000
FXUS63 KIND 171030
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
630 AM EDT Wed Oct 17 2018

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

&&

.SYNOPSIS...
Issued at 151 AM EDT Wed Oct 17 2018

Quiet and cool weather is expected the next couple of days as high
pressure in place across the northern plains builds across the
Great Lakes and Ohio Valley. This will bring mostly sunny day and
mostly clear nights along with cool temperatures through Thursday
night.

A weak cold front and upper level weather will approach and pass
Central Indiana on Friday and Friday night. This will lead to
increasing clouds on Friday and Friday Night along with chances
for some light rain showers.

Showers will be possible on Saturday afternoon as cool air and
another upper level weather disturbance passes across Central
Indiana.

High pressure is expected to return for the end of the weekend and
early next work week...bringing more dry and cooler weather.

&&

.NEAR TERM /Today/...

Issued at 151 AM EDT Wed Oct 17 2018

Surface analysis early this morning shows broad low pressure in
place across over Ontario and Quebec...extending cyclonic flow
across the Great Lakes and Indiana. High pressure was found over
the northern plains. GOES16 shows clear skies across Indiana.
Water Vapor showed a tropical plume of moisture streaming across
the deep south to the middle Atlantic states.

Time heights show plenty of dry air in place across area today
along with strong subsidence. Forecast soundings agree...showing
a dry column with a steep inversion aloft. Models suggest that the
deep upper trough in place to the northeast will slowly pull away
through the day...allowing ridging to build over the plains along
with lee-side subsidence over Indiana/Illinois/Iowa/Missouri.
Models suggest high pressure and ridging building across the area
through the day. Thus will trend toward a mostly sunny sky today
with only some passing high clouds. Models suggest cold air
advection through the day with NW flow aloft. Thus will trend
highs today at or below the forecast builder blends.

&&

.SHORT TERM /Tonight through Friday Night/...

Issued at 151 AM EDT Wed Oct 17 2018

Both the GFS and NAM suggest strong ridging building aloft through
Friday Morning. Strong high pressure looks to be settled across
the Ohio Valley tonight and slowly pushing east through Thursday
Night. Time heights and forecast soundings show a very dry
column...with subsidence and unreachable convective temperatures.
Thus the trend of sunny days and mostly clear nights will
continue through Early Friday. Given the cool air mass in place
and the lack of any kind of southerly component to the wind will
trend temps at or below the forecast builder blend through Friday
morning. Furthermore...another frost and freeze event looks
possible tonight as strong high pressure will be settled across
the Indiana with ridging aloft. This will lead to clear skies and
light winds...ideal for radiational cooling.

GFS and NAM suggest on Friday that a strong short wave and
associated cold front will approach Indiana from the northwest.
Mid level moisture fields suggest ample moisture along and ahead
of the upper trough...sweeping across Indiana Friday afternoon and
night. Forecast soundings show a gradual saturation of the column
through the day. GFS 300K Isentropic Surface shows good upglide on
Friday afternoon with specific humidities over 6 g/kg. Thus will
trend the forecast on Friday with increasing clouds and chances
for afternoon showers and more shower chances on Friday night as
the front passes.

&&

.LONG TERM /Saturday through Tuesday/...
Issued at 208 AM EDT Wed Oct 17 2018

An upper trough will pivot southeast across central Indiana Saturday
and Saturday night. The trough looks strong enough to be able to
squeeze out a few showers, mainly north and east. Prefer the middle
of the road Canadian as opposed to the faster 00z GFS and slower 12z
ECMWF. Otherwise, high pressure should result in continued dry and
cool weather.

No reason to make changes to the blend. Highs will be mostly in the
50s and lows in the 30s.

&&

.AVIATION /Discussion for 171200z TAF Issuance/...
Issued at 630 AM EDT wED Oct 17 2018

High confidence in VFR flying conditions through the TAF period with
little or no clouds.

Winds will be northwest near 10 knots after 14z and then variable
4 knots or less tonight.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...Puma
NEAR TERM...Puma
SHORT TERM...Puma
LONG TERM....MK
AVIATION...MK

NWS IND Office Area Forecast Discussion