Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 222337

Area Forecast Discussion
National Weather Service Indianapolis IN
737 PM EDT Tue Aug 22 2017


The Aviation section has been updated below.


Issued at 1256 PM EDT Tue Aug 22 2017

A cold front will exit central Indiana this afternoon and
evening...ending the precipitation threat.

High pressure over the northern plains is expected to build across
the region tonight and linger across the area through the weekend.
This will result in dry weather along with below normal
temperatures through Sunday.


.NEAR TERM /Today/...
Issued at 1256 PM EDT Tue Aug 22 2017

Surface analysis early this afternoon shows a cold front
stretching across Western Indiana to Southern Illinois and SE
Missouri. GOES 16 shows abundant cloud cover along and ahead of
the front. Radar mosaics show most precip already exited Central
Indiana. Strong high pressure was in place across the northern
plains. Water vapor shows ridging aloft over the Rockies and a
trough axis near Illinois/Indiana pivoting eastward around a
deeper upper low over Ontario. Dew points remained in the moist
upper 60s and lower 70s.

GFS and NAM suggest all the forcing with the passing cold front
will have exited the area by 00Z Tuesday. GFS shows surface
ridging and high pressure edging into Indiana tonight. Forecast
soundings and Time height sections subsidence and a dry column.
NW lower level flow suggests air from WI arriving in Central
Indiana tonight with dew points in the lower 50s...thus less humid
and drying is on the way. Given all of this...trending toward a
dry forecast and a mostly clear night appears the way to go. With
dry air arriving...widespread fog does not appear to be an
issue...but we will need to watch closely. Given the ongoing cold
air advection...Will trend lows at or below the forecast builder


.SHORT TERM /Wednesday through Friday/...
Issued at 1256 PM EDT Tue Aug 22 2017

Confidence is high for Dry weather ahead.

GFS and NAM suggest the strong ridging aloft over the western
United States will begin to slowly work eastward over the next few
days. This result in cooler...NW flow for Central
well as lee side subsidence across the Great Lakes and Ohio
Valley. The models show excellent mid level subsident persisting
through Thursday. As a result...large surface high pressure will
look to be centered over the Western Great Lakes into the Ohio
Valley with north or northeast surface flow through Friday. All of
this will add up to partly cloudy days and mostly clear
nights...along with temperatures below seasonal normals. Will not
stray far from the forecast builder.


.LONG TERM /Friday Night through Tuesday/...
Issued at 232 PM EDT Tue Aug 22 2017

Unseasonably cool conditions will continue into the long term
period as high pressure dominates through the weekend. The next
chance for precipitation looks to be early next week as the
remnants of Harvey are forecast to move into the region.
Confidence is low on timing at this time, so will keep low POPs
starting on Monday.

Mostly ran with initialized temps with highs in the upper 70s and
lows in the 50s through the weekend and lower 60s early next week.
High pressure will keep the air quite comfortable with dewpoints
in the 50s before moisture return ahead of the remnants of Harvey
begin to moisten the atmosphere.


.AVIATION /Discussion for the 23/00Z TAFs/...
Issued at 737 PM EDT Tue Aug 22 2017

VFR through the period.

High pressure will begin building into the area overnight in the
wake of the departing cold front. Skies will become mostly clear
and winds will diminish. Cannot entirely rule out light MVFR fog
mainly at the outlying sites near daybreak Wednesday, but at this
time expect drier air to work in in time to prevent this. Will
monitor trends through the night.

Winds will be 10KT or less through the period, generally out of
the northwest.





LONG TERM...White/Ryan
AVIATION...Nield is the U.S. government's official web portal to all federal, state and local government web resources and services.