Area Forecast Discussion
Issued by NWS Indianapolis, IN

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859
FXUS63 KIND 190228
AFDIND

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

.UPDATE...
The AVIATION Section has 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 190300z TAF issuance/...

Issued at 926 PM EST Sat Nov 18 2017

Updated current conditions. Some drizzle possible over the sites
over the next couple of hours. Previous discussion follows...

A cold front has passed through all the TAF sites and winds are
from 320 to 350 at 12 to 22 kts with gusts varying from only
around 20 kts to around 35 kts. These strong winds will continue
for the next few hours and then will start to slowly drop off, but
this will be a slow process. Soundings show potential for gusts of
20 to 25 kts to continue through the overnight hours and possibly
through the day Sunday. May see some slackening Sunday late
morning, and improvement will be more likely at southern sites of
KBMG and KHUF where the pressure gradient will lessen faster, but
may see gusts throughout Sunday of 20 to 25 kts at KIND and KLAF.

Ceilings currently generally low end MVFR around 1000 to 1500 ft,
with a couple of IFR spots, one of which is KLAF. Could see
flirting with IFR ceilings for an hour or two, but then should be
MVFR for the most part for several hours. Expect a slow
improvement to above 2000 ft, and then perhaps scattering out
between 12 and 18z from west to east. Low confidence in the timing
of scattering.

Area of rain showers/drizzle currently moving through the sites
should come to an end over the next few hours as it moves
southeast. Dry conditions should ensue after that.

&&

.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...CP



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