777
FXUS63 KDMX 171728
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1228 PM CDT Fri May 17 2024

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- Warm today into Saturday with highs in the 80s.

- Isolated storms remain possible Saturday afternoon.

- Several periods with storm chances from late Sunday through
  Tuesday night and again by late in the week.

&&

.DISCUSSION...
Issued at 305 AM CDT Fri May 17 2024

Quiet conditions early this morning across Iowa as surface
ridging slides across the state. Warm advection is beginning to
strengthen in western Iowa where winds have become southerly.
Farther east, winds remain light and variable underneath the
ridge axis. The warm advection overspreads the state today as
the south to southwest increase. Temperatures should respond
with relatively deep mixing and modest dewpoints allowing highs
to climb into the 80s in most areas and have gone above NBM for
highs this afternoon. Thermal ridging approaches the state
overnight with winds remaining decent, particularly in the
northwest tonight helping to keep temperatures near 60 in most
areas.

Broad upper trof across western Canada into the northwest United
States will see a shortwave pass through the base and into the
Dakotas and northern Minnesota on Saturday. The associated surface
boundary slides into Iowa on Saturday with increasing instability
ahead of the front by afternoon. Meanwhile, a decent cap is in place
into the afternoon which should keep convection at bay. However,
sufficient lift along the boundary may be sufficient for a few
isolated cells to overcome the cap and have allowed the low PoPs to
persist, mainly along and east of the Interstate 35 corridor during
the afternoon.

The upper pattern evolves through the weekend and by late Sunday
into Monday, southwest flow develops across the central United
States.  This allows ample moisture to stream back north from the
Gulf into early next week. The initial surge of moisture into Iowa
arrives Sunday into Sunday night with storms spreading from west to
east across the state. The unsettled weather remains into Monday and
Tuesday as moisture continues to flow into Iowa ahead of a shortwave
arriving on Tuesday.  Repeated rounds of thunderstorms may
eventually lead to hydrologic issues along with some threat of
severe weather into the early part of the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1225 PM CDT Fri May 17 2024

Breezy southerly winds will persist into this afternoon and
increase some through 20z. The mixed layer will decouple this
evening, likely after 01z though the wind will remain in the 5
to 8 kt range. The wind will increase mid to late Saturday
morning and become more southwesterly. Sct cumulus near 5 kft is
expected over southern and eastern IA this afternoon along with
passing mid level cloudiness. VFR conditions will persist
through the forecast period.

&&

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

&&

$$

DISCUSSION...Cogil
AVIATION...Donavon