267
FXUS63 KIND 132347
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
747 PM EDT Mon May 13 2024

.KEY MESSAGES...

- Showers and a few thunderstorms expected through Tuesday

- Up to around one inch of rain expected but locally higher amounts
  possible

- Rain chances return Thursday into Friday, again early next week.

&&

.SHORT TERM (This evening through Tuesday)...
Issued at 258 PM EDT Mon May 13 2024

Rest of This Afternoon...

Some weak lift ahead of an approaching upper system will work with
some limited instability to produce scattered showers and some
thunderstorms, primarily across the far western portions of central
Indiana. Will go with primarily chance PoPs west.

Satellite shows some holes developing in the clouds, so temperatures
still look to remain around 80 at most locations.

Tonight...

Some upper energy rotating around the approaching upper system will
bring scattered to numerous showers to the area this evening, then
some better forcing will arrive late tonight.

Moisture will be plentiful. Will go mainly chance or low likely
category PoPs this evening, then increase to likely or higher PoPs
overnight as the better energy moves in and interacts with the
moisture.

With clouds and some rain around, low temperatures will be around 60
degrees.

Tuesday...

The better forcing that arrives late tonight will continue into
Tuesday morning. Will continue with higher PoPs then.

There may be a relative lull early in the afternoon, then as heating
occurs, additional showers and some thunderstorms will develop with
the heart of the upper system arriving. Will continue with higher
PoPs.

At the moment, instability and shear look low enough to keep severe
storms at bay. However, locally heavy rain remains a threat with the
plentiful moisture. HREF local probability matched means show some
potential for localized amounts over 2 inches.

Clouds and rain will keep temperatures lower, with highs in the
lower 70s expected most areas.

&&

.LONG TERM (Tuesday night through Monday)...
Issued at 258 PM EDT Mon May 13 2024

Active weather looks to continue through the long range with
multiple storms systems possible. As of right now, no organized
severe weather appears likely.

SYNOPTIC OVERVIEW

Aloft, the polar jet stream looks to remain at least moderately
amplified to at times quasi-zonal. The subtropical jet is likely to
remain separate across the southern states. This disconnection
should preclude significant moisture transport northward.
Nevertheless, waves embedded within the broader flow should pass
through the Midwest with some regularity.

These waves are modeled to take on a generally west to east path,
which makes sense given the lack of phasing and quasi-zonal nature
of the jet stream. Like today`s system, enough moisture should be
present for scattered showers and thunderstorms. The next wave in the
series (after today`s) arrives late this week around Thursday or
Friday. Flow aloft looks rather weak and model soundings are nearly
moist adiabatic. Showers and storms are still possible, given
synoptic scale forcing...but the weak lapse rates and lack of wind
shear will limit severe potential.

The third system in the series arrives early next week, Monday or
Tuesday. Model consensus diverges quite a bit by this point,
however, so besides rain chances not much can be said about how this
system will play out.

Beyond that, ensemble guidance hints at broad troughing over the
western states and into the Plains as we close out the month. That
could allow the active pattern to persist for another week or two.
The overall signal is not terribly strong, however.

FORECAST CONFIDENCE

Confidence through the period is average. Model guidance tends to be
in agreement through the remainder of this week but diverges over
the weekend. By next week, only a loose signal remains and it`s hard
to draw any conclusions when guidance shows such a variety of
outcomes. Still, the overall picture looks a bit more active than
normal (CPC 8-14 day outlook showing wetter than normal conditions).
Lack of significant ridging should keep temps near normal for the
most part.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 747 PM EDT Mon May 13 2024

Impacts:

- Arrival of showers and thunderstorms pushed back until after 09z
- MVFR to IFR conditions developing Tuesday morning with more
widespread convection

Discussion:

Latest satellite imagery and observations show an area of low
pressure near Kansas City slowly pushing eastward. Showers and
thunderstorms have developed out ahead of it this evening; however
due to very dry conditions across Central Indiana, convection has
remained just west of the IL/IN state line. Guidance has not been
handling the dry air over the region well, bringing in the chance
for rain and storms way too early. Based on latest observations and
radar trends, have pushed back the arrival of convection until after
around 09z tonight. Potential is there for a few showers before 09z
near BMG and HUF, however confidence is low in lightning potential
and impacts as dry air will likely cause anything to weaken as it
pushes near.

Confidence still remains high that widespread showers and
thunderstorms will spread eastward into Indiana Tuesday morning and
persist through much of the day. MFVR to IFR conditions still likely
tomorrow, with chances for lightning and heavy rain under the
strongest convection.

Southerly winds gusting to 20kts will diminish after sunset then
weaken overnight to around and under 10 kts. As the low pressure
system approaches, expect winds to become more easterly through the
night and into tomorrow, remaining under 10 kts. Potential is there
for erratic wind directions and speeds under convection. Currently
severe weather is not expected.

&&

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

$$

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