Mason City, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

870
FXUS63 KDMX 251122
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
622 AM CDT Wed Mar 25 2026

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

.KEY MESSAGES...

- Unseasonably warm temperatures develop across the area today

- Cold front passage on Thursday brings breezy conditions and
  large high temperature gradient over the state. Elevated fire
  weather concerns due to gusty winds.

- Few showers possible (20 to 40%) behind the cold front on
  Thursday. Isolated thunderstorm possible in southern Iowa, but
  greatest storm risk is outside our area.

- A cooldown is expected Friday, then gradually warming through
  the weekend into early next week, while remaining generally
  dry.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 334 AM CDT Wed Mar 25 2026

>> UNSEASONABLY WARM TODAY

Unseasonably warm conditions develop today as the broad 500 mb ridge
builds eastward into Iowa, keeping the state in a northwest flow
pattern aloft. Lower down in the atmosphere, an 850 mb trough and
building surface low pressure will help to advect warmer
temperatures from beneath this ridge into the state, boosting highs
today into the 70s to near 80 in southwestern Iowa. Patchy mid and
upper level cloudiness sourcing from the pacific moisture stream
will filter sunshine through the day, so the duration of cloud cover
at any given location will likely play a role in how the temperature
forecast plays out. If clouds are less expansive and clouds clear
out, today could be a prime day for overachieving temperatures
thanks to the warm mid-level temperatures and mixing that would come
with more sunshine. Higher dewpoint air will also be streaming into
the state today, helping to negate relative humidities
completely dropping out with the warmer temperatures. RH values
drop into the 30 to 40 percent range this afternoon with light
to occasionally breezy winds, especially in southern Iowa where
gusts over 20 mph are possible at times. These moderately dry
conditions and breezy winds could allow fires to spread quickly
today, leading to some elevated fire weather concerns mainly
over southern Iowa.


>> BREEZY ON THURSDAY WITH ELEVATED FIRE DANGER

Warm conditions look to continue for at least parts of the state on
Thursday, but our mid-week warmup will be coming to an end as the
ridging to our west breaks down and troughing over Canada pushes a
cooler air mass down into the central US. On the periphery of this
cooler air will be an elongated area of low pressure, which will
first pull warm, moist air up into Iowa ahead of the cold front
passage. The cold front will then drop southward through the daytime
hours, arriving in northwest Iowa around mid-morning, bisecting the
state from southwest to northeast by around 12pm to 1pm and then
fully through the area just before sunset around 6 pm. Thanks to
this front, there will be a healthy gradient of temperatures over
Iowa on Thursday, with highs reaching the mid to upper 50s to 60s
north and the upper 70s to low 80s south. Of course, depending on a
faster or slower progression of the front, high temperatures could
fluctuate.

Increased pressure gradients around this system both at the surface
and aloft will lead to windier conditions on Thursday. This will be
especially true behind the cold front, where strong cold air
advection and pressure rises will aid in the downward momentum
transport of 30 to 40 kt winds aloft. Northerly winds of 20 to 25
mph are likely on Thursday, with gusts up to 40 mph possible. Breezy
winds will introduce some additional fire weather concerns on
Thursday, although with cloudy skies and falling temperatures, RHs
only fall to around 40 percent for most of the state. Therefore,
while fires may behave erratically on Thursday and elevated fire
danger is expected, critical fire weather concerns aren`t
anticipated. Of course, any precipitation that occurs would
negate any fire weather concerns.


>> SHOWER AND THUNDERSTORM POTENTIAL THURSDAY

In addition to winds, temperatures and potential fire weather
concerns, model guidance continues to produce token
precipitation chances as the front passes through the state.
These are mostly post-frontal, and source from mid- and upper-
level saturation. However, model soundings and cross sections
show a fairly healthy mid-level dry layer that never fully
saturates down to the surface, despite 20+ microbars of lift
occurring above it. This dry layer will put a hindrance on any
appreciable precipitation reaching the surface, but given the
healthy lift and pockets of weak instability (< 100 J/kg), would
not be surprised to see a shower or two produce enough
hydrometeors to saturate down through this layer. Saturation
will most likely be achieved as the showers have persisted,
meaning the southern and eastern portions of the state will be
most favorable for rainfall. Given all this, have pulled back on
the 50+ percent precipitation chances that NBM was forecasting,
but maintained at least some low end precipitation chances (15
to 25 percent) through the day Thursday, with slightly higher
chances (35 to 45 percent) favoring central into southern Iowa.

Finally, there does remain at least an off chance for a
thunderstorm over the far southeastern portion of our forecast
area late Thursday afternoon and evening. This will be where
instability is maximized for our forecast area, with some models
progging 1000+ J/kg of MUCAPE and plenty of shear in the layer
for a more organized updraft (albeit unidirectional). That said,
the mid-level warm nose appears to keep our area mostly capped
off through the day which would either need to mix out or be
overcome by the cold front. Despite the environmental conditions
in place, most of the high resolution guidance isn`t indicating
much for convective initiation until the front is out of our
area, likely due to this warm nose. Therefore, the risk for
storms seems fairly conditional for our area. If a storm were to
develop before the cold front pushes through, hail and gusty
winds would likely be our primary concerns. The storm prediction
center does have a very small portion of our area in the
marginal risk (level 1 of 5) for severe weather, but this again
would be contingent on storms being able to overcome the warm
nose.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 235 PM CDT Tue Mar 24 2026

By Friday, a substantial cooldown is expected to occur as cold air
advection covers the state, with a rather large area of Canadian
surface high pressure tracking into the region. Highs are expected
to be about 20-25 degrees cooler with values only in the mid to
upper 40s north and in the low 50s south. Though cooler, winds
remaining breezy and very dry air resulting in RHs to drop into the
20s to 30s will lead to additional fire weather conditions,
especially over central to southern Iowa.

A look over the western CONUS though shows mid-level ridging
building once again, suggesting the gradual return of warmer
conditions into early next week. Dry conditions are expected to
remain into the weekend as this high pressure slowly descends
southeastward across the region, departing into Sunday. There is a
weak signal for light rain Sunday in the long term guidance, driven
by very subtle features in the larger-scale flow, but the lack of
moisture and overall forcing is not enough to really increase
confidence to include precipitation chances in the forecast at this
point, so have left out. Temperatures peak Monday as the warm air
arrives overhead, with highs back through the 70s.

By Tuesday into midweek, the pattern does look to turn more
active as a few larger troughs eject into the region in terms of
potential for showers and even some storms, so something to
watch over the next several days.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 619 AM CDT Wed Mar 25 2026

Primarily VFR conditions will prevail through the period as mid-
and high clouds drift through the area today. A few hours of
LLWS are expected this morning, then diminishes as winds pick
up. Winds today will be light to occasionally breezy out of the
south. Winds then go light and variable overnight.

&&

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

&&

$$

SHORT TERM...Dodson
LONG TERM...Bury
AVIATION...Dodson