526
FXUS63 KIND 181900
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
300 PM EDT Sat May 18 2024

.KEY MESSAGES...

- Fog possible again tonight; locally dense

- Isolated showers across northern Indiana Sunday afternoon

- Unseasonably warm Sunday-Tuesday with highs in 80s...ahead
of increasing strong t-storm threat late Tuesday and Wednesday

&&

.SHORT TERM (This evening through Sunday)...
Issued at 258 PM EDT Sat May 18 2024

Isolated convection is possible through early evening, but there are
several limiting factors for more sustained/deeper convection.
Coverage is likely to be ~5% or less. Limiting factors include
subsident capping layer around 3-4-km, dry entrainment, weak winds
resulting in vertical updrafts that are short-lived. Any brief
convective showers that do form would be most likely north of a band
of wake subsidence across roughly the northern third of Indiana, and
would diminish shortly after sunset.

Deeper mixing today will redistribute some dry air making low level
moisture slightly less than the last two days. But, the air mass
largely hasn`t changed otherwise with little/no horizontal
advection. Still, with clear conditions and an MSLP pattern that
will favor light/calm winds, fog is once again expected. Dense fog
is possible. There may be a slight preference for denser fog in
areas of east- central and southeast Indiana where mixing was
delayed given the magnitude of this morning`s fog.

Ridging will build Sunday bringing a warmer pattern (temperatures at
or just above the warmest temperature so far this season; mid-80s
for maximums area wide). A northern stream wave will nudge a weak
front to near the northern portion of our area and convergence along
it may result in isolated showers and thunderstorms Sunday
afternoon/evening. Coverage should be limited. Weak flow under the
ridge will support unorganized short-lived single cells.

&&

.LONG TERM (Sunday night through Saturday)...
Issued at 258 PM EDT Sat May 18 2024

Sunday night through Monday...

Upper ridging and surface high pressure will provide quiet weather
conditions early in the extended. Expect increasing heights aloft
and S/SW low level flow to help warm temperatures well into the 80s
Monday. Thankfully relative humidity will remain low with dewpoints
generally in the low 60s so it won`t feel unbearable.

Monday night onward...

Guidance is in general agreement that the upper level pattern will
switch to more full-latitude troughing across the western CONUS
compared to split flow this past week. This should result in a more
active pattern with multiple embedded shortwaves potentially
tracking over the Midwest next week. Look for rain chances to begin
increasing Monday evening and remaining elevated through the long
term. The best chance for rain looks be late Tuesday through
Wednesday when an upper trough moves through.

Severe weather is possible late Tuesday into Tuesday night and again
on Wednesday, but uncertainties remain in the forecast. Models have
been consistent showing a deepening surface low moving towards
northern portions of the Great Lakes late Tuesday. The current
expectation is for an MCS to develop near Iowa/Missouri along an
attendant cold front before propagating eastward. The environment
should gradually become less favorable as the MCS moves out well
ahead of the front which should lead to gradual weakening with time.
If the complex of storms can survive, there would be the potential
for mainly damaging wind gusts Tuesday night. Other convective
hazards such as large hail or tornadoes cannot be completely ruled
out.

Another round of severe weather is possible Wednesday, but
uncertainties remain for this forecast as well. Latest guidance
shows variance in where exactly the aforementioned cold front will
be located. This will be the main factor for severe weather
potential as daytime heating/moisture advection ahead of the front
combined with sufficient deep-layer shear should support the
potential for organized convection. Most guidance shows at least
portions of the area remaining ahead of the cold front during the
day Wednesday which suggest there is at least low end potential for
severe weather.

Mostly quiet weather conditions should return late Wednesday into
Thursday once the cold front moves out, but rain chances quickly
return towards the end of the week as another system could move in.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 139 PM EDT Sat May 18 2024

Impacts:

- Fog once again tonight; lowest visibilities near/south of I-70

Discussion:

Clear conditions, light winds, and residual low level moisture will
result in areas of fog again tonight. Uncertainty on spatial
coverage and magnitude of visibility reduction exists since mixing
and redistribution of drier air aloft today may limit fog to a
slight degree. Best chance of dense fog will be at KBMG but
especially further east.


&&

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

$$

SHORT TERM...BRB
LONG TERM...Melo
AVIATION...BRB