659
FXUS63 KIWX 290537
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
137 AM EDT Sat Jun 29 2024

.KEY MESSAGES...

- Heavy rain and thunderstorms are expected overnight, with isolated
flooding/ponding possible in fields and on roads. A few storms late
morning/early afternoon on Saturday could be strong to severe, with
damaging winds and a brief tornado or two. The best severe chances
will be in NW Ohio. (Medium confidence)

- A second round of storms could develop later in the
afternoon/evening Saturday, with damaging winds as the main threat
(Low confidence, depends on if recovery happens behind the morning
round of storms).

- Hazardous swimming conditions are expected on Lake Michigan on
Sunday. Waves 4 to 7 feet and dangerous rip and structural currents
are likely. Stay out of the water and stay off of the pier!

- Dry with near normal temperatures Sunday through Tuesday
  morning.

&&

.DISCUSSION...
Issued at 215 PM EDT Fri Jun 28 2024

Stay weather aware overnight and into the day tomorrow as strong to
severe thunderstorms are possible within two rounds of storms. SPC
has maintained a Slight Risk (level 2 of 5) for much of our area.
GOES visible satellite shows increasing cloud cover moving in from
the west as a warm front advances across our forecast area. Dense
cloud cover persists through tonight along with a chance of showers
this afternoon and evening. Overnight and into Saturday morning, a
line of heavy rain and embedded thunderstorms is likely to develop
after midnight along a pre-frontal trough. As convection moves
eastward into far NE Indiana and NW Ohio, it is likely to intensify,
with a few strong to severe storms possible in the morning and early
afternoon. Hi-res model guidance varies in coverage and intensity of
storms, with the NAM and HRRR showing the best severe potential.
Southwesterly winds behind the warm front will advect moisture
into the area overnight, which will yield an unstable
environment for storms to form. 1500-2000 J/kg MLCAPE is
possible coinciding with 30 kts of 0-6 km shear orthogonal to
the pre-frontal trough. Low to mid level lapse rates throughout
the day Tuesday will be around 6C/km. In addition, there is
favorable 0-1 km SRH of 150-200 m2/s2. Damaging winds 40 to 60+
mph and a brief tornado or two will be possible. The best
severe chances in the morning will be where the Slight Risk is
in NW Ohio, although I wouldn`t surprised if a strong to severe
storms develops along or just east of the I-69 corridor. There
is increasing confidence in heavy rainfall and localized
flooding around midday Tuesday as record PWATs around 2 inches,
a deep warm cloud layer, and saturated low to mid levels of the
atmosphere will yield very efficient rainfall rates of 1-2
inches per hour in any storms. A cold front will come through
Saturday evening and there is low confidence in a second round
of storms developing along the front. Should a second round of
storms materialize, damaging winds 40 to 60+ mph will be the
main threat.

Hazardous swimming conditions are expected on Lake Michigan Sunday
thanks to gusty northerly winds behind the cold front. Waves will
build to 4 to 7 feet and wave periods look to stay in the 6-8 second
range (relatively high for Lake Michigan) thanks to a long fetch
down the lake. This will increase the probability of dangerous
currents, including rip and structural currents. Will hold on any
headlines for now but subsequent shifts will likely need to issue a
Beach Hazards Statement for Sunday into early Monday, as longer wave
periods and high waves may lead to current activity that persists
even once wave heights diminish. Those planning to visit the beaches
this weekend should stay out of the water and stay off of the pier!

It will be mostly dry and cooler with highs in the upper 70s to mid
80s Sunday through Tuesday morning as high pressure builds in at the
surface beneath a brief upper level ridge. Clouds move out of the
area bringing clear skies for Sunday and Monday. The next chance for
rain/storms will arrive on Tuesday afternoon/evening.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 137 AM EDT Sat Jun 29 2024

Broad warm/moist air advection ahead of a weak and disjointed
trough will support periodic showers through the morning.
Isolated thunderstorms are possible with the best chances at
KSBN where slightly higher MUCAPE resides but coverage will
remain low. Models continue to suggest some brief MVFR ceilings
during the late morning as low level moisture continues to pool
ahead of the approaching cold front. Confidence is not high but
will hold with brief MVFR mention. There is potential for a
second round of showers and isolated storms late Saturday
afternoon, mainly at KFWA, as the cold front approaches. Forcing
remains weak though and CAM`s remain very inconsistent on when
and if storms actually occur. Will therefore keep the afternoon
dry for now.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Johnson
AVIATION...AGD