Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 311814
AFDIND

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

.UPDATE...
The SYNOPSIS...NEAR TERM and SHORT TERM Sections have 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 through Monday/...
Issued at 315 AM EDT Tue May 31 2016

The upper level flow across the country will transition through the
extended from quasi-zonal to a much more amplified pattern
highlighted by a strong ridge in the west and a trough in the
eastern part of the country. This will result in cooler than normal
temperatures for the first weekend of June and into the following
week across the region.

While the main features are sampled well by the extended
models...there are discrepancies in the location of the departing
cold front for the end of this week and additional differences with
respect to the expansion of the upper trough into the area by early
next week. ECMWF maintaining the remnant front further north over
the Ohio Valley than other models on Friday...largely due to a
stronger upper ridge over the southeast states and a flatter flow
aloft initially across the region. Have maintained a dry forecast
for Friday and Friday night but certainly plausible that a low
chance pop will need to be introduced at some point if model
consensus starts trending towards the ECMWF.

Initial energy aloft will arrive into the Great Lakes over the
weekend...with mid level heights buckling and the expansion of the
broad upper ridge commencing. Surface wave and front will move
through the region late Saturday into Sunday...promoting scattered
convection and ushering in cooler temperatures in its wake.
Additional waves aloft will amplify the trough further over the
region early next week...with progressively cooler temperatures and
more threats for showers and storms for Monday and perhaps beyond
with the influence of the upper trough likely to persist for much of
next week.

High temperatures will drop slowly through the extended...with highs
in the upper 70s and lower 80s Friday falling all the way back into
the lower and mid 70s for early next week.

&&

.AVIATION /Discussion for 311800Z TAF Issuance/...
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....RYAN
AVIATION...JH



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