Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 281656
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1256 PM EDT Wed Sep 28 2016

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

&&

.SYNOPSIS...
Issued at 1257 PM EDT Wed Sep 28 2016

An extremely slow moving low pressure system will stay close to
Indiana until Sunday. A high pressure system should traverse our
state from east to west Monday through Wednesday.


&&

.NEAR TERM (Tonight)...

Issued at 1257 PM EDT Wed Sep 28 2016

The main issue is POPs.

There is extremely good model agreement about a upper low pressure
staying over the area.  This could cause convection, but nighttime
cooling should make the chance lower than during the day.

There are notable differences in the POP guidance. For instance the
MAV has likely in places where the MET has chance and visa versa.
With no model clearly better in the deterministic fields, a
consensus forecast is best so the CONSALL POP will be used.

Rain or not, the night will be mostly cloudy due to the low aloft.

Background deterministic fields and statistical guidance are all
very close with temperatures, and all support using a consensus.

&&

.SHORT TERM (Thursday through Saturday)...

Issued at 1257 PM EDT Wed Sep 28 2016

The models agree in maintaining low pressure over the area both at
the surface and aloft. Rain chances are the main forecast issue.

With the low pressure around, this will be a cloudy spell with the
rain chances being controlled by relatively subtle features
difficult to forecast. This means consensus POPs should be
superior overall.

The fields controlling temperatures are similar between the models.
Exact values will be sensitive to if and when rain falls. Breaks in
clouds, even if brief, would also have a significant impact on
temperatures. All this indicates consensus will be the best
forecast, with possible errors of 2-3 degrees.

&&

.LONG TERM /Saturday through Tuesday night/...

Issued at 334 AM EDT Wed Sep 28 2016

Light rain showers will continue to affect portions of central
Indiana, mainly northern, through Sunday morning due to an upper
low. At that point, GFS and Euro agree on the upper low moving off
to the northeast and into eastern Canada. Dry conditions will then
return and persist through the end of the extended period as high
pressure strengthens over the region. Latest initialization is
representative of this pattern, so no changes were needed.

Below normal temperatures can be expected on Saturday with highs
only in the upper 60s/low 70s. A weak warming trend will quickly
commence by Sunday though, and temperatures will climb back to
normal for the beginning of the week.

&&

.AVIATION /Discussion for the 28/18Z TAF Issuance/...
Issued at 100 PM EDT Wed Sep 28 2016

Mostly VFR with scattered showers through this evening. Then
areas of MVFR ceilings and visibilities or lower late tonight
and Thursday morning.

An area of low pressure over central Indiana will continue to
move southeast.  As a result there will be scattered showers
through the period.  An isolated thundershower possible through
00Z...but chances are too low to include mention in TAF`s at this
time.  Prevailing Ceilings will be at or above 7 thousand feet
through this evening then lowering to 1 to 2 thousand feet late
tonight with visibilities of 3 to 5 miles possible late tonight
in fog and or scattered showers.

Windds will become north 5 to 8 knots this afternoon and 5 knots
or less tonight.


&&

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

$$

SYNOPSIS...JK
NEAR TERM...JK
SHORT TERM...JK
LONG TERM....TDUD
AVIATION...JH



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