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232
FXUS63 KDMX 192352
AFDDMX

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

 ...Updated for the 00z Aviation Discussion...

.KEY MESSAGES...

- 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

&&

.DISCUSSION...
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.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
-- Changed Discussion --
Issued at 652 PM CDT Sun May 19 2024

A line of showers and storms remain over northeastern Iowa,
which are expected to move over KALO over the next hour or two
before drying for a short time. Additional more widespread
showers and storms are expected to develop later this evening
and lift across the state overnight and through much of Monday
morning. Lowered ceilings in combination with periods of heavy
rainfall is expected to allow for potential MVFR conditions at
times across the terminals. A period of drier conditions looks
to return after 15z-18z and into the afternoon, before more
showers and storms return towards the end of the period.
Uncertainty on exact timing and coverage, especially towards the
latter portions of the TAF period will likely be lower over the
next few forecast packages as details become at least a bit
more clear with these multiple rounds of showers and storms.
Outside of potential gusty winds at times with any storms, winds
gradually shifting south/southwesterly are expected at speeds
up to 15 knots.
-- End Changed Discussion --

&&

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

&&

$$

DISCUSSION...Hahn
AVIATION...Bury