Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 250619
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
219 AM EDT Sat Mar 25 2017

.UPDATE...
The LONG TERM Section has 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 /Tuesday through Friday/...

Issued at 219 AM EDT Sat Mar 25 2017

ECMWF suggests mainly quiet weather in place on Tuesday and
Wednesday across Central Indiana as strong ridging aloft is
expected to be building and pushing across the region during that
that time. Have trended grids toward a dry forecast for now even
through the ECMWF still suggests a weak lingering boundary across
Kentucky.

ECMWF suggests a much more wet period for Thursday and Friday as a
strong negatively tilted upper trough is poised to push into the
Ohio Valley. Further support is seen with the a surface low
trekking through Illinois to Michigan...placing Indiana within the
warm sector. Forecast Builder responded with likely or better
pops on Thursday through Friday...and although rain will be
expected at some time during this period...confidence for high
pops at specific times is much lower. Given the SW flow in
place...look for temps at or above normals through the period.

&&

.AVIATION /Discussion for 250600Z TAF Issuance/...
Issued at 1201 AM EDT Sat Mar 25 2017

VFR conditions expected through midday...with restrictions
developing during the afternoon in showers and embedded
thunderstorms. Lower ceilings arriving this evening.

Upper ridge giving way as upper low and associated surface wave loft
out of the southern Plains. Despite the presence of a frontal
boundary sagging south slowly over the lower Great Lakes...hi-res
guidance continues to slow the arrival of the initial surge of
showers until after daybreak 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...expect a few thunderstorms as well.
Restrictions are expected within heavier rain and storms...but
ceilings should remain VFR for the most part through the afternoon.
Model soundings and RH progs indicate the boundary layer becoming
saturated this evening and into the overnight...with more extensive
MVFR to possibly IFR stratus developing.

South-southeast winds are expected through the period...with higher
gusts approaching 25kts once again developing during the afternoon.


&&

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

$$

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


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