Area Forecast Discussion
Issued by NWS Indianapolis, IN

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069
FXUS63 KIND 272026
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
424 PM EDT SAT AUG 27 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
tonightthrough Monday. There will be another chance of
thunderstormsTuesday through Wednesday as a cold front drops
southeast toward thearea. Dry weather is expected by Wednesday night
in the wake of thefront and under the influence of high pressure.
Look for slightlyabove temperatures through the middle of next week.

&&

.NEAR TERM /Rest of this afternoon and tonight/...
Issued at 300 PM EDT Sat Aug 27 2016

The main concerns tonight will be pops. With 2 inch precipitable
water values, potential of heavy rain and isolated flash flooding
could be an issue with any storm, as the metro area and far northern
parts of the forecast area have seen several inches of rain over the
past few days, and heavy rain producers could certainly cause more
problems. However, a warm front has lifted northeast of the forecast
early this afternoon and there is no real notable upstream wave.
Latest regional radar loop was showing an area of outflow driven
thunderstorms lifting northeast, across our far eastern counties
with little activity behind it. These storms should be out of the
area by 3 pm. So, with the combo of weak synoptic forcing and radar
trends, will only go with isolated pops tonight. With surface based
CAPES over 1500 j/kg, there is a potential for some strong storms.

With lower and mid 70 afternoon dew points, prefer warmer 12z GFS
MOS. Fog or low stratus may be an issue overnight with limited cloud
cover. Will include patchy overnight fog.

&&

.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 272100Z KIND TAF Update/...
Issued at 424 PM EDT Sat Aug 27 2016

Some limited diurnal cloud based near 020 exists over parts of the
area, so will add this to the forecast for the rest of the afternoon.

Previous discussion follows.

VFR conditions will prevail today and into the evening, before
deteriorating to MVFR and possibly IFR later tonight.

Thunderstorms are exiting the area and will not impact the TAF sites
beyond 18Z. Cannot rule out isolated additional development but
chances are too low for inclusion.

Rain today, ample low level moisture, thinning cloud cover, and
light to calm winds overnight will set the stage for fog development
and perhaps some low cloud. Will take IND/LAF/HUF down to 3SM with a
BCFG mention. Will take BMG down to 1SM.

Winds will be less than 10kt throughout the period.

&&

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

&&

$$

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



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