Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 221839
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
239 PM EDT Tue May 22 2018

.SYNOPSIS...
Weak low pressure will cross the region with showers and a few
thunderstorms through this evening and areas of fog through tonight.
Surface high pressure will bring a period of dry weather Wednesday
through Friday. Afternoon high temperatures in the 70s midweek will
steadily increase to the lower 80s for the start of the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Weak low pressure across southern Ontario province will track across
New York state this afternoon and into northern New England tonight.
A weak cold front trailing this system will move across the region
through this evening. This combined with limited surface bases
instability (mainly less than 500 J/kg) will result in a line of
showers and a few thunderstorms developing across the western
Southern Tier and Finger Lakes region late this afternoon. Expect
this line to initially be scattered, but it should fill in as it
moves eastward into central New York late this afternoon and early
evening.

Areas of fog have developed across and just northeast of the lakes
ahead of the frontal boundary. This front is diffuse, with
increasing low moisture and diminishing winds resulting in more
widespread fog developing this evening. There may also be some
drizzle or light showers with this, which is probably overdone by
mesoscale and SREF guidance.

High pressure will ridge into the lower Great Lakes late tonight,
with drier air gradually building into the region. However, if skies
clear before daybreak it will probably be quickly followed by fairly
dense radiation fog. Lows tonight will be in the lower to mid 50s.

High pressure will expand across the region on Wednesday. There will
be some lingering stratus and fog in the morning, but this should
gradually dissipate by afternoon. High temperatures will be mainly
in the 70s, except slightly cooler along the immediate lakeshore.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH SATURDAY NIGHT/...
The weather will be absolutely spectacular across the region for the
over whelming majority of this period...as a negatively tilted ridge
within a split flow will track across the Great Lakes region. The
ridge will deamplify with time though...and this will end up placing
our region between a slow moving back door cold front to the north
and the fringes of a large shield of tropical moisture to our south.
As we start the weekend...this will eventually bring an end to the
fine stretch of weather with showers and thunderstorms entering the
picture.

&&

.LONG TERM /SUNDAY THROUGH MONDAY/...
The forecast remains quite uncertain for next weekend into early
next week with significant model differences and run to run flips in
models. Abundant tropical moisture will continue to stream into the
Southeast States through the period, but how much of that moisture
makes it all the way north into the eastern Great Lakes remains in
question.

The 12Z ECMWF (from 5/21) is much more consistent with previous
ECMWF runs, and the previous GFS runs in keeping any drier air
well north of our region through early next week. This solution
is the model of choice, and will keep our area warm and rather
muggy Sunday through Monday. Expect highs in the lower 80s away
from lake influences and lows in the lower 60s through the
period. There will be a chance of a few showers and
thunderstorms each day, but forcing appears weak so expect the
showers to remain scattered in nature with rain free time each
day as well. The deepest of the tropical moisture and stronger
forcing looks to remain well south of our area through Monday.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
The main concern for aviation is areas of low stratus and the
potential for dense fog. A southwesterly flow will mix moist
boundary layer air with the relatively cool lake waters resulting in
low stratus and fog northeast of the lakes which will impact BUF/ART
and to a lesser extent IAG. Expect mainly IFR or lower conditions at
these sites until after 06Z tonight when winds shift to the
northwest and advects slightly drier air. There is a potential for
dense fog if ceilings lower to the ground, with low forecast
confidence at these locations.

Otherwise, weak low pressure and an associated frontal boundary will
shift winds to the northwest which will lower JHW to IFR and
maintain ROC in the MVFR flight category. There also may be some
radiation fog late tonight if there is any clearing, which may also
be locally dense. Low moisture will gradually mix out Wednesday
morning with widespread VFR flight conditions by the afternoon.

Outlook...

Wednesday night through Friday...VFR.
Saturday...Mainly VFR. A chance of showers.
Sunday...MVFR. Showers likely.

&&

.MARINE...
Weak low pressure and an associated frontal boundary will track
across the lower Great Lakes through this evening. Winds will not be
very strong, however there will be areas of fog due to the warm
moist air across the relatively cool lake waters. Surface high
pressure will near the region Wednesday, passing over the Eastern
Great Lakes Thursday, before shifting towards the Southeast states
on Friday. This will maintain light winds and minimal waves through
the end of the week.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...Apffel/Thomas
NEAR TERM...Apffel
SHORT TERM...RSH
LONG TERM...Hitchcock
AVIATION...Apffel
MARINE...Apffel


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