783
FXUS63 KDMX 111118
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
618 AM CDT Tue Mar 11 2025

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

.KEY MESSAGES...

- Mild and dry today with diminishing winds through the day.

- Steadily warming through mid-week, with highs back in the 70s
  by Thursday and Friday.

- Multi-faceted system moving through the state Friday into
  Saturday. Showers and thunderstorms likely, some of which
  could be strong to severe. Gusty non-thunderstorm winds also
  expected.

- Potential for light snowfall north and west as system departs
  on Saturday.

&&

.DISCUSSION...
Issued at 357 AM CDT Tue Mar 11 2025

After a warm and breezy day across the state, temperatures will
continue to fall this evening as a cold front drops from
northwest to southeast. This front is accompanied by a fairly
stout temperature gradient, with values ahead of the front in
the 40s and 50s, then values behind in the 20s to low 30s. This
has equated to a nearly 30 degree temperature gradient from far
southeast Iowa to far northwest Iowa. Interestingly enough,
there is also a smattering of temperatures just ahead of the
front that have briefly fallen into the mid to upper 30s, which
is actually cooler than those behind the boundary/wind shift.
This results from an area of calm winds present just ahead of
the boundary, which is allowing sites to momentarily drop in
temperature through radiational cooling, then increase back to
the roughly mid 40s after the winds pick up again along and
behind front. The more widespread cooler temperatures behind the
boundary will continue into the state through the morning
hours, bringing breezy northwesterly winds along with them.

With the frontal passage this morning, temperatures during the
day will only climb back into the 40s north and 50s to near 60
south today. While not nearly as warm as yesterday, these
temperatures still reside on the higher end of what wed expect
to see this time of year, and should still feel quite pleasant
with the filtered sunshine and winds diminishing by mid-day.
Temperatures will steadily warm back up through mid-week, with
highs in the 60s on Wednesday and back in the 70s by Thursday,
thanks to zonal flow aloft bringing in warmer 850 hPa
temperatures and dry conditions.

By mid-day Thursday, the pattern aloft will begin to transition
as a broad 500 hPa trough begins to build in off the west coast
of the CONUS. This trough will quickly make its way east
across the Rockies through Thursday with lee-side cyclogenesis
beginning late Thursday night into Friday morning. Once the
parent wave eventually makes it over the Rockies, the upper
trough closes off and phases with the coincident surface low,
rapidly deepening as it pivots north and east over the Plains
and eventually into Iowa. Upon reaching the state, the system
will begin to occlude, with dry air wrapping in on the southern
edge of it. Gulf moisture will begin to fill in ahead of the
occlusion, leaving a window for showers and thunderstorms to
develop Friday afternoon. Given the strong kinematics associated
with the wound up low, and a warm, well mixed boundary layer,
enough instability and shear will be present for organized
convection and severe weather. We are still quite a few days out
from the arrival of the system, so dont want to speculate too
much on exact hazards, but current deterministic guidance still
suggests that strong winds will be the main concern, with large
hail also being a threat with the possibility for some rotating
updrafts. The tornado threat is less certain, as model soundings
are still eluding at high based storms which would inhibit
tornado development. That all said, we will continue to monitor
trends in the guidance through the week and iron out details as
we get closer to the high-res window.

In addition to showers and storms as the system initially
arrives, there also looks to be some precipitation that wraps
around the northwest side of the low pressure, primarily in the
northern and western portions of the state. This precipitation
will be associated with colder air as well, suggesting we could
see a burst of snowfall in those areas as the system moves
through on Saturday. With gusty winds funneling in on the
backside as well, will certainly want to keep an eye on the
precipitation type as this system departs on Saturday.
Temperatures behind the low then remain cool through the
remainder of the weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 613 AM CDT Tue Mar 11 2025

VFR conditions prevail through the period, with only a few high
upper level clouds drifting through at times. Breezy northerly
winds this morning will steadily diminish through the day and
become more northeasterly then easterly through the afternoon.

&&

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

&&

$$

DISCUSSION...Dodson
AVIATION...Dodson