Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 240225

Area Forecast Discussion
National Weather Service Indianapolis IN
1025 PM EDT SAT JUL 23 2016

The AVIATION Section has been updated below.


Issued at 330 PM EDT Sat Jul 23 2016

A broad ridge of high pressure remains in place across much of the
country, with a hot and humid airmass across central Indiana. This
heat will last through tomorrow, before a cold front approaches
the area and allows a slight cool down back toward seasonal
normals and brings slightly higher thunderstorm chances to the


.NEAR TERM /Overnight/...
Issued at 1002 PM EDT Sat Jul 23 2016

Another sultry summer evening ongoing across the region with
convective clusters to the northwest over northern Illinois and
northwest Indiana. 0130Z temps remained in the low to mid 80s with
many locations still experiencing heat indices in the 90s courtesy
of the excessive dewpoints.

Main focus for overnight deals with the consolidating convective
cluster over northern Illinois in association with an MCV. The
storms have been tracking east all evening with a southeast drift
to the complex as outflow boundaries push south. The forecast area
largely remains under the influence of the heat ridge as 700mb
temps are hovering near 12C. The MCV over northern Illinois should
continue moving E/SE over the next several hours with convection
following the instability gradient into northern Indiana. Question
becomes how far south storms can make it against the flank of the
ridge and as has occurred over the last several nights...the model
suite is leaving a lot to be desired. Recent runs of the HRRR in
particular having difficulty in capturing the specifics with
respect to the evolution of the complex.

LAPS sounding analysis over the forecast area continuing to
indicate presence of warm dry layer aloft with a cap near 750mb...
and this should serve to weaken and diminish convection as it
approaches the northern counties. With that being said...cannot
entirely rule out showers and storms working into the northern
forecast area after 05Z before dissipating as outflow boundaries
press south. Have expanded low chance pops across the northern
third of the forecast area as a result. Storms could have gusty
winds and torrential rains.

Bumped lows up a couple degrees as mid 70s may be as low as we can
go tonight considering current dewpoints. This is likely to
enhance patchy fog potential overnight as well considering the
stagnant airmass present.

Zone and grid updates out.


.SHORT TERM /Sunday through Tuesday/...
Issued at 330 PM EDT Sat Jul 23 2016

Frontal boundary will finally begin to approach the area late
Sunday. Will need slight chance or low chance pops across the area
tomorrow, ramping them up Sunday night into Monday as the front
moves through the area.

Don`t see anything beyond a pulse severe threat at any time during
the period, as dynamics will be weak.

Concern for tomorrow will be another day of heat and humidity.
Thunderstorms, if they are more expansive than expected, could
throw a wrench in the plans, but as of now expect another day with
highs in the 90s and heat index values approaching 105, so have
extended the heat advisory through 8 PM Sunday.


.LONG TERM /Tuesday night through Saturday/...
Issued at 200 PM EDT Sat Jul 23 2016

Timing of best pops related to various upper waves and surface
reflections will be the main difficulty with the long term.
However, good confidence that a mean Mississippi Valley trough,
related upper disturbances and nearby surface features will interact
with a moist and unstable atmosphere and result in thunderstorm
chances mid week through next Saturday. Regional blend reflects this
well. Lowest pops will be Tuesday night, when a stationary front is
expected to be south of the Ohio River. Look for only small chances
near and south of Terre Haute and Bloomington, then.

Thermal pattern favors near normal blend temperatures with highs in
the 80s and lows mostly in the mid and upper 60s.


.AVIATION /Updated Discussion for the 24/0000Z TAF Issuance/...

Issued at 1025 PM EDT Sat Jul 23 2016

IR Satellite imagery shows convective complex effecting northern
parts of IN this evening and is expected to remain in that area
overnight.  This is due to elongated ridge from the southern Plains
into the lower Ohio Valley. Thus, high pressure over the area will
keep winds calm, but daytime heating has dried the air mass a bit to
keep visibilities to MVFR due to haze towards early morning.

Previous discussion...

High pressure will remain over the Tennessee Valley and over the
Upper Great Lakes for Sunday. In between will be a frontal
boundary over extreme northern IN that will meander north-south
across that area. As the strong ridge of high heights breaks down
a bit due to an approaching trough over the western Great Lakes,
there could be scattered -TSRA in the afternoon on Sunday
effecting KLAF and maybe KMIE. Not much confidence at this time
whether the -TSRA activity makes it further south; have a bit more
confidence that will wait until Sunday night/Monday from KHUF and

Again due to light winds at the surface overnight, look for just
some light haze/fog at many locations to bring MVFR conditions
Sunday morning before scattered -TSRA effects mostly KLAF/KMIE during
the afternoon.


.IND Watches/Warnings/Advisories...
Heat Advisory until 8 PM EDT Sunday for INZ021-028>031-035>049-



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