Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 250203
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1003 PM EDT Fri Mar 24 2017

.UPDATE...
The NEAR TERM and AVIATION Sections have been updated below.

&&

.SYNOPSIS...
Issued at 300 PM EDT Fri Mar 24 2017

A pair of weather systems will bring numerous showers and a few
thunderstorms to central Indiana this weekend and early next week.
After a brief dry period during the middle of next week, a southern
system will bring more showers to the area late next week.

Look for seasonable to slightly above average temperatures and highs
mostly in the 60s.

&&

.NEAR TERM /Overnight/...
Issued at 1003 PM EDT Fri Mar 24 2017

Central Indiana remains under the influence of the upper ridge
with a frontal boundary slowly sagging south into northern parts
of the state. Moisture streaming north into the Missouri and
Mississippi Valleys ahead of low pressure swirling through
Oklahoma this evening. Temps remained mild at 02z largely holding
in the 60s.

The frontal boundary to the north will continue to slip south
overnight but is expected to remain north of the forecast area
through daybreak Saturday. Convection riding along the boundary
however may drift into the northern Wabash Valley after 06Z as the
boundary gets closer to the region. The moisture plume to the west
is lifting into the region more slowly...a trend that has been
picked up by most of the hi-res guidance this evening. While
chance pops remain warranted over the northern Wabash Valley with
the proximity of the boundary to the north...have backed off quite
a bit on pops over much of the rest of the area for the rest of
the night. All but W/NW counties likely to remain dry all night.

Bumped up lows a degree or two based on current temp trends this
evening. Will be quite mild with most areas remaining at or above
the mid 50s. Zone and grid updates out.

&&

.SHORT TERM.../Saturday through Monday/
Issued at 300 PM EDT Fri Mar 24 2017

Showers and thunderstorms will be the main focus this weekend into
Monday.

Models and ensembles with are similar as they open up an upper low
over the Great Lakes on Sunday and have a trailing upper trough move
to the middle Mississippi Valley late Monday. The GFS is a faster
and ECMWF slower with the first feature and the GFS is a fast
outlier with the second. A cold front will be moving through the
area late Saturday into Sunday morning. Deep moisture and synoptic
scale forcing will result in showers overspreading the area from
west to east Saturday into Sunday morning. As the front moves east
of the area and upper trough to the northeast, the showers will be
diminishing late Sunday and Sunday night. However, more southerly
flow and trailing upper trough will result in more widespread
showers moving from the east on Monday.

Model instability progs were showing enough instability this weekend
and early next week for at least isolated thunderstorm chances each
period. However, not expecting an organized severe threat.

Mild model blend temperatures reflect the southerly winds but
widespread cloud cover. However, blend temperatures look a little
too cool on Saturday. After coordination with adjacent offices,
raised temperatures a couple of degrees to the upper 60s and mid
50s. For the rest of the time, look for highs in the 60s and
possibly even lower 70s south on Monday.

&&

.LONG TERM /Monday Night through Thursday Night/...

Issued at 237 PM EDT Fri Mar 24 2017

Back to back low pressure systems are still expected to affect
the forecast area during the extended period. The period will
start out though with most of the first system already through
the area. As a result, the thunderstorm threat will diminish by
Monday night with just rain showers lingering into Tuesday. After
that, a ridge will strengthen over the area for mid-week,
resulting in dry conditions from Tuesday night through Wednesday
night. At that point, the next system tracking through the
Missouri Valley will move closer to central Indiana. So, rain will
spread across the forecast area from west to east on Thursday,
increasing in coverage by Thursday night.  Meanwhile,
temperatures through the period will be above normal with highs
generally in the 60s and lows in the 40s and 50s.

&&
5
.AVIATION /Discussion for 250300Z TAF Update/...
Issued at 1003 PM EDT Fri Mar 24 2017

Just minor adjustments needed to the forecasts late this evening
but overall trend is for a slower arrival to precipitation late
tonight and especially on Saturday morning.

00Z discussion follows.

VFR conditions expected through Saturday morning...with
restrictions developing during the afternoon in showers and
embedded thunderstorms.

The Ohio Valley remains under the influence of an upper ridge
ahead of the upper low and surface wave over the southern Plains.
Southwest winds have been gusty all day but should see the gusts
drop off around or shortly after 00Z with mixing diminishing
through the boundary layer and the development of the nocturnal
inversion overnight. Cu will dissipate with the loss of heating
this evening but will be replaced by a mid level deck which will
hold overnight as the aforementioned storm system tracks into the
Ozarks. Winds will back to a southeast direction by daybreak.

All model guidance slowing the arrival of the initial surge of
showers until Saturday morning at the earliest with a greater
impact to the terminals coming for the afternoon as a low level
jet overspreads the area and forcing aloft increases. Expect
expanded precip coverage for the afternoon as a result and
considering the presence of weak instability...cannot rule out
embedded thunderstorms within the showers. Too early and
confidence too low on timing and coverage to any potential thunder
and have left out of the terminals at this time. Restrictions
are likely to develop within heavier rain and storms...with more
extensive lower clouds developing for Saturday evening. Southerly winds
will once again become gusty on Saturday...although overall peak
gusts should be lower than those experienced today.

&&

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

&&

$$

SYNOPSIS...MK
NEAR TERM...Ryan
SHORT TERM...MK
LONG TERM....TDUD
AVIATION...Ryan


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