024
FXUS63 KIND 300239
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1039 PM EDT Mon Apr 29 2024

.KEY MESSAGES...

- Patchy dense fog likely over western central Indiana tonight.

- Warmer than normal conditions continue through the week.

- Isolated thunderstorms possible late in the day Wednesday.
  Additional thunderstorms expected late Thursday into the
  weekend.

&&

.FORECAST UPDATE...
Issued at 1039 PM EDT Mon Apr 29 2024

Showers will continue to progress eastward over the next few hours,
with most of central Indiana rain free by 2AM EDT. Behind the
showers, thick low level stratus will remain, gradually thinning out
from west to east as we enter day break.

Increased chances for fog within the Wabash Valley overnight. Prior
day rain in combination with earlier clearing should lead to at
least patchy dense for over this area. A few pockets of areal fog
coverage are possible, but confidence was too low to pinpoint at
this time.

&&

.SHORT TERM (This evening through Tuesday)...
Issued at 257 PM EDT Mon Apr 29 2024

Showers are increasing in coverage again this afternoon as another
weak wave aloft pivots around the base of the weakening upper low
over the upper Midwest. Have seen a few lightning strikes to this
point but instability remains meager. 18Z temperatures ranged from
the 60s into the lower 70s.

The presence of the aforementioned upper wave tracking through the
region in tandem with an approaching frontal boundary will keep the
threat for showers and a few storms the rest of the afternoon and
into tonight. The boundary will move through the region overnight
with dry and warm weather returning Tuesday as high pressure builds
in.

This Afternoon and Evening

After the initial surge of showers and storms earlier this
morning...coverage has been minimal with the better forcing aloft
back to the southwest closer to the upper wave. As this feature
lifts into the region over the next few hours however...expect
coverage to expand further with embedded thunder. Remain skeptical
of convective intensity as instability has been limited by the
clouds and earlier rain. Do expect some further destabilization
through peak heating but overall CAPE values should remain at or
below 1000 j/kg. The model suite has been overdoing potential
instability over the next few hours...likely due to holding firm on
much of the forecast area warming into the low to mid 70s through
late day. Considering the cloud deck and expanding rain currently...
temps are likely to struggle to get much warmer than 70 to 75 over
much of central Indiana. Periodic gusts to around 20mph will linger
for the next few hours then diminish.

A deeper moisture plume will expand into the region through this
evening with low level convergence and at least some isentropic lift
present ahead of the front as well. But the overall lack of BL shear
and meager instability combined with features that are a bit out of
phase support generally disorganized convection into the evening
with sporadic lightning and brief heavy rainfall being the primary
concerns for any outdoor activities. Will focus the primary rain
chances from late afternoon through the evening. Overall expected
rainfall will largely be a half to three quarters of an inch
although localized higher amounts are possible.

Overnight into Tuesday

Rain will end west to east late evening into the overnight as the
remnant frontal boundary sweeps across the forecast area. Expect all
of the rain will be east of central Indiana by 08-09Z. Model
soundings and RH progs do support lower stratus across the region
near and behind the front with the potential for localized fog as
well with a shallow inversion. The inversion will break up quickly
near or just after daybreak with skies becoming mostly sunny as a
high pressure ridge builds into the Ohio Valley.

Temps...have pulled back on forecast highs this afternoon
considering what temps have done to this point. As mentioned
above...expect highs from the upper 60s to the mid 70s. Lows tonight
will range from the lower 50s in the northern Wabash Valley where
some clearing will occur in the predawn hours to around 60 in the
southeast. Low level thermals support low and mid 70s for Tuesday
with light winds and abundant sunshine.

&&

.LONG TERM (Tuesday night through Monday)...
Issued at 257 PM EDT Mon Apr 29 2024

Tuesday night through Thursday...

The long term period will start off rather quiet as upper ridging
builds across the region. A weakening front is expected to move
towards the area on Wednesday which could lead to isolated showers
or storms, but confidence is relatively low. The front should be
well displaced from the parent upper wave once it reaches the IN
border thus forcing looks weak. However, moisture surging northward
and daytime heating will likely promote moderate destabilization
late in the day. This supports a slight chance for diurnal
thunderstorms. Weak deep-layer shear should limit convective
organization or the potential for severe weather, but cannot rule
out isolated downbursts and small hail in stronger storms.

Thursday looks dry as the upper ridge builds. Forecast soundings
show a drier column compared to Wednesday thanks to stronger
subsidence supporting this. Increasing heights aloft and increasing
southerly flow at the surface will warm temperatures with highs
generally in the upper 70s to mid 80s.

Thursday night onward...

Rain chances increase late Thursday into Friday as a surface low and
parent trough approach the region. 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.

There are additional chances for showers or storms into the weekend
though confidence is low. Some models show the aforementioned front
pushing through central IN providing dry conditions while others
show the front stalling over the area. Will stick with a blended
forecast of low POPs for now given the uncertainty. Severe weather
is unlikely due to limited instability and deep-layer shear. Warm
conditions should continue through the extended though highs may be
slightly cooler.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 739 PM EDT Mon Apr 29 2024

Impacts:

- MVFR and very brief IFR conditions possible in convection

- Rain ends overnight with skies clearing Tuesday morning

- MVFR ceilings likely at times overnight prior to clearing tomorrow

Discussion: Expect periodic restrictions within heavier showers and
storms this evening, progressing east and ending as the frontal
boundary passes through around 03-06z. Model soundings do favor low
stratus development near and immediately behind the front overnight
with the potential for patchy fog as well. Skies will clear Tuesday
morning as high pressure builds into the Ohio Valley. Winds will
veer to W/NW on Tuesday.


&&

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

$$

UPDATE...Updike
SHORT TERM...Ryan
LONG TERM...Melo
AVIATION...Updike