Area Forecast Discussion
Issued by NWS Indianapolis, IN

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835
FXUS63 KIND 280415
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1230 AM EDT SUN AUG 28 2016

.UPDATE...
The AVIATION Section has been updated below.

&&

.SYNOPSIS...
Issued at 300 PM EDT Sat Aug 27 2016

Upper disturbances will interact with a moist and unstable
atmosphere and trigger isolated to scattered thunderstorms
tonight through Monday. There will be another chance of
thunderstorms Tuesday through Wednesday as a cold front drops
southeast toward the area. Dry weather is expected by Wednesday
night in the wake of the front and under the influence of high
pressure. Look for slightly above temperatures through the middle
of next week.

&&

.NEAR TERM /Overnight/...
Issued at 944 PM EDT Sat Aug 27 2016

Central Indiana getting a much needed break from the active
weather this evening as the remnant warm front has shifted north
of the region into the lower Great Lakes. The airmass remained
warm and muggy with 0130Z temps ranging from the mid 70s to lower
80s and dewpoints in the 70s across the area.

Relatively quiet evening ongoing with the aforementioned warm
front to our north and little forcing aloft present over the
forecast area. Water vapor imagery showing an axis of drier air
and subsidence aligned into the forecast area and this also likely
keeping any convection from forming. Storms have formed from near
KSTL northeast into central Illinois in an area where moisture and
instability are enhanced but are moving little with the stagnant
flow through the boundary layer and not expecting any of this
activity to make it into the forecast area. Have removed pops for
the overnight for much of the area as a result.

Bumped low temps up a couple degrees based on current conditions.
With little to no surface flow and plenty of low level moisture...
expect patchy fog to develop late tonight and extend through
Sunday morning.

Zone and grid updates out.

&&

.SHORT TERM /Sunday through Tuesday/...
Issued at 300 PM EDT Sat Aug 27 2016

Main challenge for the short term will be pops. Models in good
agreement that an upper trough will pivot across eastern Ontario and
Quebec on Sunday. This will flatten the eastern ridge. This will
lead to lesser forcing for thunderstorms and more of a diurnal
threat. However, steering will also be weaker. So, any storm that
does form will have 1.5 to 2 inches of precipitable water to work
with and be a slow mover. So look for isolated to scattered mainly
daytime thunderstorms with isolated heavy rain and flash flood
threat. With weak shear through the period, not looking for severe
storms.

850 millibar temperatures do not change much over the short term,
and with some sunshine, expect similar 12z MOS temperatures to work
out with afternoon highs in the mid and upper 80s.

&&

.LONG TERM /Tuesday Night through Saturday/...
Issued at 218 PM EDT Sat Aug 27 2016

Guidance suggests a frontal zone will drop through the area early in
the period, with chances for thunderstorms Tuesday night into
Wednesday. However, in the wake of this boundary, a dome of surface
high pressure appears likely to assert control over much of the area
through the remainder of the week and into the weekend. This will
allow for a bit of a cool down and less humidity across the area, as
well as at least a few days of dry weather.

Blended initialization was reasonable and only few changes required.

&&

.AVIATION /Discussion for the 280600Z TAFS/...
Issued at 1230 AM EDT Sun Aug 28 2016

Crossover temperatures will likely be reached overnight, so expecting
areas of IFR/patchy LIFR conditions in fog through about 281300Z-281400Z.
Lower confidence in IFR at the KIND terminal tonight due to the urban heat
island.

Rather low convective temperatures coupled with an unstable air mass
suggests potential for widely scattered CB`s to develop in the vicinity of
the terminals after about 281800Z. CB bases around 030.

Surface winds at or below 6 kts through midday Sunday.

&&

.IND Watches/Warnings/Advisories...NONE.

&&

$$

SYNOPSIS...MK
NEAR TERM...RYAN
SHORT TERM...MK
LONG TERM...NIELD
AVIATION...JAS



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