072
FXUS63 KIWX 251617
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1217 PM EDT Wed Sep 25 2024

.KEY MESSAGES...

* Isolated showers possible this afternoon.

* Rain showers associated with a tropical system enter the
  forecast late Friday afternoon through the weekend.

* Seasonable temperatures are replaced by a temporary dose of
  fall by the middle of next week.

&&

.DISCUSSION...
Issued at 317 AM EDT Wed Sep 25 2024

Lake effect rain showers this morning give way to isolated showers
this afternoon. This occurs as there is hint of destabilization and
weak impulses of mid-and-upper-level vorticity in the vicinity of
stacked upper-level low moving across the mid-Mississippi Valley.
Moisture return is modest, primarily because the cold front that
moved through yesterday (now approaching the Appalacians) is the
primary focus of such moisture advection. Additionally, early-
morning thunderstorms ongoing over Arkansas and Oklahoma will
negatively impact any poleward moisture transport in the short term.
Therefore, I`ll hold steady with the inherited isolated shower
mention.

While fog has failed to materialize early this morning, fog is
plausible again tonight per ensemble forecast soundings. But, this
is at odds with high-resolution visibility guidance which indicates
otherwise. Dew point depressions will be low, but afternoon forecast
soundings appear well-mixed leaving me to think our local moisture
source could dry out, thus limiting the fog risk. With this
dichotomy, I`ll omit fog for now but pass on to the next shift for
consideration.

Friday through the weekend, our weather will be driven by a closed
low over the southern Mississippi River Valley interacting with what
is currently Tropical Storm Helene. This low will gradually drift
north toward drought-stricken southern Ohio Friday and Friday night.
The in-house blend still strikes me as woefully too-fast with the
local arrival time of POPs. This happens among the backdrop of high
pressure over the Great Lakes that needs to be displaced. So, Friday
will be primarily dry but some showers could slip into the far
southern US 24 corridor late in the day. POPs then increase through
Friday night. Passing showers will persist through the weekend,
though there will be some dry time here and there.

Look out next week as a brief, but big temperature change is
favored.  While the aformentioned low swirls just off to our south
this weekend, a ridge centered over the southern 2/3 of the CONUS
will promote anomalous 500-mb heights and permit our local
temperatures warm into the upper-70s Monday. Tuesday, in comes a
Canadian cold front. This kicks the cut-off low well to the east and
our high temperatures Wednesday will be locked into the 60s.
Temperatures rebound soon after.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1216 PM EDT Wed Sep 25 2024

Stratocu expected to mix into VFR at or shortly after issuance
this afternoon. Isolated showers are also possible near a weak
trough axis this afternoon, though point chances remain too low
to include in the TAF. Drier air infiltrates the area later
tonight into tomorrow as high pressure develops toward the Great
Lakes region. Low xover values and light/variable winds under a
clearing sky does hint at the risk for shallow BR/FG formation
later tonight at KSBN otherwise.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Brown
AVIATION...Steinwedel