Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 220301
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1101 PM EDT Mon May 21 2018

.SYNOPSIS...
A warm front will move east across Western New York overnight,
followed by a cold front on Tuesday.  Both fronts will bring some
rain along with the chance for thunderstorms.  Dry weather will
follow for the rest of the week.

&&

.NEAR TERM /THROUGH TUESDAY/...
Leading edge of the rain shield tracking ENE into the Western
Southern and will reach Western New York within the next hour
between 03Z-04Z tonight. Ongoing convection across Ohio is
continuing to move ENE but is weakening a bit as it moves towards our
our region. This convection is associated with abundant moisture
that resides to our south, which is beginning to lift into our area
tonight, its clearly seen by a tight gradient of precipitable water
with only about 0.75 over NY but up to 1.5 over OH/PA.

Otherwise, a surface low pressure system underneath the midwest
trough will develop a weak warm and trailing cold front, the first
of which will cross the region overnight.  This should have no
problem overcoming the current relatively dry airmass which will
continue to moisten. The leading edge of rain which is beginning to
move into Western New York should move east across WNY overnight,
and be near or over the Eastern Lake Ontario region by daybreak
Tuesday. QPF is currently set at about 0.5" south of Lake Ontario to
possibly over an inch near the interior Southern Tier, with about
0.25" east of Lake Ontario.  This will result in some periods of
locally heavy rainfall, but without any flood threat.

On Tuesday, much of WNY will be in a subtle but fairly saturated
warm sector as the surface low pressure system moves east across the
region.  It`s trailing cold front should be able to touch of a line
of convection originating on lake breeze boundaries southeast/south
of either/both Lake Erie/Ontario.  Otherwise expect abundant cloud
cover for much of the day.  There won`t be much of a change in
airmass ahead or behind the cold front other than a subtle wind
shift, so expect abundant clouds on both sides of the front.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH FRIDAY NIGHT/...
After a wet and unsettled day on Tuesday...we can anticipate
significant improvement in our weather as we work through Tuesday
night into Wednesday.

A ridge centered over the middle of the country Tuesday night will
amplify and drift east Wednesday and Thursday. After a few leftover
showers Tuesday evening...this scenario will lead to clearing skies
during the overnight with absolutely beautiful weather to follow for
Wednesday and Thursday. Temperatures both days will average above
normal as max temps will end up between 75 and 80. The gradual day
to day warming will be accompanied by low humidity levels...so it
should feel quite comfortable.

As a large surface high drifts east of our region Thursday night and
Friday...the return flow around the backside of the system will
circulate warmer and somewhat more humid air into our forecast area.
When full mixed...H85 temps climbing to around 16c within this
environment will fully support Friday afternoon mercury readings of
80 to 85f. Most guidance packages though are under playing forecast
highs by as much as 5 degrees f. The mid summer warmth will be
accompanied by continued fair dry weather.

&&

.LONG TERM /SATURDAY 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 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.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Leading edge of precipitation entering Western New York with the
warm front which will bring lowering CIGS and reduced VSBYS
overnight with showers and a chance of a thunderstorms. A subtle
cold front will cross the region Tuesday with another round of
showers and a chance of a thunderstorm well south and east of the
lakes.

Tuesday night, high pressure will slowly build into the region
behind the front with slow but improving conditions overnight.

Outlook...

Wednesday through Friday...VFR.
Saturday...chance of showers with some MVFR.

&&

.MARINE...
A surface low will move ENE across the lower Great Lakes by Tuesday
with a warm front overnight, followed by a cold front Tuesday
afternoon.  Wind speeds will be under SCA but with varying wind
direction, eventually becoming northwest behind the cold front late
Tuesday.  Light winds and local circulations are expected for the
remainder of the week.

&&

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

&&

$$

SYNOPSIS...AR/Zaff
NEAR TERM...AR/Zaff
SHORT TERM...RSH
LONG TERM...Hitchcock
AVIATION...AR/Zaff
MARINE...AR/Zaff


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