Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 171443

Area Forecast Discussion
National Weather Service Buffalo NY
1043 AM EDT Mon Jun 17 2019

A frontal boundary will remain stalled just south of the area
through Wednesday with a chance of a few showers at times across the
Southern Tier. Otherwise weak high pressure over southeast Ontario
and Quebec will keep the rest of the area mainly dry with
temperatures near average. Low pressure will then move through the
eastern Great Lakes Thursday with another round of more widespread


Satellite imagery shows much of forecast area seeing mostly
clear skies mid morning. Exception is over Southern Tier where
stratus is slow to diminish and mid to high clouds remain

An east-west oriented frontal zone will remain stalled today and
tonight from the Ohio Valley eastward across Pennsylvania. Numerous
weak convectively augmented shortwaves and surface waves will
continue to move east along the frontal zone, keeping the bulk of
the more active weather to our south. Isolated showers are clipping
southern fringes of the Southern Tier currently. Slightly
better chance of some showers and possibly an isold thunderstorm
will occur this afternoon over the western Southern Tier due to
diurnal instability and differential heating boundaries
combining with weak ascent from shortwaves passing by to our
south. Otherwise the remainder of the area will stay dry with an
increase in mid/high clouds.

Most of the region will stay dry tonight. The exception will again
be the western Southern Tier. Another mid level vorticity maxima
will move east across central and northern Pennsylvania, and may
support a few showers and possibly an isolated thunderstorm across
the Southern Tier.

Temperatures will be near average, with highs in the mid 70s in most
locations today. A light northeast breeze will keep the south shore
of Lake Ontario in the 60s. Areas near the Pennsylvania state line
may also stay in the 60s with thicker cloud cover. Lows tonight will
be in the mid to upper 50s in most areas, with lower 50s east of
Lake Ontario.


No major changes initially with the same old pattern in place
Tuesday. The pesky stationary frontal boundary will still be to our
south from roughly southern Indiana east into the Ohio Valley and
along or near the Mason Dixon Line. Again, with each passing
convectively augmented wave to our south a few showers or an
isolated stronger storm may develop or creep into the Western
Southern Tier. Otherwise, a majority of the forecast area will more
than likely experience dry weather thanks in part to weak surface
ridging influencing the Lower Lakes. Highs will be right where they
should be for this time of year with mid to upper 70s.

Tuesday night, no significant change other than the stalled frontal
boundary to our south will move further away. With that said, weak
surface high over the lower lakes should maintain mainly dry weather
for our forecast area. Lows temperatures overnight will generally be
found in the mid 50s by daybreak.

Wednesday, weak surface high pressure should maintain mainly dry
conditions for a majority of the Lower Lakes. The only hiccup will
be potential for an isolated shower or stronger storm to develop
along any convergent boundaries over the Western Southern Tier.
Otherwise, this should be the warmest day of the period with highs
climbing into the upper 70s near 80F.

A potential soaking rainfall Thursday...

A potent shortwave over the Midwest and associated surface lows with
this system will head east Wednesday night. Latest 00Z NAM, GFS, and
now the ECMWF all pointing towards a "LIKELY" wet second half of
this week. The question will be "HOW" much precipitation, as there
still remains a bit of uncertainty, mainly track and timing issues.
While a majority of the night should remain precipitation free, look
for increasing chances for precipitation across far Western NY by
daybreak. Lows temperatures will more than likely occur early and
then hold steady overnight with upper 50s to low 60s by sunrise.

Thursday, two distinct areas of low pressure with the shortwave, one
well displaced to our south which will track along the Mason Dixon
Line. The other low is forecast to track east across Lake Erie and
then our forecast area. With plentiful moisture in place (PWATs in
excess of 1.5 inches) and deep lift, moderate to heavy rainfall at
times will be possible as this system moves across the region. It
wouldn`t be out of the question that many locations could receive
rainfall totals of up to an inch, with localized areas exceeding
that total. Have again nudged up POPs to categorical for all
locations south of Lake Ontario.

Thursday night, while the timing of the eventual exit of this system
is still up in the air, the weak sfc low will gradually head east
overnight. In its wake, look for some lingering showers across the
forecast area, which will slowly taper off from west to east by
Friday morning. Otherwise, with some clearing taking place behind
this system and surface high pressure builds in temperatures should
fall back into the 50s areawide by daybreak.


General hgt rises will be found over the Lower Great lakes on high pressure centered over Hudson Bay will attempt to
nose south across the Lower Great Lakes. While this should encourage
fair dry weather...there is some `debate` among the various guidance
packages as to the amplitude of the mid level ridge that will be
centered to our west. A higher amplitude ridge may allow for a
subtle shortwave to drop to the south across our region with a
resulting shower threat. Will thus carry chc pops for Friday...but
am definitely leaning towards a mainly dry day.

There is greater confidence that dry weather will be in place for
Friday night and the mid level ridge will amplify with
its axis pushing east to our region.

As we close out this period though...the ridge axis will exit to our
east and open the door for the next shortwave and influx of moisture
to move into the Lower Great Lakes region. This could lead to the
next round of showers to close out the weekend.


Low stratus over the Southern Tier will dissipate late this morning,
leaving mainly VFR to prevail at all the TAF sites. A few isolated
to widely scattered showers and possibly an isolated thunderstorm
may develop during the afternoon across the higher terrain of the
Southern Tier and western Finger Lakes, but coverage is expected to
remain sparse with dry weather and VFR in most areas. A few
additional showers and possibly an isolated thunderstorm will
continue tonight across the western Southern Tier as a weak wave of
low pressure moves along the stalled frontal zone over Pennsylvania.
Low stratus and possibly some fog may re-develop overnight across
the Southern Tier with local IFR possible.


Tuesday...VFR to MVFR in scattered showers and isolated
thunderstorms, mainly across the Southern Tier.

Wednesday...Mainly VFR with isolated showers possible.

Thursday...MVFR/IFR with periods of rain and isolated thunderstorms.

Friday...MVFR. A chance of showers.


A frontal zone will remain stalled from the Ohio Valley to
Pennsylvania through Wednesday while weak high pressure settles into
southeast Ontario and southern Quebec. This will keep a weak
pressure gradient across the eastern Great Lakes, with light winds
and flat wave action.

Low pressure will track near the eastern Great Lakes on Thursday,
but the track and strength of the low is uncertain. Winds and waves
may approach Small Craft levels depending on the eventual strength
and track of this system.





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