746
FXUS63 KIWX 201913
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
313 PM EDT Fri Sep 20 2024

.KEY MESSAGES...

- Some areas may see rainfall this afternoon with widely
  scattered to scattered showers/storms.

- One more warm day Saturday with highs possibly reaching (or
  exceeding) 90 degrees before a trend to cooler temperatures.

- Confidence increasing on 1 or more chances for much needed
  rainfall Sunday into Monday, with timing/coverage details
  still to be sorted out.

&&

.DISCUSSION...
Issued at 312 PM EDT Fri Sep 20 2024

An area of storms developed over southern Lake Michigan and has
worked inland, holding its own, but struggling to develop further SW
despite unstable conditions. Main wind shift remains back over
Chicago, working slowly east. Big question is does the convection
expand further southwest of have we seen the southern extent of the
needed rainfall.  So far the main features have been brief but heavy
rainfall with locations picking up a quick half inch to over an inch
in the stronger storms. Have adjusted pops to lower somewhat further
SW based on satellite trends. Agitated cu field still is showing up
so suspect more widely scattered development could take place with a
newly developed cell near Rensselaer. Everything will move east at
around 25 mph and is expected to weaken after 00Z with loss of
heating. Higher dewpoints will remain in place overnight with drier
air not arriving till Saturday. After coordination, have added
patchy fog with areas that manage to see some rainfall today seeing
some potential for locally dense fog.

One more hot day is in store by mid Sept standards  for Sat with
highs at least into the mid to maybe upper 80s. MAV guidance remains
rather aggressive on highs in the low to middle 90s, possibly due to
increasing mixing/subsidence. Not ready to jump into that arena, but
something to watch in later forecasts.

Confidence does continue to increase on 1 or more chances for
showers and storms, possibly as early as Sunday afternoon, lingering
into Monday night as a series of disturbances move into the area and
northern stream trough digs and deepens. Trends seem to suggest the
first round being Sun afternoon/evening with another Monday
afternoon and evening. Keeping pops capped at likely for now, but
signs point towards at least some needed rainfall for many areas.

Models diverge on handling of the trough through the rest of the
period (and beyond) ranging from strong ridging overhead to a deep
cutoff low near/west of the area. To further complicate things, some
sort of tropical development is expected next week, but location and
track of this feature is equally uncertain. At least a brief dry
period seems likely late Tue night into Wednesday before remainder
of forecast has slgt chc to chc pops.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1208 PM EDT Fri Sep 20 2024

Shortwave trough centered over wrn lake Superior and attendant
swwd trailing and weakening sfc frontal zone through wrn IL
will wash ewd across the terminals this aftn. Poor moisture
return ahead of this system along with weakening upper support
suggests showers will struggle to develop this aftn.

Thus VFR expected this prevail this period. Some small
potential remains for a period of MVFR based cigs exists this
evening invof KFWA assuming sufficient boundary layer moisture
arises from post frontal showers this aftn still of low
confidence and not included in this fcst.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Air Quality Alert until midnight EDT /11 PM CDT/ tonight for
     INZ005-012>015-022-023-104-116-204-216.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Fisher
AVIATION...T