Area Forecast Discussion
Issued by NWS Wilmington, OH-- Highlight Changed Discussion --
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FXUS61 KILN 291347
Area Forecast Discussion
National Weather Service Wilmington OH
947 AM EDT MON AUG 29 2016
A warm and humid airmass will remain in place today. This heat
and humidity will keep a chance of thunderstorms in the
forecast... mainly near and south of the Ohio River this
afternoon. Slightly drier conditions can be expected Tuesday,
under the influence of weak surface high pressure. Thunderstorms
will occur Wednesday with the passage of a cold front. Cooler
temperatures and less humid air can be expected through the end of
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --A nebulous pattern remains in place across the northern Ohio
Valley, with a broad area of surface high pressure centered over
the northern lower peninsula of Michigan, and weak northeasterly
near-surface flow over the ILN forecast area. Upper ridging and
weak mid-to-upper-level flow has changed little over the past day
or so. An axis of enhanced theta-e extends from the lower Ohio
Valley through the southwestern sections of the ILN CWA, and a
weak SSW-moving front is evident on NAM/RAP theta-e analysis at
850mb. Though convergence is weak, there should be just enough
forcing (combined with any leftover boundaries from yesterday) to
allow for some showers and storms to develop again -- especially
in the southwestern two-thirds of the ILN forecast area. PoPs have
been increased slightly, though the northern tier of ILN counties
has been kept dry.
The 12Z KILN sounding is similar to the one from yesterday, though
with a few slight differences -- slightly warmer upper-level
temps and slightly lower precipitable water values (down from
about 1.75" to about 1.60"). Modifying this sounding would
produce SBCAPE values of around 2000 J/kg (which matches SPC SREF
expectations) -- with only a very tiny amount of capping to
overcome. This is, however, a little less instability than was
generated yesterday. Based on these factors, a repeat performance
of yesterday is unlikely, but some threat for additional flooding
and gusty winds will certainly exist. Wind flow through the
troposphere remains below 15 knots at any given point, so storm
motions will again be slow, and prone to storm-scale propagations.
Very little confidence, however, in getting a significant amount
of storm coverage. The current HWO appears reasonable, but will be
expanded slightly based on storm development expectations / the
850mb front / HRRR simulated reflectivity.
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.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
Any convection that develops this afternoon will diminish this
evening with the loss of heating. Lows tonight will range from the
lower 60s far north, where some drier air will filter in, to the
upper 60s far south.
Weak surface ridge and a little drier air over the region Tuesday.
Have dry forecast Tuesday with only marginal instby in the far
south. Highs look to range from the mid 80s nw to near 90 far south.
Mid level shortwave begins to work into the western Great Lakes
Tuesday night. Expect mainly clear skies in the evening, followed by
an increase in mid/high level clouds overnight. Expect lows in the
mid and upper 60s.
Upper level pattern change with mean trof developing over se
Canada and New England and ridge building over the nations mid
section. This places the Ohio Valley in a northwest flow with
surface front dropping south through the region Wednesday. Forcing
is limited with only weak convergence noted in the low levels and
even instability is limited. Will continue to limit pops to low
chance north and slight chance south.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
High pressure will build southeast across the Great Lakes and
continue off the New England coast by the end of the week. The
high will continue extend into the forecast area through the
weekend. This will provide dry conditions. Temperatures will drop
closer to normal Thursday and Friday and then start to warm over
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
Expect BR/FG to reduce visibilities early this morning in the
very humid airmass, enhanced by Sunday`s rainfall. Once the BR
burns off by mid morning, VFR should then persist today as high
pressure builds into the Great Lakes. Thunderstorms may develop
again this afternoon. Latest models show scattered thunderstorms
near CVG LUK DAY and ILN, so went with afternoon VCTS there. Sky
cover outside of any thunderstorms should stay rather sparse with
SCT cumulus and altocumulus. Winds will remain light out of the
northeast. Put BR again late in the forecast at LUK and ILN.
OUTLOOK...Thunderstorms possible through Wednesday...mainly in
the afternoon and evening.