-- Discussion containing changed information from previous version are highlighted. --
580
FXUS63 KIND 280019
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
819 PM EDT Thu Jun 27 2024

.KEY MESSAGES...

- Cloudier, warmer, and a bit more humid on Friday.
- Rain and storms return Friday night into Saturday
- A few strong to potentially severe storms possible Saturday

&&

.FORECAST UPDATE...

-- Changed Discussion --
Pre-sunset temperatures are still in the 80s over southwestern
sections whereas they were mostly in the middle and upper 70s east
of I-65. Meanwhile, visible satellite was showing thick cirrus
heading this way in WNW upper flow around the lower Mississippi
Valley ridge. This should help slow the temperature drop tonight and
prevent fog from occurring. Good confidence temperatures will not
reach dew points, which are in the 50s at some locales, east of I-
65.
-- End Changed Discussion --

&&

.SHORT TERM (This evening through Friday)...
Issued at 257 PM EDT Thu Jun 27 2024

Generally quiet weather can be expected through the short term.
Surface high pressure is building in after yesterday`s storm system,
with dry flow from the north-northeast. Large-scale subsidence has
brought mainly clear skies with the only cloud cover being diurnal
cumulus. These cumulus should diminish shortly after sunset.

Overnight, high clouds begin to increase from the northwest ahead of
an approaching shortwave trough. Cloud cover is expected to increase
through the night and lower/thicken with time. The increasing
cloudiness will likely act to keep temperatures from dropping as low
as they otherwise would. Therefore we bumped lows up a degree or two
compared to the previous forecast. Fog chances are much lower due to
drier air and cloud cover.

On Friday, winds begin to turn southeasterly in response to the
approaching system. Guidance seems a bit aggressive and too fast
advecting moisture back into the region. The NAM, for instance,
rapidly brings dew points into the lower 70s by early afternoon
across our southern counties. Added more weight to short-term
guidance which keeps Tds lower by a few degrees and delays the onset
of 70 degree Tds by a few hours. As for ambient air temps, guidance
is split between low 90s and mid to upper 80s. We`ll lean more
towards the upper-80s camp since cloud cover will be present for
much of the time.

Towards the end of the period, some members of guidance show a few
light rain showers encroaching from the northwest. Trimmed this back
a bit before 00z since we are thinking that moisture advection
within the models is a bit aggressive. Nevertheless, most guidance
shows precip arriving at some Friday night which will be covered in
the long range section below.

&&

.LONG TERM (Friday night through Thursday)...
Issued at 257 PM EDT Thu Jun 27 2024

Friday Night Through Saturday

A fairly active start to the long term period is expected with rain
expected along with the potential for a few strong to severe
thunderstorms. The upper level pattern will remain generally zonal
through Saturday but a deepening low pressure will allow the LLJ to
ramp up late Friday night bringing scattered elevated showers and a
few rumbles of thunder ahead of surface based convection Saturday.
This is expected to initiate ahead of a cold front associated with
the broader synoptic low in Southern Canada. Shear will be maximized
along the front but the thermal profile will be fairly marginal due
to the overnight convection from Friday night which will leave a
conditional but fairly unlikely threat for organized convection.

If any severe thunderstorms do form, damaging winds would be the
primary threat. Do have some concern that this system could favor
slow propagation on the southwestern portion of any organized line
which could lead to pockets of flash flooding with rainfall amounts
of 3-5 inches in a matter of hours, but this threat is being
highlighted more over Missouri and western Illinois vs across
Indiana.

Sunday Through Thursday.

Conditions will be fairly mild Sunday into Monday in the aftermath
of the frontal passage with generally clear skies and highs around
80 as the near surface flow becomes northerly to northwesterly. The
ridge of high pressure will then build back in towards the middle of
the week with a return to temperatures near 90 by Wednesday.  There
is a low threat for showers/storms across the northwestern counties
Tuesday into Wednesday but think that the ridge will be strong enough
to keep thunderstorms out of the forecast area at this time. By late
Wednesday into Wednesday night though another weak cold front should
bring scattered to potentially widespread rain and a few rumbles of
thunder with no severe weather expected at this time.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 701 PM EDT Thu Jun 27 2024

Impacts:

- None

Discussion:

Good confidence that VFR flying conditions will continue through the
TAF period as a high veil of clouds increases Friday. The worst case
scenario is perhaps some scattered fair weather CU well above 3K
feet Friday afternoon.

Winds will be from the northeast and east 6 knots and less overnight
and then southeast to near 10 knots Friday afternoon.


&&

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

$$

UPDATE...MK
SHORT TERM...Eckhoff
LONG TERM...White
AVIATION...MK