Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 221812

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

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.


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. This will
quickly move eastward into central New York.

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 and a stable upper-level northwest flow will lead to a
quiet and dry period of weather Wednesday and Thursday, as the upper
ridge axis remains anchored over the upper Midwest and western Great
Lakes. Mainly clear skies are expected during this period.
Temperatures will experience a day to day warming trend with highs
Wednesday mainly in the lower to mid 70s, and in the mid to upper
70s by Thursday.

The high will slide off to the east Thursday night and Friday with a
southwesterly flow strengthening in between the departing high and
an area of low pressure approaching the upper Great Lakes. This will
force warmer and more humid air into our forecast area. Mid-summer
warmth is expected on Friday with high temperatures mainly from 80
to 85F, although could see some upper 80s across interior sections.
Fair weather is expected to continue Friday, before some northern
stream energy helps drive the low pressure system a bit closer
Friday night with some shower activity possible for the North


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 latest 12Z GFS brings a rather strong backdoor cold
front south across our region Saturday night, with a seasonably
strong and dry high pressure building into New England which would
keep us dry Sunday through Monday. This is a major change from the
past few runs of the GFS, which kept any frontal boundary well north
of our region.

The 12Z ECMWF 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 Saturday
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.


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.


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


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.





NEAR TERM...Apffel
LONG TERM...Hitchcock
MARINE...Apffel is the U.S. government's official web portal to all federal, state and local government web resources and services.