Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 182112

Area Forecast Discussion
National Weather Service Buffalo NY
512 PM EDT Fri May 18 2018

High pressure will move off the New England coast tonight. Periods
of rain will return tonight through Saturday morning as a warm front
moves into the region. A passing cold front will bring the risk
for showers and a few thunderstorms Saturday afternoon into
Sunday morning, with dry weather returning for Sunday afternoon
to close out the weekend.


High pressure over Quebec will slide southeast across New England
tonight. Meanwhile, a broad mid level trough across the mid
Mississippi Valley will push east into the Ohio Valley. This will
force a southerly low to mid level flow into western New York,
resulting in the advection of deep layer moisture northward into the
region. The 12z model suite are in general agreement in showing
moist isentropic ascent accompanying the lead edge of moisture. The
pattern seems to support the best isentropic lift and primary moist
plume lifting northward into the western Southern Tier by mid to
late evening then across most areas south of Lake Ontario after
midnight, finally reaching the North Country late tonight or early
Saturday morning. Confidence remains high that we will see a soaking
rainfall of near a half inch to an inch. Clouds and increasing
southeasterly winds will inhibit radiational cooling tonight with
lows in the 50s across the region.

The mid level trough is expected to meander across the Ohio
Valley/eastern Great Lakes on Saturday with associated surface low
pressure forecast to track western of the region. Forcing looks to
wane for awhile during the midday and afternoon hours as area
emerges into the warm sector, before the trough and surface cold
front start to advance into the region. Relatively moist boundary
layer conditions combined with diurnal heating will support weak
late afternoon instability, warranting a chance of
showers/thunderstorms, especially across far western New York.


Rain showers will taper off from northwest to southeast Saturday
night through Sunday morning behind a cold frontal passage. High
pressure will build in across the region in the wake of the frontal
passage during the day Sunday, bringing a clearing and drying trend
into Sunday afternoon. High temperatures will be quite pleasant
Sunday with highs in the upper 60s to low 70s.

High pressure will build directly overhead Monday bringing a dry and
mostly sunny day. The day will start off crisp and cool with morning
lows in the upper 40s to low 50s. Light winds and a modifying
airmass will result in high temperatures pushing into the mid 70s.

Another wave will track across the region Tuesday bringing the next
chance for rain showers. Model differences on timing and track of
the low remain, and thus there remains uncertainty on
thunderstorm and severe weather potential.


A mid level trough and associated weak surface cold front will move
east and away from the area Tuesday night. A few scattered light
showers may linger into the first half of the night, mainly across
the higher terrain with a little added boost of upslope flow and
lingering low level moisture.

High pressure then settles into the Great Lakes Wednesday, then
slowly drifts east into New England Thursday and Friday. This will
provide an extended period of dry weather for the second half of
next week.

Temperatures will run a little above normal through the period, with
highs in the mid 70s at lower elevations away from the lakes
Wednesday and Thursday, and then upper 70s to near 80 by Friday.
Lows will generally be in the 50s.


No issues with VFR expected to continue into tonight. High/thin
cirrus will continue to stream across the area as upper level
moisture spreads north from broad low pressure over the southeast

Clouds will slowly lower and thicken this evening, with rain
spreading from south to north tonight. This will reach the Southern
Tier around or just before midnight. Rain will result in lowering
clouds with mainly MVFR conditions by late tonight with IFR
conditions possible at JHW.


Saturday and Saturday night...MVFR/IFR with periods of rain and a
chance of a few thunderstorms.
Sunday...MVFR improving to VFR. A chance of showers, mainly in
the morning.
Monday...Mainly VFR with a chance of showers.
Tuesday...VFR/MVFR with a chance of showers and thunderstorms.


Moderate northeast winds will result in Small Craft Advisory
conditions along the south shore of Lake Ontario and also Lake Erie
into this evening. Winds will shift to the southeast and diminish


MARINE...Small Craft Advisory until 9 PM EDT this evening for LEZ040-
         Small Craft Advisory until 9 PM EDT this evening for
         Small Craft Advisory until 6 PM EDT this evening for



LONG TERM...Hitchcock
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