976
FXUS63 KIND 081332
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
932 AM EDT Sat Jun 8 2024

.KEY MESSAGES...

- Rain showers later this morning, especially southwest portions
  of the CWA.

- Low chance for thunderstorms this afternoon, particularly
  northwest areas.

- Near-average temps through midweek, then warming trend late next
  week.

&&

.FORECAST UPDATE...
Issued at 932 AM EDT Sat Jun 8 2024

The cloud shield associated with the convective cluster tracking
through the Ozarks east into the lower Ohio Valley has overspread
the forecast area this morning. Weakening showers have moved into the
lower Wabash Valley with a few sprinkles further to the north. 13Z
temperatures were largely in the 60s.

The overall forecast is in good shape going forward for the rest of
the day. Rain this morning will remain confined to southwest
portions of the forecast area with very light showers or sprinkles
further northeast...gradually diminishing as it moves east into a
progressively drier airmass. While most of the rain will be gone from
the area by 18Z...the cloud cover will remain with perhaps a few
breaks in the deck for the late afternoon in the wake of the remnant
convective cluster from this morning.

There remains a low threat for isolated showers to redevelop late
day into the evening ahead of an approaching weak cold front. Most
of the CAMs data this morning is not bullish on this solution with
an abundance of dry air and convective inhibition remaining over the
region. Think the most plausible scenario is that any showers will
be confined to a narrow window in the vicinity of the cold front
later in the evening as that provides a nudge up in forcing to
generate isolated activity. Will maintain the isolated thunder
mention in the northwest during the evening but model soundings show
only paltry amounts of elevated instability immediately ahead of the
front. In summary...cannot rule out a a few rumbles of thunder this
evening into the early overnight but expecting mainly showers.

Temps...elected to leave highs as is in the mid 70s for the
afternoon based on a more pessimistic approach in extensive cloud
coverage maintaining itself over the region for much of the day.
Zone and grid updates out.

&&

.SHORT TERM (Today and tonight)...
Issued at 253 AM EDT Sat Jun 8 2024

As of around midnight, satellite imagery shows high cirrus
associated with a developing convective system spreading eastward.
These higher clouds will begin advancing into Indiana over the next
several hours. The track and evolution of this convective complex
has implications on our expected weather today. Model consensus is
now largely in agreement that this feature dives southeastward and
weakens with time. This makes sense, as with eastward extent rich
moisture, instability, and the magnitude of a low-level jet all
diminish. Rain associated with the system`s stratiform region has a
decent chance of entering southwest portions of our CWA this
morning. Rain appears likely though amounts should remain light.

Our biggest forecast challenge looks to be after the convective
system or its remnants exit the region. Guidance shows a weak
surface wave passing just to our north, with enough of a mass
response to turn winds southwesterly for a period of time. A narrow
region of instability may develop ahead of this wave and its
associated cold front. The main question is: would this be enough to
trigger a few showers or thunderstorms? The answer to this is tied
to the morning system. Should the dying complex contain a
stronger/deeper cold pool it may subdue destabilization in its wake
(as seen in the NAM Nest). If the system decays faster, with less
rainfall, then there may be enough destabilization ahead of the
front for convection (shown by the HRRR). This may also have
implications for our high temperatures forecast today.

Both scenarios are possible, and the MCS taking shape to our west
will need to be watched carefully. For now, will include chance PoPs
with slight chance thunder to account for this. The most favored
location for afternoon convective development would be our
northwestern counties, as they lie closest to the surface wave and
less effort would be needed for destabilization to occur there.
Should convection develop, model soundings and hodographs do not
suggest organized severe potential. Still, enough shear exists that
a stronger updraft is not out of the question. In this reasonable
worst-case scenario small hail and gusty winds would be the primary
hazard.

Aside from rain/storm chances, winds look to take on a southwesterly
component and occasionally gust to 20kt at times. Cloud bases
decrease with time, likely to under 3000 feet agl. Additionally,
skies likely remain mostly cloudy at best even after the morning
rain comes to an end.

By tonight, the aforementioned cold front will have swept through the
area. Winds become northerly and temperatures drop into the 50s for
the most part. Clouds remain present to some extent as upstream
convective activity keeps at least high-level clouds passing through
at times.

&&

.LONG TERM (Sunday through Friday)...
Issued at 253 AM EDT Sat Jun 8 2024

Fairly quiet weather is expected in the long range as northwesterly
flow prevails through the depth of the atmosphere. Ensemble guidance
is in fairly good agreement showing northwesterly flow continuing
through at least midweek. The best chance of precipitation through
the period looks to occur on Sunday as another convective system
passes close by to our southwest. As of right now, the bulk of
guidance keeps this far enough that don`t see much rain at all.
Should a slight shift northward occur, precip may clip southwestern
parts of our CWA Sunday morning.

Quiet weather continues into the new week within the northwesterly
flow pattern. Dry continental air from the north along with weak
synoptic forcing should limit precip chances through Wednesday.
Expect near-average temps through Wednesday as well.

Change appears increasingly likely come Thursday, as ensemble
guidance continues to show ridging aloft taking hold. Ridging over
the eastern CONUS combined with southerly/southwesterly surface flow
favors a warming trend. Indeed, blended guidance shows highs in the
upper 80s to near 90 by Friday. There remains some uncertainty here,
however, as some deterministic models delay the ridge-building a
bit. In fact, the GFS and the ECMWF both want to bring a cold front
through Thursday night into Friday. There may even be some low
precip chances with this. Regardless, a warming trend appears
increasingly likely later this coming week or next weekend.
Additionally, increasing humidity accompanies the warmth to some
extent.

Taking a look even further beyond the end of the long range, into
the day 8-14 period...we see a stronger signal for ridging within
ensemble guidance. Continued above-average warm, and near to below-
average precipitation is therefore favored through this time range.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 644 AM EDT Sat Jun 8 2024

Impacts:

- Scattered showers at times today.
- MVFR ceilings possible within showers and for a few hours this
  evening/overnight.
- 20kt wind gusts Today and Sunday.

Discussion:

Isolated showers are possible today at all terminals. However, the
best chance of morning showers are at HUF and BMG. The best chance
of afternoon and evening showers is LAF, HUF, and IND. There is a
low chance of thunderstorms as well.

A cold front should pass across Indiana from the north this evening
shifting winds from SW to NNW. A few gusts before the front arrives
may reach 20kt.

MVFR ceilings are possible within rain showers and along the frontal
boundary. A period of lower ceilings is possible in the evening and
into the night. VFR conditions return very late in the TAF period or
just after its end, as dry air flows southward behind the front.
High clouds can be expected at times Sunday. Northwest winds behind
the front may gust up to 20kt at times Sunday.

&&

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

&&

$$

UPDATE...Ryan
SHORT TERM...Eckhoff
LONG TERM...Eckhoff
AVIATION...Eckhoff