Oskaloosa, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

512
FXUS63 KDMX 261133
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
633 AM CDT Thu Mar 26 2026

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

.KEY MESSAGES...

- Large gradient of high temperatures across the state today,
  with highs in the 50s north to 80s south.

- Breezy winds with gusts up of 35 to 40 mph possible as cold
  front passes through today. High to very high fire danger
  expected with the gusty winds.

- Isolated light showers/sprinkles today move through today,
  with a few thunderstorms possible in southern Iowa this
  evening. Any stronger storms could produce hail.

- Dry and mild conditions develop Friday and Saturday, with
  occasionally breezy winds both days. Increased fire danger
  likely both days, but especially Saturday.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 346 AM CDT Thu Mar 26 2026

Satellite imagery depicts increasing cloud cover from our northwest
and KDMX is picking up light radar returns over southern Minnesota,
indicating the approach of our much discussed low pressure and cold
front today. Farther south, surface observations are showing a surge
of 50+ degree dewpoints into northern Missouri and southern Iowa as
warm, moist air is advected northward toward the state. Through the
day, the elongated surface low pressure will drop south and east
through the state, trailed by a cool, dry air mass, serving as our
main driver for weather conditions in Iowa today.

The most widely observed impact from this system`s passage today
will be breezy winds. Tightened pressure gradients both at the
surface and aloft will drive up wind speeds ahead and behind the
front, starting out of the southwest ahead and then flipping to
northerly behind. While it will be breezy everywhere, the strongest
winds will move through with the cold air advection and height rises
following the front. North winds of 20 to 25 mph are likely, with
gusts of 35 to 40 mph possible at times. With the front already
knocking on the doorstep of far northwest Iowa, expectation is for
the boundary to be entering the northern portions of our forecast
area around 6 to 7 am, through the I-80 corridor by around 12 pm to
1 pm, then through the entire area as soon as 4 to 5 pm. In addition
to the winds, the arrival of the cold, northerly flow will dictate
how warm temperatures get today. Southern Iowa will be the warmest,
as it will spend the most time within the warm air, while northern
Iowa will be coolest with the front already moving in around
sunrise. This results in a 30 degree difference from the high of 55F
forecast for Estherville to the high of 85F forecast for
Centerville.

With the breezy winds today, elevated fire weather concerns remain
on the the table today, both with the warm, moist air mass ahead of
the front and the cooler, but drier air mass behind the front.
Despite the 50 dewpoints expected in southern Iowa, relative
humidities are still expected to fall into the 35 to 45 percent
range this afternoon thanks to the unseasonably warm
temperatures. That said, winds won`t be as windy in the warm
sector as behind the front. In the cooler air behind the front,
both temperatures and dewpoints will be lower, keeping relative
humidities generally a bit more moist in the 45 to 55 percent
range. However, stronger winds behind the front and dry fuels
will still lend to erratic fire behavior even with the cooler
air. The net result is high to very high fire danger values from
the Grassland Fire Danger Index (GFDI) across Iowa today, with
the highest values favoring western into central Iowa where
winds will be strongest and humidities the lowest. Burning is
discouraged today, as fire starts and spread will be more likely
under these conditions.

Finally, some low end precipitation chances (15 to 25%) will drop
southward through the area with the boundary today, much of which
appears to be post frontal. Soundings and cross sections both
indicate an elevated mixed layer will likely evaporate most
hydrometeors that develop within the saturated layer above it,
keeping most of Iowa dry today. However, weak instability aloft and
respectable lift in this layer does imply that there could be some
top-down saturation of this layer, especially as these showers work
their way south and east into the state where soundings indicate the
EML will be a bit weaker. The net result at the surface will likely
be a few sprinkles or a brief light shower for most impacted by
precipitation during the day.

In addition to the light shower/sprinkle potential north and
central, the possibility for thunder will increase the farther south
and east the front gets. This will range from a rumble or two of
thunder being possible in south central Iowa this afternoon, to
potentially even a stronger storm in the far southeastern reaches of
the forecast area this evening. Similar to the showers, it appears
that any thunderstorm activity will likely be post frontal, as even
forcing along the surface front will struggle to overcome the warm
nose and ~200 J/kg of convective inhibition ahead of it. That said,
1000 to 1500 J/kg of MUCAPE and more saturated mid-levels will favor
a few elevated storms in the early evening hours behind the initial
front. The effective shear in the layer won`t be overly high (20 to
30kts), and would be fairly unidirectional, but it`s certainly
possible we could see some hail in far southeastern Iowa this
evening. With the storms being elevated and low and mid-levels more
saturated, downdraft CAPE values are low (~200 J/kg or less)
suggesting damaging wind is unlikely. Likewise, storms being post
frontal eliminates the threat for tornadoes. Therefore, if storms do
go, hail and lightning will be the primary concern.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 353 AM CDT Thu Mar 26 2026

Widespread north/northwesterly flow remains Friday following the
departing front to the south/east, with a large area of high
pressure descending across the region. Much cooler and drier
conditions are expected for the day, with forecast highs in the low
40s north to low 50s south. The aforementioned surface high is
slated to slowly depart the region through Saturday, with a return
to mid-level ridging across the western CONUS once again. At
the low levels, this means another warming trend on the horizon,
as warm air advection pushes warmer air back into the state
into early next week as forecast highs are expected to top out
through the 70s. Dry conditions on both Friday and Saturday may
result in high to very high fire danger as relative humidities
drop into the 20 to 30 percents both days. This is especially
true on Saturday, as warmer temperatures and breezy conditions
push RHs to critical levels. Evaluation of potentially critical
fire weather conditions on Saturday will be needed in the
coming days.

The signal remains for the overall pattern to turn more active
moving into the beginning of April as long range guidance depicts at
least a few defined troughs ejecting into the Central Plains.
Something to continue monitoring over the coming days.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 625 AM CDT Thu Mar 26 2026

Sprinkles and light showers are drifting over northern Iowa this
morning, although conditions have primarily remained VFR. There
are a few observations of a light mist, which could lead to
brief MVFR vsby reductions, but confidence is too low to
include this in any given site at this time. These light showers
will continue south and east through the day, with KALO and KOTM
most likely to be impacted. A few thunderstorms are also
possible in southern Iowa near KOTM this evening.

In addition to precipitation, a cold front dropping through
northern Iowa will flip winds from southeasterly to northerly
through the day. Breezy winds will accompany this front, with
gusts of 30 to 35 kts possible at times. The strongest winds
will be behind the windshift but breezy winds are expected prior
to it as well. Winds remain breezy into the evening, with a
slight lull tomorrow morning before picking up again on Friday.

&&

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

&&

$$

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