Area Forecast Discussion
Issued by NWS Indianapolis, IN

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819
FXUS63 KIND 181440
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
940 AM EST Sat Nov 18 2017

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

&&

.SYNOPSIS...
Issued at 332 AM EST Sat Nov 18 2017

Windy conditions and showers and thunderstorms, some strong
to severe, will impact central Indiana today due to a rather
potent low pressure system. The highest precipitation and
thunderstorm chances will be this afternoon as an associated cold
front tracks across the forecast area. After that, much cooler and
drier air will follow in the wake of the cold front on Sunday.
Further out, another cold front and upper low will pass through
the region early in the week, but the best dynamics should keep
any precipitation chances north of the forecast area.

&&

.NEAR TERM /This afternoon/...

Issued at 930 AM EST Sat Nov 18 2017

Surface analysis early this morning shows low pressure in place
over Illinois with a warm front stretching east across Indiana
through the LAF...OKK areas. Most of the forecast area was within
the warm sector...with southerly winds and temperatures surging in
to the 60s. Radar shows TSRA devlopment along the cold front over
Central Illinois.

Conditions will remain favorable for thunderstorm development
this afternoon as the strong cold front is poised to push across
Central Indiana. A warm and moist air mass will be in place as dew
point temps are in the 60s. Enhancing storm development this
afternoon ahead of the cold front the GFS suggests a 50-60 knot
LLJ. HRRR develops showers and storms across Illinois and moves
them east across Indiana through the afternoon. THus very high
pops and gusty winds still seem appropriate. Given the strong
winds aloft the slight risk for much of the forecast are appears
appropriate should any storms be able to mix down these stronger
winds aloft. Main threat today will be damaging winds and
confidence is high for showers and storms this afternoon.

&&

.SHORT TERM /Tonight through Monday Night/...

Issued at 332 AM EST Sat Nov 18 2017

Thunderstorm potential will quickly taper off by Sun 00Z with loss
of daytime heating and forcing. However, rain showers will persist
through Sun 06Z. After that, drier and much colder air will filter
into central Indiana with lows dipping into the upper 20s/low 30s.
All moisture is expected to be out of the area though before any
transition from rain to snow will be possible.

After that, dry conditions will prevail through the end of the
short term period with some slightly warmer temperatures on Monday
with a weak warm front.

&&

.LONG TERM /Tuesday through Friday/...
Issued at 219 AM EST Sat Nov 18 2017

Ensembles indicate a rather quiet weather pattern can be expected
during this period, with little threat for precipitation.

A short wave trough is progged to pass through the Great Lakes
region around Tuesday, but the better dynamics and deeper moisture
look to stay to the north of the forecast area. Will continue
with a dry extended.

&&

.AVIATION /Discussion for the 181500Z IND TAf update/...

MVFR conditions deteriorating to IFR at times will be expected
this afternoon.

While within the warm sector this morning and early
afternoon...MVFR to VFR CIGS will be likely...however as precip
arrives with cold front low MVFR to IFR conditions will be
expected due to storms. Strong winds aloft will also result in
some LLWS this morning and early afternoon. Best window for
heavier rains will be after 18Z-19Z.

Previous Discussion Below

/Discussion for the 181200Z TAFS/...
Issued at 546 AM EST Sat Nov 18 2017

Most of the more organized shower and thunderstorm activity has
moved off to the northeast of the terminals, with the back edge
near KLAF. Short term model guidance suggest an area of stronger
lift may move into the area after sunrise, so may see an increase
in shower and thunderstorms activity later this morning, especially
at the more northern terminals.

Additional organized thunderstorm activity is expected to develop
this afternoon as a cold front surges southeast across the area.
Brief IFR visibility restrictions and gusty shifting winds are
possible in and near heavier convection.

Model data suggest the core of a low level jet will be passing off
into Ohio over the next few hours, so threat of low level wind
shear should diminish over the next several hours.

Outside of convective areas, ceilings generally in the 025-050
range today in the warm sector. IFR ceilings possible this afternoon
behind the cold front.

Surface winds 190-210 degrees with frequent gusts 25-30 kts
ahead of cold front. Sharp wind shift to 310-340 degrees later
this afternoon with the passage of the cold front.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 1 AM EST Sunday for INZ042>049-051>057-
060>065-067>072.

&&

$$

SYNOPSIS...TDUD
NEAR TERM...Puma
SHORT TERM...TDUD
LONG TERM....JAS
AVIATION...JAS/JP



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