112
FXUS63 KDMX 072329
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
529 PM CST Fri Nov 7 2025

 ...Updated for the 00z Aviation Discussion...

.KEY MESSAGES...

- Accumulating snowfall for some on Saturday. This will likely
  be mostly north of I-80, but uncertainty remains high on
  location and amounts given temperatures near freezing so
  monitor for forecast changes.

- Brief snow showers possible Saturday night into early Sunday.

- Blustery and cold on Sunday.

- Turning milder next week with a mainly dry forecast.

&&

.DISCUSSION...
Issued at 314 PM CST Fri Nov 7 2025

Early afternoon satellite imagery shows an area of clouds
sagging southward this afternoon, which has reached northern
Iowa and is associated with the leading edge of a cold front.
Behind this front, 850mb and 925mb analysis shows low level cold
air advection with surface observations showing northwest winds
and cooler and drier air filling in. There may be a few showers
in far northeast Iowa with sprinkles perhaps as far southwest
as Waterloo, but overall this is passing through dry.

Upstream of Iowa over the northern Rockies along the US/Canada
border, GOES-East upper level water vapor imagery shows a compact
shortwave trough/PV anomaly. This shortwave will quickly drop into
Iowa through the day Saturday and bring our first chance of
accumulating snowfall. Clouds will increase and thicken overnight
with precipitation chances starting to tick upward along the Highway
71 corridor into our forecast area as early as 3 or 4 am. This is
when strong low level QG convergence and theta-e advection coupled
with the left exit region of a jet streak will arrive over
central Iowa. This forcing will help to spread the precipitation
chances quickly east-southeastward and be in our eastern forecast
area reaching the Highway 63 corridor by around 8 am or so.
With snowflakes expected to fly in less than 24 hours, there
still remains a great deal of uncertainty with regards to
precipitation type due to low level temperatures and dewpoints
and surface/ground temperatures as well as if rates will be
sufficient to overcome those factors for what accumulation may
occur and in what location. As has been the theme this week,
temperatures were lowered from the initial National Blend of
Models (NBM) given the clouds and falling precipitation, which
will limit how much the air warms tomorrow. In addition during
the day, dewpoints that start in the 30-34 degree range look to
rise slightly by a few degrees, which may result in wet bulb
temperatures above what would allow for snow and/or snow
accumulation. While wet bulbing may not occur, dynamically
cooling the column may be in play as cross sections show a
period of several hours of at least moderate lift, which
coincides within the dendritic growth zone (DGZ), as it passes
over the state. Latest HREF snowband probability tracker does
show several models with possible banding coming across Iowa
somewhere between Highway 20 and I-80. What`s interesting about
this potential is the lack of support in ensemble data for the
probability of 1 inch per hour snowfall rates, with no higher
than 10% in the 0z/12z HREF and up to only 30% in the 9z SREF.

So given that uncertainty, here is how we think this will play out.
Precipitation will spread in as mostly snow roughly north of
Highway 30 in the pre-dawn hours and a rain/snow mix between
Highway 30 and Highway 92. For our northwestern forecast area
from say roughly Crawford up to Pocahontas counties in the
morning hours, this may be the window of peak snowfall as the
moderate lift is in the DGZ. This may foster rates that are high
enough to be able to accumulate vs melt on the ground with 4
inch soil temperatures in the middle and upper 40s. BUFKIT
soundings at CRL show higher rates of an inch per hour or a bit
more for several hours, though these may not be showing the full
extent of melting. For those that like to look at raw snowfall
output online, looking at the snow depth output can be useful in
these borderline temperature events to show to some degree the
extent of melting. As precipitation chances slide eastward to
I-35 and more so Highway 63, the rain/snow mix may move
northward. This will be a result of moving into the part of the
day that will be `warmer` along with solar radiation still
penetrating through the clouds and helping to warm surfaces,
especially paved surfaces. With the bulk of precipitation
ending in most areas across central Iowa by late afternoon, the
potential for a flash freeze would seem to be lower given no
falling precipitation as temperatures lower into the evening.
Total snowfall still looks to be highest over northwest Iowa
into our northwestern forecast and north central Iowa. Where
there is dynamic cooling, this could lead to pockets or a narrow
corridor of snowfall higher than currently shown in the
forecast. While no winter weather advisory was issued on this
shift, it is still possible that this may occur if not tonight,
Saturday morning as upstream observation trends and webcams are
monitored. While not often desired, this may offer little lead
time other than the messaging that has been provided much of
this week.

There will be a break in the precipitation as mentioned above late in
the afternoon and early evening as the shortwave trough departs. A
second push of shortwave energy arrives Saturday night along with
the delivery of colder air. This colder air will help to steepen low
level lapse rates. Forecast soundings show some low level
instability and thus may be able to generate convective snow showers
Saturday night into a little after sunrise Sunday. These could bring
brief, passing snow bursts with visibility reductions Saturday night
into the morning hours of Sunday with this activity ending from
north to south. Otherwise, Sunday is shaping up to be a raw
November day with highs in the low and middle 30s and blustery
winds accentuating the chill of the day. These conditions will
combine to make wind chills in the upper teens to low 20s at
their highest. Needless to say, if you have outdoor plans one
will need to bundle up with their favorite winter gear.
Fortunately, temperatures will begin to rebound into next week
with 50s expected in most areas on Tuesday through week`s end
with a mainly dry forecast as the jet stream stays northwest of
the area.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 529 PM CST Fri Nov 7 2025

A large field of low stratus clouds is blanketing most of
Minnesota, Wisconsin, eastern South Dakota, and northern Iowa
this evening. Our northern terminals (MCW, ALO, FOD) are
reporting MVFR ceilings and these will continue for much or all
of the night through 12Z, with some lowering below FL020 at
times. On Saturday morning a RA/SN mix will spread across the
area, bringing reduced visibility and IFR ceilings during the
day. Have indicated general timing of these impacts in the 00Z
TAFs, but expect refinement in subsequent issuances.

&&

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

&&

$$

DISCUSSION...Ansorge
AVIATION...Lee