420
FXUS63 KIWX 132304
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
704 PM EDT Tue May 13 2025

.KEY MESSAGES...

- Scattered showers and isolated thunderstorms this afternoon, and
  again Wednesday afternoon.

- Very warm on Thursday with highs well into the 80s.

- While the daytime will be primarily dry Thursday, there is a
  chance for thunderstorms Thursday evening and overnight, some
  of which may be severe.

&&

.DISCUSSION...
Issued at 220 PM EDT Tue May 13 2025

Upper low center over the western TN Valley will finally get a push
north into the OH Valley and southern Great Lakes tonight into
Wednesday in response to a deep upper trough edging east toward the
Rockies. This system will continue to generate isolated to scattered
showers and storms (mainly diurnal) thanks to a moist column through
much of the troposphere and just enough diurnal heating, with the
greatest coverage likely focused near small scale vort lobes
rotating around the upper low. Overall weak dynamics, flow and
instability precludes a severe wx risk with lightning, brief
downpours and cold air funnels possible with heavier showers each
afternoon.

The Rockies upper low will eject into the northern Plains and Upper
Midwest Thursday into Thursday night with an associated strong sfc
low emerging over MN by Friday morning per latest guidance. A
leading warm front and low level theta-e ridge advect into the local
area on Thursday with warm temps (near records) and a conditional
severe risk Thursday night. Progged shear/instability profiles check
the box for potential deep/severe convection, however, delayed
forcing and what looks to be a very warm EML base may keep a lid on
organized convection along an incoming pre-frontal trough or
convective outflow.

Height falls eventually slide east through the Great Lakes Friday
into Saturday with the upcoming weekend trending cooler, dry and
breezy in response to the suppression. Could see another frontal
wave drive a convective complex through the region Friday PM in this
transition, though the bulk of guidance continues to favor areas off
the south for more organized convection chances. Thursday night`s
activity, or lack thereof, will dictate the timing/track of Friday`s
potential convective system.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 651 PM EDT Tue May 13 2025

With the very moist airmass in place very low cigs and perhaps
development of patchy fog overnight will be the main impacts.
VFR/MVFR conditions early on this evening will degrade through
the overnight hours with IFR and potentially LIFR conditions
after 08z Wed for KSBN. Will need to keep an eye on the trends as
KFWA looks to drop to IFR in cigs after 06z Wed but confidence
of dropping into LIFR was not as high. However, with the very
moist conditions is certainly not out of the question that
either the cigs or vsbys drop slightly further into the LIFR
category. Cigs look to improve to MVFR after 15-16z for both TAF
sites along with increased chances of rain showers. Afternoon
thunder and light rain will once again re-develop for both sites
after 20z Wed.

&&

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

&&

$$

DISCUSSION...Andersen
AVIATION...Frazier