174
FXUS63 KIND 290456
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1256 AM EDT Mon Apr 29 2024

.KEY MESSAGES...

- Showers and storms return to the Wabash Valley overnight.

- Warmer than normal conditions continue through the week.

- Additional thunderstorms expected Friday into Saturday.

&&

.FORECAST UPDATE...
Issued at 1023 PM EDT Sun Apr 28 2024

Wind gusts have wained amidst the development of a nocturnal
temperature inversion. This has also allowed for surface winds to
become more southerly without the influence of 800-900mb SW winds.
Cloud cover has increased slightly faster than originally expected
out ahead of the shortwave and lead to slightly higher overnight
over NW Indiana.

Otherwise, forecast is on track. Precipitation should move in after
midnight tonight from west to east, and continue throughout tomorrow
morning. Total rainfall amounts of around 0.25-0.5" are still
expected.

&&

.SHORT TERM (This evening through Monday)...
Issued at 252 PM EDT Sun Apr 28 2024

GOES-16 visible loop and obs were showing filtered sunshine across
central Indiana this afternoon along with some fair weather cu. Lack
of synoptic lift and only weak instability and a mid level cap have
cap convection from going up. In addition, the southerly breeze with
gusts to near 30 knots has resulted in well above normal
temperatures in the upper 70s to lower 80s early this afternoon.

H20 vapor imagery and upper air data was showing a percent ridge of
high pressure over the Appalachians with a low spinning over
southern South Dakota and northern Minnesota. The latter feature
will move into the eastern Dakotas by Monday morning and Lake
Superior Monday evening. This will bring an associated cold front to
near a western Chicago suburb to St. Louis line Monday evening.
Sufficient instability and deep moisture combined with the
approaching system and any impulses ahead of it will bring
widespread showers to the Wabash Valley overnight and all of central
Indiana Monday. Went with 70% coverage over the Wabash Valley to 20%
or less east central tonight and 70-80% over all of central Indiana
Monday.

Ensembles 25th percentile 24 hour QPF ending 00z Tuesday for the
upper Wabash Valley is 0.25 inches and the 75th percentile near and
inch. Most other locales ranged from 0.20 inches to 0.60 inches in
the respective percentiles. This should not lead to anything more
than perhaps some brief river flooding along the lower Wabash early
next week.

The widespread cloud cover and convection should keep temperatures
down more tomorrow but with breezy southerly winds continuing, they
will still be above normal with highs in the 70s expected.

&&

.LONG TERM (Monday night through Sunday)...
Issued at 252 PM EDT Sun Apr 28 2024

Monday Night Through Wednesday.

Precipitation will quickly come to an end Monday night into early
Tuesday as the line of convection continues to weaken as it pushes
further east and away from the forcing associated with the low
pressure system that has brought severe weather to much of the
Central Plains for the last few days. This will bring a brief break
in rain chances for central Indiana through early Wednesday when the
next system looks to push through the Dakotas into the Great Lakes
region. Rainfall from this low pressure system is expected to stay
to the north and west of central Indiana, but a decaying storm
complex may linger just long enough to reach the northwestern
counties Wednesday morning, but either way some enhancement in low
and mid level clouds looks likely for much of the day Wednesday.

Thursday Through Sunday.

Forecast confidence into the second half of the work week and
weekend begins to lessen with significant model spread on the
cyclogenesis timing and location of the next system that ejects
from the Rockies with spatial differences in the order of multiple
states between the 00Z GFS and 12Z GFS.  That being said, the large
scale nature of this low will be enough that there is higher
confidence in precipitation Friday into Saturday but details on the
severe potential or QPF would be more determined by the track that
the system ends up taking. Conditions then return closer to normal
in the aftermath of the late week system with low rain chances
continuing into Saturday with highs in the low 70s and lows near 50.

&&
oduce
some light rain shower or
.AVIATION (06Z TAF Issuance)...
Issued at 1256 AM EDT Mon Apr 29 2024

Impacts:

- Showers after 09z in the Wabash Valley, thunderstorms also possible

- MVFR and very brief IFR conditions possible in convection; MVFR
CIGs tomorrow

Discussion:

Convection over western IL and eastern MO is expected to advance to
the Wabash valley, including LAF and HUF near 10-12Z. However upon
approach weakening features appear in play as the LLJ appears to
exit and diminish with the approaching trough. HRRR also shows a
diminishing trend for precipitation across the area through the
morning hours and into the afternoon as the weak trough aloft
lingers across Indiana. Thus have used a vcsh mention for much of
Monday across the TAF sites as the weak features will likely produce
some light rain showers or even a stray thunderstorm, but confidence
on timing and location is too low.

Better confidence exists for precip arriving in the Wabash valley
near 10-12Z, and we have used a tempo group to account for that.

As weak high pressure build across the area tonight some MVFR cigs
may return overnight at IND along with some MVFR Fog.

&&

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

$$

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