370 
FXUS63 KIND 300210
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1010 PM EDT Sun Sep 29 2024

.KEY MESSAGES...

- Chances for showers linger into Monday 

- Fog possible early Tuesday

- Mainly dry conditions with nearly seasonable temperatures to open 
  up October

&&

.FORECAST UPDATE...
Issued at 1010 PM EDT Sun Sep 29 2024

Damp and dreary conditions persist into the overnight hours across 
Central Indiana. The remnant circulation of Helene and the upper 
level low, which have been around for days, continues to spin over 
Kentucky resulting in low clouds, isolated showers, and patchy 
drizzle for the southern 2/3 of the state. Latest IND ACARs sounding 
shows a saturated column up to 6 km agl with winds out of the 
northeast. Winds are still gusting in some spots to 20kts as 
boundary layer mixing is still occurring at this hour. Slow cooling 
overnight should allow for the boundary layer to stabilize some and 
for winds gusts to diminish. With the whole system and associated 
pressure gradient slowly weakening, expect northeast winds overall 
to keep diminishing into tomorrow. By sunrise patchy fog may develop 
in some low lying wind sheltered areas with such a saturated 
environment in place. Also kept in patchy drizzle through the 
overnight hours for the southern half of the forecast area as waves 
of energy rotating into the region squeeze out any moisture in the 
clouds. Main impacts will be to travel due to lower ceilings and 
visibility at times. 

Expect a much drier day on Monday with peaks of sunshine during the 
afternoon and evening hours and warmer temperatures in the low to 
mid 70s.

&&

.SHORT TERM (This evening through Monday)...
Issued at 234 PM EDT Sun Sep 29 2024

As the remnants of Helene continue to weaken and move east, 
conditions will gradually get drier from west to east across central 
Indiana through Monday. That being said, even with drying 
conditions, showers remain possible for parts of the area into 
Monday.

Rest of This Afternoon...

Scattered showers will continue across central Indiana as forcing 
persists on the northwest side of the remnants of Helene. Most of 
the showers has been confined to the southeast half of the forecast 
area, but some heating in the northwest will allow some showers to 
pop up there as well.

Will continue with mainly chance category PoPs and use scattered 
wording. Where sunshine breaks through (mainly northwest), 
temperatures will be in the mid 70s. Cooler temperatures will occur 
farther southeast.

Tonight...

Weak forcing will continue this evening, so will keep some low PoPs 
going, especially southeast closer to the remaining forcing. Some 
drying aloft will help end the showers overnight. However, trapped 
low level moisture will keep clouds around, and some patchy fog will 
likely develop in the southern forecast area.

With low clouds in place, temperatures will only fall back into the 
lower to middle 60s.

Monday...

Monday morning will be quiet, but some isolated to scattered showers 
will develop across the southeast forecast area in the afternoon. 
This area is where some lingering very weak forcing will linger from 
the exiting system. Will have some low PoPs there to cover.

Lower clouds will mix out during the day Monday, and the partial 
sunshine will boost temperatures into the middle and upper 70s.

&&

.LONG TERM (Monday night through Sunday)...
Issued at 234 PM EDT Sun Sep 29 2024

The long term will feature more benign weather, yet can not 
completely rule out Tuesday afternoon over eastern sections and also 
Friday and Sunday, all associated with Great Lakes upper troughs and 
associated frontal systems.

Model soundings are showing dry air above 850 millibars Monday night 
while the boundary layer remains moist underneath an inversion 
related to surface high pressure. A very weak pressure gradient 
suggest winds will be very light to calm. This will be an ideal 
setup for stratus and or fog. BUFKIT suggests low stratus will be 
more prevalent than fog at this time, however some of the CAMs and 
NBM hint at areas of fog. For now, have patchy and areas of fog over 
central Indiana. Will keep on eye on things over the next couple of 
runs for potential dense fog and or headline add. 

By Tuesday morning, the remnants of Helene will weaken over the 
Appalachians as an upper trough moves into the upper Midwest within 
northwest flow aloft. The trough will force an associated cold front 
to move quickly southeast across central Indiana, during the day. 
Deeper moisture of eastern sections combined with the synoptic 
forcing will likely lead to isolated to scattered afternoon showers 
there. Otherwise, mostly dry soundings will lead to increasing 
sunshine. Much cooler and drier air will be ushered in behind the 
front leading to clear skies and much cooler temperatures in the 40s 
Tuesday night and afternoon temperatures in the upper 60s to lower 
70s Wednesday. Meanwhile, winds will turn to southwest Thursday and 
Friday , which allow temperatures to warm back up through the 70s 
and possible even 80 degrees over the Wabash Valley Friday. Finally 
two more upper Great troughs and related frontal systems could 
trigger a few showers on Friday and Sunday.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 742 PM EDT Sun Sep 29 2024

Impacts:

- MVFR to IFR ceilings return tonight with gradual improvement on 
Monday

- Patchy fog possible late tonight and toward sunrise 

Discussion: 

Wet and dreary conditions persist into the overnight hours across 
Central Indiana. Expect cigs to drop to MVFR to IFR levels during 
the overnight hours as the boundary layer remains quite saturated. 
Lowest cigs and greatest chance for fog will be in the Wabash River 
Valley and South Central IN including KHUF and KBMG. 

After sunrise tomorrow, conditions should slowly improve at all 
sites with slowly rising cigs and vis. Expect VFR conditions by the 
late afternoon hours with ceilings beginning to break up. 

Winds will remain at or below 10 kts and out of the NE for the 
forecast period.


&&

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

$$

UPDATE...CM
SHORT TERM...50
LONG TERM...MK
AVIATION...CM