Jonesville, Michigan Weather Forecast Discussion

490
FXUS63 KIWX 061723
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
123 PM EDT Mon Oct 6 2025
.KEY MESSAGES...
- One more warm day today with highs in the mid 80s and a few
  isolated showers possible.
- Better chances for rain and a few thunderstorms arrive tonight
  into Tuesday. Severe weather is not expected.
- Dry weather returns Wednesday and Thursday with much more
  seasonable temperatures. Lows may dip into the 30s each night
  with patchy frost possible.
&&
.DISCUSSION...
Issued at 255 AM EDT Mon Oct 6 2025
Cold front that is currently still well upstream and aligned
parallel to mid/upper flow will finally begin to make some earnest
eastward progress today as a second jet streak digs into the base of
the Northern Plains trough. Tightening low level gradient ahead of
the front will result in a strengthening LLJ and associated theta-e
advection. Most guidance continues to suggest subtle 300-305K
isentropic ascent will support some isolated showers in our SE half
beginning around midday. Available moisture is highly limited both
above and below this zone however and poor midlevel lapse rates
limit whatever elevated instability might otherwise be possible.
Will acquiesce to some broad-brushed 20 PoP`s but any rain will be
very light and isolated during the day. Increasing moisture/clouds
and subsequent reduced mixing will keep highs in the low/mid 80s.
Much better chances for rain arrive in our northwest during the
evening and overnight hours as surface front approaches. A healthy
band of deep (925-700mb) fgen lights up over central MI in the right
entrance region of a 120kt upper jet but this likely only grazes our
far N/NW counties aided by some residual instability. Late arrival
and northward displacement/exit of better forcing does suggest a
weakening trend through early Tue morning as the front slowly sags
SE. Some diurnal instability recovers by late Tue morning but this
is confined in our far SE where surface front will not pass until
around 18Z. The arrival of secondary jet streak and shortwave will
maintain some elevated fgen and light showers in our area but
suspect more widespread, heavier rain will remain just SE where
better moisture/instability reside. Putting everything together best
chances for meaningful rain (more than a tenth or so) will be in the
NW late this evening and SE Tue morning with our central CWA likely
getting "skipped" with just a few light showers. Thunder remains
possible throughout the tonight and Tuesday periods but limited
MUCAPE values and increasingly stable conditions below 850mb in CAA
will likely prevent any severe weather concerns. Precip will exit
our SE around 00Z Tue evening.
Midweek period still features seasonably cool and dry conditions.
Clear skies and light easterly winds yield lows in the mid/upper 30s
both Wed and Thu nights. Some patchy frost is possible but a
widespread, killing frost/freeze still appears unlikely. Forecast
for the weekend remains quiet. There is a weak shortwave that may
pass through the area and support some light showers but chances are
low and impact negligible if it even occurs.
&&
.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 112 PM EDT Mon Oct 6 2025
Two areas of interest for rain we are monitoring for this
forecast cycle: 1, an approaching cold front currently over
extreme northeast IL. 2, an area of enhanced dew points and a
blossoming cumulus shield across east-central Indiana.
For this issuance, I did delay the rain chance in line with the
latest observations and model guidance. Dry air will be
challenging to overcome such that, in the absence of any
notable forcing, the daytime shower chance is negligible.
Instead, 850-mb flow improves overnight which will bring
increasing shower coverage toward KFWA. Over KSBN, the front
will continue to slide ENE, eventually bringing rain there too.
Can`t rule out thunder, especially prior to 09z. As of this
writing, lightning reports are nil, so will continue thunder-
free.
High confidence in a period of IFR ceilings at KSBN. Cannot
rule out LIFR ceilings behind the cold front. Confidence is a
little lower the KFWA where guidance has trended drier and thus
OVC009 is anticipated. Rain departs KSBN prior to 18z, while a
few showers may linger at KFWA.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory from 8 AM Tuesday to 5 AM EDT Wednesday
     for LMZ043-046.
&&
$$
DISCUSSION...AGD
AVIATION...Brown

NWS IWX Office Area Forecast Discussion