707
FXUS63 KIND 020128
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
928 PM EDT Thu May 1 2025

.KEY MESSAGES...

- Scattered to numerous showers and thunderstorms this afternoon
  into the evening, a few of which may be strong to severe

- Breezy today, with southwesterly winds 15-25 MPH gusting as high
  as 35 MPH

- Cooler with periodic showers this weekend into early next week

&&

.FORECAST UPDATE...
Issued at 928 PM EDT Thu May 1 2025

Low pressure was found over Michigan this evening, providing broad
cyclonic flow across the region including Central Indiana. Radar
shows a line of thunderstorms over southern Central Indiana,
progressing eastward, but diminishing in intensity as heating and
instability is lost. Southwesterly lower level flow was in place
across Central Indiana.  Looking aloft, water vapor showed ridging
in place over the east and west coast with a trough in place over
the northern plains and Great Lakes.

HRRR suggests continued convection within the cyclonic flow
streaming across central Indiana through 09Z. Given recent radar
trends along with the loss of heating, believe this is a bit
overdone and showers and storms will continue to diminish the next
few hours. Thus will keep low chance pops through about 03z-04z, but
trend toward dry weather overnight. Skies should remain partly
cloudy overnight with the cyclonic flow in place along with
lingering convective debris CI.

Slight cold air advection is in place tonight. Still with dew points
in the 50s, ongoing lows in the mid 50s appear on target.

&&

.SHORT TERM (This evening through Friday)...
Issued at 229 PM EDT Thu May 1 2025

Central Indiana has remained in the warm sector of a broad surface
low moving into the Great Lakes. With that said, destabilization in
the warm sector has been capped slightly due to a persistent mid
level cloud deck. Current ACARS sounding are showing some erosion of
this diabatic cap, but we are likely still an hour or two from
efficient storm initiation.

This upper wave will be rather amplified in the upper levels leading
to strong upper level dynamics. However, the low level kinematics
will be lacking without any strong negative height tendency over the
region. Additionally, deep cooling aloft should lead to steep lapse
rates over central Indiana this afternoon with storms initiation
between 4PM and 7PM EDT. If these storms are able to reach the
strong dynamics aloft, greater ventilation could lead to clusters
and modest organization, with the primary severe threat being 1-2"
hail. There is a non-zero damaging wind threat, but will heavily
rely on collapsing suspended cores, as linear organization is not
expected.

Without strong forcing in the buoyant sector, overall rain amounts
should be spotty today, but generally less than a half an inch, with
most locations receiving less than a tenth.

Another pressure trough will pass through the Ohio Valley tomorrow,
but the stronger upper level dynamics will remain mostly to the
east/southeast of central Indiana. There is some low level jet
development in the warm sector tomorrow, leading to some low level
pressure depletion and low pressure development. The resulting
boundary is expected to be south of central Indiana at this time,
but there is some variability leading to a very low severe threat
over far southern central Indiana for tomorrow afternoon. Rain fall
rates along this boundary are likely to be higher and more prolonged
leading to a narrow corridor of 1"+ QPF over southern Indiana.

&&

.LONG TERM (Friday night through Thursday)...
Issued at 229 PM EDT Thu May 1 2025

Saturday through Monday:

The main area of energy within the upper trough is gradually
expected to depart to the northeast this weekend. With that said,
there is a trend towards the mid level vorticity lobe detaching
from the upper level jet stream, and remaining aloft through the
weekend and into early next week. The bimodal distribution has
significantly swung towards this aforementioned solution leading to
fairly high confidence in a cut off low becoming the primary weather
driver this weekend. With the cut off low aloft, temperatures will
remain mild with highs in the upper 50s to 60s.

There is a small chance for the moderate rain along Friday`s
pressure trough to remain within central Indiana into Saturday
morning. Otherwise, any rainfall should be scattered to isolated and
light. No thunder is expected Saturday or Sunday.

Next Tuesday Onward:

With the cut off low taking hold, a large omega block is expected in
the later portions of the long range. This will hinder any trough
development over the CONUS keeping conditions fairly stagnant for
most of next week. As the low departs Tuesday, a slight warming
trend is likely, but temperatures should remain within the 70s.
Precipitation trends are much more variable leading to low
confidence on potential rainfall beyond next Thursday

&&

.AVIATION (00Z TAF Issuance)...
Issued at 653 PM EDT Thu May 1 2025

Impacts:

- Showers w/ scattered thunderstorms expected through 02Z.

- Brief MVFR cigs possible overnight.

Discussion:

Scattered diurnal convection amid cyclonic flow due to low pressure
moving through the Great Lakes will continue to wane this evening.
HRRR shows as heating is lost this evening and as the surface low
pulls northeast, expected areal coverage of ongoing showers will
continue to diminish and end. Until then VCSH as coverage remains
limited.

Models overnight suggest residual lower level moisture may result in
some MVFR cigs toward daybreak, and this has been included.

Small showers and storm chances will return on Friday afternoon as
diurnal heating along with an approaching upper trough will provide
favorable conditions for shower development. For now, have used as
VCSH mention Friday afternoon.


&&

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

$$

UPDATE...Puma
SHORT TERM...Updike
LONG TERM...Updike
AVIATION...Puma