Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 250426
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1226 AM EDT SUN SEP 25 2016

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

&&

.SYNOPSIS...
Issued at 214 PM EDT Sat Sep 24 2016

High pressure over the Great Lakes will continue to provide dry
weather tonight and Sunday across Central Indiana. A cold front
over the Central Plains will push into Central Indiana on Late
Sunday night and early on Monday...bringing chances for rain to
the state.

Cooler...more seasonable temperatures are expected to arrive on
Monday night and last into the middle of the next work week as
another High pressure system arrives.

&&

.NEAR TERM /Tonight/...
Issued at 930 PM EDT Sat Sep 24 2016

Raised dew points overnight per trends and sent new set of zones
with patchy fog mention toward daybreak and through 9 am. Also,
BUKFIT, SREF and GFS LAMP suggest stratus will not likely be as
widespread as last night. In addition, satellite was showing clear
skies over the area late this evening, so decreased cloud cover.

Issued at 214 PM EDT Sat Sep 24 2016

Water Vapor Imagery this afternoon shows a strong Ridge of High
pressure in place across the Mississippi River Valley. Visible
Pictures show lingering clouds across Northern Indiana dissipating
quickly withing daytime heating and ongoing mixing. Surface analysis
continue to show High Pressure in place across the Great Lakes with
NE flow across Indiana.

The strong protective Ridge and High pressure in place at the
surface will continue to provide dry weather for Central Indiana
tonight. Forecast soundings remain rather dry...however time heights
showing some lingering lower level moisture and dew point
depressions are expected to fall to 1f or less. With a decent
pressure gradient in place...will trend once again toward a stratus
deck forming overnight and patchy fog cannot be ruled out.
A blend on low temps will work nicely.

&&

.SHORT TERM /Sunday through Tuesday/...

Issued at 214 PM EDT Sat Sep 24 2016

NAM and GFS suggest the ridge of High pressure and associated
surface High will begin to drift east on Sunday. The protection of
the high will last through the day to provide one more day of
summer like heat along with light southerly winds. Forecast
soundings remain dry...thus partly cloudy skies will be expected.

Big weather change arrives on Sunday Night and Monday as GFS and
NAM suggest the strong trough aloft over the upper midwest will
drop southeast onto the Ohio Valley. An associated cold front
will accompany the system...providing ample dynamics. The 305K GFS
isentropic surface shows some upglide with a very moist air mass
with specific humidities over 9 g/kg. Time heights and forecast
soundings also hint at deep saturation...mainly aft 06z. Thus will
trend toward a dry evening on sunday...but ramp pops up on late
sunday night and early monday.

Cold front and associated moisture will be moving through Central
Indiana near 12Z...but exits quickly by 18Z and models suggest the
cold front and best moisture pushes well to the southeast by
then. forecast soundings show excellent subsidence and drying by
18z. Thus Will try to contain any pops on Monday to mainly the
morning hours. Again will ramp pops higher than
MAVMOs...particularly across the SE where timing is most
favorable. Given the expected cold air advection in the wake of
the front will trend highs on monday closer to the 3 hourly values
and trend toward wetbulbs on Sunday night lows.

HIgh pressure and strong subsidence look to remain in place into
Tuesday with forecast soundings showing a dry column and
unreachable convective temperatures. Thus will trend toward a
partly cloudy sky and a blend on temps here.

&&

.LONG TERM (Tuesday Night through Saturday)...
Issued at 138 PM EDT Sat Sep 24 2016

A departing large upper low will give way to broad surface high
pressure during the long term period. This will produce a seasonably
mild, dry period throughout the long term portion of the forecast.

Initialization handled this well and few changes were required.

&&

.AVIATION /Discussion for the 25/0600Z TAF Issuance/...

Issued at 1222 AM EDT Sun Sep 25 2016

Expect to see some fog develop in the next several hours with mostly
clear skies and light winds. Mainly expect MVFR visibilities for a
few hours until after daybreak. Think KIND will not drop lower than
that due to dry advection from easterly component flow. Other sites,
though, may be west enough to not get the drier air in and could fog
a little more. Confidence in this lower scenario still is not high,
though, and a few parameters still suggest that stratus will form.
May include a tempo IFR at KBMG and KHUF. Precipitation could move
into the sites before the end of the extended TAF portion, but
probabilities prior to 6z on the 26th are low enough that no mention
in the TAFs is necessary yet.

&&

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

&&

$$

SYNOPSIS...PUMA
NEAR TERM...PUMA/MK
SHORT TERM...PUMA
LONG TERM....NIELD
AVIATION...CP



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