826
FXUS63 KIND 301339
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
939 AM EDT Tue Apr 30 2024

.KEY MESSAGES...

- Becoming Mostly Sunny Today; Warm

- Mostly Clear this evening, increasing clouds overnight; Mild.

- Warmer than normal conditions continue through the week.

- Additional thunderstorms expected late Thursday into the weekend.

&&

.FORECAST UPDATE...
Issued at 939 AM EDT Tue Apr 30 2024

Observations and satellite imagery show that the morning fog has
come to an end across all but the most rural portions of central
Indiana with the low stratus continuing to scour out now that
daytime heating has begun and near surface dew point depressions
begin to increase.

Focus then turns to afternoon highs with the potential for
overachieving highs as clouds quickly clear out.  As mixing
increases, dewpoints should fall into the low to mid 50s allowing
for a very pleasant day with no hazardous weather.

&&

.SHORT TERM (Today and tonight)...
Issued at 309 AM EDT Tue Apr 30 2024

Synopsis:

Surface analysis early this morning shows Low pressure over Lake
Superior with a cold front extending from that system across MI to
western Indiana and western KY. Radar shows showers found ahead of
that front, over southeast Indiana, pushing east into Ohio. Surface
high pressure was found over MO and Arkansas, with a ridge extending
north into the Upper Mississippi Valley. Areas of low stratus and
fog had formed in the Wabash valley, but GOES16 show clear skies
across much of IL/MO and IA. Aloft weak ridging was found over the
high plains and an upper low was pushing north into western Ontario.

Today...

Models today suggest the parent upper low over Ontario will continue
to push northeast today and this will continue to allow its
associated cold front to push farther east today also. This results
in nearly zonal flow in place across Central Indiana and the region
with minimal forcing passing. Meanwhile within the lower levels the
surface ridging to our west is expected build across Indiana through
the day. Forecast soundings reveal a dry column through the day as
subsidence and high pressure reside across our area. However, given
our recent satellite and observational trends, the day should begin
cloudy due to the low stratus deck in place. The combination of
heating and mixing after daybreak along with drier air arriving on
westerly surface winds will allow for skies to become mostly sunny.

Minimal temperature advection is place today. Thus given the
westerly flow and plentiful sunshine, highs in the middle and upper
70s will be common.

Tonight...

Dry and mild weather is expected tonight. Surface high pressure is
expected to linger across eastern KY and eastern TN, allowing a
continued mild SW flow into central Indiana. The mainly zonal flow
is depicted to remain in place aloft, however a weak upper wave is
expected to pass within the flow aloft. This feature is associated
with another low pushing through the upper midwest. These features
do not appear to pass across Central Indiana until after 06Z,
however through the entire night the lower levels appear to remain
quite dry under the influence of the high pressure system to the
southeast. Forecast soundings only show some high passing saturation
late overnight. Thus after a mostly clear evening, some passing high
clouds will expected late.

Possible caveat: HRRR suggests convection with this upper wave
pushing across IA and IL during the evening hours, diminishing upon
approach to IN. Should this hold together, some pops could be needed
for the Wabash valley late tonight. Limited deep moisture and weak
instability make this solution appear less likely.

Regarding temps, warm air advection remains in play with southerly
flow on the back side of the surface high to the southeast. This
will allow for a mild night with low temperatures in the middle to
upper 50s.

&&

.LONG TERM (Wednesday through Monday)...
Issued at 309 AM EDT Tue Apr 30 2024

Central Indiana will continue to see the pattern of above normal
temperatures and multiple rounds of showers and thunderstorms. The
warmest day of the period will be Thursday with highs forecasted to
be nearing record highs.

Upper ridging will start off the long term and paired with a surface
high just to the SE of the area. This should be enough to hold off
on any precip (other than a few sprinkles in the west) for the day
despite models showing a boundary near the area. Dry weather will
continue into Thursday but by the afternoon, the first chances of
precipitation from a potent approaching system will be possible.
This large upper low will be moving from the northern Plains into
Canada and north of the Great Lakes. The warm front will be
progressing northward through the forecast area late Wednesday night
which may prompt some showers to form but those should move out by
daybreak. Thursday we will then be in the warm sector, waiting for
the storms ahead of the cold front to arrive. Models still vary on
the time of arrival so for now keeping with guidance of slight PoPs
Thursday afternoon with better chances for storms arriving on
Friday. Stronger forcing and a relatively narrow corridor of deeper
moisture ahead of an approaching cold front supports better chances
for precipitation. The one caveat is guidance shows the approaching
front becoming displaced from the parent trough. This would limit
overall forcing and rainfall amounts across central IN. For this
reason, heavy rainfall does not appear to be a threat this time.
Severe weather also does not look likely at this time.

Models show additional chances for showers and storms into the
weekend though confidence is low due to a wide array of solutions.
It does appear that another wave will arrive late in the weekend
which may allow for a brief dry period on Saturday, between systems.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 554 AM EDT Tue Apr 30 2024

Impacts:

- IFR to LIFR conditions will improve to VFR by mid to late morning.

Discussion:

Residual and left over lower level moisture along with light winds
have allowed for the formation of IFR stratus and fog at the TAF
sites. Clear skies and P6SM can be found upstream over Central
IL. The IFR or worse conditions will quickly improve after sunrise
as mixing and heating return. Thus we expect a quick burn off
allowing a return to VFR conditions.

Forecast soundings after 14Z show a dry column today and tonight as
a weak area of surface high pressure and ridging builds across the
area. Some high clouds may arrive late tonight as an upper level
weather disturbance arrives in Central Indiana. Thus after 14Z-15Z
VFR will be expected for the rest of the period.


&&

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

$$

UPDATE...White
SHORT TERM...Puma
LONG TERM...KF
AVIATION...Puma