Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 281408
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1008 AM EDT THU JUL 28 2016

.UPDATE...
The NEAR 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 through Wednesday/...

Issued at 223 AM EDT Thu Jul 28 2016

ECMWF suggests high pressure building acrs the Great lakes and Nrn
Indiana in the wake of the departing low pressure system...and
have trended toward a dry forecast. However the ECMWF also
suggests ridging along with embedded ridge riding short waves
moving across the middle mississippi river valley and slowly
edging toward Indiana as this long term progresses. Confidence
for precip on Monday will remain low as subsidence remains in
place...but as we progress into Tuesday and Wednesday...warmer and
humid air begins to arrive on southerly flow. Meanwhile...the
ridge riding short waves begin to advect east in to the Ohio
valley. Thus will keep some pops in the forecast during this time
as suggested by superblend.

&&

.AVIATION /Discussion for the 281200z tafs/...

Issued at 557 AM EDT Thu Jul 28 2016

VFR CIGS are expected for much of the day. MVFR/IFR FOG will be
possible overnight tonight.

Tropical plume of moisture combines with a weak surface low
pushing across Indiana today will result in sct TSRA and SHRA
today. Confidence for precise timing remains too low...thus have
painted a large window of VCTS mention for now.

Time heights and Forecast soundings both show a saturated column
through the day with marginal lift. Daytime heating may provide a
trigger through the afternoon...thus again...will use the VCTS
window.

Light winds and moist ground expected tonight along with dew point
depressions less than 1-2F. Thus have trended toward MVFR/IFR fog
at BMG/LAF/ and HUF.

&&

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

&&

$$

SYNOPSIS...CP
NEAR TERM...RYAN
SHORT TERM...CP
LONG TERM....PUMA
AVIATION...JP


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