-- Discussion containing changed information from previous version are highlighted. --
885
FXUS63 KIND 210847
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
447 AM EDT Sat Sep 21 2024

.KEY MESSAGES...

_ Dense Fog Advisory through 9 AM Today

- Hot and dry Today

- Thunderstorms moving in overnight

- Turning cooler and more active with greater rain chances Sunday
through early next week

&&

.SHORT TERM (Today and tonight)...
Issued at 301 AM EDT Sat Sep 21 2024

Overnight fog and timing and coverage of additional convection
later today and tonight will be the main concerns for the short term.

Early morning radar was showing the convection was shrinking in
coverage and diminishing. This trend should continue with little or
no lingering activity by 09z as the atmosphere stabilizes.

Fog will be the next issue as clearing, residual boundary layer
moisture and very light to calm winds were shaping for an ideal
radiational fog setup especially over northern sections and the
Wabash Valley where temperatures were closing in on their dew
points. Hi-Res soundings and the Hi-Res models in general are all
supporting this with the best timing in the 09z-13z time frame.
After, getting a recent report of quarter mile or less visibility in
Tipton and Hamilton counties and talking with adjacent offices, will
post a dense fog advisory through 13z for our northern third and the
Wabash Valley and mention patchy sense fog elsewhere.

By morning, the front will be stalling near the Ohio River and then
return north as a warm front during the day. Ridging from the Great
Lakes to Texas should keep it dry at least most of the day, although
some of the CAMs attempt to trigger afternoon convection over
southwest parts of central Indiana, where mixed CAPEs will rebound
to as high as 2000 J/kg per DESI. The big limiting factor will be
lack of synoptic forcing, but left over boundaries and or weak
impulses moving through the ridge could be enough. For now, will
leave PoPs out. Otherwise, the fog should burn off by 13z or so as
mainly solar heating should allow temperatures to recover back into
the upper 80s to lower 90s during the afternoon. This will be the
last of the well above normal temperatures through at least next
week.

The ridge will move east of the area tonight as an upper wave moves
into northern Ontario as a center of surface low pressure moves to
Lake Michigan and associated cold front stretches from the low
center to northern Missouri by 12z Sunday. Hi-Res soundings are
indicating a deep moist profile overnight tonight with near max
moving average PWATs and at least some weak instability. This
supports 60% PoPs toward 12z Sunday over the Wabash Valley tapering
off to 20% PoPs over the I-65 corridor.

&&

.LONG TERM (Sunday through Friday)...
Issued at 301 AM EDT Sat Sep 21 2024

Longer term guidance continues to show a fairly abrupt shift back to
much more seasonably mild conditions and potential for scattered to
numerous showers and a few thunderstorms, particularly late in the
weekend into the early portion of the work week.

Uncertainty increases greatly from mid week and beyond as guidance
begins to diverge significantly in its handling of the large scale
pattern and how quickly the upper troughing will depart the region,
along with the potential for tropical remnant influence.

Nonetheless, there appears to be solid potential for the first
appreciable rainfall in many parts of central Indiana in two to
three plus weeks, which may arrest further deterioration in the
local hydrologic situation - though the ongoing drought conditions
are unlikely to be significantly alleviated without multiple
episodes of soaking rainfalls totaling several inches. The couple of
inches that appear possible throughout the coming week will not be
enough to offer dramatic improvement.

With the shifting and weakening of the upper level ridge,
temperatures will moderate significantly, with highs likely to be in
the 70s much of the coming week, much closer to seasonal norms.

&&

.AVIATION (12Z TAF Issuance)...
-- Changed Discussion --
Issued at 444 AM EDT Sat Sep 21 2024

Impacts:

- IFR and worse fog is expected through 13z-14z, especially at
  the smaller airports that received the most rain

- Thunderstorms are possible starting 07z-10z from west to east

Discussion:

IFR and possibly worse fog and or stratus will be the main concern
this morning, especially at the smaller airports, which received
more rain. The visibility has already fallen to a quarter mile
at these sites and KHUF and KLAF have also seen VV001-VV002
lending good confidence.

Showers and or thunderstorm chances will increase overnight tonight
as a cold front approaches from the west and interacts with a very
warm, moist and unstable atmosphere.

Winds will be most very light to calm through the TAF period.
-- End Changed Discussion --

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM EDT this morning for INZ021-
028>031-035>047-049-051>054-060>062-067>070.

&&

$$

SHORT TERM...MK
LONG TERM...Nield
AVIATION...MK