408
FXUS63 KDMX 272057
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
257 PM CST Thu Nov 27 2025

.KEY MESSAGES...

- Cool and quiet tonight through mid-day Friday

- Widespread snowfall beginning late Friday afternoon and
  persisting through the day Saturday. Snowfall of 8 to 12" with
  higher amounts possible.

&&

.DISCUSSION...
Issued at 253 PM CST Thu Nov 27 2025

With quiet and cool weather today, there`s no doubt the talk around
Thanksgiving dinner will be the upcoming snow storm beginning in
western Iowa late Friday afternoon and spreading across Iowa
overnight Friday into Saturday. This snow will arrive as the result
of a 500 mb wave, currently over the pacific northwest, diving
southeastward over the Rockies and into the central US. As this
occurs, the wave will deepen into a longwave trough, resulting in
lee-side cyclogenesis over the plains. This surface low will then
track east northeast along the base of the trough, taking it right
over southern Iowa and putting a majority of the area in the cold
sector. At the same time, gulf moisture will stream up ahead of the
system, phasing with the lift around the deepening low pressure. The
result will be a prolonged period of snowfall beginning late Friday
and continuing through Saturday.

The initial arrival of snowfall looks to occur late Friday afternoon
and evening, as the initial warm air advection wing lifts into the
state. Weak frontogenesis will provide steady lift through the DGZ,
bringing light to moderate snowfall to much of northern into central
Iowa by Saturday morning. 3 to 5 inches of snow is possible through
central Iowa by daybreak. Through the morning Saturday, the low will
deepen and pivot through the state, resulting in a prolonged period
of snowfall over central Iowa. This will bring another 4 to 6 inches
of snowfall to the area Saturday morning into mid-day, resulting in
amounts around 10 to 12 inches, with some localized areas
potentially seeing amounts higher than that. Recent trends in
guidance have been showing a tightening of the area with the
heaviest amounts, generally east of interstate 35 and between
interstate 80 and highway 20. A slight southeastward trend has also
been seen, which has brought values down a bit over northern Iowa.
Will want to continue to monitor this trend as short range guidance
becomes available. Regardless, given the high confidence of
impactful snowfall in the area, have decided to upgrade the Winter
Storm Watch to a Winter Storm Warning for much of central Iowa,
beginning late Friday and ending early Sunday.

Farther south and west in the state, saturation in the DGZ seems to
lack as precipitation initially arrives in the state Friday evening.
This is especially true in some of the newer high resolution
guidance. This, in conjunction with mid-level temperatures near 0C,
could result in a brief period of freezing rain/freezing drizzle in
these areas overnight Friday into Saturday morning. However,
expectation is for this dry mid-level layer to eventually
saturate through with the modest lift and the moist layer aloft
and below. Once ice introduction is achieved, the melting layer
will be the only concern for freezing rain/drizzle, but even
then, this layer is fairly weak, so expecting this to fall as a
slightly melted snow/refrozen snow. Through the day Saturday,
warmer surface temperatures begin to make their way up into the
state, which will cause rain to mix in with snow at times. This
potential for melting will limit snowfall amounts along the
Iowa/Missouri border. With the southerly trend and in
coordination with the NWS Pleasant Hill office, decided to give
this area another round of data before deciding on headlines,
and have therefore kept them in a winter storm watch.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1135 AM CST Thu Nov 27 2025

Short term challenge is the MVFR stratus covering northern sites
at the TAF issuance time. Delayed improvements until after 00z.
Confidence not high this reaches KDSM, but left a FEW deck to
account for the possibility. Stratus will be replaced by
midlevel clouds with cigs between 10-20kft overnight. A wind
shift happens for KFOD and KDSM near the end of the TAF period.
Snow timing looks to be after 18z, so this will begin to be
covered in the next issuance.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 3 PM Friday to 6 AM CST Sunday for
IAZ004-005-015-023>025-033>036-044>047-057>059-070>072-082-083.
Winter Storm Warning from 6 PM Friday to 6 AM CST Sunday for
IAZ006-007-016-017-026>028-037>039-048>050-060>062-073>075-
084>086.
Winter Storm Watch from Friday evening through late Saturday
night for IAZ081-092>097.

&&

$$

DISCUSSION...Dodson
AVIATION...Jimenez