000
FXUS63 KIND 220153
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
953 PM EDT Sun Apr 21 2024

.KEY MESSAGES...

- Mostly Clear tonight with Frost

- Morning sunshine with high clouds arriving on Monday; Warmer

- Increasing rain chances Tuesday with low chance for
  thunderstorms, temperatures near or below normal through Thursday

- Active pattern likely to return late this week into the weekend
  with above normal temperatures

&&

.FORECAST UPDATE...
Issued at 953 PM EDT Sun Apr 21 2024

Forecast is in great shape so not notable updates were needed.

Surface high pressure is settling into the area which has allowed
winds to become light and variable while skies have cleared out.
Conditions still look good for temperatures to drop to the low to
mid 30s and for patchy to areas of frost to form.

&&

.SHORT TERM (This evening through Monday)...
Issued at 253 PM EDT Sun Apr 21 2024

Synopsis:

Surface analysis early this afternoon shows strong high pressure in
place over KS and OK. A surface ridge of high pressure extended east
from the high across IL to northern Indiana. GOES16 shows cloud
cover from last night has exited east of the forecast area and
scattered diurnal CU had formed across much of Central Indiana.
Surface flow remained from the northwest and dew points remained dry
in the middle 20s. Aloft, a deep polar low was in place over Hudson
Bay, keeping a northwest cyclonic flow in place across the Great
Lakes and our region. Ridging aloft was found on the lee side of the
Rockies. This was resulting in subsidence and the creation of the
strong surface high across the plains and Ohio Valley.

Tonight...

Models show the ridging aloft over the Rockies quickly moving across
the Plains tonight. This will help to continue to create subsidence
across the middle Mississippi and Ohio Valleys. The lower levels
depict strong surface ridging remaining across Central Indiana along
with a weakening surface pressure gradient. GOES16 shows clear skies
upstream. Forecast soundings and time heights also show a dry column
through the overnight hours. Thus a mostly clear sky and cool
conditions are expected overnight with light winds. This will be
ideal conditions for frost. Dew points in the middle 20s should
easily allow surface temps to fall to the middle 30s for lows, again
favorable for Frost. Thus the ongoing Frost Advisory will continue.

Monday...

Models on Monday start the day with the strong surface high centered
over OK and TX, with a strong ridge axis still extending northeast
across Indiana toward the Great Lakes. Aloft, strong ridging will
still be in place over Indiana. Forecast soundings show a dry column
through the morning, however trend toward saturation aloft during
the afternoon. This upper level saturation will be due to the
arrival of an upper level wave on the backside of the departing
ridge aloft. HRRR and other models suggest the high level saturation
arriving in the afternoon from the northwest. Thus look for a mostly
sunny morning with increasing clouds during the afternoon.

Warm air advection is in play on Monday as west to southwest flow
becomes more predominate within the lower levels. This should allow
for a warmer day on Monday as highs reach the low to middle 60s.

&&

.LONG TERM (Monday night through Sunday)...
Issued at 253 PM EDT Sun Apr 21 2024

Monday night through Tuesday night...

Quiet weather conditions are likely to persist through the beginning
of the extended as surface ridging remains across central Indiana.
An approaching shortwave and associated low pressure system will
then move in late Tuesday bringing an end to the stretch of drier
weather over the past few days. Subsidence induced dry air across
the mid-south may limit overall gulf moisture return and rainfall
amounts. Despite this, increasing large scale ascent and warm air
advection combined with a relatively narrow corridor of sufficient
moisture supports widespread precipitation. The best chance for rain
will likely be during the afternoon/evening and QPF amounts should
generally be around half an inch or less. Weak destabilization
could support a few embedded storms, but this potential is low.

Look for return flow and increasing clouds to keep temperatures
warmer Monday night with lows in the mid-upper 40s. Rain/clouds will
likely limit diurnal heating Tuesday. Highs are expected to range
from the mid 50s to mid 60s. A progressive pattern aloft should help
push the aforementioned system further east overnight allowing drier
conditions to return.

Wednesday through Thursday...

Cold air advection and surface high pressure building in behind the
departing low will allow for brief cooler and quiet weather
conditions to persist into Thursday. Below normal highs in the mid
50s to low 60s are expected for Wednesday. Temperatures falling into
the 30s under good radiational cooling conditions Thursday morning
leads to some frost concern as high pressure becomes centered over
the Great Lakes Region. The greatest potential for frost should be
across northeast portions of the area closer to the high.

Late week...

Models begin to diverge by late week into the weekend which limits
forecast confidence, but there is a general signal for an active
pattern to return. A low end threat for strong to severe storms
cannot be ruled out heading into the weekend as increasing
instability and mid-upper level flow from approaching disturbances
could support organized convection. However, confidence is low due
to the disagreement between guidance. CSU machine learning currently
shows low probabilities for severe weather over central Indiana
during this period. The better setup for severe weather looks to be
further west where better instability and deep layer shear is
likely. Warm air advection will likely result in above normal
temperatures during this period.

One thing to note, Indianapolis is already in the top 13 for wettest
April`s on record. Numerous chances for rainfall Tuesday, and then
again late next week into the weekend will likely push Indianapolis
at least into the top 10 for wettest April`s on record.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 747 PM EDT Sun Apr 21 2024

Impacts:

- Southwesterly winds Monday increasing to 7 to 12 kts during the
afternoon

Discussion:

VFR conditions expected throughout the TAF period.

Strong high pressure and upper level ridging will lead to continued
subsidence and dry weather this TAF period.

Forecast soundings remain dry through 18Z Monday. Thus a mostly
clear sky is expected with mainly unlimited ceilings. After 18Z
Monday, an upper trough pushing SE from the northern plains will
spread high CI across the TAF sites.

Winds will start off out of the NW and become variable and somewhat
light overnight. By early Monday morning, all sites will see
southwesterly winds. These winds will increase through the day
tomorrow, becoming 7-12 kts by midday to the afternoon hours.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 1 AM to 10 AM EDT Monday for INZ021-028>031-
035>049-051>057-060>065-067>072.

&&

$$

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