IWX issues Area Forecast Discussion (AFD) at Oct 6, 1:36 AM EDT969
FXUS63 KIWX 060536
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
136 AM EDT Mon Oct 6 2025
.KEY MESSAGES...
- Warm, dry, and breezy conditions will lead to a continued elevated
fire danger through the rest of this afternoon.
- Rain is expected Monday night through late Tuesday with amounts up
to a half-inch possible.
- Much cooler conditions expected for Wednesday and Thursday
before temperatures moderate to slightly above normal again
for next weekend.
&&
.DISCUSSION...
Issued at 330 PM EDT Sun Oct 5 2025
Fire weather concerns continue to be the near term forecast issue of
interest this afternoon. Drier low level air advecting northward is
starting to become more evident in sfc observations as diurnal
mixing has started to mix this drier air to the surface. The
lowest late afternoon dew points are expected generally along
and south of US Route 24 corridor where near sfc soil moisture
is at a minimum with the ongoing drought conditions. Minimum
afternoon relative humidities in this area could drop as low as
20 to 25 percent for a brief this afternoon.
Otherwise for tonight, the longwave upper ridge axis across eastern
CONUS will continue to shift off to the east tonight. This will
allow some sheared vorticity to lift north into the Ohio River
Valley into the southern Great Lakes. Low level confluent flow in
this pattern will allow some higher low level dew points to advect
northward into the local area later tonight into Monday. This should
limit any additional fire weather concerns for Monday. It will
remain warm for Monday (highs in low to mid 80s) as anomalously warm
low level thermal ridge persists across the region in advance of a
cool frontal boundary from the northern Great Lakes into the Mid Ms
Rvr Valley. While low level moisture will be greater for the daytime
Monday, the stronger low level moisture transport will build into
northeast IN/northwest OH via a strengthening southwesterly low
level jet, particularly along and south of US 24. Some increase in
low level fgen forcing is expected later in the day Monday, but
given what still should be a dry subcloud layer, instability
magnitudes should be quite limited and will maintain slight chance
PoPs during the day.
Greater chances of rain still appear to be in store for the later
Monday/Tuesday period as large scale frontal forcing begins to
interact with the deeper moisture profiles across the southeast
half of the forecast area. Some sfc based instability (500-1000
J/kg) is expected Tuesday across the southeast half of the area
with this more anomalous moisture, which should coincide with the
greatest potential of thunder. EPS/GEFS still support 0.25-0.5"
rainfall amounts with the possibility of higher amounts
along/south of US 24 where some convective elements are possible
on Tuesday. Confidence in rainfall amounts is on the low side
for the northwest half of the area as moisture quality
initially will be more limited and some question as to strength
of low level frontogenesis axis as this forcing drops across the
southern Great Lakes.
Conditions dry out for middle of the work week with temperatures
likely just below seasonable normals. Early indications still
suggest at least a potential of frost Wednesday night and possibly
Thursday night as passage of low level anticyclone across the Great
Lakes allows for better radiational cooling conditions. Temperatures
should moderate back to just above normal toward end of this
period.
&&
.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 125 AM EDT Mon Oct 6 2025
VFR conditions are expected at the TAF sites, with mainly rain
chances and mid/high level clouds to contend with. A cold front
currently extending from northern ontario into the UP of
MI/WI/IA will drift slowly eastward through the day, reaching
our northwest this evening. Have VCSH from 23-03z at KSBN,
shifting to -SHRA 3-6z. The more challenging forecast is for
KFWA as we deal with a weak shortwave rippling around the ridge
to our southeast. We do see a period during the day of
isentropic ascent, which could lead to some shower development
around 18z that persists into the evening before the front and
larger scale ascent arrive overnight. Given lower confidence
(some models suggest dry conditions until 00z, others as early
as 15-18z)--opted to use VCSH around 18z-00z with a prob30 for
showers, then have rain as the predominant from 3z onward. It is
possible that there could be a break in activity around 00-6z,
but it will depend on how earlier in the day evolves.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Marsili
AVIATION...MCD
Source:
IWX issues Area Forecast Discussion (AFD) at Oct 6, 1:36 AM EDT---------------
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