Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 260832
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
430 AM EDT THU MAY 26 2016

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

&&

.SYNOPSIS...
Issued at 312 AM EDT Thu May 26 2016

Warm and humid conditions will continue through the Holiday weekend
and the middle of next week. Also...occasional weak upper
disturbances will also combine with the soupy atmosphere to touch
off a few thunderstorms from time to time.

Temperatures will be a few degrees above normal with afternoon highs
in the lower to mid 80s and lows in the 60s on tap.

&&

.NEAR TERM /Today and Tonight/...
Issued at 315 AM EDT Thu May 26 2016

Pops will be the main issue today as the southwestern trough
continues to send weak short waves northeast across the Ohio Valley
and Great Lakes...and southerly flow around the Bermuda High
continues to supply moisture and instability to the area.

Very little activity occurred over Central Indiana yesterday or last
night despite instability and a weak short wave moving through the
southwest flow aloft. This is leading to less confidence in the
forecast for today and tonight. 00z MOS from the GFS and NAM really
illustrate this as the NAM has low chance pops today and
tonight...while the GFS has low chance pops today but likely to
occasional pops tonight. Current thinking is closer to the NAM but
can not completely discount the GFS MOS as a pair of northeastward
ejected waves move over Lake Michigan and Northwestern Indiana this
afternoon and overnight...and models have moderate to strong
instability this afternoon and weak to moderate instability tonight.
In addition...the eastern part of a 30 knot low level jet will be
moving into Southwestern Indiana this PM. So...despite low to
moderate confidence in thunderstorm coverage...will go with small
chance pops today and mainly during the afternoon and
southwest...closer to the low level speed max. Tonight...will go
with good chance pops northwest and small pops southeast as another
wave moves across. The best chances will be overnight with this
feature.

Any activity with the current wave passing through should be east of
the forecast area by 12z this morning.

Should see a lot of clouds today...but should see enough breaks in
the sunshine to see temperatures at least as warm as 00z MOS if not
warmer with highs in the lower to mid 80s looking good.
Meanwhile...with a light southerly wind and lower to mid 60 dew
points...overnight lows in the mid to upper 60s look like a good bet
tonight.

&&

.SHORT TERM /Friday through Saturday night/...
Issued at 315 AM EDT Thu May 26 2016

The same issues will carry over to the short term...as the
Southwestern upper low opens up and gets shunted north by a strong
Eastern ridge but another large scale trough takes over across
California. The result will be the same with a series of weak
upperwaves slingshotted northeast from the base of the trough to the
OhioValley and Great Lakes. At the same time...the Bermuda High
keepsthe low level flow southerly ahead of a stalled Plains front.
This will keep the threat of storms around through the short term
and beyond. The devil will be in the details with the timing of each
impulse. With no significant wave to key in on...will continue with
chance pops through Saturday night with the best chances in the PM.

With air mass unchanged...persistence a good bet with highs in the
lower to mid 80s and lows in the 60s.

&&

.LONG TERM /Sunday through next Wednesday/...

Issued at 225 AM EDT Thu May 26 2016

Ensembles in fairly good agreement during this period. An upper
trough is expected to eject into the western Great Lakes during
the day Sunday. Will keep chance PoPs going on Sunday to cover
this feature.

Looking like there may be a relative lull in the convective threat
from about Sunday night into Tuesday as heights build a bit in
the wake of the weekend trough. Ensembles are trending drier
during this period, but there are still quite a few members that
suggests widely scattered diurnal type convection is possible.
Will keep some small chance PoPs mainly during the daytime periods
on Monday and Tuesday for now, but could be taken out at a later
time if trends continue.

Ensembles suggest another upper disturbance may lift northeast
towards the western Great Lakes towards the middle of next week.
Will go with chance PoPs for next Wednesday.

&&

.AVIATION /Discussion for the 260900Z KIND TAF update/...
Issued at 430 AM EDT THU May 26 2016

Areas of MVFR ceilings 015-025 have been developing across the area over
the past couple of hours, but at this time, they have not become too
widespread. Short term model guidance suggests these ceilings may linger
into the late morning hours, but based on what is currently upstream,
this may be overdone. For now, will keep MVFR ceilings in the forecast
until about 261600Z and monitor trends.

Also, took out the visibility restricitions in light fog early this
morning, as it appears winds/cloud cover generally unfavorable for fog
formation.

Previous discussion follows.

VFR conditions to start at the sites. Could see some MVFR
visbilities develop around/after 9z with dew points currently in the
60s and temperatures still dropping. Also guidance is showing
development of MVFR ceilings or worse around the same time. Upstream
obs do show some MVFR decks developing and spreading toward the
sites, so will include a ceiling drop as well. Time heights and
forecast soundings indicate ceilings and vsbys should improve during
the morning, around 14z or so. Could see thunderstorm development
Thursday late afternoon/early evening but confidence is low enough
to leave out, with the exception of a broken deck around 4 kft.

&&

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

$$

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



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