Hail and Damaging Winds in Indiana, August 25, 2018

Area Forecast Discussion
National Weather Service Indianapolis IN
425 PM EDT Sat Aug 25 2018

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

&&

.SYNOPSIS...
Issued at 232 PM EDT Sat Aug 25 2018

An upper level disturbance will result in some chances for
convection through Sunday. High pressure will build into the area
for the early parts of next week. A frontal system may affect the
area by the middle parts of next week.

&&

.NEAR TERM /Rest of This Afternoon and Tonight/...
Issued at 232 PM EDT Sat Aug 25 2018

Shower and thunderstorm activity expected to diminish across the
area over the next couple of hours as the upper disturbance
responsible moves off into Ohio.

Model data suggest that although the upper feature will move away, a
trailing vorticity lobe will hang back over the area through
tonight. This, coupled with an enhanced area of flow at 850mb, may
be enough to spark scattered convection from late this afternoon
through tonight. Will keep some chance PoPs going through tonight as
a result.

Deep layer shear and lapse rates are marginally favorable for strong
convection this afternoon and evening. Shear look to diminish by
late tonight.

Low level thicknesses suggest the GFS MOS guidance lows tonight look
reasonable.

&&

.SHORT TERM /Sunday through Tuesday/...
Issued at 232 PM EDT Sat Aug 25 2018

Model data suggest an upper ridge will expand across the Ohio and
Tennessee Valley regions during this period, while a short wave
trough moves across the northern Rockies and Plains early next week.

It appears that the air mass locally will be close to being capped
off, but not confident mid level temperatures will be warm enough
to hold off some convection, given attainable convective
temperatures and a highly unstable air mass. Models suggest that
there may still be a mid level vorticity lobe lingering over the
area as well. Based on above, would prefer to keep some small chance
PoPs going for Sunday.

After Sunday, appears the cap will strengthen and instability will
diminish as mid level temperatures warm. At this time, not really
seeing anything in the operational or ensemble data that suggests a
mentionable precipitation threat, so will go with a dry forecast
after Sunday.

Progged low level thicknesses suggest the GFS MOS highs on Sunday
look a little cool. Will nudge up the guidance about 2-4 degrees in
that period. The remainder of the periods look OK for now.

&&

.LONG TERM /Tuesday night through Saturday/...

Issued at 245 PM EDT Sat Aug 25 2018

ECMWF suggests a short wave passing through the upper midwest and
Great Lakes on Tuesday night and Wednesday. The tail of this
system looks to pass across Central Indiana and given the very
warm and humid air mass that will be in place...chances for
showers and storms appear reasonable.

On Thursday into Saturday....mainly zonal flow is found aloft with
little in the way of forcing dynamics. Meanwhile the ECMWF
suggests high pressure moving across the Great Lakes...providing
easterly flow to Central Indiana. As the High drifts farther east
on Saturday...warmer and more humid southerly flow will return to
Central Indiana. This will allow for at least a mention of
diurnally driven chances for rain on Saturday.

&&

.AVIATION /Discussion for the 252100Z IND TAF Update/...
Issued at 425 PM EDT Sat Aug 25 2018

Increased wind speed to 17 knots based on ob trends.

Previous discussion follows...

Issued at 125 PM EDT Sat Aug 25 2018

Mainly VFR conditions are expected this taf period.

Short wave exiting Central Indiana will bring an end to scattered
showers and storms. This should result in a return to VFR
conditions as weak ridging begins to build across Indiana late
this afternoon and tonight. Forecast soundings indicate mid level
subsidence and drying ...but lingering lower level moisture. Dew
point temps are expected to surge toward the 70s as seen upstream
and across Central and southern Illinois. This along with recent
rains may result in patchy fog overnight...particularly at the
more rural taf sites. For now...no MVFR fog will be included...but
be aware of this potential change in the future updates.

After any fog on Sunday morning...a quick return to VFR will be
expected as ridging builds aloft over the area.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SYNOPSIS...JAS
NEAR TERM...JAS
SHORT TERM...JAS
LONG TERM....Puma
AVIATION...JP/MK

Hazardous Weather Outlook
National Weather Service Indianapolis IN
434 PM EDT Sat Aug 25 2018

INZ021-028>031-035>049-051>057-060>065-067>072-261000-
Carroll-Warren-Tippecanoe-Clinton-Howard-Fountain-Montgomery-Boone-
Tipton-Hamilton-Madison-Delaware-Randolph-Vermillion-Parke-Putnam-
Hendricks-Marion-Hancock-Henry-Vigo-Clay-Owen-Morgan-Johnson-Shelby-
Rush-Sullivan-Greene-Monroe-Brown-Bartholomew-Decatur-Knox-Daviess-
Martin-Lawrence-Jackson-Jennings-
Including the cities of Lafayette, Frankfort, Kokomo,
Crawfordsville, Anderson, Muncie, Indianapolis, Terre Haute,
Shelbyville, Bloomington, Columbus, Vincennes, Bedford, and Seymour
434 PM EDT Sat Aug 25 2018

This hazardous weather outlook is for central Indiana.

.DAY ONE...Tonight.

Outlook: Thunderstorm activity is possible through tonight. Isolated
strong to severe storms are possible, mainly from late this afternoon
through the late evening hours.

Hazards: Cloud to ground lightning, heavy rainfall that may lead to
localized flooding, strong gusty winds that may result in isolated
damage, and hail.

Timing: Best chances for strong to severe storms through about
midnight EDT.

Discussion: A low pressure system moving across the Great Lakes will
result in the potential for thunderstorms activity through tonight.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Outlook: Thunderstorm activity is possible on Sunday, and from
Tuesday night into Wednesday. Severe storms are not expected at this
time. A few storms could be strong during the middle portion of next
week as a frontal boundary moves into the area. Cloud to ground
lightning, brief heavy rain, and gusty winds are possible with any
storm.

The heat and humidity will return on Sunday. The heat index could
approach or even exceed 100 degrees during the afternoon hours from Sunday
to Tuesday.

Discussion: An upper ridge will expand into the Ohio Valley...
bringing oppressive conditions Sunday through the middle of next
week. A cold front arriving Wednesday will increase the threat for
thunderstorms and bring a cool down from the heat.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

&&

More information, along with other weather, hydrological and climate
information can be found at http://weather.gov/ind

Special Weather Statement
National Weather Service Indianapolis IN
406 PM EDT SAT AUG 25 2018

INZ040-041-049-252030-
Henry-Madison-Delaware-
406 PM EDT SAT AUG 25 2018

...A STRONG THUNDERSTORM WILL AFFECT EAST CENTRAL MADISON...SOUTHERN
DELAWARE AND NORTHERN HENRY COUNTIES...

At 405 PM EDT, a strong thunderstorm was located 7 miles northeast of
Anderson, moving east at 40 mph.

Winds in excess of 40 mph and pea size hail are possible with this
storm.

Locations impacted include...
Muncie, Anderson, Yorktown, Chesterfield, Daleville, Selma,
Mooreland, Springport, Blountsville, Summit Lake State Park, Prairie
Creek Reservoir and Ball State University.

This includes Interstate 69 between mile markers 229 and 242.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 4007 8569 4025 8566 4024 8522 4001 8521
      4000 8521 4000 8520 3999 8520
TIME...MOT...LOC 2005Z 277DEG 34KT 4015 8556

JAS