038
FXUS63 KDMX 101147
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
647 AM CDT Sat Aug 10 2024

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

.KEY MESSAGES...

- Continued dry and pleasant today, but potential for showers
  and storms increases late Sunday into early Monday morning

- More typical summer pattern by the middle of next week with
  intermittent chances for storms and more seasonal warmth and
  humidity

&&

.DISCUSSION...
Issued at 347 AM CDT Sat Aug 10 2024

Today`s weather should be much like recent days with seasonally
cool temps and low humidities. With mostly clear skies and
light west winds early this morning, this cool, dry airmass has
allowed 08z temps to approach record lows in a few spots with
readings in the upper 40s to middle 50s. Mason City, Lamoni, and
Ottumwa would be the more likely candidates, if they can cool
sufficiently over the next few hours. Weak short waves along the
PV gradient and jet segment from CO into NE will advance into
the MO Valley later today with some mid and high cloudiness due
to warm advection aloft, but surface high pressure along and
west of the MO Valley will keep our airmass little changed.

This situation will change later tomorrow however as Pacific NW
short waves follow the aforementioned track into the Plains.
This will sharpen the H85/H7 trough upstream, and resultant
warm/theta-e advection into the state, with kinematic
contributions also increasing lift and column saturation by the
early morning hours Monday. MUCAPEs get to 1000 J/kg at most,
and are generally lower, so overall the severe weather potential
is low. However with 40-50kt effective shear and elongated
hodographs, a few strong storms with hail can`t be ruled out if
higher instability is realized. Much of this lift should exit
into midday Monday with only spotty slight chances lingering
into Tuesday as upper level ridging approaches the MO Valley.

Confidence decreases for the middle to latter portions of next
week however, especially in the details. However, there is good
larger scale agreement that the flow will weaken, allowing more
seasonal warmth and humidity to return. Recent EC/NAEFS ensemble
output notes seasonally anomalous values of specific humidity
and precipitable water back into the MO Valley by Wednesday into
Thursday. The models are struggling with upper trough timing,
strength, and location, as well as surface features, but the
overall pattern suggests a few windows for MCS development
midweek through the end of the period. This results in several
days with slight to chance PoPs until confidence increases.
Would not be surprised to eventually see some severe weather
potential, but with models having difficulty aligning focusing
mechanisms, and what the shear/instability parameter space would
look like at those times, the severe weather potential would
best be described as low for the time being. The latest Colorado
State machine learning severe weather probabilities (09/00z)
reflect that as well with little signal as of yet.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 647 AM CDT Sat Aug 10 2024

Confidence is high that VFR conditions will persist through the
period with varied degrees of mid and high level cloudiness,
mainly south and west. W-NW winds will increase a bit into peak
heating, but then become light again by evening.

&&

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

&&

$$

DISCUSSION...Small
AVIATION...Small