098
FXUS63 KIND 261839
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
239 PM EDT Wed Jun 26 2024

.KEY MESSAGES...

- Showers and thunderstorms will be around at times through evening.
- An isolated strong to severe storm is possible along with a low
  flood threat.
- Clearing skies with patchy fog possible overnight.
- A brief respite from heat and humidity Thursday and Friday before
  another warm up and additional storm chances late Friday through
  the day Saturday.

&&

.SHORT TERM (This evening through Thursday)...
Issued at 239 PM EDT Wed Jun 26 2024

Our primary forecast challenge through the short term will be
convective coverage and timing this afternoon. Satellite imagery as
of 1pm shows an area of clearing across western Indiana from
Lafayette down to Vincennes, with thinner cirrus above. Despite the
thin cirrus, enough sunshine has been able to get through to allow
for modest destabilization. Some weak convective cores have
developed north and west of the Indianapolis metro area and are
drifting southeastward. Another area, a bit more organized, has
develop just north of our CWA in northern Indiana. All of this
activity is expected to drift southward with time as a cold front
pushes in from the north.

ACARS soundings out of IND show the modest instability in greater
detail. CAPE profiles are relatively wide in the lower levels then
tapering with height due to decreasing lapse rates aloft. Freezing
levels reside around 13,000 feet, and LCLs are quite low around 2500
feet. Such a wide spread between the freezing level and LCL,
combined with meager lapse rates, may lead to efficient rainfall
production via warm rain processes. Shear is low, so storms may be
pulse-like/single cells and/or multi-cell clusters. A cold pool,
should it develop, may help things organize into a broken line.

Heavy rainfall and isolated flooding may be possible with slow-
moving and training storm cells. As for severe weather, an isolated
strong wind gust is possible especially in the strongest updrafts or
if storms can organize along the edge of a sustained cold pool. Hail
seems less likely, given the narrowing CAPE profile with height and
high freezing levels. In most cases, pea-sized hail would be the
likely outcome. However, a very isolated instance of hail up to 1
inch would not be out of the question in the strongest of updrafts
today.

By this evening, the aforementioned cold front will be clearing the
area and any lingering showers/storms should come to an end. Winds
shift to northerly behind the front but may go light and variable at
times overnight. Light winds, clearing skies, and recent rainfall
may lead to some patchy fog at times overnight as well. Low
temperatures may dip into the upper 50s in a few spots, but most
locations will hover around 60 or in the low 60s.

As surface high pressure moves in during the day Thursday, we`ll be
left with mainly sunny skies amidst a northeasterly breeze. Some
diurnal cumulus and perhaps high cirrus may occur during the
afternoon hours. Despite the sun, afternoon highs may struggle to
reach 80 north of I-70, with readings in the low 80s south of there.
Overall, a very pleasant day expected tomorrow.

&&

.LONG TERM (Thursday night through Wednesday)...
Issued at 239 PM EDT Wed Jun 26 2024

Thursday Night Through Saturday.

The short break from precipitation potential will come to and end
going into Friday as the pattern begins to shift ahead of another
round of strong to potentially severe weather Friday into Saturday.
The upper level pattern will remain generally zonal through the
event but a deepening low pressure will allow the LLJ to ramp up
late Friday night bringing scattered elevated showers and a few
rumbles of thunder ahead of surface based convection Saturday which
is expected to initiate ahead of a cold front associated with the
broader synoptic low in Southern Canada. Shear will be maximized
along the front but the thermal profile will be fairly marginal due
to the overnight convection from Friday night which will leave a
conditional but fairly unlikely threat for organized convection.

If any severe thunderstorms do form, damaging winds would be the
primary threat. Do have some concern that this system could favor
slow propagation on the southwestern portion of any organized line
which could lead to pockets of flash flooding with rainfall amounts
of 3-5 inches in a matter of hours, but confidence on location or
potential of occurrence is fairly low at this time.

Sunday Through Wednesday.

Conditions will be fairly mild Sunday into Monday in the aftermath
of the frontal passage with generally clear skies and highs around
80 as the near surface flow becomes northerly to northwesterly. The
ridge of high pressure will then build back in towards the middle of
the week with a return to temperatures near 90 by Wednesday.  There
is a low threat for showers/storms across the northwestern counties
Tuesday into Wednesday but think that the ridge will be strong enough
to keep thunderstorms out of the forecast area at this time.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 139 PM EDT Wed Jun 26 2024

Impacts:

- Scattered showers and thunderstorms today, brief reductions to
  MVFR or lower possible

- Clearing overnight with patchy fog possible, especially HUF to BMG

- Wind shift to northerly this evening, becoming northeasterly on
  Thursday

Discussion:

Scattered showers and thunderstorms are developing across central
Indiana this afternoon as a cold front drops southward. Should a
shower or storm impact a terminal, then a period of poor flying
conditions is possible. Expect MVFR, or lower, within any shower or
storm.

Showers and storms clear out around 00z as the front sweeps
southward. Clearing skies along with a wind shift to northerly will
accompany the frontal passage. Clear skies, light winds, and
recent rainfall may lead to patchy fog overnight. The best chance
of this is from HUF to BMG.

On Thursday, VFR conditions return with light flow (around 10
knots) from the northeast.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...Eckhoff
LONG TERM...White
AVIATION...Eckhoff