Area Forecast Discussion
Issued by NWS Indianapolis, IN

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817
FXUS63 KIND 252028
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
428 PM EDT WED MAY 25 2016

.UPDATE...
Aviation section updated

&&

.SYNOPSIS...
Issued at 356 PM EDT Wed May 25 2016

Summer has arrived and will be in full force across central
Indiana over the seven day forecast period. Highs in the 80s, lows
in the 60s, and ever present shower and thunderstorm chances
characterize the entire forecast period as a warm and humid
airmass remains in place with multiple subtle, weak, and difficult
to time upper level disturbances providing the focus for the
thunderstorm threat.

&&

.NEAR TERM /Tonight/...
Issued at 356 PM EDT Wed May 25 2016

Guidance depicts an upper level wave moving into the area late
this afternoon into the overnight. This would potentially be the
focus for shower and thunderstorm activity but activity over
western Kentucky and another complex over northeastern Arkansas
this afternoon appear to be the dominant reflections of this wave.
Will remove guidance likelies and carry a 50 pop overnight, but
even this may be too high unless more robust development can occur
over the next few hours in Illinois, which does not appear to be
occurring particularly quickly at this time.

Marginal risk was expanded into the area earlier this afternoon,
and while this isn`t unreasonable, any severe risk would be
extremely limited, in the form of isolated microbursts as deep
layer shear is minimal at best.

Consensus temperatures overnight appear reasonable.

&&

.SHORT TERM /Thursday through Saturday/...
Issued at 356 PM EDT Wed May 25 2016

Multiple weak and poorly resolved waves will move through the area
over the next few days, and in the absence of more significant
synoptic support, expect that thunderstorm threat will be highly
diurnal in nature and will reflect this to the degree reasonable
in grids. Cannot justify more than chance pops in any one period
as a result of the significant uncertainty and low forecast
confidence.

Consensus temperatures appeared reasonable throughout. Bumped up
maxes a bit per low level thicknesses and left mins alone. Little
change in airmass over the next few days will result in only minor
day to day variability in temperatures.

&&

.LONG TERM /Saturday Night through Wednesday/...
Issued at 208 PM EDT Wed May 25 2016

ECMWF really has no significant changes to the ongoing pattern
during the extended period. Warm and moist southerly flow
continues to stream into the Ohio Valley. Strong ridging looks to
remain across the east coast...keeping any passing short waves
well to the north of Indiana. Given the warm and moist air mass in
place...diurnal thunderstorms cannot be ruled out as superblend
continues to carry pops each day. Again, no washout days are
expected...but daily showers and storms will be possible. Given
the expected warm and moist southerly flow...the trend of slightly
above normal temperatures given by superblend seems reasonable.

&&

.AVIATION /Discussion for the 252100z IND taf update/...

VFR conditions will continue the next several hours. Radar shows a
weak area of showers over east Central Illinois drifting
northeast...but diminishing upon approach. Have trended the vcts
mention later by a few hours.

Previous discussion below

/Discussion for the 251800z tafs/...
Issued at 1251 PM EDT Wed May 25 2016

Mainly VFR conditions are expected this TAF period. Brief MVFR
conditions will be possible with any TSRA that may occur this
afternoon and evening.

GFS suggests a weak short wave over Illinois to progress across
indiana late this afternoon and evening. Forecast soundings
suggest steep lapse rates with large CAPE. Thus expect sct TSRA to
develop along and ahead of the wave during the max heating hours
this afternoon and evening. Uncertainty remains with precise
timing and will update to prevailing as showers and storms
develop.

Patchy Fog may be possible late tonight...particularly in those
areas that get rain. Have included MVFR fog at the TAF sites for
now. A lull in convective activity is expected on Thursday morning
as Indiana should remain between short waves. Time heights
suggest subsidence and forecast soundings are capped through at
least 18z.


&&

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

$$

SYNOPSIS...NIELD
NEAR TERM...NIELD
SHORT TERM...NIELD
LONG TERM...PUMA
AVIATION...JP



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