592
FXUS63 KIND 080604
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
204 AM EDT Sun Sep 8 2024

.KEY MESSAGES...

- Chilly start to the morning with temperatures in the upper 30s to
low 40s

- Dry air will oversee a trend to very warm/marginally hot
conditions by Wednesday-Thursday...with slightly elevated fire
weather this week, especially on Tuesday-Wednesday

- A developing tropical cyclone approaching from the western Gulf
will bring rainfall chances Friday-Saturday, especially towards the
Ohio Valley

&&

.SHORT TERM (Today and tonight)...
Issued at 203 AM EDT Sun Sep 8 2024

Today.

Temperatures continue to steadily drop under clear skies with most
of central Indiana now in the mid to upper 40s.  Wind speeds haven`t
dropped off quite as much as was earlier expected which limit the
coverage of upper 30 degree temperatures. Winds will remain light
through the day today with high pressure firmly in place and with
the loss of stronger northerly flow, expect to see temperatures rise
into the low 70s for much of central Indiana.  Diurnal cu coverage
will be minimal as model soundings show a dry column with RH at the
top of the boundary layer unfavorable for cu development.

Tonight.

Another chilly night is expected under continued clear skies, but
winds will gradually become more southerly through the night which
will begin to moderate temperatures a bit.  That being said, the dry
air mass in place will still allow for efficient radiational cooling
with lows in the mid to upper 40s.

&&

.LONG TERM (Monday through Saturday)...
Issued at 203 AM EDT Sun Sep 8 2024

Monday through Thursday...

Dry conditions will continue through at least mid-week as broad,
stacked ridging continues to prevail over much of the eastern two-
thirds of North America.  The broad H500 ridge resting over the
continent`s middle meridians...will be amplified over the central
CONUS and northward into Hudson Bay during the mid-week...by an
upper trough plunging down the western US.  Corresponding surface
high pressure that has brought recent cool conditions will
consequently shift from a Missouri-Virginia axis Monday...towards
the Mid-Atlantic.  The surface ridge`s broad western portions will
continue to occupy much of the central US, into Indiana - blocking
all but perhaps a feeble attempt of Gulf moisture to return
northward, while overseeing light southerly flow...that will trend
H850 temperatures from 12 to perhaps 20 degrees Celsius.

Conditions for the local region will therefore be an overall
moderation featuring persistent broad diurnal temperature ranges,
promoted by dewpoints in the 40s to 50s.  Forecast soundings note
deep afternoon boundary layers, well-mixed up to 700-800 mb, with
dewpoint depressions still nearing 10 degrees Fahrenheit at the top
of the boundary layer.  Resultant often clear conditions will help
facilitate the positive feedback of cool mornings and very warm days
over increasingly dry ground.  Expect additional cool mornings
through the early week to lead to a seasonable Monday and very warm
Tuesday.  Readings approaching marginal heat on Wednesday and
Thursday should include near-normal minimums by Wednesday night.  No
heat impacts are expected so far, with low humidity guiding maximum
heat indices to sub-90 levels.  However, slightly elevated fire
danger will be driven by minimum relative humidity levels of mainly
25-30 percent on both Tuesday and Wednesday, although wind gusts
generally under 10 mph will mitigate this potential.

Friday and Saturday...

A wild card to the upcoming unseasonable warmth will be a developing
tropical wave wave/cyclone that is expected to spin from the far
southwestern Gulf of Mexico Monday, into the Deep South by the late
workweek. While confidence is increasing in this feature providing
some clouds, and chance POPs into the Midwest...less certainty
surrounds how it will interact with the prevailing cut-off upper
ridge across the northern Great Lakes, and therefore ultimate which
portions of the region will see appreciable rainfall, if any.

Nonetheless, expect increased cloudiness, a more-easterly wind, and
at least widely scattered rain showers to promote slightly more
reasonable, yet above-normal, warmth for the Friday-Saturday period.
Measurable rain chances will be greater towards the Ohio Valley. The
normal max/min at Indianapolis through the long term is 80/59.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 133 AM EDT Sun Sep 8 2024

Impacts:

-None.

Discussion:

VFR conditions expected through the TAF periods with only occasional
passing cirrus. Winds will generally remain northerly at less than
10 kts through the period with a slight shift to a more westerly
direction at LAF after 16Z. Can`t rule out brief fog towards
daybreak this morning, but chances are too low for a TAF mention.


&&

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

$$

SHORT TERM...White
LONG TERM...AGM
AVIATION...White