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000
FXUS61 KILN 160759
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
359 AM EDT Tue Jul 16 2019

.SYNOPSIS...
What remains of the decayed Tropical Depression Barry will move
through the Ohio Valley tonight and Wednesday, bringing an
increase in showers and a few thunderstorms, primarily tonight
into Wednesday. It will remain muggy through the entire week
with very warm and humid conditions expected Thursday through
the weekend as a large dome of heat develops over much of the
eastern half of the United States. Outside of rain chances
tonight and Wednesday, much of the rest of the week and into the
weekend will remain dry.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
What remains of the former Tropical Depression Barry is still
spinning slowly northeast over Missouri per radar mosaics and
GOES water vapor imagery. Per WSR-88D and TDWR VWPs, a belt of
modestly enhanced low-mid level flow still exists on the eastern
semi-circle of the circulation with belt of deeper moisture
extending northeast from the Ark-La-Tex into the lower Ohio
Valley. The 16.00Z KILN RAOB sampled some of this moisture
/1.75" PWAT/ although the sounding had convective debris
enhancing moisture just a bit. At 08Z, a large shield of
sprinkles/light rain was still developing and shifting northeast
into IN and southwestern OH downstream of the stronger height
falls/vorticity maximum with the remnants of Barry. There is
good model agreement that this activity will shift northeast
along the OH/IN border this morning with some light
rain/sprinkles continuing esp our southeast IN counties up into
west-central Ohio. In the wake of this activity, there is a
decided lull in forcing as we wait for the primary shortwave
trough/vort max to eject out of MO/AR into the Ohio Valley later
this afternoon. So - once the arc of light rain
showers/sprinkles moves northeast across our western areas this
morning, expect most of the day to be dry and again quite humid
as low level moisture is entrenched and being enhanced by the
modest feed of tropical southwesterly winds tied to the
approaching trough.

Expect highs into the 80s all areas - warmest southeast /lower
Scioto Valley and northeast Kentucky/ which will be furthest
removed from deeper inbound moisture. Could see heat indices in
this area approach the mid 90s by afternoon. Can`t completely
rule out a random/weakly forced shower to pop up with diurnal
destabilization especially west of I-71 this afternoon but
forecast soundings reflect the lull in forcing as PWATs pull
back a bit with some mid-level drying with somewhat of stability
maximum over the ILN CWA in comparison to areas southwest/west
which will destabilize far more readily through the day. So
broad-brushed low PoPs in place this afternoon to cover the
potential for a random storm or two.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Primary vort maximum and height falls attendant to the weakening
remnants of Barry will push northeast into Indiana early this
evening as it slowly accelerates and the magnitude/sharpness of
the trough decays. Expect the arrival of this forcing to
manifest in a large area of increasing showers/storms (still
quite scattered in coverage initially) to move into
Indiana/western Ohio as the night wears on. Attendant to the
arrival of this forcing will be deeper moisture with PWATs
surging toward 2.10" or so, and low level /1km/ flow increasing
to 30kts. Thus, any updrafts will have the potential to produce
torrential rainfall rates of 2"+ /primary concern/ and very
isolated gusty winds/marginally severe threats /distant
secondary concern/. Despite very low LCLs and 0-1km shear >
25kts suggesting a non-zero weak tornado threat, think there`s
better chances for isolated impacts tonight from localized flash
flooding or brief water-loaded downdrafts causing sporadic tree
damage /SPC MRGL risk/.

