Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 140456

Area Forecast Discussion
National Weather Service Indianapolis IN
1156 PM EST Wed Dec 13 2017

The AVIATION Section has been updated below.


Issued at 400 PM EST Wed Dec 13 2017

Windy conditions will continue across central Indiana this evening
and tonight along with low chances for measurable precipitation as
a cold front moves through the area. Colder than normal
temperatures will be in the place then until the weekend, when a
warmup to normal is in store. Much uncertainty exists for next
week with models showing a large variety of solutions.


.NEAR TERM /Overnight/...

Issued at 1007 PM EST Wed Dec 13 2017

Surface analysis late this evening shows strong Low pressure was
in place over Northwest Ohio. A strong pressure gradient was in
place across Indiana...resulting in gusty NW winds with gusts to
near 40 mph. Satellite shows a cloud shield over Indiana and
Northern Illinois amid the cyclonic flow across Indiana.

Cloudy skies are expected to remain overnight as the cyclonic
flow is expected to persist. Time heights show saturated lower
levels...which seems reasonable given the satellite trends. for
now will keep any snow or flurry mention to out of Central Indiana
and radar echos remain to the north for now. Will expect winds to
diminish as the surface low pulls east as the night progresses.
Stuck close to the model blend on low temps.


.SHORT TERM /Thursday through Saturday/...

Issued at 400 PM EST Wed Dec 13 2017

Thursday looks dry, with the possible exception of some ongoing scattered lake
effect flurries in the northwestern counties to start the day.
Winds will be much lighter than the last couple of days with a
weak gradient over the area. Temperatures will warm into the upper
20s to middle 30s in the afternoon as sunshine increases.

Friday a clipper system will move through the Great Lakes, but models have been
trending north with this system and thus now have only a slight
chance for snow across the northern counties during the day. Do
not expect much in the way of accumulation, and uncertain if those
counties will see anything more than a flurry with the best
forcing well north of the area.

Saturday temperatures will start to warm up as upper ridging builds over
the area. Look for highs in the 40s and dry weather.


.LONG TERM /Saturday night through Wednesday/...

Issued at 400 PM EST Wed Dec 13 2017

Next chance for precipitation will arrive late Saturday night into
Sunday as a low pressure system approaches from the southwest.
Models are showing a good deal of spread for the long term, so
generally a low confidence forecast on both temperatures and
precip chances. ECM ensembles are showing standard deviations of
double digits at times during this period, and the GFS ensembles
are not quite as spread but not much better. Thus accepted blended
initialization but error for temperatures could be on the order of
plus or minus 10 degrees.


.AVIATION /Discussion for the 140600z TAFs/...

Issued at 1156 PM EST Wed Dec 13 2017

MVFR conditions are expected to improve to VFR this taf period.

Surface analysis shows deep and strong low pressure over NW
Ohio...quickly moving east. A strong cyclonic pressure gradient
was in place across Central Indiana...resulting in gusty NW winds
of 25-35 mph. Satellite shows a shield of MVFR Cloud across
Central Indiana and upstream across Northern Illinois and Nrn
Indiana poised to sweep into the state.

Time heights keep low level moisture present through at least the
mid morning hours...and given the amount of cloud upstream and the
expected cyclonic flow...this appears quite reasonable. Thus will
continue the MVFR CIGS through much of the overnight. Some break
over Wisconsin should begin to arrive on Thursday morning as the
low departs.

Lower level flow becomes anticyclonic by Thursday afternoon and
the pressure gradient becomes relaxed. Thus CIGSs are expected to
be lost by Thursday afternoon and winds will diminish.




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