Mason City, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

799
FXUS63 KDMX 230453
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1053 PM CST Mon Dec 22 2025

 ...Updated for the 06z Aviation Discussion...

.KEY MESSAGES...

- Mild, above normal temperatures this week. Low potential for
  fog over snowpack tonight.

- Cloudy through Christmas Eve and Christmas day, with low
  chance (less than 20%) for precipitation in the south and east.

&&

.DISCUSSION...
Issued at 202 PM CST Mon Dec 22 2025

Warm southerly flow today has boosted temperatures into the upper
40s to near 50 in southern and central Iowa, with slightly cooler
temperatures in the mid to upper 30s over snow pack in north central
and northern Iowa. With this warmer flow blowing directly into the
snowpack and wetbulb temperatures in the upper 30s to low 40s
advecting into the area, snow should melt nicely through the
afternoon. This will be especially true as the gulf moisture stream
pushes eastward and cloud cover diminishes. Tonight, a weak surface
low will pass over the state, flipping flow to westerly, then
northerly by tomorrow. With the diminishing winds and melting
snow tonight, fog may develop over snowpack as temperatures
cool through tomorrow morning. However, winds struggle to go
calm until the surface low fully departs and high pressure moves
in, which may limit radiational cooling and fog potential.
Therefore, while there is a chance for fog tonight and tomorrow
morning, it`s not a high confidence scenario.

Iowa will generally be placed along the periphery of a 500 mb ridge
through mid-week, resulting in mild, above normal temperatures
through much of the week. Subtle waves in the broadly zonal
pattern will bring variations in the surface pattern through the
week but, to most, conditions will appear fairly similar
through mid- week. Temperatures are only forecast to vary by a
couple of degrees each day, all of which will have above normal
highs. Winds also remain light through this period with partly
to mostly cloudy skies.

The main change from previous forecast cycles has been a
considerable drop in forecasted highs from the national blend of
models (NBM) for Christmas Day. As was alluded to in previous
discussions, NBM had been running a bit warm with temperatures for
Thursday, resulting in highs in the 60s over central and southern
Iowa, despite expectations of cloud cover. Today, NBM has
rubber- banded back the other direction, slashing Thursday
(Christmas Day) highs by almost 10 degrees, now generally in the
40s to mid 50s. This is in part due to the expected cloud cover
through the day, but also because of an easterly surface flow
pattern which isn`t as conducive for strong WAA. NBM may be
slightly over-reacting with these cooler temperatures, so have
bumped forecasted highs back toward the 75th percentile of NBM.
However, given the expected setup, colder highs is certainly a
trend in the right direction. There also remains a signal for
some light rain/drizzle Wednesday (Christmas Eve), then again
Thursday (Christmas Day) afternoon as better low level moisture
rotates up into southern and southeastern Iowa. Lift is quite
weak, and saturation marginal, so confidence is fairly low in
this occurring, but it does show up to varying degrees in the
guidance. Fortunately, temperatures should be warm enough to
negate any freezing concerns or potential impacts beyond a moist
holiday.

A change in the pattern comes this weekend as the ridge begins to
break down and a slightly more amplified wave passes through
the area. This wave will bring colder temperatures down into
the state Saturday night into Sunday. However, there are still
some significant discrepancies between guidance on the
evolution and track of this wave, as well as any associated
precipitation, so will continue to monitor in the coming days.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1053 PM CST Mon Dec 22 2025

Mainly VFR conditions are forecast, however, as winds turn to
northwest later tonight and through Tuesday, an area of low
stratus clouds currently over northern North Dakota (and based
around FL007-014) will move southeastward into Minnesota and
South Dakota. The leading edge will gradually erode and heights
will slowly arise during the day as the clouds approach, and
confidence in any low ceilings reaching our area is relatively
low (less than 50%) and mainly confined to northern Iowa. Have
introduced some SCT low clouds and 6SM BR at MCW Tuesday
afternoon/evening accordingly, but will monitor satellite
imagery and short-term model guidance through the night and
morning to see if expansion of IFR/MVFR conditions is warranted
in later TAF updates.

&&

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

&&

$$

DISCUSSION...Dodson
AVIATION...Lee