208
FXUS63 KIND 171005
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
605 AM EDT Sat May 17 2025

.KEY MESSAGES...

- Partly Cloudy and cooler today

- Dry and Pleasant Sunday

- Showers and thunderstorms chances return Monday through Wednesday

&&

.SHORT TERM (Today and tonight)...
Issued at 245 AM EDT Sat May 17 2025

Synopsis:

Surface analysis early this morning shows low pressure in place over
Lake Superior, with broad cyclonic flow in place across the Great
Lakes and as far south as the Ohio Valley and west to the
Dakotas. Meanwhile High pressure was spilling into Montana and WY.
Aloft, water vapor imagery showed a deep upper low over WI. This
low appeared to becoming embedded within the mainly westerly flow
aloft from the Pacific northwest across the Great Plains. GOES16
shows abundant cloud cover across the upper midwest around the
upper low. some of these clouds were headed for Central Indiana. A
moderate pressure gradient was found across Indiana due to the
deep and broad surface low to the north.

Today -

The surface and upper low to the north is expected to make continued
progress eastward, crossing the Great Lakes. This is expected to
keep cyclonic lower level flow across Central Indiana today along
with a moderate pressure gradient. Clouds found upstream over
northern IL should reach central Indiana early this morning.
Furthermore, time heights and forecast soundings show lower level
saturation today beneath a mid level inversion, indicative of
stratocu. Thus will expect additional cloud development today as
heating begins. All of this should just add up to partly cloudy
skies. Cold air advection remains in place today with 850mb temps
falling to 6-8C. This is much cooler than yesterday. Highs should
only reach the upper 60s to around 70.

The moderate pressure gradient across the area will also result in
wind gusts of 15-25 mph.

Tonight -

The low pressure system to the north is expected to continue to exit
the Great Lakes, ending its influence across Central Indiana.
Stronger high pressure is expected to settle across the Mississippi
Valley and begin to build east toward Indiana as upper ridging
builds across the Plains States. This will place Indiana within an
area of subsidence and northwest flow aloft. Forecast soundings show
the arrival of dry column overnight as diurnal stratocu dissipates
in the evening. Thus becoming mostly clear will be expected along
with cooler lows in the upper 40s and lower 50s.

&&

.LONG TERM (Sunday through Friday)...
Issued at 245 AM EDT Sat May 17 2025

Sunday through Monday Morning -

Dry weather is expected during this time as strong ridging aloft
over the Plains on Sunday slowly pushes east to Indiana. Associated
surface high pressure with ongoing subsidence will continue to
dominate Indiana`s weather on Sunday through Monday morning.
Forecast soundings through this period show a dry column as ridging
moves through the area. Thus Mostly Sunny weather is expected on
Sunday and Mostly clear skies will be expected on Sunday night,
along with near normal temperatures.

Monday afternoon through Wednesday -

Another area of low pressure is expected to develop over the plains
on Monday. As the upper ridge begins to depart Indiana on Monday
afternoon, southwest flow and stronger warm air advection will
develop. A weak short wave is shown approaching the Ohio valley late
in the day and into Tuesday night. Forecast soundings trend toward
saturation by 00Z Tuesday, thus chances for showers and storms will
be needed.

Models show this low pressure system slowly moving across Illinois
and Indiana through Wednesday. Accompanying the surface low, a well
organized upper low is also expected to push across the the plains
and into the Ohio Valley. Thus continued chances for rain will be
needed here. Given the weak instability suggested, a rumble of
thunder will be possible.

Thursday and Friday -

The upper low is expected to advance to the northeastern states,
allowing for subsidence and cooler northwest flow to arrive across
Central Indiana on Thursday and Friday. Thus will trend toward a dry
and cooler forecast here.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 605 AM EDT Sat May 17 2025

Impacts:

- VFR Conditions are expected this TAF period.

Discussion:

No significant changes to the ongoing forecast.

An upper low over MN and WI will move across the Great Lakes today
along with broad surface low pressure. This will keep cyclonic flow
across Central Indiana. Much less moisture will be present today as
the lower level flow has become more westerly. GOES16 shows cloud
coverage over the upper midwest and western Great Lakes pinwheeling
around the low, and some of these clouds were sweeping across
northern Indiana.

Late this morning, forecast soundings, show attainable convective
temperatures and lower level saturation indicative of CU. This
should be still in the VFR category and persist through the day.

As high pressure builds across Central Indiana from the plains
tonight and diurnal heating is lost, Cigs will become unlimited as
CU dissipates.

A moderate pressure gradient today will result in wind gusts of 15
to 25 mph.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...Puma
LONG TERM...Puma
AVIATION...Puma