328
FXUS63 KIND 190110
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
910 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

&&

.FORECAST UPDATE...
Issued at 910 PM EDT Sat May 18 2024

- Mostly Clear with Fog overnight.
- Lows in the upper 50s and lower 60s

Surface analysis this evening shows a large area of disorganized
high pressure stretching from the eastern Great Lakes, across
Indiana to the southern Mississippi river valley.  A weak cold front
was found stretching across western WI to central IA and then SW to
KS. The front could be seen on GOES16 via a thin line of clouds that
were present near it. Convection near the front was limited to a few
storms in KS and WI. Over Indiana, skies had become mostly clear as
diurnal CU had  dissipated. Weak southerly winds were in place, with
dew points in the upper 50s and lower 60s, similar to last night.
Overall, there has been little change in the air mass.

Overnight the disorganized area of high pressure will remain across
Central Indiana. The cold front will push toward Central Indiana,
but will not  arrive, rather becoming elongated to the north. All of
this will provide a continued trend of mostly clear skies and light
winds. Once again, models suggest dew point depressions will fall to
2-3F.  This will result in mostly clear skies with fog development
near diurnal minimums. Patchy dense fog will be possible,
particularly in low lying and more rural areas.

&&

.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 (00Z TAF Issuance)...
Issued at 638 PM EDT Sat May 18 2024

Impacts:

- Fog once again tonight; Otherwise mainly VFR

Discussion:

Little change since the previous discussion. Clear conditions,
light winds, and residual low level moisture will result in areas of
fog again tonight near diurnal minimums.

IFR or LIFR fog will be possible at LAF...BMG and HUF. Models
suggest dew point depressions overnight near 2-3F, a bit higher than
last night. However, with little change in the present air mass a
persistence type forecast seems best.

After morning fog burns off on Sunday, a quick return to VFR
conditions is expected with sct-bkn VFR CU development.


&&

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

$$

UPDATE...Puma
SHORT TERM...BRB
LONG TERM...Melo
AVIATION...Puma