000
FXUS63 KIND 111658
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1258 PM EDT Thu Apr 11 2024

.KEY MESSAGES...

- Rain will persist through this evening, but decreasing coverage
- Minor Flooding possible
- Rainfall in the next 48 hours will may prolong ongoing river
flooding at a minimum, and lead to some renewed lowland flooding
along main stem rivers.
- Active weather pattern continues into next week with numerous
chances for rain and storms.
- Above normal temperatures Sunday into most of next week.

&&

.FORECAST UPDATE...
Issued at 933 AM EDT Thu Apr 11 2024

- Rain Showers becoming more scattered to isolated by mid to late
afternoon
- Cloudy and Cool with steady state temperatures
- Minor Flooding/ponding of water continues

Surface analysis this morning shows deep low pressure over southwest
Indiana, with a warm front that extended northeast into NW Ohio and
WNY. A cold front extended south across southern Indiana to western
KY. Aloft, a deep upper trough was found over the upper Midwest
through the Mississippi Valley. This was resulting in southerly flow
across Indiana ahead of the approaching upper trough axis. A moist
air mass remained across Central Indiana with dew points in the 50s.
IND ACARS soundings show a saturated column this morning with pwats
above 1.10 inches. Radar this morning shows the heaviest rains have
pushed to northern Central Indiana, continuing their northeastward
progress. More scattered to isolated type precipitation was found
upstream over SW Indiana.

The upper trough axis is expected to become negatively tilted this
afternoon as it begins to pivot across Central Indiana. By late
afternoon, best forcing will become located northeast of Central
Indiana. As this occurs, winds across Central Indiana are expected
to become northwest as the associated surface area of low pressure
pushes to Ohio this afternoon. This will allow the intrusion of dry
air into the system as forecast sounding show some drying by late
afternoon. HRRR shows rain showers over Central Indiana rapidly
departing late this morning, before suggesting some redevelopment
during the afternoon. Thus scattered rain showers are still expected
to be found across much of Central Indiana late this morning and
afternoon, but areal coverage and amounts of precipitation should
continue to trend lower. Will continue with at least likely pops
through the mid afternoon, trending toward chance pops near 00Z.

Given the expected clouds and rain along with the arrival of
northwest winds and cold air advection in the wake of the cold
front, temperatures will remain rather steady today and begin to
fall this afternoon. Expect todays highs near current temperatures.

&&

.SHORT TERM (Today and tonight)...
Issued at 253 AM EDT Thu Apr 11 2024

Early This Morning...Large precip shield continues to lift north
across the state. Parcels still seeing stronger collision taking
place within the axis of steadier rain from Michigan City
south/southwest through East Central Illinois. With the surface low
displaced to the south, parcels are still ascending along isentropic
surfaces that are already saturated, which is helping to maintain
development of light showers feeding over similar locations.
Overnight heavier pockets of rain had fallen south of Indy Metro,
but the good news was things had not been a prolonged period of
moderate/heavy rainfall and was progressive. Several areas have
picked up in excess of 1.5", and expect continued flow of steady
showers through the morning hours.

With the surface low progged to lift north over Southern Indiana mid-
morning, expect this will bring a decrease in the pressure gradient,
as the mid-lvl trough axis approaches from the west. This decreased
gradient should be enough to bring a brief period of lighter
conditions to Indiana, and could allow ceilings and perhaps
visibilities to briefly reduce.

The timing for the frontal boundary will remain the focus for this
afternoon/evening. Guidance has been trending slightly slower,
likely a function of the downstream weak ridging slowing the forward
progression to the trough axis. Isallobaric pressure gradient
quickly arrives along the backside of the surface wave this
afternoon, and will quickly turn winds northwesterly. Guidance has
been learning towards winds around 15 to 25 mph, but occasional
gusts could approach 35 mph. The tight gradient does linger into the
evening/overnight hours. This should bring a change to the precip
shield tonight, with the lack of ascending moist parcels going
through more of a downward movement and starting to dry. This should
allow light precip with smaller less efficient hydrometeors falling.
Will bring a reduction to the POPs, with a continued feed of drier
air working back into the region overnight.

