Area Forecast Discussion
Issued by NWS Indianapolis, IN

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042
FXUS63 KIND 271728
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
128 PM EDT SAT AUG 27 2016

.UPDATE...

The Aviation section has been updated below.

&&

.SYNOPSIS...
Issued at 343 AM EDT Sat Aug 27 2016

A front meandering across central Indiana will interact with upper
waves on the periphery of an upper ridge to prompt thunderstorm
chances for the next several days. Temperatures will run higher
than normal until the latter part of the work week, when they will
drop to near normal.

&&

.NEAR TERM /Today/...
Issued at 1004 AM EDT Sat Aug 27 2016

Latest radar loop was showing a strong area of thunderstorms lifting
northeast across our Carroll and Clinton counties. IWX base
velocitites of near 45 knots prompted a strong thunderstorm
advisory. Upped pops to likely in this area the next couple of
hours.

Previous discussion follows...
Issued at 343 AM EDT Sat Aug 27 2016

Radar mosaic at 330 am shows a large area of thunderstorms over
much of Illinois and some weakening echoes moving north through
southwestern Indiana. Over the next few hours expect the storms
over eastern Illinois to move into the northwest forecast area and
could still see some scattered development along an outflow
boundary that stretches from those storms southeast across the
area. Thus have likely pops going across western portions of the
forecast area at times over the next few hours with lesser pops
heading southeast.

An upper wave moving through the area to the north will provide a
focusing mechanism for more convection throughout the day today.
With high pressure centered southeast of the area have the lowest
pops going in the southeast but have likelies for parts of the day
in the north and west closest to the best upper forcing. The
front, which had settled near the Ohio River, could move north
again and stall in the forecast area, but bring dew points back
into the 70s. With that juicy air, heavy rain and flooding will
again be a threat. And while low level jet will not be impressive,
and enhancement of 15-20 kts does move across the area during the
afternoon and evening. Combining this with the front, low LCLs
from moist airmass and based on recent days, cannot rule out an
isolated tornado.

&&

.SHORT TERM /Tonight through Monday night/...
Issued at 343 AM EDT Sat Aug 27 2016

A series of upper waves moving through the periphery of an upper
ridge will impact central Indiana through the short term, bringing
chances for thunderstorms to the area. Models are showing
discrepancies in timing of the individual waves so low confidence
on that, but moderate confidence there will be some storms around
the area at some point during the days and lesser confidence of
storms at night without additional help from daytime heating. For
temperatures generally leaned on warmer end of guidance envelope
based on recent verification. Very humid air will continue across
the area through the period and thus heavy rain will remain a
threat throughout.

&&

.LONG TERM /Tuesday through Friday/...
Issued at 238 AM EDT Sat Aug 27 2016

ECMWF suggests NW flow persists aloft on Tuesday as a weak short
wave sweeps through Great lakes and brushes Indiana. Best forcing
looks to remain well north of Central Indiana...however and
associated cold front is expected to push across Indiana and the
Ohio valley On wednesday. Change in air mass is expected with
much less humid air arriving on Northerly winds. Thus expected at
least low chc pops for Tuesday and into Wednesday as these
features pass.

Dry weather is expected on Thursday and Friday. ECMWF suggests
high pressure building across the area along with ridging in the
upper levels. Furthermore excellent subsidence is seen in the
middle levels streaming into Indiana on dry NE winds. Thus have
trended dry at time with a return to near normal temperatures.

&&

.AVIATION /Discussion for the 27/18z TAFs/...
Issued at 128 PM EDT Sat Aug 27 2016

VFR conditions will prevail today and into the evening, before
deteriorating to MVFR and possibly IFR later tonight.

Thunderstorms are exiting the area and will not impact the TAF sites
beyond 18Z. Cannot rule out isolated additional development but
chances are too low for inclusion.

Rain today, ample low level moisture, thinning cloud cover, and
light to calm winds overnight will set the stage for fog development
and perhaps some low cloud. Will take IND/LAF/HUF down to 3SM with a
BCFG mention. Will take BMG down to 1SM.

Winds will be less than 10kt throughout the period.

&&

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

&&

$$

SYNOPSIS...CP
NEAR TERM...CP/MK
SHORT TERM...CP
LONG TERM...PUMA
AVIATION...NIELD



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