402
FXUS63 KDMX 061131
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
531 AM CST Fri Mar 6 2026

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

.KEY MESSAGES...

- Storms this morning will produce small hail, though a few
  stronger storms may produce hail up to the size of quarters.

- Higher chances for severe storms very late this afternoon into
  this evening. Large hail and damaging wind gusts will be
  possible and a few tornadoes may also occur depending on any
  sunshine.

- Freezing rain potential remains in our far northwest forecast
  area (Emmet, Palo Alto, northern Kossuth) late tonight into
  pre-dawn hours of Saturday.

- Breezy and cooler Saturday followed by breezy and warmer on Sunday.
  Elevated fire weather concerns may develop on Sunday as well
  given the warm, breezy, and drier airmass.

- Next chance for rain and storms is later Tuesday into Tuesday
  night.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 130 AM CST Fri Mar 6 2026

Upper level water vapor imagery shows a trough approaching from
the Rockies tonight, which has spawn storms ahead of it across
the southern and central Plains. In the low levels, strong warm
air advection is ongoing and has aided in storm development and
seeing these storms move through central Iowa this morning.
Forecast soundings show an elevated warm layer and this will
keep storms elevated not surface based. SPC mesoanalysis has
shown strong 0-6km shear of around 40 to 50 knots, but this is
not being fully realized with effective shear around 30 knots.
Most unstable CAPE has been anywhere from 500 to 1500 J/kg with
CAPE within the hail growth zone of several hundred up to around
500 J/kg. And hail up to the size of quarters or so is the main
concern as these storms first move into the area into early
this morning, but so far have had mainly pea sized hail. With
forecast soundings showing the column quickly saturating, these
moist profiles do not support gusty winds with weak downdraft
CAPE and no dry air to entrain into a downdraft. This is
confirmed by looking at the wind gust fields from convective
allowing models, which show no worse than 40 knots and that
seems generous.

While whatever severe threat wanes toward sunrise, showers
and a few storms may continue to linger through much of the morning
before generally lifting north or northeastward. Models continue to
show the trough moving closer to Iowa through the day as an open
wave similar to how Thursday afternoon`s discussion mentioned. The
attendant surface low pressure with this trough will also move east
from the central Rockies into Kansas and there will be an elongated
low pressure zone setting up into Iowa by late this afternoon
into this evening. Surface dewpoints should rise well into the
50s over the state and even low 60s over far southern Iowa with
cloud cover remaining stout through the day per HREF, though
there could be a few brief breaks here or there. As the synoptic
forcing arrives in concert with low level thermodynamic
forcing, expect to see a few storm clusters develop late in the
afternoon over western Iowa and vicinity. By this time frame,
forecast soundings agree there will be strong deep layer shear
and sufficient effective shear along with 1000 to 1500 J/kg of
surface based instability, but models vary on the level of
inhibition/CIN and this presents at least two possible
scenarios. First scenario, if there is a bit of sunshine, the
CIN may be weaker and allow for surface based severe potential.
This would bring tornado potential into play a bit more,
especially if the winds can back a bit from what they will
mostly be south- southwest much of the day. This is shown in a
few models, such as the HRRR and NAMNest, and would increase the
low level hodograph curvature. Large hail and damaging winds
would be possible as well. Second scenario, inhibition remains
too strong to overcome and storms do not root at the surface and
remain elevated. This would favor large hail and gusty winds.
Regardless of scenario, strong to severe storms are likely with
timing remaining largely consistent being late in the day into
the evening. Storms are expected to grow into a broken line by
this evening and will have to be mindful of mesovortex spin ups
on the leading edge with 30 to 40 knots of 0-3km bulk shear.
Given the orientation of the 0-3km shear vector, a line
acceleration to the northeast would likely be needed to see this
generation. Much of this activity will exit our forecast area by
midnight or shortly thereafter.

That covers the severe weather concerns on Friday, but now onto
the winter weather concerns over northwestern Iowa and our
northwestern forecast area Friday night. As the storms pushed
off to the east, a cold front will move into the state. Colder
air will arrive quicker at the surface than aloft and set up the
potential for freezing rain and freezing drizzle. The GFS is
slower with the front and thus has little in the way of icing,
but the NAM and RAP are the most robust in this potential
having 6+ hours of freezing rain with the 0z HREF freezing rain
accumulation model (FRAM) showing a tenth of an inch at
Estherville. Icing efficiency will be a question as surfaces
will be initially wet and have to cool with 4 inch soil
temperatures tonight in the middle 30s. Elevated surfaces such
as trees and bridges in Emmet, Palo Alto, and northern Kossuth
Counties would be most prone to freezing first with roadways
likely delayed and impacts in question. Given the uncertainty in
how quickly the cold front pushes into the area and icing
efficiency, will continue to monitor for possible Winter Weather
Advisory issuance.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 130 AM CST Fri Mar 6 2026

Behind the aforementioned cold front, breezy winds from the
northwest averaging 10 to 20 mph will deliver drier and cooler, more
seasonable air. This cooler airmass will not last long as winds
become from the southwest at 10 to 20 mph on Sunday returning the
warmth with highs well into the 60s. With the warm, windy
conditions, fully cured fuels, and relative humidity values in the
afternoon falling to between 30 and 40%, elevated fire weather
concerns may materialize. Winds will be not as strong on
Monday and may mitigate fire weather concerns with similar
conditions otherwise as low pressure tracking over southern
Canada sends a cold front into the state with uncertainty in
its placement. Initial National Blend of Models (NBM) shows
this uncertainty in its temperature forecast with 25th-75th
spreads of 20 degrees and run to run inconsistency in its
deterministic forecast. While it is still confident to say that
temperatures will be above normal, how much will be the
question on Monday and Tuesday. As the Baja closed low opens up
into the southern Plains late Tuesday, the northern stream
trough will begin to push southward towards Iowa. There does
look to be theta-e advection ahead of these features that will
lift the stalled front back into some portion of the state and
bring a chance for showers and storm. Depending on the location
of the boundary, there may be appreciable instability and shear
for stronger storms in southern or southeastern Iowa with this
supported by the AI/ML convective hazard forecasts as well. As
the northern stream trough pushes this all out of Iowa
Wednesday, should see cooler, but still above normal
temperatures somewhere in or around the 50s through the end of
the week.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 529 AM CST Fri Mar 6 2026

A Colorado Low has begun its journey this morning northeast towards
the Great Lakes producing an abundance of low level moisture
advection across IA. Ceilings continue to fluctuate between MVFR to
IFR and LIFR at times with scattered thunderstorm activity across
the region. South to southeasterly flow will continue through the
day allowing for ongoing shower and storm chances, at this time
severe storms are looking less favorable with this morning batch of
storms. However, as the low pressure elongates this evening a sharp
boundary will move northwest to southeast. This boundary will spawn
a line of storms that will have the potential to be strong to
severe. As the boundary passes thunderstorm activity will quickly
taper off and there will be an abrupt shift in winds streaming out
of the northwest.

&&

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

&&

$$

SHORT TERM...Ansorge
LONG TERM...Ansorge
AVIATION...Britt