556
FXUS63 KIWX 200928
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
528 AM EDT Sun Apr 20 2025

.KEY MESSAGES...

- Plenty of dry hours today but there is a slight chance (20%)
  of an afternoon shower.

- Showers and perhaps a thunderstorm move through late tonight.
  Severe weather is not expected.

- Mild with chances (30-60%) for rain both mid and late week.

&&

.DISCUSSION...
Issued at 303 AM EDT Sun Apr 20 2025

High pressure over the upper Great Lakes this morning is the
antagonist to rain chances later today. Dew points are in the mid-
40s south of US 30 and in the upper 30s across southern MI. Cross
sections show poor mid- and low-level saturation, especially at
KFWA. Along and west of US 31, a dry sub-cloud layer persists but
mid-level moisture is improved somewhat. RAP guidance suggest the
best moisture pooling is along the Mississippi River, closer to the
low tracking north toward Kansas City this afternoon. Overall, have
maintained an aggressive dry-bias in the POPs today. If there are
showers, the afternoon seems to be the better chance as the warm
front (forcing) lifts in and dew points eventually creep up.
Otherwise, plenty of dry time today.

The aformentioned low will be the forcing mechanism for severe
thunderstorms elsewhere in the Midwest (and Mid-Mississippi Valley)
this evening. Remnants from what is anticipated to be a line of
storms along a cold front moves in after midnight. Instability is
poor at 500j/kg and forecast soundings are once again capped. Just
like 24 hours ago, shear is our best ingredient at 50 knots. Given
the lackluster arrival time, waning instability and CAMs that favor
right-flank development well south of the forecast area, severe
weather is not expected locally; just leftover showers and maybe a
rumble of thunder. Drying out after sunrise Monday.

Zonal flow takes shape for the remainder of the week permitting
normal to above-normal temperatures. On Wednesday, we`ll monitor the
chance for showers and thunderstorms to pass through Michigan
associated with a low wrapping up near Winnipeg. The chance for
showers and thunderstorms increases area-wide late in the week with
low pressures taking shape over the southern Mississippi River
Valley and the Northern Plains.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/
... Issued at 524 AM EDT Sun Apr 20 2025

Few changes needed for the 12Z TAFs. High pressure centered
over northern Lower Michigan will keep dry conditions around
the upper Great Lakes for the first half of the TAF forecast
period. Winds will remain light early this morning, ramping up
by mid morning with easterly wind gusts 20 to 25 kts possible
through much of the day today. As a warm front lifts north
today, a few scattered showers will be possible in the
afternoon. The biggest change to the TAF has been to remove the
PROB30 group at KFWA becuase soundings and models suggest dry
air will limit showers east of US 31. Have kept the PROB30
groups at KSBN for showers and MVFR ceilings/visibilities; the
NBM has 20-30% chances of MVFR ceilings for a few hours in the
afternoon today along with chances for a few scattered showers
in northwest Indiana. Winds remain elevated through the evening
and overnight hours as our next weather system approaches. Along
and ahead of a cold front, a broken line of showers and
embedded storms is expected to move through the area, likely
between 04Z-12Z Monday. Severe weather is not expected,
although some storms could contain strong wind gusts in excess
of 35 kts. Storms will likely arrive at KSBN between 04-06Z and
at KFWA between 07-09Z.

&&

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

&&

$$

DISCUSSION...Brown
AVIATION...Johnson