Matteson Lake, Michigan Weather Forecast Discussion

383
FXUS63 KIWX 201608
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1208 PM EDT Sat Sep 20 2025
.KEY MESSAGES...
- Chances (30-60%) for showers and a few thunderstorms
  increasing through the day and into tonight, especially west
  of I 69. Mostly cloudy with highs in the 80s. Lows overnight
  in the 60s.
- A more active pattern ahead, with daily chances (20-60%) for
  showers and storms through next Saturday. The best chances
  will be Sunday and Monday. A few stronger storms are possible
  Sunday afternoon and evening, with gusty winds the primary
  threat.
- High temperatures Sunday will be in the upper 70s and low to
  mid 80s, then remain in the 70s through the remainder of the
  work week. Lows will be in the 50s and low 60s.
&&
.DISCUSSION...
Issued at 440 AM EDT Sat Sep 20 2025
Showers and thunderstorms just along our western border,
particularly near White County, IN. Left pops around 20-30 percent
there through the day, eventually expanding to the remainder of the
CWA through the afternoon and overnight and increasing to around 30-
60 percent depending on location (best chances west of I 69). A
stalled boundary draped from MN into the Chicago area and southeast
into Portland, IN lingers-with east flow to the north of it, and
nearly calm to light E-SE/S winds to the south. The showers/storms
are focused along a trough/axis of moisture convergence-with decent
moisture transport and elevated instability at 850-925 mb.
Eventually our stalled front will lift northeastward this morning as
a warm front before stalling again this evening roughly from Van
Buren Co, MI through Fulton/Defiance/Henry, OH and into Lake Erie. A
500mb trough swings through extending from low pressure over the
northern plains/upper MS valley towards the afternoon into the
overnight, providing better forcing (especially west) for
showers/storms to develop-especially along the frontal boundary.
Flow is pretty weak aloft so don`t expect any severe weather today.
Highs will rise into the mid-upper 80s, with lows dropping to around
60 degrees overnight.
Late tonight into Sunday we have a couple stronger waves move
through, especially in the afternoon and evening. With better
forcing, decent afternoon instability (500-1000J/kg sfc cape/mid
level lapse rates around 6.5C/km), and a belt of mid level flow to
35-40 knots or so--we could see some stronger storms develop. SPC
has our area in a marginal risk, which is reasonable. Main threat
would be gusty winds in the 40-50 mph range with any downbursts in
stronger cells, with isolated gusts to around 60 mph. Chances for
rain max out in the 60-80 percent range, which is welcome given
drought/abnormally dry conditions around the area. Highs will be in
the upper 70s and low to mid 80s, warmest in NW OH.
Monday and beyond confidence lowers, as much will depend on the
evolution of the upper level pattern which is still in question.
Have the best potential Monday-Monday night (55-70% max) tied to the
strongest waves rippling through the flow along the trough/Upper low
(afternoon/evening hours). Tuesday into Friday we could have an
upper low centered right over our CWA and the Great Lakes (favors
better rain chances), or if solutions like the ECMWF are right-the
low dives southward towards the gulf and we end up with more of an
elongated low/trough (and lesser chances). Have 20-50% chances from
Tuesday into next Saturday, which is reasonable given expected
pattern. Overall, temperatures with a low/trough overhead and
probably more extensive cloud cover will likely be in the 70s, with
overnight lows dropping into the 50s.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1208 PM EDT Sat Sep 20 2025
Isolated convection remains just west of KSBN near a north to
south oriented moisture/instability axis. Chance for scattered
showers and isolated thunderstorms do increase mid afternoon
through early evening at KSBN as this warm front gets a push
east in advance of an approaching Mid MS Valley upper trough.
Conditions will remain VFR outside of any thunderstorms which
could bring brief restrictions. KFWA more removed from better
moisture transport/forcing with lower confidence in shower/storm
coverage late this afternoon and evening. Opted to hold with a
Prob30 group for now as a result.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...MCD
AVIATION...Steinwedel

NWS IWX Office Area Forecast Discussion