328
FXUS63 KIND 110621
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
221 AM EDT Sat May 11 2024

.KEY MESSAGES...

- Brief period of rain through 8 AM across north central Indiana
- Afternoon wind gusts of 30-35 mph today
- Showers and storms return Monday into Monday night
- Near normal temperatures for next week

&&

.SHORT TERM (Today and tonight)...
Issued at 221 AM EDT Sat May 11 2024

Aurora viewing over the last few hours has been somewhat successful
across central Indiana as clouds have remained scattered.
However...starting to see an increase in mid level clouds ahead of a
cold front currently located across the western Great Lakes with an
area of showers along it. Rain is most numerous across lower parts
of Lake Michigan with convection much more scattered south into
central Illinois. 06Z temperatures were predominantly in the mid and
upper 50s with light southwest winds.

The frontal boundary is the primary focus in the immediate near term
as it will sweep southeast across the forecast area during the
predawn hours into the first part of the morning. Beyond that...much
of today will be dry with windy conditions developing due to a
combination of cold advection and a tight surface pressure gradient
in the wake of the frontal passage.

Clouds will overspread the northern half of the forecast area over
the next few hours with a narrow band of showers following close
behind. These showers will quickly drop southeast across the
northeast half of the forecast area over the next 4-6 hours as the
front moves across the region. Rainfall amounts will be light with
most areas receiving no more than a tenth of an inch. Across the
southwest half of the forecast area...it will largely remain dry
with the wind shift from southwest to northwest signifying the
frontal passage. Showers will be east of the forecast area by 12-13Z.

The rest of the day will be similar to Friday with a mixture of sun
and clouds as a healthy cu field develops for the afternoon in the
cold advection and cyclonic flow present aloft. The primary
difference from Friday will be the winds which will be higher for
much of the day as the airmass becomes well mixed with dry adiabatic
conditions up into the 650-700mb layer by mid to late afternoon.
This should easily enable stronger winds to be drawn to the surface
with gusts likely to peak at 30-35mph. Gusts will drop off quickly
with sunset as high pressure expands across the Ohio Valley. Cu will
diminish with the loss of heating and leave mainly clear skies
overnight with light northerly flow.

Temps...low level thermals are supportive of highs this afternoon
ranging from the mid 60s northeast to the lower 70s southwest. With
ideal radiational cooling conditions developing
tonight...temperatures will fall into the mid and upper 40s over
much of the forecast area.

&&

.LONG TERM (Sunday through Friday)...
Issued at 221 AM EDT Sat May 11 2024

A quasi-zonal pattern will dominate through much of the extended
with a slow moving cutoff upper level low set to bring another round
of wet and unsettled weather for the first half of next week.
Another system will impact the Ohio Valley by Friday with another
chance for rain. With the subtropical jet displaced well to our
south throughout the extended...severe weather is not expected and
the lack of appreciable instability will keep even the threat for
thunderstorms limited through much of the extended.

Sunday and Sunday Night

Continued high pressure and the arrival of ridging aloft will make
for a fantastic Sunday with abundant sunshine and temperatures
recovering into the 70s to potentially lower 80s across the forecast
area. CAMs beginning to pick up on a weak wave aloft drifting across
northern portions of Indiana by the afternoon. With a deeply mixed
airmass up to 700mb and little to no instability...not sure the wave
will be able to generate much more than a light shower. That being
said...closer analysis of the model soundings for late Sunday
afternoon highlight steep lapse rates up through about 8kft which
might be enough to get locally gusty winds to the surface with any
isolated shower especially with dewpoint depressions on the order of
30-35 degrees. Will continue to monitor but most areas will remain
dry all day Sunday.

A cutoff upper level low will eject out of the Rockies on Sunday and
move slowly east through the central Plains through early Monday.
Mid and high clouds will begin to increase Sunday night ahead of
this feature and the associated surface wave approaching from the
west. Model soundings show residual dry air and subsidence will
linger Sunday night and with moisture advection associated with the
surface wave largely delayed until during the day Monday...dry
conditions will persist Sunday night.

Monday through Tuesday Night

The upper low and associated surface wave will be over central
Kansas Monday morning...and will track slowly east through the
Missouri...mid Mississippi...Ohio and Tennessee Valleys through
early Wednesday. Showers will gradually increase in coverage
throughout the day Monday with the best chances for rain to come
Monday night into Tuesday as the surface low drifts through the
region. Recent model trends have initiated weakening of the upper
low more rapidly as it arrives over the Ohio Valley with the
attendant surface wave tracking further south than previously
thought. This would result in the locally heavier rainfall rates
potentially shifting closer to the Ohio River and points south and
the sounding data supports this thinking as well with less moisture
present through the depth of the column.

Instability will remain weak throughout much of the period with
abundant cloud cover limiting heating. CAPE values are subtly better
on Tuesday in the immediate vicinity of the surface low but expect
thunderstorms to be isolated to scattered at best. Despite the lower
moisture levels showing up in the soundings...precip water values
peak near 1.25 late Monday night into Tuesday. The setup supports
the potential for non-uniform pockets of moderate to heavy
rainfall...particularly on Tuesday and likely focused over southern
portions of the forecast area with any slow moving convection.
Expect 0.50 to 0.75 inches for much of the forecast area by Tuesday
night with locally higher amounts confined to southern Indiana in
closer proximity to the surface low track. High temperatures will
rise into the 70s both Monday and Tuesday...held down slightly on
Tuesday with increased rain and clouds over the region.

Wednesday through Friday

The upper low will weaken and eventually become absorbed by the mean
flow aloft as it moves away from the region on Wednesday. After a
cloudy start Wednesday as low level moisture lingers in the wake of
the upper low...clouds will scatter as ridging aloft builds into the
Ohio Valley. Temperatures will warm back up into the mid and upper
70s for Wednesday and Thursday with dry conditions. A surface low
with an associated frontal boundary will move across the region late
week with scattered showers and storms focused especially during the
day Friday.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1227 AM EDT Sat May 11 2024

Impacts:

- Northwesterly wind gusts 23-27KT 17Z to 00Z
- Brief period of showers 09Z-12Z

Discussion:

VFR conditions expected through the TAF period outside of a low
chance for MVFR vsbys during rain from 09Z to 12Z with best chance
at LAF. Northwesterly winds will occasionally gust to around 25kts
through much of the afternoon hours before weakening after sunset.
Cloud cover will gradually decrease in the aftermath of the rain
this morning, but diurnal cu should fill back in later in the day.


&&

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

$$

SHORT TERM...Ryan
LONG TERM...Ryan
AVIATION...White