081
FXUS63 KDMX 042343
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
643 PM CDT Sat May 4 2024

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

.KEY MESSAGES...

- Winds becoming light overnight with the threat of low lying
  fog.

- Strong to potentially severe storms on Monday evening into
  early Tuesday. Locally heavy rainfall also a possibility.

- Unsettled weather persist for much of the work week.

&&

.DISCUSSION...
Issued at 239 PM CDT Sat May 4 2024

Extensive clouds field across the forecast area this afternoon in
the wake of the system which passed through central Iowa this
morning. However, the threat of any rainfall has ended with the
passage of the boundary with decent cold advection on the backside.
Surface ridging approaches from the west tonight with winds backing
off considerably this evening as skies clear allowing the decoupling
of the winds.  As surface ridge arrives overnight, winds become
light and variable with the potential for some ground fog given the
recent moist conditions across the state and have included patchy
fog in the forecast for portions of the area although locally dense
fog would not be surprising.

Relatively quiet and pleasant conditions are expected into Sunday as
the surface ridging slides east of the state with sunshine
returning.  Warm advection intensifies on Sunday night into Monday
in response to a vigorous shortwave passing through the
Rockies. This draws moisture northward into the state during the
day on Monday into Monday evening ahead of the increasingly
negatively tilted shortwave. Convection is likely to develop
ahead of the surface trof within the instability axis in
Nebraska southward into Texas. This convection slides eastward
during the evening and enters into Iowa. The convective system
is fed by a strong 40-50kt low level jet into the evening and
overnight. Main question is how far east it will be able to
travel before exhausting the narrowing instability axis across
Iowa. There is sufficient bulk shear of over 40kts and somewhat
robust SRH to support the system and some severe weather seems
likely in the west. However, the CAPE profiles become skinnier
to the east which is likely to limit the eastward extent of the
severe weather. Some moderate to locally heavy rainfall may also
occur given the strong moisture transport into the state.

The upper low trudges across the northern Plains into the middle of
the week before another shortwave ejects across Iowa on Wednesday.
This keeps unsettled weather in and around the state through the
middle of the week with a continued threat for rainfall along with
seasonably mild conditions.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 635 PM CDT Sat May 4 2024

VFR conditions to persist for most terminals over the next 6
hours. Fog to settle into northern terminals overnight with IFR
vsbys possible at KFOD and KMCW. Lower confidence at KALO so
kept vsbys higher. VFR skies with light winds expected after
13z.

&&

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

&&

$$

DISCUSSION...Cogil
AVIATION...Jimenez