IND issues Area Forecast Discussion (AFD) at Sep 11, 9:22 PM EDT256
FXUS63 KIND 120122
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
922 PM EDT Wed Sep 11 2024
.KEY MESSAGES...
- Rainfall from Hurricane Francine likely late Thursday night into
Friday across southern Indiana, northern extent remains uncertain.
- Cooler weather with highs in the upper 70s to lower 80s for the
weekend
- Highs in the 80s next week
&&
.FORECAST UPDATE...
Issued at 922 PM EDT Wed Sep 11 2024
Clear skies continue across central Indiana this evening as the
region remains under the influence of high pressure. Already there
was a wide variance in temperatures after sunset ranging from the
mid 60s to the mid 70s.
Quiet weather continues with dry air across the region. An infusion
of deeper subsidence ahead of the advancing cirrus shield from
Francine has lifted into the Ohio Valley and will aid in maintaining
mostly clear skies for the forecast area overnight. The leading
fringes of cirrus expanding from the south will rise into southern
parts of the Hoosier state late tonight but more expansive high
level cloud cover will hold off until late day Thursday.
Excellent scenario for radiational cooling again tonight with light
easterly flow. Lows will vary from the lower 50s in our normal cool
spots to the lower 60s over south central Indiana.
Zone and grid updates out.
&&
.SHORT TERM (This evening through Thursday)...
Issued at 219 PM EDT Wed Sep 11 2024
Today and Tonight
Quiet are expected to continue through the day, as the surface high
pressure that has dominated the weather pattern for the last few
days continues remain near. Winds will become more consistently out
of the SE with the pressure gradient steepening upon the approach
of Hurricane Francine.
Slightly elevated fire weather conditions are possible this
afternoon as dew points are again expected to drop into the low 40s.
This will combine with afternoon highs in the upper 80s to bring RH
values as low as 15-20 percent, especially across the southwestern
counties where the ongoing drought conditions are leading to lower
afternoon dew points. Fuels will remain moist enough to combine with
the calm winds to limit the overall fire danger, but an increased
threat for smaller fires will be active this afternoon and evening.
HRRR smoke and visible satelitte output shows an elevated layer of
smoke over most of the Midwest. No surface impacts are expected, but
this will continue to create some opaqueness in the cloud cover and
more picturesque sunsets.
Tomorrow...
Much of the same is expected tomorrow as high pressure remains over
the northern Ohio Valley. There will be a few changes however, as
the remnants of TS Francine approach from the south. The
aforementioned high will act to suppress the warm core low's
northward progression, but there still likely be some upper level
spiral bands that reach central Indiana by mid day providing SCT to
BKN cloud decks. By the evening, most of central Indiana will likely
be beneath BKN to OVC cloud decks.
With most of the cloud cover arriving in the mid afternoon and
later, temperature impacts are likely to be minimal. Still, a few
degrees of temperature decrease are expected versus usual for this
type of air mass with a more uniform afternoon high of 84-87F across
the region. Any precipitation is expected to be delayed until the
overnight hours (See next section).
&&
.LONG TERM (Thursday night through Wednesday)...
Issued at 219 PM EDT Wed Sep 11 2024
Thursday night into Friday...
Model consensus is that the remnants of Francine will stall well
southwest of central Indiana, thanks in part to an upper high across
the Great Lakes. Moisture from the remnants will work into central
Indiana mainly later Thursday night and then into Friday.
Meanwhile, surface high pressure to the northeast of the area will
continue to influence central Indiana with a dry easterly flow.
With the remnants well southwest of central Indiana, decent forcing
will be confined to the southwestern portions of the area. This
forcing and the available moisture will produce rain across the
southwest, so will go likely or higher PoPs across the southwestern
1/4 to 1/3 of the area late Thursday night into Friday.
Farther northeast, the drier easterly flow will create a sharp
cutoff to the rain, with that cutoff likely being near the I-74
corridor. Will have a sharper gradient to the PoPs to the northeast
of the likely PoPs.
Rainfall amounts through Friday could reach around an inch in the
extreme southwest part of central Indiana, with amounts quickly
tapering off to the northeast.
Rain and clouds will keep temperatures in the 70s for much of the
area Friday, with some lower 80s expected in the north and northeast.
Saturday into Sunday...
Lingering moisture from the remnants will linger into the weekend,
mainly across southern and western portions of the area. Weak upper
troughing will be near this area. Thus, wouldn't be surprised to see
some isolated to scattered showers and storms, mainly west and
south.
Will have some low PoPs in these areas, with the lowest PoPs on
Sunday as forcing continues to weaken.
Highs in the 80s will return to most areas Saturday and for all
areas on Sunday.
Monday and beyond...
Uncertainty ramps up more early next week.
First, questions remain about potential pop up convection with some
lingering moisture around Monday. Not sure if any convection will be
around though, especially with surface high pressure nudging in from
the northeast.
Next, a weakening potential tropical system will move inland from
off the East Coast Tuesday into Wednesday. Models try to have the
system survive its trek across the mountains and potentially bring
rain to central Indiana by Wednesday. Confidence is low in this
scenario at the moment.
Temperatures will remain above normal with highs in the lower to
middle 80s.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 623 PM EDT Wed Sep 11 2024
Impacts:
- Gusts to near 20kts possible Thursday afternoon
Discussion:
A large area of high pressure remains draped across the region with
mainly clear skies and a continued haze from smoke in the upper
levels of the atmosphere. The high will slowly shift east into
Thursday as Francine makes landfall on the northern Gulf coast this
evening and gradually tracks north into northern Mississippi by late
day Thursday.
Deep subsidence ahead of the hurricane will overspread the area
tonight and most of Thursday and keep skies mainly clear across
central Indiana. An increase in high level clouds from the tropical
system will begin to expand into the region by later in the
afternoon into the evening. The approach of the remnants of Francine
should aid in pushing the stagnant smoke layer over the Ohio Valley
out of the area to the northwest on Thursday. Surface winds will
increase from the E/SE as the day progresses with gusts up to 20kts
at times.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
UPDATE...Ryan
SHORT TERM...Updike
LONG TERM...50
AVIATION...Ryan
Source:
IND issues Area Forecast Discussion (AFD) at Sep 11, 9:22 PM EDT---------------
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