822
FXUS61 KILN 141326
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
926 AM EDT Wed Aug 14 2024

.SYNOPSIS...
Surface high pressure will continue to bring dry weather conditions
through mid week. The next chance of precipitation will arrive
late Thursday into Friday as a frontal system approaches the
Ohio Valley. The threat for precipitation will continue through
the weekend as low pressure tracks through the Great Lakes.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Nothing of significance to add to the ongoing fcst as abundant
sunshine and seasonably mild temperatures are on tap through the
near term period. Negative PWAT anomalies will remain entrenched
across the region through tonight, translating to tranquil and
pleasant conditions locally.

PREVIOUS DISCUSSION...
Upper level pattern characterized by a long wave trof over New
England and southeast Canada and a ridge over the MS Valley.
This places the Ohio Valley in northwest flow with a large area
of surface high pressure over the Great Lakes. In dry airmass
expect only a few to scattered cumulus clouds along with a few
high level clouds spilling over the ridge to our west.

As the ridge nudges a little east we will observe height and
thickness rises yielding temperatures a few degrees warmer than
yesterday. Under mostly sunny skies expect highs to range from
the lower 80s north to the upper 80s south.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Narrow mid level ridge axis to build east into the area early
Thursday. Diurnally driven cumulus clouds will dissipate with
the loss of daytime heating yielding mostly clear skies this
evening. High level clouds will then increase toward sunrise
Thursday. Overnight lows to bottom out in the lower 60s in most
locations. Exceptions - A few upper 50s will be possible in the
far eastern typical cold spots and some city locations will
remain in the mid 60s.

Narrow mid level ridge to quickly build east across the area
Thursday. A lead mid level shortwave in the wake of this ridge
to approach the area Thursday afternoon. Model consensus shows
best forcing and moisture to remain to our west during the
daylight hours. Therefore, have limited any mention of a shower
to chance/slight chance and confined these pops to west central
Ohio late in the day. Most locations will warm to readings in
the mid and upper 80s. The exception is the northwest - where
clouds and possible showers will keep highs in the lower 80s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
On Thursday evening, the axis of a mid-level ridge will be passing
eastward through the Ohio Valley. On the back side of the ridge,
theta-e advection aloft will begin, with a significant amount of
moisture increasing above 850mb. A broad mid-level trough will be
moving east across the northern tier of states, reaching the upper
Midwest by 12Z Friday morning. On the southern periphery of this
broad trough, forcing will be on the increase over the Ohio Valley,
as a result of some shortwaves rotating around the base of the
trough. Convection is expected to be ongoing to the west of the ILN
CWA on Thursday night, associated with an initial shortwave.
Initially surface based (and possibly strong) this convection will
eventually weaken as it moves east of the instability axis, reaching
the ILN CWA after 06Z. The boundary layer is expected to remain
generally stable during this time frame, so any storms arriving
early Friday morning will be elevated and with only a low
probability of severe weather (a marginal wind threat as indicated
by the SPC D2 outlook). Overall, precipitation will be fairly
widespread, as a result of the forcing and increasing deep-layer
moisture. Likely PoPs have been included for much of the forecast
area in the 06Z-15Z time frame.

Attention will then turn to the potential for additional convective
development on Friday afternoon. The potential strength of these
storms will be dependent on several factors, including the degree of
contamination from the morning precipitation. Model soundings
suggest the atmosphere will destabilize, though the degree is
unclear, especially as there are differences in the handling of
lapse rates (particularly mid-level lapse rates). There does appear
to be some broad forcing for ascent as a result of the trough, as
well as some renewed 925mb-850mb theta-e advection during the
afternoon. Wind shear appears sufficient for some degree of storm
organization, and precipitable water values will be approaching two
inches. Though uncertainty remains, this setup does support at least
some lower-end risk for severe weather and heavy rainfall. Specific
timing details and thermodynamic profiles will be the main
questions, and uncertainty on those factors precludes a greater
concern as of now.

Models are coming into somewhat better agreement on the progression
of the trough over the weekend. It will be moving slowly, but may
only briefly develop into a closed low before it continues moving
east. The Ohio Valley will be on its southern periphery, in a regime
of generally westerly flow -- with chances for precipitation
continuing. PoPs will be kept in the forecast each day from Saturday
through Monday, but with gradually diminishing chances from one day
to the next due to temporal forecast uncertainty and the fact that
stronger forcing will likely be displaced to the north and east with
time.

Temperatures in the middle to upper 80s are expected Friday, with
cooler values in the lower to mid 80s over the weekend and into next
week.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
Large area of high pressure to continue to offer mainly VFR
conditions thru the TAF forecast period.

Few to scattered VFR diurnal cumulus to develop this afternoon.
These clouds will dissipate with sunset leaving mostly clear
sky conditions heading into this evening. Some high level clouds
spill into the area late tonight. Some river valley fog will be
possible at KLUK overnight in the light wind/mainly clear
regime.

Light north winds veer to the east/northeast today at speeds
less than 10 kts. These light winds are east at 5 kts or less
overnight and then southeast at less than 10 kts Thursday.

OUTLOOK...Thunderstorms are possible Friday.

&&

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

&&

$$
SYNOPSIS...AR
NEAR TERM...KC/AR
SHORT TERM...AR
LONG TERM...Hatzos
AVIATION...AR