Area Forecast Discussion
Issued by NWS Wilmington, OH
FXUS61 KILN 261057
Area Forecast Discussion
National Weather Service Wilmington OH
657 AM EDT FRI AUG 26 2016
Warm and humid conditions will continue through the weekend. A
weak front will drop south though the region, providing a chance
of a thunderstorm. In the warm and humid airmass on Saturday, a
few afternoon thunderstorms will remain possible. By Sunday into Monday,
several weak upper level disturbances will provide a little
better chance for a few showers and thunderstorms in the area.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A few showers and isold thunderstorms have developed in the weak
low level convergence field provided by e-w weak front. These
storms were developing in a region of weak instby with boundary
layer cape values at or below 500 j/kg. Have included a slight
chance mention of a shower or storm as this weak front drops
slowly south today and loses its identity. Mid level ridge
centered to our se with warm and humid airmass over the Ohio
valley. Expect highs to range from the mid 80s nw to near 90
south. These warm temperatures, combined with surface dewpoints
in the lower 70s will result in heat indices in the mid to upper
90s. Will mention these indices in the HWO product.
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
Mid level ridge axis centered to our se builds a little north and
east on Saturday. Moderate instability develops Saturday afternoon
across ILN/s western counties. Due to lack of significant forcing,
have limited pops to slight chance across the west around the
periphery of the mid level high durg the aftn. Have tweaked
temperatures a ltl warmer with highs from the upper 80s nw to the
lower 90s se. These warm readings combined with humid conditions
will result in heat indices in the mid/upr 90s acrs the southern
half of the FA.
Elongated mid level ridge remains centered to our se with a s/w
moving thru the Great Lakes, Saturday night/Sunday. Moderate
instby develops acrs the north and have chance pops there with
slight chance acrs the south, closer to mid level ridge. Warm
readings expected again on Sunday with highs from the upper 80s nw
to the lower 90s se. Mid and upper 90s heat indices expected
again Sunday aftn.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Large area of high pressure over the southeastern U.S. will keep a
westerly flatten out as a shortwave crosses north of the Great Lakes
region on Sunday night. West-southwest flow at this level will turn
westerly through the early part of the week and then the tropical
system muddies the forecast significantly. European bombs the low
into the Florida panhandle whereas the GFS barely scratches the
surface pressure field and WPC forecasts are trending towards a much
weaker surface field with the positioning of the European
Regardless of the tropical evolution, a surface boundary should
migrate from the I-70 corridor on Monday towards the Ohio River
vicinity by mid week. A stronger cold front is expected to push
through the region on Wednesday as a large area of surface high
pressure builds in Canada. This specific evolution remains to be
seen and is likely to see large forecast shifts between now and then.
Numerical guidance is not showing much of a day to day change with
mid 80s to low 90s for highs and overnight lows in the upper 60s to
low 70s. Diurnal heating would maximize the thunderstorm threats in
the late day, but the presence of a surface boundary and moist
airmass may necessitate keeping some low chance of storms through
the overnight hours.
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Slow moving frontal boundary is across northwestern Ohio. Humid
airmass in place south of the front is forecast to cause a few
problems for aviators this morning and again late tonight to early
Saturday. Visibilities will continue to be reduced as low as VLIFR
early this morning. Look for improvement back to VFR by 14z as
temperatures rise quickly, with VFR continuing through today under
weak high pressure. Thunderstorms developing to the west should
remain north of TAF sites as they move around the periphery of the
high. Expect BR to reduce visibilities again late in the TAF
period, though increasing high clouds may mitigate the effects.
Winds will remain light, with direction changing from northwest to
northeast by the end of the forecast period. CVG will see VFR with
light southeast winds after 12z Saturday.
OUTLOOK...Thunderstorms possible Monday and Tuesday.