074
FXUS63 KIWX 250009
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
809 PM EDT Mon Jun 24 2024

.KEY MESSAGES...

- A line of thunderstorms is expected to move through late
  overnight through early Tuesday morning bringing a chance for
  locally strong/damaging winds.

- Confidence remains low on details regarding Tuesday
  afternoon/evening showers and thunderstorms. If these develop,
  large hail, damaging winds, and locally heavy rain will be
  main threats.

- Seasonable temperatures and dry conditions expected Thursday
  and Friday before additional rain chances return Saturday.

&&

.UPDATE...
Issued at 809 PM EDT Mon Jun 24 2024

Main focus remains on convective chances and intensity later tonight
into Tuesday morning as convection over MN/WI congeals into an
upscale growing MCS. The genesis of this is currently underway well
upstream over northern MN. Of note through is a separate area of
scattered convection north of a warm in srn MN and sw WI as of this
writing. The HRRR is starting to pick up on this and hints at
this elevated activity surviving east into the area between
7-11z as a corridor of strong low-mid level theta-e advection
overspreads the area from west to east. Bumped up PoPs during
this time to account for these trends, with this activity to
generally hold below severe limits. Attention then turns to the
upscale growing MCS and a possible bowing segment turning south
into the area between roughly 11-15z Tue AM. This activity does
outpace more favorable flow and instability with a trend toward
backbuilding and an outflow dominant line this far south,
though a wind threat (50-60 mph winds) definitely remains in
play across northern portions of the forecast area if a more
pronounced bowing segment is realized upstream over WI and Lake
MI.

&&

.DISCUSSION...
Issued at 250 PM EDT Mon Jun 24 2024

After our extended heat wave last week, we return to a more
active, complex weather pattern over the next 24-36 hours.
Convection currently in the Dakotas and MN will grow upscale and
evolve into a MCS as we head through the evening and overnight
hours. Overall agreement is for this complex to maintain
intensity through Wisconsin where the greatest instability will
reside, along with the stronger shear. A gradual weakening
should take place as it works its way southeastward across SE
Lake Michigan and Indiana where a rapid dropoff in overnight
instability will be located. Nevertheless, mesoscale maintenance
of the stronger cells may allow them to produce instances of
strong/damaging wind gusts as they push into our forecast area
and the updated Day 1 Outlook from SPC now drags a Slight Risk
(2 of 5) into North Central Indiana and Southwest Michigan. CAMs
have begun to latch onto this better as well, and given the 4mb
pressure rises on the HRRR as the MCV moves across the lake,
there is some concern for seiche activity along with an increase
in wave action and rip current risk leading into Tuesday. Some
closer evaluation of this will be needed as we head into the
overnight hours...

In the wake of the late overnight into early tomorrow morning
convective complex, steep low/mid level lapse rates and hot
daytime temperatures will contribute to rapid and intense
instability across the forecast area. Bulk shear will be
limited, ranging from 20-30kt, which will likely prevent a more
significant severe episode if anything develops (more below). A
corridor of low LCL heights will be favorable for a tornado
environment, however, we will need existing surface boundaries
to enhance low level helicity as this parameter looks meager.
It`s worth noting that confidence in triggers due to the
aforementioned earlier convection, and a lack of strong forcing
during the day, may keep a lid on afternoon thunderstorms
altogether. Therefore, at this time, confidence is very low in
Tuesday afternoon/evening severe potential. If anything does
develop, the thermodynamic profile will help to create robust
updrafts with a hail and damaging wind threat; we`ll just have
to see how the AM convection shakes out first.

Fortunately, the hottest day of the week will be tomorrow
before a frontal passage returns us back into more seasonable
temperatures. We will have dry days on Thursday and Friday
before another shortwave and surface front brings additional
chances for rain and storms.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 651 PM EDT Mon Jun 24 2024

VFR conditions and light winds will persist into the early overnight
on the back edge of stable high pressure. Chances for convection
(and associated brief vis/cig restrictions and gusty winds) then
enter the picture later tonight through early Tuesday afternoon as a
MCS likely develops southeast through WI and MI, with a trailing
outflow and incoming warm front allowing at least a broken/weakening
line of convection to drop south into northern IN, best chances in
the 12-16z window. Scattered elevated convection could even
develop in advance of the main line in roughly the 9-12z window,
though confidence in coverage and timing of convection remains
low as activity will outpace better flow and instability. Winds
will increase and back more to the west-southwest during the
day tomorrow otherwise.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory from 2 AM to 2 PM EDT Tuesday for LMZ043-
     046.

&&

$$

UPDATE...Steinwedel
DISCUSSION...Norman
AVIATION...Steinwedel