283
FXUS63 KDMX 052317
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
617 PM CDT Wed Jun 5 2024

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

.KEY MESSAGES...

- A few showers and storms possible through early evening. Gusty
  winds are possible with this activity.

- Gusty winds expected Thursday. Wind gusts over 40 mph are
  possible, especially over northern Iowa.

&&

.DISCUSSION...
Issued at 342 PM CDT Wed Jun 5 2024

A boundary is currently across southeast Minnesota, northwest Iowa
and into Nebraska and will continue to move southeast through the
state into this evening. Some surface dew point recovery was ongoing
earlier today with a narrow ribbon of upper 50 to near 60 dew points
wrapping around the west side of a high to the south and pooling
ahead of the boundary. Those dew points have since mixed out some
this afternoon into the low to mid 50s. Some modest surface
instability has develop ahead of the boundary with around 500 J/kg
CAPE. Some light rain has been moving across southern Minnesota and
into northwest IA and in the past 15 minutes, some convection is
developing into far northwest Iowa.

Despite improved effective shear profiles of 25+ kts, not expecting
any organized activity to develop. Gusty winds will be possible with
any and cannot discount gusts over 50 mph. The shower and storm
potential will progress southeast along the boundary into this
evening. A wind advisory remains in effect over far northern Iowa.
The potential remains for some deeper mixing over the next few hours
to result in increased winds and that will remain in effect through
7 pm.

The wind will diminish and the skies will clear later this evening
and into the overnight. The main weather story on Thursday will
again be increasing winds. Despite the potential for 40kts of wind
near the top of the mixed layer Thursday, the lack of strong cold
advection will limit how much wind does mix to the surface and the
lack of a good pressure gradient is also a limit. Therefore, there
remains enough uncertainty to remain headline free for Thursday.

Two upper lows with one from the northeast CONUS and another over
central Alberta along with an upper ridge over the western CONUS,
will combine to create a weak upper northwest flow  over Iowa from
Thursday through much of Saturday. A short wave will rotate south
late Saturday into early Sunday which will lead to some cooler
temperatures Sunday. With so many strong upper level next weak,
there is a lot of noise in the data beyond Monday leading to less
confidence in that time period.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 613 PM CDT Wed Jun 5 2024

VFR conditions are forecast through the TAF period. A broken
band of -shra activity is pushing through central Iowa this
evening. Much of this activity is rooted at or above 10k feet
with some precipitation not reaching the ground. This makes it
difficult to pinpoint if/when precip may occur at a given
terminal, and have opted to cover with VCSH although a brief
downpour may occur. The shower activity may also be accompanied
by sporadic gusty winds.

Dry conditions are then forecast by mid to late evening through
the remainder of the TAF period. Gusty west-northwest winds
return tomorrow morning. The strongest winds reside over
northern Iowa where gusts above 30 kts may be common,
particularly during the afternoon hours.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 7 PM CDT this evening for IAZ004>007-
015>017.

&&

$$

DISCUSSION...Donavon
AVIATION...Martin