Area Forecast Discussion
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FXUS61 KILN 240738
Area Forecast Discussion
National Weather Service Wilmington OH
338 AM EDT WED AUG 24 2016
With upper level ridging over the southeastern states, warm and
moist air will begin to flow into the region today. Embedded waves
in the mid-level flow will bring chances for showers and storms
today and Thursday, in the northern Ohio Valley and southern Great
Lakes. High pressure over the Great Lakes will bring drier
conditions for Friday and Saturday, before chances for storms
increase slightly on Sunday and into the new week.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As surface high pressure continues to move away to the east, an
increasing gradient is setting up over the Ohio Valley. Ridging
over the southeastern states is centered due south of the Ohio
Valley, meaning that the mid-level flow is more westerly than
southwesterly. Nonetheless, flow from 850mb and lower will have a
significant southwesterly (theta-e advection) component, with both
temperatures and dewpoints forecast to increase today. The
atmosphere will be increasingly moist (precipitable water of
around 1.8-1.9 inches) and unstable (MLCAPE of 750-1250 J/kg).
Forcing is the clear limiting factor in terms of convective
potential today. Warm frontal processes are failing to generate
much upstream activity early this morning, though a few showers
may still be possible in the northwestern CWA between 09Z-15Z.
With no discernible surface features in the area today, attention
will turn toward forcing slightly further aloft, though notably
focused to the north and west of the ILN forecast area. A
shortwave is forecast to move across southern Michigan during the
late afternoon, with convergence in an area of enhanced
925mb-850mb flow pushing across northern Indiana. This should
spark convection upstream of the region, which may eventually
propagate into the forecast area toward the greater instability.
With storms following this pattern ending up separated from the
stronger flow and the source of lift, it is not surprising that
high-resolution models have been fairly sparse in forecast
coverage this far south. Will keep PoPs in a similar range as the
previous forecast -- 20 percent in the south to 40 percent in the
north. In terms of hazards, hard to see more than perhaps a threat
for some gusty winds as the isolated/scattered storms propagate
forward, but the severe threat over the ILN CWA appears pretty low
without higher-end instability or a better-organized source of
GFS/NAM projections indicate a 3C-4C rise in 925mb/850mb
temperatures from yesterday to today, and max temps have been
adjusted accordingly. This should allow for rises from yesterday of
a few degrees in the northern CWA (where clouds will be a little
more prevalent) and as much as 4-6 degrees in the south (where
temps are likely to top out in the upper 80s).
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
The short term forecast discussion will be updated shortly.
Previous discussion >
Wednesday night the better pcpn chances remain across the nrn
counties as upper level energy works through the flow. By
Thursday, a cdfnt begins to approach the fa. It still looks like
the northern half of the CWA will be most likely to be affected by
storms on Thursday, but kept a slight chance for the srn counties.
High temperatures will be a few degrees warmer ranging from 85 to
Forcing is very weak Thursday night, so washed out pcpn chances
as the night progressed.
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
A few showers and thunderstorms may linger on Friday in residual
moisture and forcing near a weakening frontal boundary along and
south of the Ohio River, including the Cincinnati metro area.
Locations to the north including Dayton and Columbus should remain
dry. High pressure and a dry airmass are expected for Saturday.
For Sunday, moisture and energy spilling southeastward from Great
Lakes low pressure will provide a chance of thunderstorms.
Additional thunderstorms will be possible Monday when the low is
forecast to drag a cold front across Ohio. A few thunderstorms may
persist on Tuesday as the boundary sags gradually south to Kentucky.
With a large and slow moving high in the upper atmosphere centered
from the Central Appalachians to the Mid-Atlantic coast, and with
mainly warm advection in the lower levels, a return to mid-summer
heat is indicated. High temperatures ranging from the mid 80s to the
low 90s will couple with dew points near 70 to make outdoor
activities uncomfortable at best.
.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
A mid level ridge over the lower Gulf Coast states will slowly
build northward through the TAF period. At the same time, embedded
disturbances will rotate eastward through the Great Lakes. Return
moist flow, along with the proximity of the disturbances, will
bring at least a chance of showers and thunderstorms to the
terminals today. Chances do not appear high at this time, with the
best chance likely occurring near the KDAY terminal this
afternoon. Have maintained a VCTS/CB at this location. Southeast
to south surface flow will become south later this morning around
10 to 12 knots with some local gusts in the 15 to 20 knot range by
For tonight, the latest high resolution/convection allowing
models indicate that the threat for showers/storms overnight will
likely be closer to the lower Great Lakes, or mainly north or
northwest of the terminals. As a result, have just VFR conditions
at this time.
OUTLOOK...Thunderstorms possible from Thursday into Thursday
night, mainly near the northern terminals.