Amboy, Indiana Weather Forecast Discussion

799
FXUS63 KIWX 211809
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
209 PM EDT Sun Sep 21 2025
.KEY MESSAGES...
- Showers and storms will redevelop late this afternooon into
  early tonight.
- Strong to possibly severe storms later today may bring locally
  damaging wind gusts, heavy rain and small hail.
- 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 /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 640 AM EDT Sun Sep 21 2025
The combination of broad isentropic upglide and what appears to
be convectively enhanced short wave kicking out of northern
Illinois has been sufficient for large area of rain showers
across northern Indiana early this morning. Some weak elevated
instability is noted per RAP analysis soundings for 850 mb based
parcels, but still expecting thunder coverage this morning to
be very limited. Rain showers should tend to diminish after 14
or 15Z this morning with a possible lull in rain shower coverage
through early to mid afternoon. Forecast confidence on
convective trends remains low given a complex mid/upper level
pattern. Upstream short waves are being modified by ongoing
convection early this morning across southern IL/MO and also
across KS/OK. This leads to low predictability in forecast
details regarding the track and strength of these short waves.
Both of these areas of convection may allow for some
convectively enhanced short wave to lift northeast into northern
Indiana later this afternoon into tonight.
Low level southerly flow will be a bit stronger today in
advance of these forcing mechanisms, which should also help
sustain advective forcing into this evening. Have included TEMPO
SHRA mention from mid afternoon into early evening hours
coincident with peak diurnal instability, but iso-sct thunder
remains a distinct possibility given steep lower level lapse
rates and most guidance indicating 1000-1500 J/kg of sfc based
instability by later this afternoon. Will remain conservative
with precip mention after 01Z, as forecast confidence remains
low given the uncertainty in upstream short wave track/strength.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Skipper
AVIATION...Marsili

NWS IWX Office Area Forecast Discussion