Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 260249
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1049 PM EDT Thu May 25 2017

.SYNOPSIS...
An upper level low will track just to the south of the region
overnight and Friday, maintaining cool, cloudy conditions with
scattered light rain showers. Temperatures will moderate back to
normal for the weekend, though there will remain a chance for a
shower early Saturday, and then more widespread showers and
perhaps a thunderstorm later Sunday and Sunday night.

&&

.NEAR TERM /THROUGH FRIDAY/...
A closed upper low will move into Southern New England overnight.
Meanwhile latest surface analysis shows a broad surface low
reflections loosely centered across Eastern Pennsylvania. There
are spotty showers and some drizzle across Western New York,
which will continue overnight. As the surface low passes, a
subtle northerly flow will mix two already moist air masses with
lots of low level moisture and some fog likely to develop south
of Lake Ontario late this evening.

Tomorrow the surface low will become better organized off the mid-
Atlantic coastline, though a surface trough will linger westward
behind this low. Within this trough, and under a west to northwest
flow will remain chances for a few sprinkles/light rain showers
through the day Friday. As the deeper moisture slides eastward
tomorrow the light shower activity will end through the day.

Temperatures will remain nearly steady tonight under the thick
cloud cover with lows in the lower to mid 50s. With the upper
level trough still overhead, highs tomorrow will only rebound
back to the low to mid 60s.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
Weak surface-based ridging will slide eastward into our region from
the Central Great Lakes and Ohio Valley Friday night and Saturday.
In addition, heights aloft will build over the region as shortwave
ridge pushes east into the region. A wave embedded within the
northern edge will slide across the region with the possibility of a
few stray showers Friday night and Saturday morning with the
Southern Tier having the best chance to see any measurable
precipitation. The arrival of somewhat drier air behind the wave
from mid day through the afternoon should help to bring some partial
sunshine. Weak warm air advection and sunshine should allow
afternoon highs to reach the upper 60s to lower 70s.

Surface and upper ridging remains over the area for much of Saturday
night. Lead wave ahead of main upper trough will drop into the Great
Lakes as associated surface wave moves into the Ohio Valley. For the
most part Saturday night will be dry, before the leading edge of
some scattered shower activity returns to far western sections
toward Sunday morning.

Latest models continuing to highlight the Sunday and Sunday time
frame with increasing chances for showers and embedded
thunderstorms, as the deepen trough moves in from the west. Models
remaining inconsistent on timing, but with the combination of
falling heights and warm air advection on the eastern flank we
should see showers and embedded thunderstorms fill in during the
day, especially by afternoon and continuing into Sunday night.
Temperatures look to remain above average with highs in the lower to
mid 70s Sunday followed by lows in the mid to upper 50s Sunday night.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
For much of next week a large upper level low will slowly meander its
way across the Great Lakes and southern Canada. As a result
temperatures will trend from slightly above normal values Monday
(highs in the low 70s ) to slightly below normal values by mid-week
(highs in the 60s). Several shortwaves embedded in the general
cyclonic flow will support numerous opportunities for scattered
showers across the region, with a few embedded thunderstorms also
possible with the steep lapse rates aloft.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Flight conditions are expected to deteriorate further tonight.
IFR conditions are already quite prevalent south of Lake Ontario at
02Z TAF and as the weak surface low passes to the south a light
northerly flow will cause upsloping and mix two already moist
air masses resulting in very moist boundary layer conditions.
IFR or lower conditions are expected south of Lake Ontario at
BUF/IAG/ROC/JHW, with LIFR/VLIFR conditions possible in very low
CIGS and fog later tonight. This trend is indicated by forecast
BUFKIT soundings, and supported by HRRR and MOS guidance.
Otherwise, there will be some light showers or drizzle lingering
overnight, but this will have little impact on flight
conditions.

Friday, with a still light westerly flow flight conditions will
slowly improve back to MVFR with daytime mixing and deeper moisture
exits to the east. This is likely to be a slow process, with IFR
conditions likely to linger through most (if not all) of the
morning hours south of Lake Ontario.

Outlook...
Friday night...MVFR/VFR with isolated showers.
Saturday...Mainly VFR. Chc of showers early to the west.
Sunday...Mainly MVFR with showers likely.
Monday and Tuesday...MVFR/VFR with a chance of showers.

&&

.MARINE...
An easterly wind will continue across Lake Ontario this
evening with small craft advisory worthy waves and winds on the
far western shoreline. Otherwise an upper level low will track
across Lake Erie and to the south of Lake Ontario overnight and
tomorrow. Winds will relax under this feature and this will
allow for the SCA to end overnight.

&&

.TIDES/COASTAL FLOODING...
Low pressure will track from Pennsylvania to Southern New
England. Winds have diminished this evening, but there are waves
up to 5 ft across western portions of Lake Ontario so we kept
the lakeshore flood warning up for now with this set to expire
at 2 am.

&&

.CLIMATE...
Buffalo has exceeded the daily precipitation record of 1.21
inches established in 1874. Rochester is close to a recorded
rainfall, while the rain continues across Watertown. Daily
record rainfall for Rochester is 1.74 inches set back in 1943
and Watertown`s record for today is 1.13 inches set back in
1979. With rain continuing east of Lake Ontario, and possible
showers across Buffalo and Rochester final daily totals be known
after the climatic day (1 AM EDT to 1 AM EDT) ends.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Lakeshore Flood Warning until 2 AM EDT Friday for NYZ001>003.
MARINE...Small Craft Advisory until 2 AM EDT Friday for LOZ042.

&&

$$

SYNOPSIS...APFFEL/THOMAS
NEAR TERM...APFFEL/THOMAS
SHORT TERM...TMA
LONG TERM...CHURCH
AVIATION...APFFEL/THOMAS
MARINE...APFFEL/THOMAS
TIDES/COASTAL FLOODING...HITCHCOCK/WOOD/APFFEL/THOMAS
CLIMATE...THOMAS



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