Boston Corner, Indiana Weather Forecast Discussion

847
FXUS63 KIWX 221041
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
641 AM EDT Mon Sep 22 2025
.KEY MESSAGES...
- Chances for showers and thunderstorms persist through the
  week, with the greatest potential today into tonight (50-90
  percent) and then again on Wednesday (around 65 percent).
- Isolated stronger storms are possible through this afternoon,
  mainly along and south of US 24 east of I 69. Damaging winds
  would be the main threat with the strongest storms.
- Highs will be in the upper 60s and 70s through the week, with
  lows in the 50s and low 60s.
&&
.DISCUSSION...
Issued at 520 AM EDT Mon Sep 22 2025
We`re in a slight lull in the precipitation as of this writing (9z),
however expect some re-development through the morning and afternoon
hours as we deal with yet another shortwave moving through and
continued moisture transport from a weak LLJ this morning. Patchy
fog is possible in NW OH (Fulton currently around 1 SM). An MCV-like
feature moving through White county, IN area may also lead to some
showers and/or serve as an initiation point for storms into the
afternoon-particularly as the upper level forcing arrives. The
shortwave responsible for the convection southwest of our area in
MO/IL/Southern IN will lift into our area, but it`s unclear how
intense the convection will be once it gets here---it`s possible the
better moisture is cut off to our south and will struggle to make it
all the way north through our area. That being said, have pops in
the 20-30% range this morning increasing to the 50-90 percent range
by the afternoon, highest along and south of US 24, especially
along/east of Interstate 69. It`s possible we see a few stronger
cells develop in this timeframe near Lima, OH (SPC Marginal Risk).
Main threat would be damaging winds. Mid level lapse rates are
fairly paltry today, and it`s questionable how much instability we
can get from daytime heating with the more expansive cloud cover in
place/expected-though dewpoints are into the mid-upper 60s this
afternoon. The NAM suggests around 500-1200 J/kg of CAPE (highest
just east of us), which is sufficient. Weak flow will limit the
overall severe potential, but can`t rule out isolated
downbursts. High temperatures today will be in the 70s. Lows
tonight will fall into the low to mid 60s.
Tonight into Tuesday is a bit tricky as a lot depends on how today
evolves, but the NAM and some of the hi-res suggest a surface low
lifting into our southeastern CWA--where I kept pops higher (around
60 percent) in the event this occurs. That exits our CWA by early
Tuesday morning, then we go into another lull period before
additional chances return in the afternoon. This is questionable-
with most of the guidance now keeping the development further
northwest until Tuesday night into Wednesday morning with another
shortwave and surface cold front dropping into our area. Have pops
in the 20-45 percent range in this period, with potential for some
thunder (especially in the early evening). Patchy fog is expected
overnight into early Tuesday morning as well, with some areas
becoming locally dense. Highs Tuesday will be in the upper 70s and
low 80s.
Wednesday into Friday is coming into view, with models consolidating
around the closed upper low centering somewhere around Lower MI or
Chicago/NW IN area through Thursday afternoon before weakening to
more of a trough that stays into Friday. The attendant surface low
with this develops somewhere over IL/MO and lifts E-NE through the
period, with some solutions suggesting further east track (and
deeper low) over OH and others right overhead in northern IN (weaker
low) by Wed night into Thursday morning. Most solutions have the low
moving into the lower Great Lakes/NE CONUS by late Thursday
morning/afternoon. Where the low tracks will impact our chances and
the wind field, with the stronger low moving into OH potentially
causing marine issues on Lake MI. Temps will be cooler, with highs
in the upper 60s and low to mid 70s.
Low chances for showers/isolated storms on Saturday, especially
during the afternoon as another upper level trough moves through-but
many of the models are starting to lean dry for this day. Have broad
slight chances on that day. An upper level ridge builds in Saturday
night into Sunday, with a surface high below. This will keep us dry
through the start of next week, with highs in the 70s.
&&
.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 635 AM EDT Mon Sep 22 2025
A weak short wave across northwest Indiana is accompanied by
some isolated showers on the northern periphery of this
disturbance. This forcing should be transitory with just a low
end potential of a brief shower at KSBN through 13Z. A more
impactful and broader upper trough is working across southwest
Illinois this morning and appears to have contribution to its
strength from ongoing convection across southern Illinois. Some
enhancement to a weak low level jet is expected to continue
across southwest Indiana this morning, with the nose of this low
level jet expected to work into east central Indiana early this
afternoon. Rain showers across east central Illinois should
continue to expand northeast this morning as an axis of better
moisture transport/low level moisture convergence migrates
northeast. KFWA stands the best chance of a more prolonged
period of rain showers later this morning into mid afternoon in
closer proximity to these forcing mechanisms. An isolated storm
is possible but point probabilities remain too low to include
with 12Z TAFs as instability magnitudes will be more limited
today.
Rain showers should tend to focus east/southeast of KFWA by
late afternoon or early evening with primarily dry conditions
at terminals later evening/overnight. A weak ridge of high
pressure building behind today`s short wave and a good deal of
near sfc moisture availability should promote fog formation
tonight across northeast IN with IFR/LIFR conditions looking to
be at least a possibility at KFWA toward end of the period.
Confidence in fog potential is somewhat lower at KSBN given
slight displacement from best near sfc moisture axis and better
near sfc moisture source from today`s additional rainfall.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...MCD
AVIATION...Marsili

NWS IWX Office Area Forecast Discussion