Union, Michigan Weather Forecast Discussion

708
FXUS63 KIWX 220557
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
157 AM EDT Mon Sep 22 2025
.KEY MESSAGES...
- Scattered showers and isolated storms are expected to continue
  overnight. Severe weather is not expected but brief heavy
  rainfall is possible.
- More rain is expected Monday into Monday night. The flood
  threat with this rain is very low.
&&
.DISCUSSION...
Issued at 1224 PM EDT Sun Sep 21 2025
Abundant cloudiness remained over northern Indiana in the wake
of precipitation from earlier today, although clouds were
starting to break up west of I-69. Short wave energy from an
approaching upper level trof had brought these showers with
scattered thunderstorms across the forecast area this morning.
By early afternoon, the activity was lifting rapidly northeast
and should clear the area by 3pm or 4pm. Have made some major
forecast updates to greatly reduce rain chances late this
afternoon. More showers are expected to develop and move into
northern Indiana tonight as the upper low and trof lingers over
the area. The latest HRRR has activity redeveloping after 01Z
(9pm EDT). Periods of showers and isolated storms at times
should continue into early Tuesday. Rainfall amounts through
Tuesday night should rain from 1.00" to 1.50". Given the longer
duration of the rain and relatively low amounts expected,
flooding is not anticipated.
Rain chances will continue through the upcoming weekend as the
upper level trof transitions into a closed low, and then to an
open trof by late Friday. This pattern will feature cloudy skies
and abundant showers. A thunderstorm is possible at times, but
severe weather is not anticipated later this week.
&&
.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 157 AM EDT Mon Sep 22 2025
Several convectively enhanced short waves are rippling through
a southwesterly flow regime across the southern Great Lakes and
Ohio River Valley early this morning. One of these small scale
disturbances appears to be tracking across northeast
Indiana/southeast Lower Michigan, with a second short wave
across central Illinois. Back to the west, a larger scale upper
trough axis extends from west central WI into eastern MO. The IL
short wave coupled with a weak low level jet and weak elevated
instability may allow for isolated to scattered showers to
redevelop at terminals in the 10Z-14Z timeframe.
Some uncertainty exists with how the larger scale upstream
trough will influence precip chances later this afternoon and
evening. Guidance has trended a bit southeast with heavier
precipitation in response to southward trend in favored low
level moisture convergence with LLJ and southward displacement
of low level fgen. Cooling low level thermal profiles and loss
of modest mid level lapse rates through daybreak should make
thunder much more limited today. In terms of cigs, some MVFR
cigs have affected KFWA over the past hour in wake of an outflow
boundary, but this threat should be short lived and primary VFR
through the day. Chances of MVFR cigs return toward end of this
period as weak sfc ridging develops in wake of stronger upper
trough with plenty of leftover low level moisture.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Skipper
AVIATION...Marsili

NWS IWX Office Area Forecast Discussion