&&

.LONG TERM (Friday through Wednesday)...
Issued at 253 AM EDT Thu Apr 11 2024

Friday...Deep trough and potent shortwave will still be influencing
the weather setup for Great Lakes/Ohio Valley. Heights aloft do
amplify upstream across the Northern Plains, and should start to
arrive across the Ohio Valley by midday/afternoon hours Fri. Prior
to this though the shortwave will prolong a thick moisture field
over Indiana with a northerly flow. Downstream of the shortwave the
pattern does appear to open up, but this may not occur until late
Fri. As a result expect a slow eastward progression to the trough
axis, and thus likely holding onto the clouds and light precip a
touch longer into the afternoon Fri for portions of Indiana.

While the thick solar shielding will likely limit surface heating,
there doesn`t appear to be a potent thermal trough overhead, expect
temps to be rather uniform in the upper 50s to low 60s.

Saturday through Sunday... Trough axis finally pivots east of the
region, with heights on the rise from west to east. This should help
usher in diffluent downward air into the Ohio Valley, while the
surface ridge is displaced well south. This will maintain a light
westerly flow over Indiana, which could set the stage for diurnal
cumulus field to develop late Sat morning through the afternoon.
Guidance presently is not indicating this, but the setup is pointing
towards a diurnal cu layer developing and will likely pose some
limits to the direct sunlight. Given the abundance of recent
precipitation, expect parcels to see an increased capacity and likely
not see a large diurnal curve to temps Sat. Temps will definitely
warm into the 60s, but with mixed layer bringing 30kts to the
surface and perhaps a cloud layer, this will likely slow temps a
touch. If diurnal clouds are thick enough Sat, this will impact the
depth to the mixed layer.

500mb longwave setup favors a progressive flow for the Great
Lakes/Ohio Valley, and this appears to be the case for Sun.
Fortunately the weak vort max that arrives Sun will be moisture
starved as it arrives across the Great Lakes, which should only
bring a slight increase in cloud cover. The more important feature
for Sun is the low-level southwest flow increasing. Thermal ridge is
progged to develop and quickly advect north, allowing temps to reach
the 70s. Given the volume of recent rainfall just a few days prior,
expect parcels to see a slower diurnal curve. Some points may be
able to warm into the upper 70s Sun afternoon.

Monday through Wednesday...Amplified ridging returns to the Northern
Plains Mon into Tue, which should assist in strengthening the
southwest/warm flow into the Ohio Valley. Guidance has gone all-in
with pushing temps Mon into the 80s, but have some concerns to
seeing such a large diurnal curve. The positives to the setup is
that precip should still hold off through Mon. Moving into Tue
guidance has a shortwave that slides east from the Central Rockies,
but then lifts north. There may be enough moisture to overspread
precip chances by Tue into Wed.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1258 PM EDT Thu Apr 11 2024

Impacts:

- IFR Conditions briefly will improve to VFR late this afternoon.
- MVFR Conditions return late this evening and persist overnight.
- VFR returns by late Friday morning.
- Gusty west winds around 30 knts possible tonight and Friday.

Discussion:

Low pressure over eastern Indiana will quickly depart to Ohio and
points northeast this afternoon. An associated upper trough axis is
also expected to depart northeast. Ongoing radar trends suggest less
forcing and drier air working into the system as shower coverage has
dropped off dramatically, becoming more scattered in coverage.

Lower level cyclonic flow and the trough axis aloft will continue to
persist across the area through the afternoon. This will result in
continued chances for scattered light rain and continued IFR Cigs.
Upstream over IL, VFR cigs were present. As the low departs east,
these higher cigs should begin to arrive across the TAF sites
through the early evening.

Another quick moving upper disturbance is expected to arrive
overnight within the trough-like flow aloft. The feature should once
again generate some scattered rain showers. Forecast soundings
overnight trend toward saturation, although the HRRR does not show
widespread precipitation coverage. Thus have trended toward VCSH and
MVFR Cigs as this feature passes.

A return to VFR is expected on Friday as high pressure builds across
Indiana and low pressure departs northeast. Still a strong cyclonic
pressure gradient will remain across Central Indiana, allowing for
gusty winds tonight and Friday. Wind gusts to near 30-35 knts will
be possible.

&&

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

$$

UPDATE...Puma
SHORT TERM...Beach
LONG TERM...Beach
AVIATION...Puma