Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 181927
AFDIND

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

.UPDATE...
The SYNOPSIS, NEAR TERM and SHORT TERM Sections have been updated
below.

&&

.SYNOPSIS...
Issued at 226 PM EST Sat Nov 18 2017

A cold front will move east of central Indiana late this afternoon
and an upper trough will sweep through in its wake this evening.
This will put an end to the showers and thunderstorms. However, it
will remain windy through early Sunday. Then, high pressure will
result in dry weather and below normal temperatures through next
Friday. Finally, a frontal system will bring another threat for
showers to the area by next Saturday.

&&

.NEAR TERM /Late this afternoon and tonight/...
Issued at 226 PM EST Sat Nov 18 2017

The main concern for the near term will be the possibility for
severe storms early and then the wind as a strong cold front and
trailing upper trough move through from the west.

High Resolution Rapid Refresh reflectivity progs and radar trends
all support the convection ending from west to east before 06z
tonight. However, strong low pressure gradient in the wake of the
low will result in windy conditions through the night. Wind Advisory
through 1 am continues to look good with sustained winds to 30 mph
and gusts to 45 mph possible. Damaging thunderstorm winds will also
remain possible through 4 or 5 pm per the SPC Day1 Severe Weather
Outlook, mainly south of Interstate 70, east of Interstate 65 and
southeast of Interstate 69.

Could see some clearing toward daybreak, mainly southwest of
Lafayette, Indianapolis and Seymour. Finally, with strong cold
advection, it will be much colder tonight with subfreezing lows
likely per Superblend.

&&

.SHORT TERM /Sunday through Tuesday/...
Issued at 226 PM EST Sat Nov 18 2017

Very good model agreement that surface high pressure, over the
southern Plains, will move into the Tennessee Valley Sunday night
and Monday. That will bring dry weather to the area with moderating
temperatures by Monday. Then, a sharp upper trough will pivot across
the Great Lakes on Tuesday. However, model rh time sections suggest
the column will be too dry for any showers.

Temperatures to start off well below normal in post-frontal cold
advection pattern Sunday despite some sunshine. Blend highs in the
30s look good with good confidence. After that, with the high
pressure settling south, good confidence that temperatures will
rebound by Monday under plenty of sunshine.

&&

.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...MK
NEAR TERM...MK
SHORT TERM...MK
LONG TERM....MK
AVIATION...MK



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