Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 231458

Area Forecast Discussion
National Weather Service Indianapolis IN
1050 AM EDT Mon Oct 23 2017

The AVIATION Section has been updated below.


Issued at 400 AM EDT Mon Oct 23 2017

A slow moving frontal boundary and secondary low pressure system
will move through the area today, followed by a large upper level
low tonight into Tuesday night. This will provide ample
opportunity for widespread rainfall and a turn toward much cooler
temperatures. Another frontal system and reinforcing shot of
cooler air will come late in the week, bringing additional chances
for precipitation and continued cool conditions.


.NEAR TERM /This afternoon/...

Issued at 926 AM EDT Mon Oct 23 2017

Surface analysis late this morning shows low pressure over West
Central Indiana. Radar shows abundant rain showers across the
forecast area. Aloft water vapor shows a negatively tilted trough
stretching from the middle Mississippi Valley toward
Florida...with SE flow aloft still over Indiana. GOES16 shows
plentiful cloud cover. Surface front still appears to be west of surface flow remains mainly southeasterly. Cooler NW flow
was found over Illinois.

The Low pressure system and upper trough are expected to progress
eastward today...allowing cooler air behind the front to filter
into Central Indiana. Time heights show a saturated column as do
the forecast soundings and ample lift is expected given the
dynamics in the area. Given the expected clouds and rain...have
stuck close to 100 pops. Will also use a non-diurnal temp trend as
rain and clouds will prevent much heating and cooler air arriving
late in the day will also allow temps to fall.


.SHORT TERM /Tonight through Wednesday Night/...
Issued at 400 AM EDT Mon Oct 23 2017

As the secondary low moves north of the area tonight, a much
larger upper level low will drop into the area and strongly
intensify the surface low. Showers associated with this upper
level low will be a threat across the area into Tuesday night.
Final storm total rainfall amounts of 1 to 1.5 inches, with
isolated higher amounts, can be expected.

Windy conditions can be expected with the presence of the intense
surface low and attendant pressure gradient Tuesday, and wind
gusts around 30 MPH or more will be likely.

Dry weather will return Wednesday and Wednesday night as weak
upper level ridging replaces the departing low.

Temperatures will turn sharply cooler with highs struggling into
the upper 40s to low 50s across the area and lows in the mid to
upper 30s. Will have to monitor for frost potential but will
exclude from grids this far out. Consensus temperatures were
generally in the ballpark.


.LONG TERM /Thursday through Sunday Night/...
Issued at 343 AM EDT Mon Oct 23 2017

The extended period will initially start out with dry conditions
due to brief ridging over the area and slightly warmer
temperatures in the 60s. However, the next system is progged to
enter the Upper Midwest by Friday, increasing rain chances and
lowering temperatures with an associated cold front. This colder
air could result in some snow showers mixed in with lingering rain
showers on Saturday night as a second upper low drops into the
region. Highs will only top off in the upper 40s/low 50s on
Saturday and Sunday with lows at the freezing mark on Saturday


.AVIATION /Discussion for the 231500Z TAF Update/...
Issued at 1058 AM EDT Mon Oct 23 2017

Mid morning adjustments made based on current observations. 12Z
discussion follows.

Poor flight conditions will prevail for the majority of the TAF
period with widespread rainfall across the area. Conditions are
ranging anywhere from IFR to VFR at this time, but will generally
be around the MVFR mark. There will be little improvement as rain
lingers through tonight. Winds will gradually veer to the west and
northwest with sustained speeds of 5 to 11 kts, and low level
wind shear will also be a concern this afternoon with frontal





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