756
FXUS63 KDMX 130544
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1244 AM CDT Thu Jun 13 2024

 ...Updated for the 06z Aviation Discussion...

.KEY MESSAGES...

- Showers and thunderstorms earlier today with more possible
  later this evening.

- Robust thunderstorms expected across southern Iowa tomorrow
  afternoon with severe storms and heavy rain likely,

- Hot through the end of the week and early next week with
  temperatures in the 90s and heat indicies in the low 100s for
  some.

&&

.DISCUSSION...
Issued at 243 PM CDT Wed Jun 12 2024

Showers and thunderstorms have moved across northern Iowa from late
morning into the early afternoon. Very dry air is in place near the
surface, most notable in soundings which show over 1200 J/kg of
CAPE, steep lapse rates, and a deep inverted-V shape. This has
resulted in breezy environmental winds with convection
enhancing the winds further. So far gusts in northern Iowa with
showers have gusted 40-55+ mph. The more robust thunderstorms
are shifting off to the east this afternoon, but showers will
linger across the area into the after across the area. Much
later this evening a secondary round of thunderstorms is
expected to sweep across norther area, skimming northern
portions of the area. HREF runs this morning have shown UH
tracks identifying better updrafts mainly across northern to
northeast Iowa very late tonight. Gusty winds will remain a
concern, along with hail with good updraft support, with any
storms that develop in the area overnight. This will weaken
towards early morning and continue to move into eastern Iowa
and parts of Wisconsin and Illinois.

Our attention then turns to Thursday. Another embedded wave will
pass across the area with a boundary hanging up across southern Iowa
in the afternoon. This boundary will provide the focus for
thunderstorms develop in the afternoon and evening. Expect to
see much more robust convection on Thursday with SPC increasing
to an Enhanced (Level 3 of 5) in southeast Iowa. Storms will
have no problem initiating with a boundary to fire on and CAPE
of 2000-3000 J/kg, along with another inverted-v sounding shape.
This will be highly supportive of gusty winds with storms and
larger hail with strong updrafts. CAMs have been fairly
consistent in developing gusty wind with the storms that develop
in southeast Iowa, including the HRRR consistently putting out
some high end thunderstorms gusts. Given similar dry air in
place with doubled instability tomorrow, this makes sense with
the gusts we`ve seen so far today. Tornadoes would also be
possible, though not the main concern, with modest SRH in
soundings and curved low level hodographs. Also of concern is
hydrologic impacts. Weak flow keeps storm motions slow and
storms in CAMs look to look to line up and train along the
boundary. PWATs are 2"+ in the vicinity of the boundary in
southeast Iowa, so a few areas could pick up some heavier rain.
At the same time, heat will continue to be a concern with
temperatures into the 90s across central and southern Iowa with
heat indicies in southern Iowa pushing 100 degrees.

Temperatures moderate some into Friday and Saturday, but it will
still remain pretty warm with temperatures into the 80s. Additional
thunderstorms are possible into Saturday with another wave passing
across the area. The pattern remains active into early next week
with another robust wave progged for Monday. This one could bring
another chance for severe storms with SPC outlining a day 6 outlook
in our north. At the same time heat continues to build into early
next week with temperatures in the 90s and heat indicies near 100.
There will be little relief overnight as low still remain in the
70s.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1244 AM CDT Thu Jun 13 2024

Outside of a small cluster of storms near KALO, VFR/mostly clear
skies were in place across the forecast area early this morning.
This should continue for several more hours, but the convective
evolution is uncertain later this morning and through the early
evening hours. A weak front is expected to pass through the area
during the late morning and afternoon hours, with scattered
storms developing along it. The question is how far north and
east initiation begins, with more confidence farther south
toward KOTM. Thus, that location is the only spot where thunder
has been mentioned for now due to low confidence in location
and timing. Confidence does increase that clearing and VFR
conditions should occur toward the end of the period Thursday
evening.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

DISCUSSION...Hagenhoff
AVIATION...Small