Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 221835
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
235 PM EDT Sun Oct 22 2017

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

&&

.SYNOPSIS...
Issued at 235 PM EDT Sun Oct 22 2017

A cold front will sweep across Central Indiana tonight...bringing
large changes to Indiana`s weather in the week ahead. Rain showers
are expected ahead of the front tonight as it passes.

Colder air will arrive on Monday through Tuesday...along with
several passing upper level weather disturbances. This will result
in daily chances for rain showers through Tuesday along with below
normal temperatures.

Cool High pressure is expected to arrive in the area by the
middle of the work week with might lead to a first frost across
much of Central Indiana. Below normal temperatures are expected
through next weekend.

&&

.NEAR TERM /Today/...

Issued at 235 PM EDT Sun Oct 22 2017

Surface analysis early this afternoon shows a cold front over
Central Illinois. Radar mosaics show an area of showers along and
in the wake of the front. Warm southerly flow was in place across
Central Indiana. Water vapor imagery shows plentiful moisture
streaming into Indiana on Southerly winds ahead of a deep trough
over the Central Plains. Dew point temps across the area were in
the moist upper 50s to near 60.

Rain is a good bet for tonight. the strong front will be quickly
swept east tonight as the models suggest the deep trough to the
west passes east. Forecast soundings and time height sections show
deep saturation through the column arriving in the area tonight.
Given the expected forcing...near 100 pops will be required. best
chances look to be 02Z-09Z as the front passes.

Given the expected cloud and rain will trend toward expected
wetbulbs.

&&

.SHORT TERM /Monday through Wednesday/...

Issued at 235 PM EDT Sun Oct 22 2017

A big change is in store this period. Models suggest that as the
deep trough progresses east tonight...a broad deep trough is
reinforced over the Great Lakes and Ohio Valley through
Wednesday. Several embedded short waves are poised to push through
the region withing the broad cyclonic flow aloft. Models suggest
wave of moisture passing within this flow each day.

There will be a few dry spots between waves as depicted by the
forecast soundings. First dry spot looks to be monday afternoon
and evening as the cold front and associated moisture departs.

Better chances for rain will arrive as the next wave moves in on
Tuesday. Furthermore at that time...forecast sounding show a
favorable convective sounding with very cold air aloft. Convective
temperatures are only in the lower 50s. This should lead to cold
rain showers. Will trend pops on Tuesday afternoon a bit higher
than the forecast builder blend.

The large trough aloft appears to begin shifting eastward by
Wednesday. However...another short wave appears to push through
the area as a quick moving low pushes out of the upper midwest.
Thus more pops chances...particularly across the northeast will be
required.

Given the strong cold air advection in the wake of the front will
trend highs as steady or slowly falling on Monday. This will
result in highs lower than the MAVMOS. Otherwise with the cold air
pattern through wednesday will stick close to forecast builder on
lows...but trend highs at or below the forecast builder blend.

&&

.LONG TERM /Wednesday through Saturday Night/...

Issued at 345 AM EDT Sun Oct 22 2017

Models are in agreement in regard to lingering rain showers
(mainly NE) Wednesday as an upper low drops into the Ohio Valley
from the Great Lakes Region. However, high pressure will quickly
strengthen over the Upper Midwest by Wednesday evening. So, dry
conditions will return through Thursday night. After that, focus
then turns to the next frontal system late in the week. Its
associated cold front will bring additional rain chances to
central Indiana on Friday, and the trailing upper low will keep
rain in the forecast through the weekend.

Below normal temperatures through the period will result in a
frost threat around mid-week that will have to be monitored.
Daytime highs will only be in the upper 40s/low 50s on Wednesday
with lows in the upper 30s that night. There will be a weak warm-
up on Thursday, but temperatures will quickly drop again for the
weekend.

&&

.AVIATION /Discussion for the 22/18Z TAF Issuance/...
Issued at 1250 PM EDT Sun Oct 22 2017

Good confidence in VFR conditions through 00z tonight, but then
increasing chances of MVFR and possibly IFR conditions 00-03z and
beyond as showers overspread the terminals. The showers will become
less prevalent at the western airports after 12z Monday. Overall,
confidence in trends is good, but exact timing is not.

South and southwest winds to over 10 knots but gusting to 25 to 28
knots will decrease to 10 knots or less 21z-22z shift to northwest
behind the cold front that should reach LAF and HUF near 02z but the
other sites not until after 12z Monday.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...Puma
NEAR TERM...Puma
SHORT TERM...Puma
LONG TERM....TDUD
AVIATION...MK



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