346 
FXUS63 KIND 090717
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
317 AM EDT Fri May 9 2025

.KEY MESSAGES...

- Briefly cooler today, then warmer temperatures this weekend into 
  next week

- Mainly isolated/scattered showers/t-storms Monday-Wednesday

- Expect very warm conditions w/moderate humidity late next week

&&

.SHORT TERM (Today and tonight)...
Issued at 300 AM EDT Fri May 9 2025

Northeasterly winds between 10 to 15 mph remain ahead of an 
approaching surface high from the north. Winds gradually die down 
through the afternoon today as the surface high center arrives this 
evening. Light and variable to calm winds then persist through the 
remainder of the short term period.

The air mass arriving with the high is fairly dry, especially 
between 925mb and 500mb. Little in the way of cloud cover is 
anticipated given the dry and subsident column. There is a bit of 
moisture at 250mb along with a northeast to southwest oriented jet 
streak, which could lead to some thin cirrus at times.

Back towards the surface, model soundings show fairly deep mixing 
which will promote temperatures rebounding into the high 60s to near 
70. Our primary forecast challenge may be dew points, given the very 
dry air located between 925mb and 850mb. Guidance can struggle with 
deep boundary layer mixing and fail to capture how much dry air 
mixes to the surface. We will add more weight to the HRRR (which may 
be too dry) in order to bring Tds down a bit. Relative humidity 
values may drop as low as 20-25 percent, especially across our 
northern counties.

Light and variable winds along with mainly clear skies will promote 
ideal radiational cooling conditions tonight. Temperatures should 
drop quickly after sunset and fall into the 40s for most locations. 
A few isolated locations may dip into the upper 30s. Not expecting 
much in the way of fog, given the dry atmosphere in place...but some 
patchy ground fog cannot be ruled out over southern Indiana in 
typically fog-prone locations.

&&

.LONG TERM (Saturday through Thursday)...
Issued at 312 AM EDT Fri May 9 2025

A broad and overall retracted upper-level pattern in a sort of weak 
Rex-Block formation will promote a slow transition...from pleasant 
late-spring conditions this weekend...to occasional showers, amid 
increasing humidity, and eventually warmth, by the middle of next 
week.  Broad yet rather weak surface high pressure extending from 
eastern Ontario to the Ohio Valley this weekend will provide light 
breezes under mostly clear skies, while above normal heights bring 
readings indicative of late May, ranging from the 50s to mid/upper 
70s.

Dry conditions through Sunday night will be replaced by chances for 
isolated to scattered showers/t-storms that should exhibit 
diurnal enhancement, across the Monday to Wednesday timeframe. 
Stacked yet weak low pressure over the Lower Mississippi Valley 
will slowly lift towards the Midwest as the blocked slowly breaks 
down. Ample precipitable water values in the 1.25-1.50 inch range 
and surface dewpoints climbing through the 50s to at least the low
60s will pose the potential for precipitation, although 
disorganized lift from the broad trough's remnant fragments 
should limit heavier rainfall to isolated locations.

Towards the end of the long term, the left-over southern 
circulation should interact with a more northern-stream trough 
near the High Plains to act as a sort of warm-frontal zone...ahead
of an upper subtropical ridge building northward from the 
southern Plains. This may well allow the local region's first very
warm to perhaps marginally hot days of the year, with widespread 
mid to upper 80s on the table for the late workweek should the 
pattern trend as currently expected. The normal max/min at 
Indianapolis through the long term is 72/52.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 133 AM EDT Fri May 9 2025

Impacts: 

- None.

Discussion:

VFR conditions expected through the TAF period.

Northeasterly winds around 10 knots should persist into the morning 
hours before tapering off after noon. Winds die down even further 
becoming light and variable Friday night into Saturday.

Cloud cover should be limited to occasional thin cirrus.


&&

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

$$

SHORT TERM...Eckhoff
LONG TERM...AGM
AVIATION...Eckhoff