705
FXUS63 KIND 150634
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
234 AM EDT Wed May 15 2024

.KEY MESSAGES...

- Scattered showers and a few rumbles of thunder through the
  afternoon.

- Rain and storm chances return at times late Thursday into Saturday.

- Above normal temperatures for this weekend through the middle of
next week.

&&

.SHORT TERM (Today and tonight)...
Issued at 234 AM EDT Wed May 15 2024

Through Daybreak.

Pockets of locally heavy rain will continue through the night as
showers continue to slowly circle around the surface low pressure
situated over southern Indiana. The heaviest rain has fallen across
northwestern Hendricks county and across the US50 corridor from
Vincennes to around Bedford but so far only very limited impacts
have been noted due to the sporadic and spatially sparse areas of
heavier rain. Over the last hour the rain coverage and intensity has
gradually lessened as the better forcing begins to exit and the with
the surface low now directly overhead, the moisture flow into
southern Indiana has been cut off.  Focus going into the morning
hours will then be on locally heavy showers on the northwest side of
the surface low as it slowly pushes off to the east. Temperatures
will remain near steady state in the low 60s through the rest of the
night with thick cloud cover helping to insulate the lower levels.

Today.

By daybreak this morning morning the low pressure system associated
the recent rain will begin to exit the forecast area as it moves
into southwestern Ohio. The main focus area for rain through the
afternoon hours will be associated a residual area of lift around
700mb to the northwest of the exiting surface low.  Latest high
resolution models are showing that subsidence at around 700mb will
begin to inhibit shower formation but also help to keep the clouds
in place through much of the daytime hours.

Current thoughts are that by early afternoon coverage will be
scattered with only isolated showers by later into the day. Thunder
will be minimal but not non-existent due to a lack of instability
so will cap the thunder mention to isolated through today. The thick
cloud cover and lack of southerly flow will also help to moderate
temperatures again today with highs only around 70.

Tonight.

Clouds will likely stick around for much of the night tonight with
model soundings showing persistent saturation at the top of the
boundary layer, but will have to keep an eye out for any locations
that do begin to clear as the recent rains will help to
supersaturate the low levels and may allow for some fog formation.
The low confidence that things will clear out enough for widespread
fog makes a Dense Fog Advisory seem a bit overdone at this time, but
will have to monitor things going into this evening.

&&

.LONG TERM (Thursday through Tuesday)...
Issued at 234 AM EDT Wed May 15 2024

Progressive...quasi-zonal flow aloft will continue across the
country through the end of the week with rain chances returning as
early as Thursday afternoon and persisting into the first half of
the weekend. A more amplified regime will develop by early next week
with a trough in the western states and ridging over the eastern
half of the country. This will bring warmer temperatures along with
the potential for more substantial convective risks as pieces of
energy aloft eject out of the western trough.

Thursday through Saturday

Despite the presence of surface ridging Thursday morning...model
soundings and low level RH progs remain saturated within the
boundary layer with the presence of an inversion. Expect a
combination of low stratus and fog over the forecast area as a
result to start Thursday with some sunshine returning through
midday.

This will be short lived as moisture ahead of the next storm system
will encroach in the region Thursday afternoon. Initially forcing
aloft will be weak with showers likely to be light and scattered.
The arrival of stronger isentropic lift into the area Thursday night
as low pressure passes to the northwest of central Indiana will lead
to an uptick in shower coverage and at least some potential for
embedded convection with minimal instability. But overall...sounding
profiles hints at lingering dry air within the column which will
likely keep rain from becoming widespread and overall rates
relatively light through daybreak Friday.

Moisture advection and forcing aloft will notably increase Friday as
the combination of an upper level wave and surface low pressure
tracks northeast into the lower Ohio Valley. A strong low level jet
will nose into the region Friday afternoon...enhancing isentropic
lift and leading to more efficient precipitation rates as strong
convergence in the 925-850mb and 850-700mb layers coincide across
the Ohio Valley Friday afternoon and evening. In addition..precip
water values will peak near 1.50 inches on Friday with model
soundings showing a saturated column. All of these factors support a
growing threat for locally heavy rainfall and higher rates within
convective cells with 1 to 2 inches again possible Friday and Friday
night across the forecast area. Considering the recent rains from
Tuesday and so far early this morning...localized flooding concerns
would be elevated should this setup come to fruition.

The model suite diverges with the handling of the upper level wave
into the first part of the weekend...and that has implications with
respect to rainfall chances and coverage on Saturday. Considering
the progressive nature of the flow regime aloft...prefer the
solutions supporting convection diminishing by Saturday afternoon as
weak high pressure at the surface and ridging aloft attempts to
expand into the Ohio Valley.

Temperatures will remain seasonable through Saturday with highs in
the 70s. The coolest day is likely to be Friday as rain coverage
increases with the approach of the upper low and surface wave from
the southwest.

Saturday Night through Tuesday

The presence of weak surface high pressure in tandem with ridging
aloft will enable mainly dry conditions Saturday night into Monday.
Highs will warm with the upper ridge building into the Ohio Valley
with low to mid 80s expected by Sunday and Monday.

The forecast remains fluid and low confidence for early next week.
There remains a signal for increasing convective activity impacting
the region as the ridge flattens and multiple waves aloft traverse
west to east across the area. Extended model guidance also continues
to highlight a stronger piece of energy ejecting out of the western
trough and spinning up a deeper surface low over the upper Midwest
by Tuesday or Wednesday. While we remain well too far for
specifics...the signal for an uptick in convection and potentially
severe weather is present for the early and middle part of next week
across the Great Lakes and parts of the Ohio Valley. Temperatures
will remain warm with highs in the 80s daily.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1214 AM EDT Wed May 15 2024

Impacts:
- IFR to MVFR cigs through 20Z
- MVFR vsbys through 16Z due to -RA

Discussion:

Periods of IFR to MVFR cigs are expected through the rest of the
overnight hours as rain continues across central Indiana.  Cigs
should gradually improve to consistently MVFR after 12Z before
scattering out around 20Z. Rain coverage will gradually decrease
after 12Z but occasional showers are expected through the early
afternoon.  Winds will generally remain easterly to northeasterly at
5-10kts through the TAF period.


&&

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

$$

SHORT TERM...White
LONG TERM...Ryan
AVIATION...White