973
FXUS61 KILN 170001
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
801 PM EDT Thu May 16 2024

.SYNOPSIS...
Southwest flow in the Ohio Valley will increase moisture ahead
of a surface low that will remain west of the region. Upper
level shortwave energy in a mean southwest flow will interact
with the moisture, producing an area of showers with some
thunderstorms that enters from the west late tonight. A more
pronounced shortwave is expected to continue this wet pattern
through the day Friday, possibly lingering overnight in some
spots.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
The overall message of overspreading showers is pretty uniform
for tonight, continued differences in model solutions bring an
element of uncertainty to the table. This is more concerning the
timing of the leading edge but to a lesser extent coverage and
placement.

Looking at forecast soundings, the pre-storm environment shows
steep low level lapse rates. These rates are found in the yet
unmixed layer below the LFC and quickly become less favorable as
the moisture becomes deeper with the mixing found on the
leading edge of this activity. Likewise, most unstable CAPE
values under 400 J/kg are only briefly found at the onset of
precip. This is indicative of an atmosphere that does not have a
forcing mechanism in the lower levels such as tonight. Mid
level vorticity appears to be the driving force for upward
motion. The smaller areal nature and wider range of placement of
the shortwave, as well as location and timing of associated
vorticity maxima necessitate a broad brush in rain and
thunderstorm chances tonight. Given the lack of indicies
supporting discrete thunderstorms, expect this to be more of a
showers with some thunder flavoring for the overnight hours.
Used pops >40% to include a slight chance of thunder and pops
>50% for a chance of thunderstorms.

Increased low level moisture and incoming clouds from the west
will limit low temperatures to the lower 60s.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Showers and some thunderstorms will continue across the CWA Friday,
potentially lingering overnight for some locations, moreso in
the southeast.

While particularly strong storms are not expected through the
period, some sw-ne training may occur and increase the flood
potential.

Highs in the mid 70s may be on the warm side if a cooling rain
process is noted to linger in the afternoon for some locations.

Overnight will keep a slight southerly flow in a moist airmass
once again. Lows will drop to around 60.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Southern stream mid level low to track east thru the Ohio
Valley Saturday. Moist sounding profile and slow storm motion
could lead to a threat for some localized heavy rain and
flooding with the focus looking to be across ILN/s southern
counties.

Model solution spread continues regarding the speed of this
system. Have followed a slightly more progressive solution, only
keeping a slight chance in the far east by Sunday.

A narrow mid level ridge will build across the area late Sunday
into Monday, providing a brief period of dry weather. This dry
period will be short lived, as the flow backs westerly turning
more progressive.

Moisture increase with a gradual increase in instability but
due to lack of forcing have limited pops to low chance category
on Tuesday. Moisture and instability increases ahead of a
stronger trof with a surface cold front moving thru the area
Wednesday. Given potential moderate instability and the passage
of stronger front - will have to watch this period for the
potential for strong storms.

Warm temperatures to continue with highs likely reaching the
80s by Sunday and then in the lower and middle 80s on both
Monday and Tuesday. Highs remain above normal but pull back into
the mid and upper 70s Wednesday and Thursday.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR conditions are expected through the early morning hours as
mid-level clouds increase ahead of an approaching disturbance.
The initial area of showers is likely to arrive to the
DAY/CVG/LUK area around 07-09Z. Based on the skinny CAPE in the
model soundings, expecting only isolated thunder so have
represented these with VCTS. This initial area of showers will
progress to the east by mid morning, leaving only isolated
coverage behind. Wouldn`t be surprised to see ceilings
temporarily drop below 3,000 feet Friday mid-late morning at DAY
and a bit later at CMH/LCK.

The second area of showers is likely to impact mostly southern
terminals from the afternoon through early evening. At this same
time, there could be a few isolated storms develop from DAY
across to CMH.

Conditions look to improve near the end of the TAF period as the
system exits to the east.

OUTLOOK...MVFR CIGs are possible Friday night.

&&

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

&&

$$
SYNOPSIS...Franks
NEAR TERM...Franks
SHORT TERM...Franks
LONG TERM...AR
AVIATION...