220 
FXUS63 KIND 261908
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
308 PM EDT Thu Oct 26 2023

.Short Term...(This evening through Friday)
Issued at 308 PM EDT Thu Oct 26 2023

* Near record warm low temperatures tonight
* Isolated to scattered showers overnight into Friday

A warm, cloudy, and breezy weather pattern continues today and 
tomorrow for the state of Indiana as a strong baroclinic zone 
remains parked over the region. Current satellite imagery clearly 
depicts a ridge of high pressure over the Southeast CONUS with 
tropical moisture streaming northward on its western periphery. At 
the surface, high pressure is centered over North Carolina with an 
elongated area of low pressure/frontal boundary from the Front Range 
to Minnesota. Over the next few days, mid and upper level waves will 
ride along the baroclinic zone periodically bringing increased 
clouds and showers to the region. See the Long Term Forecast for 
details on when the heaviest rain is expected for Central Indiana 
this weekend. Currently, the best forcing for ascent and moisture 
advection is located just north and west of the region, however 
everything shifts eastward tonight and tomorrow with increasing rain 
chances for Central Indiana. 

.This evening and tonight...

Current satellite imagery clearly depicts broad southwest flow over 
the entire region with thickest cloud cover and convection located 
from Arkansas to Southern Wisconsin. Mainly dry conditions have been 
reported across Central Indiana this afternoon and evening so far 
with temperatures in the mid 70s. Short term guidance shows 
southwest flow increasing at all levels this evening and overnight 
as the baroclinic zone slowly pushes eastward over the region with 
an upper wave passing through. Increasing moisture advection aloft 
will result in the atmospheric profile becoming more saturated in 
the lower levels. Current IND ACARS sounding shows a very dry 
environment not supportive of any shower activity before at least 
sunset. The presence of such a large dry layer will likely keep any 
showers light and widely scattered overnight until deeper saturation 
occurs. PoPs remain under 30 percent through around 09z tonight 
across the region, then begin to increase in the southern half of 
the state closer to sunrise tomorrow morning. 

With this weather pattern in place, warm, southerly flow and cloud 
cover will keep temperatures from falling much overnight. Forecast 
lows are in the mid 60s across the entire region. In fact, a few 
locations could set daily record warm low temperatures by Friday 
morning. 

.Friday...

A strong 35-45 kt low level jet will continue to pump moisture into 
the region on Friday resulting in overcast skies much of the day and 
the chance for showers. As mentioned above, showers will have a lot 
of dry air to overcome, which will likely keep convective 
development more isolated with lower rainfall amounts. Friday 
morning into early Friday afternoon, Southwest and South Central 
Indiana have the best threat at seeing more widespread showers as 
the environment will likely saturate quicker in that area. Not 
expecting a wash out of a day though as there likely be a break in 
the showers during the afternoon and evening before heavier rain 
pushes in Friday night. Potential is there for an isolated lightning 
strike or rumble of thunder across the south, but any instability 
amounts look quite low. Keeping isolated thunderstorm wording in the 
forecast to account for this, but not overly impressed with what 
guidance is showing. 

Highs Friday were lowered towards the NBM25th percentile as the 
presence of scattered showers and thicker cloud cover will likely 
limit boundary layer heating despite strong warm air advection. 
Still kept highs in the low to mid 70s everywhere, which is well 
above average for this time of October anyway.

&&

.Long Term...(Friday night through Thursday)
Issued at 308 PM EDT Thu Oct 26 2023

* Heavy rainfall possible over the weekend
* Unseasonably cold temperatures next week with near record values 
  possible (resulting in a widespread hard freeze)

A trough will be approaching at the beginning of the long term 
period while a blocked ridge persists in the SW. This will allow for 
the leading edge of the trough to stall near or over the region, 
setting up SW flow from around Texas to the Great Lakes, with 
moisture advecting into the area with it. Associated rain and 
thunderstorms will begin around or prior to the start of the period 
with best chances for rain and heavy rain being Saturday late 
afternoon through Sunday night. Models show that an extra surge of 
moisture may ride along the leading edge sometime this weekend, due 
to remnants from Hurricane Otis tracking northward. Exact timing and 
locality of heavy rain as well as higher QPFs remain uncertain as 
models vary on where the stalled trough sets up. Best chances for 
those higher amounts will be over southern Indiana but the bullseye 
has the potential to set up anywhere from central Indiana down to 
south and/or west of the Ohio River. At least a half an inch over 
the weekend is likely across our forecast area with amounts 
potentially reaching near 2 inches or higher for some areas. 
Luckily, the ground is dry and river and creek basins are low, so 
there is the capacity for several inches over a few days. The 
flooding concern will come from the potential of higher rain rates 
dumping a lot of rain in one area over a short amount of time, so it 
is still a hazard to watch for. 

Eventually, the ridge will break down sometime early next week 
allowing for the large upper trough to progress eastward and rain to 
exit to the east. In its wake expect much colder temperatures for 
Halloween and the start of November. 

High temperatures this weekend will be in the 50s and 60s before 
dropping into the 40s for next work week. Behind the front, 
overnight lows are forecasted to be in the 20s for next week as 
well.

&&

.Aviation...(18Z TAF Issuance)
Issued at 132 PM EDT Thu Oct 26 2023

Impacts:

* Wind gusts 20-27KT from 190-200 degrees through 23z tonight
* Non-convective low level wind shear 23z tonight - 15z Friday
* Gusty southerly winds 20-25 kts Friday after 15z 

Discussion: 

VFR conditions are expected with winds out of the south (180-210 
degrees) throughout the period. Sustained winds have already picked 
up to around 15 kts this afternoon with gusts 20-27 kts. Afternoon 
mixing in addition to a tight pressure gradient is responsible for 
the higher gusts. Expect gusts to decrease around sunset, but winds 
should remain elevated overnight around 8-12 kts. Strong flow just 
off the surface will remain, thus will carry low level wind shear at 
all sites, roughly 210 degrees at 40KT.

Ceilings will gradually lower later in the period, but should remain 
VFR. Isolated to scattered showers are possible overnight into 
tomorrow; however with such dry air through the column, not 
expecting much impact to vis or cigs for now. Added VCSH at all 
sites for tonight into tomorrow.


&&

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

$$

Short Term...CM
Long Term...KH
Aviation...CM