557
FXUS63 KIWX 100809
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
409 AM EDT Mon Jun 10 2024

.KEY MESSAGES...

- Cool today with highs near 68, much warmer by Thursday with
  highs near 90.

- Becoming hot and humid early next week with with highs around
  90 to 95 with heat indices near 100 next Monday.

- Dry through Wednesday then chances for storms Thursday
  afternoon and Thursday night.

&&

.DISCUSSION...
Issued at 115 AM EDT Mon Jun 10 2024

Chilly air behind a weak upper level system and associated cold
front will spread south out of Canada today. 850 mb temperatures
will dip to around +4C per GFS. The latest model guidance favors
highs close to 12 degrees below normal and lows well down into
the 40s by Tuesday morning. Return flow around a large surface
high will begin Tuesday and allow highs to recover well above
normal. Believe the dry conditions during the past 7+ days
should allow a little feedback and thus favor highs rising
close to 90 Thursday.

Showers and storms associated with a weak cold front are possible
in what appears to be a fairly small window for storms from
Thursday afternoon into Thursday night. Max CAPE values per GFS
range still were below 2000 J/Kg. Given modest CAPE, limited
bulk shear by afternoon and modest precipitable water values,
these environment factors favor gusty winds and locally heavy
rainfall with unorganized storms. However, if an upstream
convective develops into a MCS and moves into the area, stronger
winds are likely. Have removed storms from the forecast Friday
given the ECMWF`s capitulation to a dry forecast with storms
farther south Friday (where the best chances for storms will
likely be in the higher theta E in the vicinity of the front).
Otherwise, hot and humid conditions will develop Sunday and
likely persist until at least next Tuesday. The blend for the
new Day 7 (next Monday) was loaded without modification with
highs of 92 to 95 and heat indices near 100F. GFS and ECMWF 850
mb temperatures near 20C favor highs above 90 Monday given
percentiles of climatological data from SPC (upper air soundings)
where ILX 90th percentile for this time of year is +18.6C and
max/100% is >22C per 850 mb. These percentiles correspond to
highs at Ft Wayne of 92F (90th percentile); 93F (94th
percentile); 94F (96th percentile). Given high confidence in
this scenario, will start to message the heat & humidity in the
Hazardous Weather Product for now. Substantial precipitable
water values >= 1.7" with high CAPEs will support chances for
stronger storms with heavy rainfall.


&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1220 AM EDT Mon Jun 10 2024

MVFR cigs are likely to fill in later tonight behind another
low level trough in persistent northwest flow. Post-frontal dry
advection and deeper mixing should support improvement back to
VFR by late morning at KSBN and early afternoon at KFWA with a
few northerly gusts up to near 20 knots during this time (mainly
at KSBN given some lake enhancement). High pressure then builds
in tonight with light winds and mainly clear skies.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement through this evening for INZ103.
OH...None.
MI...Beach Hazards Statement through this evening for MIZ177-277.
MARINE...Small Craft Advisory until 11 PM EDT this evening for LMZ043-
     046.

&&

$$

DISCUSSION...Skipper
AVIATION...Steinwedel