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806
FXUS63 KDMX 191947
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
247 PM CDT Sun May 19 2024

.KEY MESSAGES...

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- Active pattern to persist through early next week with
  multiple rounds of thunderstorms, some of which may be severe

- Tuesday carries the most widespread and high impact severe
  weather potential with widespread Enhanced Risk (3/5)

- Storms will likely be accompanied by heavy rain through
  Tuesday as moisture increases
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&&

.DISCUSSION...
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Issued at 247 PM CDT Sun May 19 2024

Progressive pattern continues through early this week with
multiple shortwave troughs lifting northeast across IA.
Periodic thunderstorms will be the result with varying severe
weather threats, some of which will depend upon overnight
convection and the impact on insolation/instability.

Elevated storms have been pesky today, maintaining for longer
and stronger than most models had indicated. The more organized
updrafts have hugged a MUCAPE gradients thats draped across
southern IA. Convection has been isolated and weaker elsewhere.
Expect this trend to continue for the remainder of the
afternoon. Looking upstream, satellite clearly depicts next
shortwave accelerating across the high plains, with convection
erupting in advance. This shortwave tracks across the state
later today and overnight, providing the next potential (this
evening) for severe convection give sufficient deep layer shear
and instability. Thunderstorms will linger through the
overnight; although severe threat decreases later this evening.

Shortwave trough moves east of the CWA on Monday morning, likely
providing a relative minimum in storm chances immediately in its
wake, sometime around midday. Even so, surface boundary will
remain draped across the state and when combined with SBCAPE
values of 2000-2500 j/kg will provide the potential for another
round of afternoon/early evening convection. Coverage/strength
will depend on how quickly the morning shortwave departs and how
much destabilization can occur behind.

Attention then shifts to Tuesday as the strongest shortwave of
the period takes aim on the Midwest during diurnal heating.
Latest guidance tracks the surface low pressure into NW IA or S
MN by mid-afternoon. Parameters are progd be more than
sufficient for severe in the warm sector with SBCAPEs progd
3000+ j/kg and deep layer shear of 50-60 knots. There is some
questions on timing and location of synoptic features, which
will dictate where storms initiate and resultant impact on
severity. As always, the devils in the details, which will
become more clear in the next 24-36 hours.

The system departs quickly Tuesday night, giving way to a couple
of drier days on Wednesday and Thursday. More storm chances
returning by the end of the week.
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&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1245 PM CDT Sun May 19 2024

Main focus was timing best storm chances at area terminals thru
this forecast cycle. Ongoing thunderstorm across central IA has
missed TAF sites thus far, but still may clip KDSM yet thru
19z. Otherwise, uncertainty remains in how much thunderstorm
coverage will redevelop this afternoon, which will depend on
how much sun can get through thick mid/high-level cloud shield.
Still think better chance for thunderstorms will be later this
evening and overnight with the arrival of the primary storm
system ejecting from the plains. Have trended TAFs to focus on
the 04-13z time period for best thunderstorm coverage as a
result.

&&

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

&&

$$

DISCUSSION...Hahn
AVIATION...Hahn