Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 281018
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
618 AM EDT Tue Mar 28 2017

.UPDATE...
The AVIATION section has been updated below.

&&

.SYNOPSIS...
Issued at 200 AM EDT Tue Mar 28 2017

Low pressure over Indiana will depart the area early this
morning...allowing high pressure to build across the Hoosier
state. This will result in dry weather for Central Indiana through
Wednesday...as the high moves through the region.

On late Wednesday Night...another low pressure system over the
southern plains will begin to push toward Indiana. This will bring
the best chances for rain back to Central Indiana by Thursday and
Thursday night.

At that point, the pattern will almost repeat again as High
pressure arrives with a dry period for the weekend followed by
another Low pressure system bringing rain early next work week.

&&

.NEAR TERM /Today/...

Issued at 200 AM EDT Tue Mar 28 2017

Surface analysis early this morning shows low pressure in place
across east Central Indiana...slowly advecting eastward. Radar
shows scattered showers across our forecast area...slowly rotating
and exiting eastward. IR Images show extensive cloud cover
associated with the low across the state. Plenty of lower level
stratocu was found further upstream across Illinois...Wisconsin
and Iowa.

Models suggest deep moisture and forcing will exit the area early
this morning as the upper low and associated short wave depart.
GFS and NAM suggest ridging building aloft today and tonight as
Time heights show good mid level subsidence. However time heights
suggest that the lower level moisture will continue to linger
through today and tonight. Given Satellite trends upstream and the
lack of strong anti-cyclonic flow across the area...will trend
toward mostly cloudy skies today. Weak cold air advection is
expected within the north to northeast flow in the wake of the
departing low. A forecast builder blend will probably be suitable
here.


&&

.SHORT TERM /Tonight through Thursday night/...

Issued at 200 AM EDT Tue Mar 28 2017

Quiet weather will be expected at least through Wednesday across
Central Indiana. GFS and NAM show strong ridging building
across Indiana. Time heights and forecast soundings show excellent
subsidence in the mid and upper levels. However a different story
remains in play in the lower levels. Lower level moisture appears
to linger as the models suggest a dirty northeast flow across
Indiana...around the high north of the Great Lakes. THus will keep
mostly cloudy through Tonight. May trend cloud cover slightly less
on Wednesday as best ridging remains in place at that time and
lower level moisture appears to slightly dry out. Again a blend on
Temps will work just fine.

On Wednesday night and Thursday changeable weather is expected to
return. GFS shows Low pressure developing again over the souther
plains...pushing a warm front and tight baroclinic zone toward
Indiana from the southwest. Forecast soundings show lower level
saturation arriving by 12Z Thursday amid a warm air advection
inversion. Meanwhile the GFS 300K isentropic surface shows strong
up-glide arriving with specific humidities over 5 g/kg. With best
saturation not appearing until close to 12Z Thursday...will try
to minimize pops on late wednesday night as much of the night
should be dry. However By thursday all the previous mentioned
ingredients begin to come in to play...and will trend to
categorical pops then. An elevated thunderstorm will be possible
on Thursday given the advance of the warm front...however the
lower level inversion should just keep any storm isolated.

As for temps will trend lows on wednesday night warmer than a
forecast builder blend given the expected warm front and low cloud
arrival. Will trend highs on Thursday at or below a blend given
the expected rain.

Best forcing appears lost on Thursday night...however lingering
pops will need to be carried ans lower level flow looks to remain
cyclonic...with lingering lower level moisture available.

&&


.LONG TERM /Friday Through Monday/...
Issued at 250 AM EDT Tue Mar 28 2017

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

The seemingly endless parade of low pressure systems will continue
into the Long Term period.

The first system will continue to bring rain chances on Friday.
Saturday and Sunday will be dry with high pressure building in. The
model blend attempted to bring rain in some areas on Sunday, but the
GFS, most of the GFS ensembles, and the ECWMF all are dry across the
forecast area. (The blend relied too much on the Canadian which is
an outlier with its rainfall).

The models all differ on how the next upper and surface systems
develop and in their impact on central Indiana on Monday (and
beyond). Thus confidence is quite low and made no changes to the
PoPs the blend gave for Monday.

Temperatures will remain near average to above average.

&&


.AVIATION (Discussion for the 281200Z TAF Issuance)...
Issued at 618 AM EDT Tue Mar 28 2017

IFR conditions expected to improve to MVFR by mid to late morning,
with MVFR persisting most areas through the remainder of the period.

Area of drizzle currently lowering visibility at some sites will
move out of the sites by valid time. Drier air has worked into KLAF
and should help prevent IFR ceilings from returning there, and
ceilings may bounce all through the MVFR category there today.

At the other sites, IFR ceilings will gradually lift this morning,
but an inversion should keep ceilings from improving beyond the MVFR
category. Some lowering through the MVFR category may occur again
after 00Z.

&&

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

$$

SYNOPSIS...Puma
NEAR TERM...Puma
SHORT TERM...Puma
LONG TERM....50
AVIATION...50


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