Area Forecast Discussion
Issued by NWS Indianapolis, IN

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952
FXUS63 KIND 312031
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
430 PM EDT TUE MAY 31 2016

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

&&

.SYNOPSIS...
Issued at 117 PM EDT Tue May 31 2016

Tonight high pressure east of Indiana will continue to drift
farther east. Meanwhile a cold front over Minnesota and Iowa will
begin to push toward Indiana...before crossing the state on
Wednesday. Scattered showers and thunderstorms are expected on
Wednesday as the front passes across the Hoosierland.

Weak high pressure will then settle across Indiana on Wednesday
night and continue to persist across the area on through the end
of the work week. The high is expected to bring cooler and less
humid weather...along with northerly winds.

&&

.NEAR TERM /tonight/...

Issued at 117 PM EDT Tue May 31 2016

Surface analysis early this afternoon shows weak and poorly
organized high pressure in place over Appalachia. A cold front
was in place across Iowa and Minnesota...pushing southeast. Radar
shows some scattered rain showers breaking out over west Central
Indiana and eastern Illinois associated with the heating of the
day and a weak short wave over the Central Plains states.

Main forecast challenge tonight will be pops. Any lingering
diurnal convection will be dissipating rather quickly as heating
is lost. At this time...coverage appears to be too isolated to
warrant any pops...however will monitor closely for any last
minute changes. Satellite indicates a dirty southerly flow with an
abundance of clouds upstream...and not all of a diurnal nature.
Thus will trend skies toward partly cloudy overnight and also
trend lows warmer than mavmos given the expected cloud cover and
southerly flow ahead of the cold front.

&&

.SHORT TERM /Wednesday through Friday/...

Issued at 117 PM EDT Tue May 31 2016

Wednesday looks to be the active weather day across Central
Indiana during this time period. Models suggest the previously
mentioned cold front and an associated short wave will push across
Central Indiana on Wednesday. Forecast soundings hint toward the
possibility of deep saturation with the caveat for convection
also. convective temps look like they could be reached along with
plenty of CAPE. Time heights on Wednesday show good lower and mid
level saturation. 305K GFS isentropic surface also shows good lift
ahead of the cold front along with specific humidities in excess
of 8 g/kg. Thus will trend pops higher than mavmos on Wednesday as
this system passes. Given the uncertainty for an all day rain and
the potential for some heating will stick close to mavmos for
highs.

On Wednesday night best forcing appears to be lost to the east and
the models suggest the short wave and cold front have exited the
area. The 305K Isentropic surface shows the only lingering lift
across the far eastern parts of the forecast area...while moisture
lingers and subsidence builds in the wake of the front. Thus will
trend toward some pops for the first few hours of the period in
the far eastern parts of the forecast area...while the rest of
central Indiana will get a dry forecast. Given the lingering
clouds but minimal temperature advection...will trend lows near
mavmos values.

Forecast soundings and time heights then show a dry column with
subsidence across the area on Thursday through Friday...with
minimal temperature advection. Cooler and less humid northerly
surface flow looks to remain in place as high pressure remains in
place over the Mississippi Valley. With a short wave pushing
dynamics across the northern Great Lakes at this time...a few
passing clouds cannot be entirely ruled out. Thus partly cloudy
looks like the way to go. Given the air mass...a blend of mavmos
and mexmos temps should work nicely.

&&

.LONG TERM /Friday Night through Tuesday/...
Issued at 252 PM EDT Tue May 31 2016

Models deepen an upper trough over the great lakes early on in the
long term and move it to the St. Lawrence valley early next week.
This will result in temperatures near or slightly cooler than
normal.  Much of the weekend looks wet as an upper disturbance
moves into the Ohio valley late Friday night and a cold front moves
southeast across our region Sunday.  Most models have trended a little
wetter over the weekend.

I have low confidence there will be much less Sunday night as the GEMNH
and new Euro are dry then...while the GFS is a wetter outlier. For now
will carry slight chance POPS some areas Sunday night.   On Monday we
might see a slightly better chance of showers as the upper trough deepens.
However dry weather will be the rule Monday night and Tuesday as high
pressure builds into our areas.

Models are in good agreement on temperatures and in most cases stayed
close to Super Blend numbers.

&&

.AVIATION /Discussion for 312100Z IND TAF Update/...
Issued at 430 PM EDT Tue May 31 2016

Increased wind speed a few knots to 11 knots per trends.

Previous discussion follows...
Issued at 100 PM EDT Tue May 31 2016

VFR through the period...although a few thunderstorms could be an
issue some areas midday Wednesday on.

Weather depiction indicates few cu around 5 thousand feet and high thin clouds
across Indiana and widely scattered thundershowers across Illinois. Could see
an isolated cell northwest parts of our region this afternoon...but chances are
too low to mention at this time.  High pressure ridge over Ohio and eastern Kentucky
will move on to the east low pressure over the northern plains moves east northeast.
It will remain VFR but with a little more clouds later tonight and Wednesday.

Of more significance models indicate an increasing chance of thunderstorms northwest
sections after midday Wednesday and over most other areas by late Wednesday.
Will add VCTS after 17Z WED at KLAF and 20Z WED at KIND which uses a 30 hour TAF.

Winds will be southeast at 6 knots or less this afternoon...light tonight and
southwest up to 8 knots Wednesday.


&&

.IND Watches/Warnings/Advisories...
NONE.
&&

$$

SYNOPSIS...PUMA
NEAR TERM...PUMA
SHORT TERM...PUMA
LONG TERM....JH
AVIATION...JH/MK



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