090
FXUS63 KIWX 271647
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1247 PM EDT Mon Jul 27 2026

.KEY MESSAGES...

- There is an Enhanced Risk for severe weather today. Clusters
  of strong to severe storms are expected this afternoon and
  evening. The greatest severe weather threat is expected from
  2pm to 10pm EDT.

- Damaging wind gusts of 60 to 70 mph will be the main threat,
  with potential for scattered significant gusts over 75 mph.
  An isolated tornado or two cannot be ruled out.

- Dry and seasonable Tuesday through Thursday.

- High Swim Risk Tuesday for southeast Lake Michigan beaches.

&&

.UPDATE...
Issued at 1058 AM EDT Mon Jul 27 2026

Factors appear to be coming together for an increased risk of
severe storms this afternoon into early this evening. An initial
band of showers and isolated storms at leading edge of fairly
strong low level theta-e gradient has largely weakened, but
renewed convective development has been noted past hour from
central Lake MI to northeast Illinois. These storms are forming
in a very unstable environment with RAP near term analyses
indicating 4-5K J/kg of MLCAPE across northern Illinois. A
minimum in instability is noted across northeast Indiana this
morning, but this instability gradient should be shifting
eastward over the next few hours. In addition, some synoptic
support will increase over next few hours for an organized
severe threat as mid/upper jet streak shifts eastward across the
southern Great Lakes region with effective shear values
increasing to 50-60 knots. Damaging wind gusts of 70+ mph still
appears to be the primary threat, but isolated large hail will
be possible (especially through mid/late afternoon). Also, with
increasing shear profiles cannot rule out some potential of
embedded circulations in the line given 0-3km shear vectors from
northwest around 30 knots. A good deal of uncertainty still
persists regarding window of discrete storm development and
extent of more organized MCS cold pool that could yield
widespread damaging winds. Timing of the greatest severe threat
from 18Z-02Z still looks reasonable, although if more organized
forward propagating system develops this timing could be moved
up a bit with earlier diminishment in severe threat later this
evening.

&&

.DISCUSSION...
Issued at 305 AM EDT Mon Jul 27 2026

Our area has been upgraded into an Enhanced Risk (level 3 of 5) for
severe weather with strong to severe storms likely later today.
Today`s severe weather setup is becoming more clear and confidence
is increasing as model guidance (especially recent runs of the HRRR)
points towards a strong MCS pushing through this afternoon and early
evening. Radar and satellite trends over the past 6-12 hours show
that convection has been slow to develop overnight in Minnesota and
Wisconsin, which means timing has shifted towards the the
afternoon into the evening for strong to severe storms in our
forecast area. We continue to monitor ongoing thunderstorms
over northeast Minnesota and northern Wisconsin, as this
activity should intensity as it propagates south/southeast along
the periphery of the upper level ridge into Michigan and
eventually northern Indiana and northwest Ohio by early to mid
afternoon. There is still some uncertainty on exact track and
timing of storms but the best timing appears to be between 2
EDT to 8 PM EDT today. With a lack of storms in the area this
morning, this allows the airmass overhead ample time to heat up
and destabilize before storms come through around peak diurnal
heating. Highs are expected to be near 90s today with dewpoints
in the 70s, which should fuel SBCAPE values of up to 2500-4000
J/kg by early afternoon. Shear is expected to be around 30 to 40
kts and mid level lapse rates look favorable around 7-8 C/km.
These are favorable parameters that will support a threat for
damaging winds of 60-70 mph. There is potential for significant
gusts over 75 mph as CIG 1 hatching has been added for our
entire forecast area by SPC in the new Day 1 outlook. An
isolated brief tornado or two is also possible, especially with
O-1 km SRH values of 150-250 m2/s2.

Additional scattered storms are possible after 8 PM along a diffuse
frontal boundary that tracks northwest to southeast, potentially
clipping northeast Indiana and northwest Ohio. Have maintained NBM
PoPs from 8 PM EDT tonight to 2 AM EDT Tuesday given considerable
uncertainty. The severe threat should be much lower with these
storms given the likelihood for a stronger MCS earlier in the day as
mentioned above.

The good news is that after this evening, the threat for severe
weather will be over and we will have several dry days ahead. A cold
front will sweep through Tuesday, setting the stage for several days
with highs in the mid 80s as high pressure builds over the Great
Lakes. It will be dry at least through Thursday with intermittent
low chances (20-30%) for rain/storm returning by Friday and into the
weekend.

Additionally, as winds shift to become northwesterly on Tuesday,
dangerous swimming conditions are expected to develop for southeast
Lake Michigan beaches on Tuesday. Waves of 3 to 5 feet Tuesday
morning will build to 7 to 10 feet by Tuesday afternoon/evening.
With direct onshore flow, strong structural, rip, and longshore
currents are expected. Structural currents will be especially strong
on the north side of piers. Stay out of the water and stay off of
the piers! Beach Hazards Statements have been issued for La Porte
County, IN and Berrien County, MI from early Tuesday through
daybreak Wednesday.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1245 PM EDT Mon Jul 27 2026

Cluster of thunderstorms from MKE south through ORD are the
primary item of focus for this TAF period. Rather high
confidence in storms persisting through KSBN, and perhaps a
tinge of uncertainty toward KFWA. For now, the environment is
highly supportive of sustained convection.

Behind these thunderstorms, northerly flow eventually brings an
area of stratus down behind a thermal trough descending through
Michigan prior to sunrise. As always, it is uncertain how long
stratus will persist into Tuesday.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Heat Advisory until 6 PM EDT /5 PM CDT/ this evening for
     INZ012-013-020-103-203.
     Beach Hazards Statement from late tonight through Wednesday
     morning for INZ103.
OH...None.
MI...Beach Hazards Statement from late tonight through Wednesday
     morning for MIZ177-277.
MARINE...Small Craft Advisory from 2 AM Tuesday to 2 AM EDT Wednesday
     for LMZ043-046.

&&

$$

UPDATE...Marsili
DISCUSSION...Johnson
AVIATION...Brown