly cloud free skies.

The fine VFR weather will continue through at least the first
half of tonight...then clouds will lower and thicken from the
southeast during the wee hours of Tuesday morning. There may
even be some light showers over the western counties by the end
of the night.


Tuesday...Mainly VFR with showers likely.
Thursday...VFR/MVFR with a chance of showers and thunderstorms.
Friday...Mainly VFR with a slight chance of showers and


Northeast winds will freshen before daybreak on Lake Ontario
resulting in Small Craft Advisories along the south shore for
Monday. This increase in winds and waves is due to a tightening
pressure gradient between a slow moving surface low moving up the
East Coast and high pressure centered over northern Ontario
Province. Winds and waves on Lake Erie are not expected to reach
advisory levels as the winds are parallel with the southern lake

Winds will veer to the east Tuesday, as a ridge across the region
becomes re-oriented, shunting most of the wave action to Canadian
waters. By mid-week, conditions on the lakes will become more
tranquil as the pressure gradient relaxes.


MARINE...Small Craft Advisory from 5 AM early this morning to 8 PM EDT
         this evening for LOZ042>044.



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