576 
FXUS63 KIND 271904
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
304 PM EDT Sun Oct 27 2024

.KEY MESSAGES...

- Near record warmth Tuesday and Wednesday along with wind gusts of 
30 to 40 mph 

- Rain expected for Halloween, most likely period of rain during the 
morning to afternoon

&&

.SHORT TERM (This evening through Monday)...
Issued at 304 PM EDT Sun Oct 27 2024

Spectacular fall weather continues this afternoon as central Indiana 
enjoys sunny skies and seasonable temperatures. 18Z temps ranged 
from the mid 50s to the lower 60s.

The surface high will remain as the primary feature influencing 
weather across the Ohio Valley into Monday. The center of the high 
will shift east over the next 24 hours which will enable return 
southerly flow to commence by Monday afternoon. This in tandem with 
expanding ridging aloft will start the temperature rises that will 
culminate with near record warming for the forecast area Tuesday and 
Wednesday.

Cloudless skies will continue for the rest of the afternoon and most 
if not all of tonight with broad subsidence in place across the 
entire area. RH values have dropped into the 25-35% range this 
afternoon but the lack of of stronger winds is largely mitigating 
overall fire danger concerns. Predominant southeast winds will back 
subtly and diminish to less than 5mph for tonight...setting the 
stage for another frosty start early Monday over parts of central 
Indiana. 

The return flow begins in earnest on Monday with a subtle uptick in 
moisture advection in advance of a warm front that will lift into 
the mid Mississippi Valley by the evening. Mid and high clouds will 
be more prevalent by Monday afternoon and there is even some 
potential for a bit of diurnal cu as well with the moisture 
advecting into the area from the southwest. Surface winds will back 
to southeast by late day in response to the approaching warm front. 
A tightening pressure gradient will enable some gusts at 15-20mph 
over the Wabash Valley by mid to late afternoon as well.

Temps...nudged low temps down a couple degrees from the blend as 
ideal radiational cooling conditions in tandem with the antecedent 
dry conditions...noted by the dewpoints dropping lower than model 
guidance...will likely enable temps to fall into the lower to mid 
30s over much of the forecast area by daybreak Monday. The Indy 
metro will stay a bit warmer with the light easterly flow bringing 
modified air off the city. LOw level thermals support highs in the 
upper 60s and lower 70s for much of the area on Monday.

&&

.LONG TERM (Monday night through Sunday)...
Issued at 304 PM EDT Sun Oct 27 2024

The long term period will start off warm and breezy. Broad ridging 
aloft will become more amplified through midweek while southerly 
flow at the surface will bring WAA and potentially record breaking 
warm temperatures. Highs on Tuesday and Wednesday are expected to be 
in the low 80s. Pressure gradients will tighten up as the ridge 
amplifies and a trough approaches from the west, leading to a jet 
setting up to the NW of the area and breezy conditions Tuesday 
through Thursday. Gusts of around 35 mph will be possible at times 
for the first few days of the long term, with highest winds expected 
across the north. Can't quite rule out slightly elevated fire 
weather conditions for the first few days given how dry the ground 
is with winds, but Min RH values improving to around 40-50% which 
should help. 

A surface low and associated cold front will bring likely showers 
and thunderstorms on Halloween, with rain moving in from the west 
during the early morning hours and pushing eastward through the day. 
Guidance has been pushing up the timing of the rain the last few 
runs. If that sped up timing comes to fruition, some areas, mainly 
northwest of I-69, could have the rain end before trick or treating 
begins. Still not fully confident on when rain comes to an end in 
regards to trick or treating, but more confident that rain should 
exit the forecast area by around midnight at the latest per current 
guidance. 

Cooler and drier air will settle back in behind the front, leading 
to highs near 60 again for Friday. Afterwards highs will slowly warm 
the rest of the weekend with a return to more southerly winds. There 
will also be a slight chance of rain again over the weekend.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1215 PM EDT Sun Oct 27 2024

Impacts: 

- None

Discussion:

VFR conditions will continue through the forecast period as high 
pressure remains draped across the Ohio Valley. Winds will be 
primarily from the southeast through the afternoon backing slightly 
and diminishing tonight under clear skies.

The high will shift further east on Monday allowing for return flow 
from the south to establish and increase over the region. There will 
be an increase in cirrus with also the potential for at least some 
diurnal cu as moisture slowly advects into the region.


&&

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

$$

SHORT TERM...Ryan
LONG TERM...KF
AVIATION...Ryan