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000
FXUS63 KIND 242321
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
721 PM EDT Wed Apr 24 2024

.KEY MESSAGES...

- Cool tonight into Thursday, with some frost across northern
  portions of central Indiana tonight.

- Active pattern returns Friday into next week with above normal
  temperatures and frequent storm chances

&&

.SHORT TERM (This evening through Thursday)...
Issued at 247 PM EDT Wed Apr 24 2024

Rest of This Afternoon...

Satellite shows large patches of the low cloud deck becoming more
cellular looking with breaks in between. Thicker clouds remain
across the northeastern forecast area.

Thus believe that clouds will continue to slowly break up across
much of the area, with thicker patches remaining in the northeast.
Will allow skies to become partly cloudy most areas (far south may
be mostly sunny, with far northeast mostly cloudy).

The returning sunshine will allow temperatures to warm some but
remain well below normal across the north. The south will be warmer
but still below normal.

Tonight...

High pressure will remain centered well northeast of the area, but
its influence will still be enough for winds to become light
overnight.

Lower clouds will linger across the northeastern forecast area into
the night as colder air aloft hangs around. There remains higher
than desired uncertainty on how long they`ll stay though. The NAM
would keep skies cloudy through the night, while ensembles are less
pessimistic.

Even if the low clouds dissipate, high clouds will be streaming in
from the northwest as they flow over an approaching upper ridge.

Usually, these types of issues would not have much impact. However,
tonight, they will have an impact on frost potential and coverage.
More clouds would mean less frost and vice versa.

Would rather err on the side of caution and after coordination with
neighboring offices, will go with a Frost Advisory across the north
overnight tonight. Again, confidence is lower than desired.

Lows will be in the middle to upper 30s most areas.

Thursday...

Quiet weather will continue on Thursday with high pressure in
control. High clouds will pass through from time to time.

Winds will still remain mainly easterly, so temperatures will not be
much warmer than today. Will go with highs in the upper 50s to lower
60s.

&&

.LONG TERM (Thursday night through Wednesday)...
Issued at 247 PM EDT Wed Apr 24 2024

The long term will be the beginning of our warming trend, with 800-
700mb modest WAA initiating deep ridging aloft. Initially, surface
warm air will lag behind the mid to upper level push, leaving an
elongated warm-front over the Ohio Valley late Thursday into Friday.
Isentropic lift along the warm front will eventually saturate the
low to mid levels, leading to scattered rain showers across the
State. This will primarily occur between late Thursday night and
Friday afternoon, but lingering showers could remain throughout the
day/night on Friday. A weak shortwave within the broad upstream
portion of the upper level trough may induce enough lift for
isolated to scattered showers/thunderstorms overnight on Friday, but
most areas should remain relatively dry.

By Saturday, central Indiana should be well positioned inside the
warm sector, with surface temperatures reaching the upper 70s to low
80s Saturday afternoon. Temperatures should increase even further
into Sunday as southerly low level winds increase. The current
expectation is for highs in the low 80s on Sunday, but the daily
record of 86 for Indianapolis is not out of reach, depending on
cloud cover from upstream MCSs.

These aforementioned upstream MCSs will be the main source of
uncertainty for rain/thunderstorms over central Indiana on Saturday
and Sunday. Overall, the environment will lack sufficient lift for
convective initiation, but left over boundaries or upscale growth
upstream could change this current line of thinking. Best chances
for any thunderstorms would likely be over western portions of
Indiana.

By early next week, a cold front will approach from the west,
providing an increased thunderstorm threat. Its still too far out to
determine severity, but current parameter spacing expectations could
lead to deep convection and a non-zero severe threat. This should
become more clear in the coming days.

Day 8-14: Multi-model ensemble mean shows anomalous ridging and
warmer than normal temperatures for much of this period.
Precipitation opportunities will still be present within less
dramatic forcing regime, but with sufficient moisture
and instability, leading to some convection.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 720 PM EDT Wed Apr 24 2024

Impacts:

- Light winds veering from northerly to easterly overnight

Discussion:

Dry and VFR conditions will oversee surface high pressure, centered
over the Great Lakes...continuing to build into central Indiana
tonight while sliding to our northeast.

FEW/SCT clouds around 3,000FT may linger near KLAF through 3z
before departing to the east...with FEW/SCT high clouds remaining
over the region into Thursday morning. Sky cover should reach a
minimum around early afternoon Thursday, before more FEW/SCT high
clouds approach from the southwest ahead of the next system.

Winds tonight around 7KT are expected to veer to 060-070 degrees by
9Z...with easterly flow to be sustained generally under 10KT through
the remainder of the forecast period.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 1 AM to 9 AM EDT Thursday for INZ021-028>031-
035>043-049.

&&

$$

SHORT TERM...50
LONG TERM...Updike
AVIATION...AGM