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000
FXUS63 KIND 150712
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
312 AM EDT Mon Apr 15 2024

.KEY MESSAGES...

- Isolated thunderstorms possible late today in the far southwest,
  with additional storms developing tonight. Some hail is possible
  with these storms.
- Ongoing River Flooding
- Multiple rounds of showers and storms this week, severe weather
  possible late Tuesday and Wednesday
- Cooling trend late next week.

&&

.SHORT TERM (Today and tonight)...
Issued at 312 AM EDT Mon Apr 15 2024

Today...

A cold front, which is across northern Indiana early this morning,
will gradually sink south across the forecast area today. Lack of
upper support and good moisture will keep the threat of any
convection at bay for most of the day.

Late this afternoon, depending on where the front ends up, there may
be enough moisture for some isolated convection in the extreme
southwestern forecast area. Confidence is low in this happening, but
if it does, some hail and gusty winds may accompany the storms. Will
go with an isolated mention in the far southwest late today.

Even though the front will move through today, much of the colder
air will remain north of central Indiana. This combined with a good
deal of sunshine will lead to highs around 80 to the lower 80s for
much of the area. Parts of the north will be cooler with highs in
the mid and upper 70s.

Tonight...

As low pressure develops well west of central Indiana, the surface
front will return to the northeast into the area. An upper level
wave will add some upper support. Moisture looks adequate for some
convection to develop as the front returns northeast.

Will go with some chance PoPs across the southwestern half or so of
the forecast area at some point during the tonight period as the
front moves northeast.

While surface based instability will diminish with loss of heating,
there will remain some decent lapse rates aloft. Thus, some hail
would still be possible with stronger convection.

Lows will be in the 50s to around 60.

&&

.LONG TERM (Tuesday through Sunday)...
Issued at 312 AM EDT Mon Apr 15 2024

A semi-cut off mid to upper-level low pressure system currently
resides over the western US. This feature is expected to eject
eastward into the Plains today, triggering surface cyclogenesis over
the central Plains. The resulting surface low heads northeastward
towards Indiana on Tuesday/Wednesday. Primary forecast concerns
through the long range revolve around this system, namely the
potential for strong to severe thunderstorms.

Guidance is fairly clustered regarding the evolution of the larger-
scale system, with minor differences primarily in timing. Models
have trended slightly slower over the past few cycles, which may
have some implications regarding severe potential on Wednesday.
Convection appears to arrive in two rounds, with one late Tuesday
night and the second on Wednesday. Round one looks to develop over
Missouri and Illinois Tuesday afternoon and progress eastward,
possibly outpacing the main axis of instability. Some uncertainty
remains on how this first round evolves and in what form it reaches
Indiana. Though it is likely in a weakening state, thermal profiles
and sufficient shear lead to a non-zero risk of severe though the
risk appears low at this time.

On Wednesday, the first round of storms should be out of the region
with the system`s cold front/dry line approaching from the west. At
this point we will be well within the warm sector, though the parent
system is expected to be weakening. As the system weakens, upper-
level flow becomes more westerly which may change the shear vector
enough to add some curvature to the hodographs. Model soundings show
robust CAPE, moisture, and steep lapse rates. As such, all
convective hazards are possible on Wednesday. A few questions
remain, however, primarily regarding timing and convective
evolution. As mentioned before, models continue to trend slower
which places the cold front in our CWA during peak heating. While a
not a limiting factor in the off season, as buoyancy can be
maintained by advection alone...Additional instability from solar
insolation could steepen low-level lapse rates a bit. Additionally,
how the previous round of convection evolves may have some impact on
the second round. Will continue to monitor trends as this system
approaches.

Beyond Wednesday, a cooling trend looks to take hold as flow aloft
becomes more zonal and near-surface flow attains a northerly
component. Ensemble guidance has backed off a bit on the magnitude
of cold air advection later this week, but a few nights with lows in
the 30s still appear possible. Patchy frost would not be out of the
question based on current data.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1257 AM EDT Mon Apr 15 2024

Impacts:

- A wind shift will work its way south through the sites into the
  daylight hours of Monday morning. Winds will shift to the north.

Discussion:

VFR conditions are expected through the period. A cold front will
drop slowly south and shift the winds. Confidence in the timing of
the wind shift is moderate at best due to the apparent slowing down
of the front from recent expectations.


&&

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

$$

SHORT TERM...50
LONG TERM...Eckhoff
AVIATION...50