011
FXUS63 KIND 031037
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
637 AM EDT Fri May 3 2024

.KEY MESSAGES...

- Damp and mild today, with widespread showers and a few
  thunderstorms, especially this morning.

- Potential for fog late tonight.

- Multiple chances for showers and storms throughout most of the
  forecast period, with continued above normal temperatures.

- Potential for severe weather during the middle of next week,
  highest chances Tuesday evening and Wednesday night.

&&

.SHORT TERM (Today and tonight)...
Issued at 257 AM EDT Fri May 3 2024

A fairly ordinary damp spring day is expected across central Indiana
today, with weak surface low pressure to our northwest pushing a
frontal boundary through the region as a modest upper level
disturbance slides through the area.

Despite the presence of a fairly moist airmass, with precipitable
water values toward the upper end of climatology, modest forcing and
what should be very weak destabilization given fairly widespread
cloud cover throughout the morning and into the afternoon will limit
intensity of showers and coverage of thunderstorms, though a slight
uptick in the latter may be seen along the boundary this afternoon
if some clearing can occur. Very weak deep layer shear will limit
the intensity of these storms even in the presence of some slightly
more modest instability.

Total rainfall across the area through tonight should be light,
around a third of an inch or less.

Fairly good dry advection throughout much of the column will bring
an end to any lingering showers and storms during the evening hours,
with most of the area dry throughout tonight. Depending on the
degree of lingering high cloud cover, the damp ground may promote
fog development late tonight, and will have to keep an eye out for
dense fog if more significant clearing occurs.

Widespread clouds and precip, especially early in the day, will
limit insolation and keep highs today no warmer than about the mid
70s, with lows tonight in the mid 50s to low 60s.

&&

.LONG TERM (Saturday through Thursday)...
Issued at 257 AM EDT Fri May 3 2024

Saturday Through Sunday.

For much of the long term, the Ohio Valley will be well positioned
within an unstable atmosphere, leading to unsettled weather and
higher uncertainty than usual.

For Saturday, the surface moisture will recover quickly behind a
weak cold front with steady low to mid level lapse rates leading to
widespread 1000-2000 J/kg of CAPE by the afternoon. There will not
be much in the way of forcing given the short wave still well off to
the east, but weak subtle waves from upstream convection should be
enough for isolated to scattered thunderstorms (With a focus over S.
IN) for much of Saturday afternoon and evening. Severe weather looks
unlikely for Saturday (Given negligible dynamics), but cannot be
ruled due to a shallow midlevel dry layer and a deep instability
profile. This should allow a few isolated thunderstorm cores to
reach >25kft, of which could produce small hail and strong wind
gusts.

A boundary out ahead of the aforementioned wave will progress
eastward throughout the day Saturday, leading to a continued threat
for convection on Saturday night. This boundary is expected to
initiate an MCS over IA/IL during the day on Saturday, but mid to
upper level dynamics will be weak, and will make eastward
propagation more challenging, especially as diurnal temperature
inversions develop Saturday night. With that said, if updrafts can
sustain themselves into western Indiana, an isolated severe threat
(although unlikely) is possible Saturday evening. Regardless, this
boundary should pass throughout Saturday night, with
showers/thunderstorms weakening as they progress across the state.
Barring a few lingering showers Sunday morning, the remainder of the
day should be quiet with highs in the mid 70s.

Monday Through Thursday.

By early next week, another shortwave is expected to develop within
the subtropical jet and push E/N into the Ohio Valley. High pressure
in the wake of the previous system could hinder northward progression
of the wave, creating some uncertainty if showers and thunderstorms
will reach this far north on Monday. Given the short period of
potential rainfall, QPF isnt expected to be high, but long range
soundings are hinting at rather efficient rain producers leading to
a marginal concern for flooding. Details are still very hazy at this
point, leading to low confidence in any hazards for Monday

The next round of unsettled weather will push into the region
shortly after, with another trough, albeit deeper, over the Inter-
Mountain West by Tuesday. This time around, a more organized low
pressure system is expected to develop, rapidly deepening as it
reaches the Great Plains. As the low develops, convergence east of
the low should create a weak warm-frontal region and associated
isentropic ascent. This lift is expected to reach the Great Lakes
and Ohio Valley sometime Monday night into Tuesday, leading to
showers and some elevated thunderstorms.

Following this warm front passage, central Indiana will be within a
moderately unstable environment with a mid and upper level jet
aloft. Although uncertainty is high on timing and specifics, this
should lead to a few rounds of more organized convection Tuesday
through Thursday, including a threat for severe convection. Greatest
chances for severe weather looks to be Tuesday and Wednesday
evenings. The thunderstorm and severe threat should decrease late
week as AVA and modest CAA returns leading to high pressure and a
drier overall airmass.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 637 AM EDT Fri May 3 2024

Impacts:

- Scattered showers early in the period, with occasional MVFR
  conditions mid morning into early afternoon.

- Isolated thunderstorms possible, but too uncertain for inclusion.

- Fog possible very late in the period, depending upon how much
  cloud cover lingers tonight.

Discussion:

Scattered showers have overspread much of the area this morning.
This activity will continue much of the morning into early
afternoon, before lessening from west to east as a front moves
through the area. Some occasional MVFR conditions will be possible
in these showers, though not as widespread as previous expectations.
Will carry TEMPO MVFR conditions at all sites but LAF. A few
thunderstorms will be possible, but too low probability/uncertain
for inclusion in the TAFs.

Winds will be variable or westerly early on, becoming more northerly
and then northeasterly later in the period, 10KT or less throughout.

Depending upon the character of the mid and high cloud cover that
will linger tonight, and the degree of clearing, some fog will be
possible, but will not mention at this time. If clearing is
substantial, wet ground from the rainfall may promote patchy dense
fog late tonight into Saturday morning.

&&

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

&&

$$

SHORT TERM...Nield
LONG TERM...Updike
AVIATION...Nield