500
FXUS63 KDMX 121126
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
626 AM CDT Sun May 12 2024

 ...Updated for the 12z Aviation Discussion...

.KEY MESSAGES...

* Unsettled weather returns later today into Monday - showers/non-
  severe storms

* Cooler after today - highs fall back into upper 60s to mid 70s
  through much of next week

* Additional shower/thunder chances return Wed/Thur - severe
  chances remain low

&&

.DISCUSSION...
Issued at 332 AM CDT Sun May 12 2024

While the auroras were no where near as strong last night as they
were Friday night, skies did generally cooperate for those that did
stick it out for another glimpse.

As of early this morning, the next weather maker for the area could
be clearly seen on various satellite products, churning its way
across the eastern Rockies, about to come out onto the Colorado
Front Range. Ahead of this system, the nighttime microphysics
product, showed mid-upper level cloud cover building across much of
western into central Kansas and southern into central Nebraska. For
much of today, the most notable changes in conditions will be
southerly winds, increasing cloud cover, and temperatures a couple-
few degrees warmer than Saturday. Dew points will increase some, but
will not make a marked impact on "feel" outside. While the overall
boundary layer will remain quite dry, the increased moisture will
allow for scattered showers/thunder to develop by the mid-late
afternoon. CAM soundings depict deep mixing once again with inverted
V soundings and cloud bases around 5-6kft. Main concern, if any,
with showers/storms will be potential for some gusty winds as
precipitation falls into/through that substantially dry boundary
layer. Additional activity across northern Iowa into South Dakota
and Minnesota will be driven by the cool front sagging in from the
north. Activity overnight and into Monday will be tied more directly
with the approaching upper low, but is likely to struggle to produce
much substantial precipitation with little to no MUCAPE to work with
and at least initially dry air to work through. Expect southern
areas to see the most precipitation from Sunday PM through Monday
with the most persistent lift and moisture to work with, while
northern areas of Iowa may be dry by midnight tonight. Biggest
question marks through central Iowa and how far north precipitation
can linger after this afternoon/evening.

Briefly quiet Tuesday into Wednesday before next series of
shortwaves glide through the southern and northern streams. Story
generally remains the same as previous discussions, with synoptic
guidance and ensembles in broad agreement on increasing chances
Wednesday afternoon through Thursday. One notable change is the
weaker northern stream wave and by virtue precipitation chances.
Southern stream wave remains fairly robust and precipitation amounts
could mirror what is expected later today through Monday. Strong to
severe chances remain quite low with sub-par CAPE and wind fields
depicted.

After Thursday, Euro and GFS continue to diverge in their handling
of the late week into next weekend pattern with GFS lingering
precipitation chances into Friday before drying out and the Euro dry
Friday but brings a northern stream shortwave trough and
precipitation chances further south to start the weekend. As a
result, NBM PoPs/precipitation chances appear never ending from
Wednesday onward. Inevitably, there will be windows of dry
conditions, just unable to to pinpoint at this time.

Temperatures after today will be a handful of degrees cooler across
the state thanks to aforementioned precipitation opportunities,
cloud cover, and periods of cooler northerly/northwesterly winds.
Expect highs predominantly in the upper 60s to mid 70s and lows in
the 40s to 50s.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 621 AM CDT Sun May 12 2024

Initial VFR conditions will give way to uncertain TSRA/VCTS
opportunities around/after 21z and through much of the rest of
the TAF period. TSRA activity should be pretty widely scattered
initially, so have generally kept mentions out due to low
confidence in proximity to TAF sites and overall spatial
coverage. Have attempted to time VCTS mentions as best as
possible, including transition to SHRA at KDSM as greater
confidence in precipitation chances/coverage move in from the SW
late in the TAF period. Otherwise, SW winds prevail around 10
to 15 kts with periodic gusts around 20 kts. Cloud cover should
remain higher based until late in the TAF period or after when
MVFR/IFR ceilings slated to move in.

&&

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

&&

$$

DISCUSSION...Curtis
AVIATION...Curtis