Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 050824
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
324 AM EST Mon Dec 5 2016

.UPDATE...
The SYNOPSIS, NEAR TERM, SHORT TERM, LONG TERM, and AVIATION sections
have been updated below.

&&

.SYNOPSIS...
Issued at 324 AM EST Mon Dec 5 2016

A brief break in the precipitation chances will occur today as high
pressure moves across. Precipitation returns tonight into Tuesday as
an upper system moves across the area. A potent cold front will
bring some snow chances mid week and then usher in much colder air.
Another system will bring more chances for rain and snow this
weekend.

&&

.NEAR TERM.../Today/
Issued at 324 AM EST Mon Dec 5 2016

The clearing line across Illinois that was moving toward the area
is no longer making good progress east. An inversion will continue
to develop across the area this morning, trapping these clouds. Thus
will go pessimistic with cloud cover this morning.

Forecast soundings show that some breaks in the clouds will develop
this afternoon as the center of high pressure moves off to the east.
Will go cautiously optimistic and allow for partly cloudy skies by
late afternoon.

Some short term models are showing fog developing early this
morning. However, they`re already overdoing fog coverage right now.
With the clouds sticking around, do not believe fog will become
significant.

With the cloud cover, went below (and in some cases well below) MOS
for highs, closer to a raw model blend.

&&

.SHORT TERM.../Tonight through Wednesday night/
Issued at 324 AM EST Mon Dec 5 2016

Models are close enough that the SuperBlend initialization
was accepted for most items.

Clouds will quickly increase tonight ahead of an approaching upper
system. However, it now looks like forcing and moisture with this
system is a little slower than previously thought, so went dry most
areas this evening. During the overnight, isentropic lift ramps up
and moisture increases, so went likely PoPs far south by late
tonight with chance PoPs elsewhere.

While there could be some mixed rain/snow at precipitation onset,
feel that temperatures will rise enough that rain will be the main
type by the end of the night.

Forcing continues across the area Tuesday morning, with the best
forcing across southeast areas closer to the upper system. Kept the
blend`s likely or higher PoPs southeast half and chance PoPs
elsewhere. Forcing quickly exits, allowing most areas to be dry
Tuesday afternoon.

Colder air flows into the area for the remainder of the short term.
A weak upper system will bring some forcing Wednesday night. Models
aren`t very bullish with forcing or QPF (with the exception of the
Canadian). However feel that with the cold advection and the upper
wave, chance category PoPs are still warranted.

&&

.LONG TERM /Thursday Through Sunday/...
Issued at 324 AM EDT Mon Dec 5 2016

Ensembles suggest the system that may affect the area at the
tail end of the short term will be passing off to the east on
Thursday. Will keep some small chance PoPs for light snow over the
eastern zones on Thursday.

It appears upper flow will become zonal towards the end of the
week. There continues to be large differences with respect to the
next upper trough that is progged to move into the middle of the
country by the weekend. Slim majority of the ensembles suggest this
feature will remain progressive and weak, however there are still
quite a few that suggest a stronger trough is possible.

Ensembles are trending farther north with the potential for warm
advection snow on Saturday. Will keep some chance PoPs over the
northern zones on Saturday to cover this. Minor accumulations still
look possible over the north on Saturday. Will go with chance PoPs
for mixed precipitation by Sunday.

&&

.AVIATION /Discussion for 050900z TAF Update/...

Issued at 324 AM EST Mon Dec 5 2016

Confidence is moderate that IFR ceilings will return to KIND so made
no significant changes were made to the KIND TAF. Confidence is low
on fog developing at KLAF, so made some adjustments up there.

Previous discussion follows...

MVFR ceilings at all sites but KLAF (already IFR) should drop to
IFR after a few hours as stratus deck sinks. After that
visibilities could drop to MVFR as well if the winds can drop off
as forecast. There is a chance KLAF could see visibilities drop
to around a mile or less for a few hours around daybreak, but
confidence not high in the possibility given the winds there so
will leave out anything lower. Hi res models indicate ceilings
will be slow to scatter/rise even with high pressure building in
and may not see improvement until late morning. By early afternoon
should be seeing VFR everywhere. Then Monday night another system
moves in and brings more rain chances to the area. Westerly to
northwesterly winds through the night around 8-14 kts now will
drop in speed later during the overnight and then back to the
southeast during the morning before backing to the east Monday
night.

&&

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

$$

SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM....JAS
AVIATION...CP/50


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