Westerville, Ohio 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

533
FXUS61 KILN 161742
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
142 PM EDT Thu Jul 16 2026

.WHAT HAS CHANGED...
No significant changes

&&

.KEY MESSAGES...
1) Hot, humid, and hazy conditions continue.

2) Showers and thunderstorms are forecast to develop Friday and
continue into the weekend, bringing a risk for localized flash
flooding and gusty winds.

&&

.DISCUSSION...
KEY MESSAGE 1)

Mid level ridge axis situated northwest to southeast across the
region will sag slowly south tonight and break down/ weaken. As such,
a very moist airmass has begun to encroach into the Ohio Valley
region on Thursday. This has acted to raise Tds even more so than
yesterday, resulting in some very muggy conditions. Have continued
the Special Weather Statement for hot and humid conditions through
Thursday evening. CAMs still indicate some isolated thunderstorm
activity primarily south of I-70 today, so have kept a low end PoP in
the grids.

Wildfire smoke from the northern US/Canada will continue to wrap
through the larger flow and into the Ohio Valley. HRRR smoke modeling
suggests that near surface smoke will primarily remain across
northern Ohio today before percolating southward on Friday. It`s not
unheard of for temperatures to be impacted a couple of degrees from a
thick column of smoke, as insolation is inhibited, so have tweaked
daily highs down a couple degrees accordingly for Friday, though kept
Tds as is, given the moist airmass.

Even with the smoke and increasing cloud cover, muggy conditions are
expected to continue through the weekend with scattered
thunderstorms.

KEY MESSAGE 2)
Showers and thunderstorm chances are reintroduced to the forecast on
Friday and Saturday as midlevel flow becomes more northwesterly and
shortwaves move through the larger flow. As previously mentioned,
moisture from the Gulf will surge into the Ohio Valley, increasing
PWATs to 2+ inches, which is well above the 90% percentile and
nearing climatological maximums. This moist airmass will be present
both Friday and Saturday, allowing for a saturated column as well as
surface Tds in the low to mid 70s.

On Friday, the first weak shortwave will move through the flow,
sparking showers and thunderstorms Friday afternoon into late
evening. An instability gradient will exist from west to east, with
more robust instability building in from the west southwest.
Scattered thunderstorms are expected to develop beginning Friday
afternoon and continuing through the evening hours. Shear is nearly
non-existant but DCAPE will be over 900 J/kg and MLCAPE will 1500
J/kg+. Given that and the high PWATs, storm motions will be very slow
and water loaded storms may quickly collapse, producing instances of
gusty winds. Localized heavy rainfall may result in isolated flooding
issues.

A larger shortwave will then pivot through the flow Saturday into
Sunday, dragging a surface low pressure system through the northern
Great Lakes region. The associated cold front will sag into our area
Saturday afternoon into the overnight hours, bringing additional
thunderstorm chances.

Given the larger shortwave, around 30 knots of bulk shear will swing
through, which (while not overly robust) may be able to help support
more organized thunderstorm development and propagation. In addition
to this, instability looks to build in area wide with with various
guidance suggesting anywhere between 2000-3000 J/kg of SBCAPE
available during the late afternoon, getting pinched off as we head
into the evening and overnight. Main concerns right now are damaging
wind gusts with stronger storms and would not rule out some large
hail, especially during the afternoon hours.

&&

.AVIATION /13Z THURSDAY THROUGH MONDAY/...
VFR conditions continue through the period with the exception of LUK,
where an early Friday morning MVFR fog restriction was added.

A very isolated shower or storm chance exists this afternoon for
KDAY, KLUK, KCVG but chances are low enough that chose to not include
in the TAF at this time. Any storms would dissipate shortly after
sunset. Scattered cu linger throughout the day today and into the
overnight hours. A mid level deck builds in on Friday ahead of
thunderstorms that arrive Friday evening, primarily for western
sites. Have introduced this in the longer CVG TAF.

Winds out of the north today will become variable overnight before
swinging around to easterly by Friday morning, then southerly by
Friday afternoon.

OUTLOOK...Thunderstorms possible on Friday afternoon and Saturday
afternoon into the overnight.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Air Quality Alert until midnight EDT tonight for OHZ026-034-035-
     042>046-051>056-060>065-070>074-077>082-088.
KY...Air Quality Alert until midnight EDT tonight for KYZ091>093.
IN...Air Quality Alert until midnight EDT tonight for INZ074.

&&

$$

DISCUSSION...Aiena
AVIATION...Aiena