Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 221430
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1030 AM EDT Mon May 22 2017

.SYNOPSIS...
Showers across the eastern Lake Ontario region will taper off from
west to east today and temperatures will remain fairly steady as a
cold front crosses the region. High pressure will help bring dry and
warmer conditions on Tuesday into Wednesday before the next round of
unsettled weather arrives by Wednesday evening, as a slow moving low
pressure system tracks from the Ohio valley towards the Great Lakes.
Showers associated with this system will affect the forecast area
through the second half of the week, while temperatures will remain
near average.

&&

.NEAR TERM /THROUGH TONIGHT/...
A line of showers is increasing in coverage late this morning across
the Finger Lakes along a low level convergence zone just ahead of
the surface cold front. High resolution guidance such as the HRRR
have a good handle on this, and move this line of showers northeast
across the eastern Lake Ontario region during the late morning and
early afternoon. This will produce an hour or so of steadier
showers, and possibly even a weak thunderstorm as very modest
instability develops by midday. Once this main area of showers moves
through the eastern Lake Ontario region early afternoon, a few
scattered showers may remain through late afternoon as the actual
cold front crosses the area.

Current temperatures will change little across far western New York,
as daytime heating will be offset by cold air advection behind the
front. Temperatures across the eastern half of the forecast area
will have an opportunity to climb into the mid 60s before the cooler
air arrives late in the day.

The last of the post-frontal cloudiness should scatter out this
afternoon across western New York aided by a developing lake shadow
in brisk southwest flow off Lake Erie, and skies should clear out
this evening across the North Country as post-frontal subsidence and
associated drying makes its way across the area. This, along with a
narrow area of high pressure moving overhead will make for a quiet
night across the region, with temperatures falling into the 40s.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
High pressure will be centered over New York Tuesday morning and is
forecast to drift/expand into New England through the next 24-36
hours. This should bring dry weather into Wednesday morning while
being supported with low amplitude ridging building over the
Northeast states so have backed off/delayed arrival of POPs for
Wednesday afternoon. Skies will be partly cloudy while the surface
high keeps any precipitation shielded to our northwest and
southeast. Temps warm above normal into the low to mid 70s on
Tuesday and Wednesday benefiting from warm air advection under
southerly flow. Overnight temps Tuesday night will remain mild also
due to southerly flow and warm advection aloft with lows only
slipping into the 50s.

Chance POPs are in place for Wednesday afternoon increasing to likely
Wednesday night into Thursday as a surface/700mb low is shown by
models slowly lifting across the Ohio Valley or southwest Ontario
depending on your model of choice. The combination of mid-upper
forcing from a deep trough, mid-low level moisture transport and a
low level jet and occluded front should result in fairly widespread
rain showers shifting across western and central NY ahead of the
low. There is also a possibility of a few elevated thunderstorms
Thursday as the core of the mid-level low pivots near western NY.
The low looks to transfer its center from near the eastern Great
Lakes to off the southern New England coast Thursday night as the
trough becomes negatively tilted. Chance POPs are in place behind
this low with some lingering wrap around moisture Thursday night.
Temperature-wise, readings should remain just above average
Wednesday with highs in the upper 60s/lower 70s slipping back into
the low to mid 50s Wednesday night. Cooler temps are expected
Thursday just shy of climo due to the extensive cloud cover and
associated precipitation.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
The newly positioned coastal low will shift north into the Gulf of
Maine on Friday. Wrap around moisture and west to northwest upslope
flow off the lakes will keep chance POPs in play across western and
central New York. Slight to low chance POPs are forecast for Friday
night and Saturday as 00z models generally show our forecast area
between storm systems albeit with some timing differences with the
arrival of the next system. 00z EC and GEM models then show the next
system could bring in rain Saturday night or Sunday morning. The
system is forecast to then spread some rain showers north and east
across western and central NY through Sunday where mid-range chance
POPs have been included.

In regards to temperatures...the mercury will average close to
normal for Friday under weak cool advection and chances of showers
with max temps mainly in the mid 60s. Warmer air is then expected to
arrive for the weekend when highs will be upper 60s to lower 70s
with mid 70s possible is spots on Sunday. Low temps will remain
mild, only dipping into the low to mid 50s each night as dewpoints
do not slip below 50.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
An area of showers will move northeast across the eastern Lake
Ontario region through early afternoon, with an isolated
thunderstorm also possible. These showers will produce a brief
period of MVFR/IFR as they move east of Lake Ontario. Otherwise for
the rest of the area, stratus with a mix of MVFR and VFR CIGS will
scatter out from west to east later this afternoon with a return to
VFR as a cold front crosses the area.

The frontal passage will be accompanied by veering westerly winds
that will gust 25-30 kts this afternoon across the western half of
the forecast area. Winds should diminish tonight as an area of high
pressure moves overhead, with widespread VFR conditions expected
overnight.


Outlook...

Tuesday and Tuesday Night...Mainly VFR.
Wednesday...VFR/MVFR with a chance of showers.
Thursday...VFR/MVFR with showers likely.
Friday...VFR/MVFR with a chance of showers.
Saturday...Mainly VFR.

&&

.MARINE...
Southerly flow across the lakes this morning will give way to
freshening southwesterly flow this afternoon as a cold front crosses
the region. The flow will build waves to 3-5 feet on the east end of
Lake Erie with a brief period of Small Craft conditions this
afternoon. Winds and waves will be lower on Lake Ontario, with
conditions expected to remain below Small Craft Advisory criteria.
The stronger winds will be short-lived, as high pressure moves over
the lakes tonight. Otherwise, tranquil conditions will prevail on
the lakes at least through the middle of the week, as the high
pressure is supplanted by a broad area of low pressure that will
maintain a weak pressure gradient across the region.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Beach Hazards Statement until 8 PM EDT this evening for NYZ010-
     019-085.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ020-
         040-041.

&&

$$

SYNOPSIS...HITCHCOCK/WOOD
NEAR TERM...HITCHCOCK/WOOD
SHORT TERM...SMITH
LONG TERM...SMITH
AVIATION...HITCHCOCK/WOOD
MARINE...HITCHCOCK/WOOD


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