Model QPF footprints continue to be underwhelming and mostly <
1". In fact, an amalgam of CAM QPFs show numerous very narrow
swaths of ~1" to 1.25" amounts suggesting that an absence of a
defined low level focus/convergence maximum will keep convection
from being widespread or focused/tied to a particular area which
is vastly different from the QPF footprints we saw in past days
to our southwest when Barry had much more defined low level
features. Thus, while confidence is high that there will be
rain in most areas overnight, have capped PoPs around 75%
because there will likely be some areas that dodge these swaths
of locally heavy rain due to expected mode being
narrow/progressive bands of showers/shallow thunderstorms.
Supporting this is shrinking of WPC SLGT risk in the ILN CWA
tonight /focused in far west-central Ohio/ and in Scioto Valley
of southeastern Ohio on Wednesday. All things considered from a
forcing/moisture perspective, feel the most confident that
heaviest /relative/ QPF from this system will focus west of I-71
and north of I-70 (mostly west-central Ohio) this evening. Have
added heavy rain to the forecast in all areas tonight into
Wednesday morning to cover the potential for torrential rainfall
rates with any convectively enhanced activity.

On Wednesday, axis of very deep moisture with bands of showers
and shallow thunderstorms will progress steadily through the ILN
CWA, especially through the morning. By afternoon, the mid level
trough axis will be shifting out with mid level flow turning
westerly and a gradual loss of larger scale forcing. This should
tend to allow activity to become more scattered into the
afternoon. Temperatures with plenty of clouds will be tempered -
mainly in the lower 80s but still very humid with dewpoints
remaining in the 70s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Moisture and forcing associated with Barry remnants will be pushing
east of the area Wednesday night, bringing an end to most showers
and thunderstorms by Thursday morning. Isolated thunderstorms may
still develop on Thursday afternoon, before a cap under a broad
upper ridge keeps convection from forming on Friday and Saturday,
resulting in sunny skies.

Upper ridge is forecast to begin breaking down on Sunday, signaling
the start of a change in the pattern. Lowering geopotential heights
and somewhat cooler air aloft will produce an increase in
instability, allowing scattered thunderstorms to form Sunday and
Monday, aided by convergence and enhanced wind fields associated
with a surface cold front.

Hot temperatures and heat indices will the main story for this
period. Highs in the low 90s Thursday will increase to the mid and
upper 90s Friday and Saturday. Combined with a very humid airmass,
heat indices will rise over 100, requiring heat headlines. As
geopotential heights drop, and clouds, precip and modest cold
advection arrive with the cold front, readings will transition
slowly down to about 90 by Monday.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
At 05Z, VFR conditions across the TAF sites except for ILN where
some shallow MVFR visibilities had developed thanks to evening
storms and a brief period of clearing. Think most sites will be
susceptible to a brief period of MVFR visibility through
sunrise if some clearing can develop and persist for an hour or
two, but looking at latest GOES imagery shows most of the
pockets of clearing are quite small, so expect mostly cloudy
skies /mid clouds/ to persist through sunrise.

After sunrise, there may be a few showers that develop toward
CVG/LUK/DAY on an arc of weak moisture transport but don`t
expect much in the way of restrictions. Think sct/broken VFR
clouds will persist across the sites through the day, and bulk
of the day will be dry. Past 19Z or 20Z, expect scattered
showers and a few storms to develop in random/scattered nature
over the entire area as remnants of TD Barry approach as an
opening shortwave trough, but a more focused/concentrated area
of activity to the west over Indiana. This will move/develop
toward KDAY/KCVG/KLUK by early to mid evening. Could be some
brief MVFR or even IFR restrictions in torrential rainfall rates
with this activity, but don`t have confidence in
coverage/location to indicate anything more than prevailing
showers /VFR/ right now. This axis of moisture/forcing will
cross the TAF sites tonight but again - don`t have a good
feeling for coverage and don`t think this will be a
widespread/long event at any given TAF site - instead being
bands of progressive showers and a few storms with very heavy
rainfall rates for brief periods of time. Expect TAFs to be
refined in later issuances in terms of timing of heaviest
showers which may bring MVFR/IFR restrictions especially in the
evening to early overnight. Late in the night could see a
ceilings lower to MVFR categories as low level moisture peaks
with the passage of the trough.

OUTLOOK...MVFR/IFR ceilings possible Wednesday. Thunderstorms
possible Wednesday.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.

&&

$$
SYNOPSIS...Binau
NEAR TERM...Binau
SHORT TERM...Binau
LONG TERM...Coniglio
AVIATION...Binau