414
FXUS63 KDMX 250942
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
342 AM CST Mon Nov 25 2024

.KEY MESSAGES...

- Non-accumulating wintry mix this morning in the north. Mix
  will consist of mostly drizzle with some flurries.

- Colder temperatures this week with highs in the 30s into the
  low 40s. Post-holiday highs to drop into the 20s.

- Wednesday system trending south. Confidence in rain/snow mix
  now less than 40% for southern Iowa. Additional system on the
  horizon next weekend with low confidence in location (~20%).
  Continue to monitor the forecast.

&&

.DISCUSSION...
Issued at 341 AM CST Mon Nov 25 2024

Stratus continued to fill in and lower overnight in the north
with conditions beneath consisting of a drizzle. The deformation
zone of a surface low to the east will provide some weak lift
through the morning hours. With the below freezing temperatures
coming into the picture at this point, one would suspect some
frozen precipitation will be seen. This of course will depend on
ice introduction present in soundings, and models have
consistently kept a pesky dry layer at about 700-800mb. So while
the DGZ approaches saturation above, flakes would be subject to
some sublimation through the morning. This would at the very
least limit the amount of flakes flying early this morning. In
regards to any freezing drizzle potential, the ground remains
too warm to prompt cause for concern on most surfaces. The
northwest flow will set in firmly for the day and an encroaching
surface high will tighten the pressure gradient. Gusts could
peak at around 35 mph this afternoon. Clouds will clear out by
mid afternoon, but this won`t help the warmth factor. Highs
won`t make it out of the 30s for most of the area this
afternoon, save for the far southeast.

The midweek system continues to trend south and the 00z
deterministic. Highest confidence in precipitation of any type would
be along and south of Highway 34 on Wednesday, but that confidence
is less than 40%. For areas north of 34, confidence in seeing precip
is below 20%. 00z ensemble guidance has backed off further on QPF
and snowfall amounts for Iowa which would make NBM guidance PoPs too
high. The surface low will track across the Mid South and turn winds
in southern Iowa briefly southerly on Tuesday, bringing highs back
in the low 40s for that area through Wednesday. A rain snow mix
could occur during the morning Wednesday, transitioning to all rain
as temperatures rise above freezing. Precipitation exits the picture
for Thanksgiving Day, but temperatures drop more. Highs for the
holiday will be near freezing and in the upper 20s north. Another
system is on track to impact the region on Saturday. Preserving the
20% confidence mentioned in the previous discussion. A wintry
airmass will settle in behind, with lows through early next week in
the single digits.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1133 PM CST Sun Nov 24 2024

MVFR to IFR stratus is expanding across northern Iowa with
patchy, intermittent fog and drizzle being reported in a few
spots. This is expected to continue across northern Iowa
through the overnight with low stratus expanding south across
all sites. Skies will clear and return to VFR tomorrow from west
to east through midday. Northwest winds have increased across
western Iowa already this evening. Gusts of 20-25+ kts will
expand across all sites by Monday morning and continue through
the end of the TAF period.

&&

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

&&

$$

DISCUSSION...Jimenez
AVIATION...Hagenhoff