Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 200544

Area Forecast Discussion
National Weather Service Buffalo NY
144 AM EDT FRI MAY 20 2016

High pressure across the region will keep fair weather with a slow
warming trend in place into the weekend. A low pressure system will
move through the Mid-Atlantic this weekend, and may bring some
showers to the Southern Tier, while much of the area will see a
pleasant spring weekend with temperatures near normal.


High pressure covers the Great Lakes to New York State and onward
to southern New England.

Overnight, with high pressure overhead, skies will be mostly clear
with light winds. Radiational cooling will bring temperatures into
the upper 30s and low 40s, warmest near the lakes. Interior
portions of the western Southern Tier may see some patchy frost
tonight, mainly in the valleys.

High pressure, clear skies and sunshine will make for a splendid day
on Friday. The chance of rain is near zero across the region. With
the axis of the surface ridge across the region, the winds will be
light and variable. There should be enough temperature difference to
develop a lake breeze circulation along the shores of both Lake Erie
and Lake Ontario. Afternoon high temperatures will range from the
upper 60s to lower 70s east of Lake Ontario and in the lower to mid
70s for the rest of the region. Lake breezes will keep the shores of
the Great Lakes in the lower to mid 60s.


The upper level pattern that will set the stage for the weekend
currently features an upper level low over the Pacific Northwest.
While this system will have no direct impact on the Eastern Great
Lakes region, it will help to amplify a downstream ridge over the
Northern Plains.  This too will have little effect on the region,
except that it will allow a weak low over Northern MN to progress
southeastward toward the region.  This will add a little uncertainty
to what would otherwise be a dry forecast for Saturday.

The main player for the weekend however will be the upper level low
over the TX panhandle.  This feature will head east toward the mid
MS valley and into the OH valley by Saturday.  This has been in the
forecast for several days.  But, with the relatively weak upper
level flow, there has been little change in confidence to the
outcome, namely where the northern extent of rainfall will end up on
Saturday.  The end result will be a continued chance of showers over
the southern tier. However, have added a little more cloud cover
than earlier forecasts and added sprinkles for areas well south of
Lake Ontario as lift from the first system complicates the moisture
field. Possible rain amounts in the Southern Tier look relatively
minor, but there may be enough rain (if it falls) to wet surfaces
and cause some concern for those planning outdoor activities.

The 12Z high resolution ARW and NMM valid through 12Z Saturday do
not show much support for rain at that time, but a reasonable number
of operational runs together with numerous ensemble perturbations
show measurable rainfall over portions of western and central NY
throughout the day.

Once this system moves through, expect a more impressive surface
response off the Mid Atlantic coast as the upper level features
combine to be provide more lift Saturday Night and Sunday.  By this
time most of the developing precipitation should be east of the
region, although some rain in the deformation region on the back
side of the system may affect portions of the eastern Finger Lakes
and/or Western Adirondacks on Sunday.

High pressure slowly moves into the region from the west on Monday.


As this period opens on Tuesday, a closed mid and upper level low
will be meandering along the New England Coastline. Immediately to
its west, surface-based ridging and drier air will remain draped
across our area, along with amplifying upper level ridging. The net
result for our region will be another dry day, along with warmer
temperatures due to the combination of modest warm advection aloft
and increasing large-scale subsidence, which will help to push
daytime highs into the mid and upper 70s in most locations.

As we progress into the middle portions of next week, the closed
upper low will eject northeastward across the Canadian Maritimes and
out to sea, while a broad southwesterly flow will remain intact
across our region. This will result in a general increase in
humidity levels along with continued above normal temperatures,
with daytime highs potentially breaching the 80 degree mark by next
Wednesday. The increasing warmth and moisture will also eventually
lead to an increasing potential for showers and thunderstorms
sometime in the Wednesday to Thursday time frame, by which time
such rainfall would be rather welcome following an extended spell
of mainly dry weather.


Sprawling high pressure across the region will promote mostly clear
skies and light winds with VFR conditions prevailing today and
tonight. Typical lake breezes will develop this afternoon.


Saturday and Saturday Night...VFR with a chance of
showers...mainly across the Southern Tier.
Sunday through Tuesday...VFR.


High pressure will remain across the Eastern Great Lakes region into
the weekend. Light winds and negligible waves can be expected on the
Eastern Great Lakes waters and Saint Lawrence River.





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