Area Forecast Discussion
Issued by NWS Indianapolis, IN

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680
FXUS63 KIND 281824
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
224 PM EDT THU JUL 28 2016

.UPDATE...
The LONG TERM Section has been updated below.

&&

.SYNOPSIS...
Issued at 337 AM EDT Thu Jul 28 2016

An active pattern continues with a frontal boundary stuck in the
area and upper troughing bringing a series of upper waves to
interact with it. This will continue until early next week when
upper ridging starts to build back in over the area and the trough
kicks east.

&&

.NEAR TERM /Rest of Today/...
Issued at 1008 AM EDT Thu Jul 28 2016

After a relative lull in convection and heavy rain over the last
few hours...scattered storms are now moving into the Wabash Valley
ahead of another weak wave aloft. Under mainly cloudy skies...14Z
temps were in the 70s.

Main focus for the morning update is to freshen and attempt to
better define timing for storms through the remainder of the day.
Slow moving convection currently over eastern Illinois and moving
into the Wabash Valley appears to be drifting E/SE along a weak
instability gradient. Have focused highest pops through early
afternoon over the southwest half of the forecast area to account
for this thinking...with precip chances increasing everywhere
thereafter as a more robust wave aloft currently over western
Missouri approaches late day.

Main threat from storms will be the potential for torrential
rainfall and flash flooding from slow moving storms as steering
currents remain stagnant. Area of greatest flooding concern will
be over far southern counties which received heavy rain early this
morning on top of heavy rains back on Tuesday. PWATs will slowly
fall back from the 2 inch+ totals over the south this morning but
still remain quite high in the psuedotropical airmass.

Low to mid 80s for highs still look reasonable considering plenty
of clouds today. Zone and grid updates out.

&&

.SHORT TERM /Tonight through Saturday night/...

Issued at 337 AM EDT Thu Jul 28 2016

A diffuse surface front with an upper trough bringing waves
through the area will keep thunderstorm chances in the forecast
through the short term. Low confidence on timing of any particular
wave so kept to consensus of mid range chances for thunderstorms
throughout, with slightly lower PoPs Saturday night as forcing
then looks a little less evident. For temperatures did not deviate
from a model blend, where more sunshine and less precip on any of
the days could increase highs several degrees or an all day
washout (not anticipated but not to be ruled out either) could
do the same in the opposite direction. Humid atmosphere will
remain in place though, with no model indications of dewpoints
dropping below 60s and most of the time hanging in the upper 60s
to lower 70s. Due to the ample moisture and slow storm motion,
heavy rainfall leading to flooding will be a threat but too low
confidence on location or timing to go with headline.

&&

.LONG TERM /Sunday Night through next Thursday/...
Issued at 223 PM EDT Thu Jul 28 2016

Ensembles in good agreement in expanding heat ridge, initially
over the southern Rockies, northeast into the Midwest and Ohio
Valley by the middle of next week. This may serve to cap off
convective potential by that time. For now, will keep some
chance PoPs going throughout the extended. If a trend towards
drier conditions continue, PoPs may be trimmed back next week.

&&

.AVIATION /Discussion for the 281800Z TAFS/...
Issued at 1256 PM EDT Thu Jul 28 2016

Weak vorticity lobe currently over Illinois is progged to drift
eastward through the local area later this afternoon and evening.
Scattered convection possible in association with this feature,
but confidence is low in direct impacts at this time. Short term
models suggest this vorticity lobe will pass east of the terminals
around 290400Z, so convective threat should diminish by then.
Brief IFR visibility restricitions in heavier convective cells. CB
bases near 020.

Otherwise, should see some visibility restricitions develop in
light fog after dark due to the high moisture content of the air
mass and little wind. Pattern favorable for widespread IFR/LIFR
conditions after 290600Z.

Surface winds generally below 7 kts through this evening.

&&

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

$$

SYNOPSIS...CP
NEAR TERM...RYAN
SHORT TERM...CP
LONG TERM....JAS
AVIATION...JAS



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