Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 181753
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1253 PM EST Sat Nov 18 2017

.UPDATE...
The LONG TERM Section has 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 night through Saturday/...
Issued at 1253 PM EST Sat Nov 18 2017

Ensembles and deterministic models in very good agreement that high
pressure will and northwest flow aloft will provide dry and cold
weather through Thursday. Then, southerly flow and an approaching
cold front will result in moderating temperatures Friday and
Saturday with showery weather Saturday.

With such good model agreement will accept blend temperatures and
pops.

&&

.AVIATION /Discussion for the 181800Z TAf Issuance/...
Issued at 1233 PM EST Sat Nov 18 2017

Very poor flying conditions possible along and ahead of a squall
line, that is currently producing wind damage. LAF is under the gun
through 19z and the other sites through 21z or so. Shortly after
that, a cold front will sweep through which will shift the winds to
northwest with gusts to 30 knots or so all through the night and up
until 14z or so Sunday. Also, there could be a few lingering showers
behind the front through 04z or so.

Went with a 2 hour tempo thunder group with 50 knot gusts for a 2
hour period with the squall line per the High Resolution Rapid
Refresh and radar trends.

Good confidence that flying conditions will be MVFR with through 14z
or so with brief IFR possible, especially in showers and
thunderstorms.




&&

.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....MK
AVIATION...MK



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