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000
FXUS63 KIWX 131026
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
626 AM EDT Sat Apr 13 2024

.KEY MESSAGES...

- Potential for heavy rainfall this upcoming week to once again
  aggravate ongoing river flooding with several chances for
  showers and storms in a very moist environment.

- Chances for thunderstorms at times Sunday through Thursday to include
  a marginal risk of severe thunderstorms Sunday afternoon and
  another severe risk Tuesday.

- Warm Sunday through Wednesday with highs in the 70s. Turning
  much colder late in the week with a good chance of
  temperatures near freezing this upcoming weekend.

&&

.DISCUSSION...
Issued at 310 AM EDT Sat Apr 13 2024

The powerful low that caused the strong winds yesterday was
occluding and filling near James Bay. A surface ridge axis well
to the southwest of the low was west of the area and will move
east with winds over the forecast area backing to the southwest
by this evening. A weak upper level system with approach the
area Sunday in tandem with an elevated mixed layer (EML). A
substantial/steep 700mb/500mb lapse rate close to 8.5C/Km will
provide an environment for stronger storms; however, maximum
CAPES generally should only be 1.0K to 1.5K J/Kg. Fairly strong
capping may completely inhibit storm development as indicated by
several CAMS and some of the spectral models.

For Monday into Thursday, it looks like the storm mode will
evolve into more of a heavy rain threat with tall by thin CAPEs
and high precipitable water values. The only exception is late
Tuesday into Tuesday night with a strong negatively tilted trof
moving into the forecast area. SPC has maintained a 15% severe
risk for the "old" Day 5 at this time. Current thinking is with
ongoing flood issues, addition rainfall that may become locally
heavy with any training will aggravate the current situation.
Otherwise, it looks like a pattern change to cooler and drier
weather will begin late with week with as a longwave trof axis
sets up over east North America. Temperatures may drop to
freezing this coming weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 626 AM EDT Sat Apr 13 2024

Mid level subsidence continues this morning between broad
upstream ridging across the Central/Northern Plains and a
stronger upper low across northeast CONUS/southeast Canada. The
strongest low level height gradient will reside across far
northeast Indiana today where some gusts to 20 knots are
possible. While depth of mixed layer will be favorable at KSBN,
low level wind fields will be diminishing this afternoon that
could limit sfc wind gusts. Brief lull in winds expected late
afternoon/early evening, but progressive pressure pattern will
allow for quick return of stronger southerly gradient for
tonight. A 40-45 knot low level jet will also support some
marginal LLWS conditions developing later this evening into the
overnight hours. Otherwise, VFR conditions should hold this
forecast period with some increase in cloudiness possible
tonight as low/mid level theta-e gradient surges back northward.

&&

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

&&

$$

DISCUSSION...Skipper
AVIATION...Marsili