Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 281556
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1055 AM EST Tue Feb 28 2017

.UPDATE...

The AVIATION and Near Term sections have been updated below.

&&

.SYNOPSIS...
Issued at 400 AM EST Tue Feb 28 2017

A strong storm system will bring strong to severe thunderstorms to
central Indiana late today...tonight and Wednesday morning. Then,
more seasonable weather will return. A clipper system will bring a
chance of rain or snow to the area Thursday. Mild weather will
return this weekend as well the potential for more unsettled weather
as a cold front approaches the Ohio Valley and Great Lakes Sunday
night.

&&

.NEAR TERM /Rest of Today/...
Issued at 1100 AM EST Tue Feb 28 2017

Radar mosaic shows most rain and showers moving out of the area,
with the exception of the southwestern counties where a few showers
and thunderstorms have popped back up and are moving northeast. Hi
res models still indicating a lull in activity this afternoon and
thus trended pops down across much of the area for most of the day
with cap overhead. Little has changed in the thinking for the today
portion of the forecast from the previous discussion.

Previous discussion follows...

As the warm front lifts northeast of the area this afternoon, gusty
southerly winds should allow for temperatures to reach the mid and
upper 60s late in the afternoon. In addition dew points will
approach 60. Expect the current showers to spread east across
central Indiana through mid morning. Then, expect a lull.

Under thick cloud cover and convective inhibition, do not think
there will be very good thunderstorm coverage this afternoon. The
High Resolution Rapid Refresh supports this thinking. Can not
completely rule out isolated severe storms, but think the main risk
for severe weather will be after 00z tonight. Instability progs do
show enough instability for thunder inclusion. In addition, winds
will pick up. Could see wind gusts to 30 mph or more late in the
day.

&&

.SHORT TERM /Tonight through Wednesday night/...
Issued at 400 AM EST Tue Feb 28 2017

The main concern for the short term will be severe storms tonight as
a frontal system approaches from the west accompanied by strong
dynamics including a 140 knot upper jet and 50 plus knot low level
jet. The low level jet will advect plenty of moisture and
instability northward over the area ahead of the front.

The latest HRRR suggests a line or two may start forming across the
Ozarks and central Illinois around 00z tonight. It was not hinting
at any prefrontal supercell activity over central Indiana. Current
thinking is that a squall line will move east across central Indiana
around 03z-09z. All kinds of severe weather will be possible but
mostly damaging winds. Could see a brief spin up or two as well
along the line. Will also mention brief heavy rain threat in the
Hazardous Weather Outlook.

SPC left slight risk in on Wednesday near and south of a Bedford to
Greensburg line and a Marginal Risk near and south of a Anderson to
Indianapolis to Sullivan line. Not as confident that we will see
anything after 12z due to typical weakening for that time of day.
The front should be southeast of the area after 18z. Left lingering
small pops in Wednesday evening northeast. Could see a very brief
mix over to snow before it ends by 06z Thursday.

After a mostly dry Thursday under surface high pressure, a clipper
system will bring a chance of rain and then snow to the area
Thursday night, with the best chance northeast, close to the upper
wave.

Blend temperatures look reasonable considering frontal timing, cloud
cover and low level thermal progs. Look for above normal highs on
Wednesday but then seasonable from Tuesday night on, in the wake of
the cold front.

&&

.LONG TERM /Friday through Monday Night/...

Issued at 349 AM EST Tue Feb 28 2017

The extended period will start out under the effects of high
pressure. As a result, dry conditions can be expected on Friday.
Nonetheless, a few snow showers will move in on Friday night as
isentropic lift strengthens with a warm front. The pattern will
shift behind this front, and daytime highs will soar into the 60s by
Sunday and MOnday in this warm sector. Further out, rain chances
will increase starting Sunday night as a surface low tracks through
the Great Lakes Region. The fluctuating pattern will then resume
late in the period when cooler air filters in behind an associated
cold front. Latest Superblend initialization was accepted for all
situations.

&&

.AVIATION /Discussion for the 28/12Z TAF Issuance/...
Issued at 1055 AM EST Tue Feb 28 2017

Drizzle and IFR conditions with low ceilings and visibility
reductions have developed over the sites. Expect these conditions
should improve some as more wind gusts develop and the warm front
moves a little further north. Pushed back some of the VCTS with less
likely this afternoon. Previous discussion follows...

Low to moderate confidence flying conditions will deteriorate to IFR
or worse 14z and later. Good confidence thunderstorm coverage will
not be enough for more than a VCTS 18z-24z. Then, will go with
prevailing showers and VCTS and MVFR as a squall line or two are
expected to move through.

South winds will be gusty 20 to 25 knots outside of thunderstorms
after 18z. Winds will shift to southwest toward 12z Wednesday, when
a strong cold front will approach from the west.

&&

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

&&

$$

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


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