Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 261034

Area Forecast Discussion
National Weather Service Indianapolis IN
635 AM EDT Wed Apr 26 2017

Aviation section has been updated below.

Synopsis... Low pressure over eastern Iowa with a cold front
extending across the middle Mississippi valley to Texas will move
east across Indiana later tonight and early Thursday bringing
numerous showers and scattered thunderstorms.

Brief drying will occur late Thursday and Thursday night as weak
ridge of high pressure briefly builds in.

Very wet weather will occur over the weekend as a warm front
develops over the Ohio valley Friday and moves slowly north as
low pressure over the southern plains moves towards the great lakes
by Sunday night.   A trailing cold front will push east across
Indiana Sunday night

Quieter weather will occur after the weekend...but another system
will move our way by the middle of next week.


.NEAR TERM /Today and Tonight/...
Issued at 355 AM EDT Wed Apr 26 2017

It was mostly clear across eastern sections...while high thin clouds
were occurring over western Indiana.   Farther west numerous
thunderstorms were occurring across Missouri and eastern Oklahoma.

Main focus will be onset of showers and thunderstorms as low pressure
over eastern Iowa moves towards the great lakes.  Models track the
trailing cold front across Indiana late Tonight.  Most models keep
us dry until late afternoon and then thunderstorms spreading into
far west and northwest sections after 21Z.   Will mention chance of
storms along and west of a line from near Vincennes to just east of
Lafayette after 21Z.

Thunderstorms will become more numerous tonight as a strong short
wave over the southern plains rotates our way and a cold front over
the Mississippi valley pushes towards Indiana.  Will go with high
POPS all areas except only chance POPS far east by late tonight.

There will be an increasing southerly flow today and early tonight.
MOS guidance has trended a little cooler today and I can accept this
across the west where there will be more clouds.  However eastern
sections will see lots of sun today and raised highs there into the
lower to middle 80s.  Went a little warmer with low temperatures
tonight across the east half of our region as the cold front should
arrive there near or shortly after 12Z Thursday.

south winds will increase to 15 to 20 MPH and gusts to 25 to 30 mph
are possible late today and tonight.


.SHORT TERM /Thursday through Friday Night/...
Issued at 355 AM EDT Wed Apr 26 2017

A cold front extending south from a surface low over the northern
great lakes across Indiana around 12Z Thursday will move rapidly
to the east.  Thursday will start out breezy and wet with showers
and a few thunderstorms.   All of this will end Thursday afternoon
as cold front moves quickly east and weak ridge of high pressure
temporarily builds in Thursday night.

Models develop a warm front over the Ohio valley Friday and move it
north Friday and Friday night as low pressure deepens over the
southern plains.   We can expect a chance of showers by Friday
afternoon and numerous showers and a few thunderstorms developing
Friday night as we move towards a very wet weekend.

In most cases stayed close to a MOS blend on temperatures and overall
Superblend temperatures generally accepted with only a few minor


.LONG TERM /Saturday through Wednesday/...
Issued at 253 AM EDT Wed Apr 26 2017

Models continue to suggest a very active long term period. Warm
frontal zone is likely to set up somewhere in the region, likely
south, early in the weekend with widespread precipitation and likely
thunderstorms along and north of the boundary. A low pressure system
will organize and move into the Great Lakes, pushing the warm front
north and allowing the area into the warm sector, before the cold
front swings through the area Sunday night. Thus, expect a wet
weekend with multiple rounds of showers and thunderstorms.
Precipitation potential with the upper low and wraparound will
necessitate some low chances for showers into Monday.

These multiple rounds of showers and storms could pose a hydrologic
threat and will merit monitoring as the week wears on, especially
with the potential for prior precipitation during the short term
period. Even accounting for the GFS tendency to overdo moisture,
precipitable water values over the region this weekend will likely
approach and perhaps even briefly exceed the 99th percentile value
for the time of year climatologically speaking. River interests and
those in flood prone areas should remain alert to the forecast as
the week wears on.


.AVIATION /Discussion for the 26/1200Z TAF Issuance/...
Issued at 635 AM EDT Wed Apr 26 2017

VFR through early evening...then becoming MVFR or even IFR
Ceilings with showers and few thunderstorms late tonight.

Low pressure over eastern Iowa will track across the great lakes
tonight and a trailing cold front will move east across Indiana
early Thursday morning.

Mainly mid/high clouds across Indiana with numerous showers and
thunderstorms over middle Mississippi valley.  The showers and
Thunderstorms will reach far western Indiana by late afternoon and
spread east across Indiana overnight.  Ceilings will lower to
4 thousand feet by evening and to 1 to 2 thousand feet late tonight.
Visibilities 5 miles or less later tonight with showers and few

Winds will be south increasing to 15 to 25 knots this afternoon.





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