Cedar Falls, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

123
FXUS63 KDMX 122316
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
616 PM CDT Wed Mar 12 2025

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

.KEY MESSAGES...

- Warmer temperatures into Thursday with increasing south winds.

- Strong system arrives on Friday bringing strong south winds,
  increased fire danger and the potential for severe storms.
  Damaging winds and hail are the main concerns.

- Additional light precipitation and strong winds expected
  Friday night into Saturday with cooler air arriving.

&&

.DISCUSSION...
Issued at 353 PM CDT Wed Mar 12 2025

A relatively quiet and pleasant day today with light winds and warm
temperatures for mid March.  Readings have returned into the 50s and
60s with a few 70s in far southern Iowa with plenty of sunshine.
Meanwhile, an upper system passes through the southern Plains into
the southeast US tonight into Thursday.  While not directly
impacting the weather for Iowa tonight or Thursday, its passage will
influence Fridays outcome with regards to moisture.  Otherwise, warm
advection increases into Thursday across Iowa and surrounding areas
with highs around 5 to 10 degrees warmer than today.  Fire weather
concerns also increase with the stronger winds and relative humidity
values drop to between 30 to 40 percent by Thursday afternoon
although the overall threat remains somewhat localized.

By Thursday night, the main shortwave passes through the southern
Rockies and emerges into the central Plains on Friday.  Southerly
flow intensifies ahead of the system with a low level jet
approaching 50kts by early morning Friday.  However, the
aforementioned Thursday system will have pushed much of the low
level moisture farther east and a resurgence of moisture from the
Gulf is needed into Friday to return deeper moisture into the state.
Had that initial system not passed south of the state on Thursday,
it is likely substantially more moisture would have been available
with the low level jet on Thursday night/early Friday with a threat
of convection.  However, despite the very strong low level jet, the
threat of convection remains minimal Thursday night into Friday
given the general lack of deeper moisture.

Activity picks up on Friday as mixing increases through the day
allowing higher momentum air to mix down toward the surface.  Wind
gusts and sustained winds are likely to approach Wind Advisory
criteria by afternoon and headlines may be needed.  Fire weather may
also be a concern by afternoon with the strong winds and cured
grasses although minimum relative humidity values remain above 40
percent in most areas as dewpoints increase during the day. At a
minimum, there will be elevated fire conditions during the afternoon
prior to any convection.  Speaking of which, instability builds
through the day as moisture returns northward on the continuing
strong south flow. MUCAPE values climb to over 1000 J/KG by
afternoon ahead of the approaching dry trof axis lifting northward
quickly from Missouri.  Soundings have a distinct inverted-V profile
by afternoon along with strong low level speed shear.  These
profiles are quite indicative of damaging winds and perhaps some
large hail.  The tornado threat still seems limited given higher
clouds bases - LCLs around 1400m at KDSM, although a locally
modified airmass may be able to produce a brief spin-up or two. Main
concern would be if more moisture returns than anticipated which
would increase MUCAPES and lower LCLs.  Convection is expected to
develop rapidly along the dry trof into the mid afternoon as it
lifts quickly northward and with a mean wind of around 50kts,
forward motion of 50+ mph seems reasonable at this time.  The
convection is likely to form into a line or a few separate lines as
it races northeast across the forecast area during the late
afternoon into early evening hours with the damaging winds remaining
the main concern.

Strong gradient winds may occur briefly on the backside of the line
prior to weakening as daytime heating subsides along with the deeper
mixing.  However, the strong winds return from the northwest on
Saturday as strong cold advection pushes into the state with Wind
Advisories possible once again.  Wrap around precipitation may also
linger across northwest portions of the forecast area Friday night
into Saturday as the system lifts northeast with some transition to
snow and light accumulations in the far northwest.  A quick look
into the extended continues to show the threat of a decent system
around the middle of next week although significant difference in
timing continue between the GFS and Euro.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 614 PM CDT Wed Mar 12 2025

Another period of VFR conditions with only high level passing
clouds. Light east to northeast wind tonight will become more
southeasterly on Thursday. The wind may become breezy at times
by the afternoon mainly over the northern sites (KMCW/KFOD/KALO)
while KDSM/KOTM will remain mostly below 12 kts.

&&

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

&&

$$

DISCUSSION...Cogil
AVIATION...Donavon