018
FXUS63 KDMX 181920
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
220 PM CDT Fri Apr 18 2025

.KEY MESSAGES...

- Drizzle ends this afternoon, cooler weekend ahead

- 75% or higher chance of widespread rainfall Sunday with a few
  storms possible - no severe weather forecast at this time

- Turning warmer next week with highs back into the 60s and 70s

- Additional shower and storm chances toward and into midweek, but
  high degree of uncertainty on details

&&

.DISCUSSION...
Issued at 220 PM CDT Fri Apr 18 2025

Cold front has passed out of our forecast area with surface and flow
at 925mb and 850mb from some northerly direction with plenty of
stratus clouds behind the front as seen on GOES-East Day Cloud Phase
Distinction RGB. Cross sections reveal lots of low level moisture,
which along with weak lingering lift has been sufficient for drizzle
or light showers at times, particularly over central into parts of
northern Iowa. Temperatures are obviously much cooler than this time
yesterday with temperatures in the upper 40s to upper 50s. While the
front will push south of the state tonight into Saturday, the flow
aloft will remain southwesterly as the positively tilted trough is
stretched from Hudson Bay to the southwestern US. This will keep the
front active with showers and thunderstorms largely south of the
state, but with mid and high level cloudiness over at least southern
Iowa Saturday.

As the shortwave trough at the base of the elongated trough begins
to move east and then lift northeast toward the region this weekend,
will see a surge of low level thermal lift and QG convergence
pushing into Iowa. This will result in widespread shower and storm
chances spreading from south to north across the state on Sunday.
Highs on Sunday were lowered from the initial National Blend of
Models, which its 50th percentile was above the max of available
guidance. BUFKIT forecast soundings show saturated profiles with
precipitable water values of 1.5 inches along with NAM and GFS
surface temperatures in the upper 40s outside of whatever warm
sector makes it up into southeast Iowa. Therefore, highs were
lowered into the upper 40s to low 50s. In addition, soundings show
that any instability will be above a low level inversion and mainly
focused over the southeastern half of Iowa. So while there will be
rumbles of thunder at times, no severe weather is expected with a
widespread, beneficial soil recharge of rainfall anywhere from a
half an inch near Estherville to 1 to 1.5 inches from around a Mason
City to Creston line eastward in Iowa. Hydrologic concerns are low
despite last night`s rainfall that brought several streaks of 1 to
perhaps 2 inches of rainfall with one along Highway 34 west of I-35,
another just south of I-80, and a final one between Highways 3 and
18. Responses on rivers so far have been quite minor given dry soils
that were readily able to absorb the rainfall. Given the relatively
localized nature of this past rainfall along with expected light to
perhaps moderate rates on Sunday, not expecting any short term
hydrology concerns. Rivers may see within bank rises with nothing
notable in the QPF ensemble hydrographs, experimental Hydrologic
Ensemble Forecasting Service (HEFS), or National Water Model`s high
flow magnitude forecast annual exceedance probability. As the low
departs Sunday night into Monday, this will bring an end to the
rainfall with breezy to windy conditions following.

The week ahead looks to see additional shower and storm chances as
the northern jet stream stays active with impulses in the southern
jet stream at times. This will bring passing shortwaves with limited
moisture for rainfall over parts of Iowa on Tuesday. Temperatures
early in the week will be rebounding back and staying above normal
through weeks end. Highs in the 60s and 70s will be common.
Additional rain or storm chances are possible by midweek, but there
is a higher degree of uncertainty at this time.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1214 PM CDT Fri Apr 18 2025

Stratus with IFR or MVFR ceilings will prevail this afternoon
and drizzle or mist may occur at times under these ceilings.
A return to VFR conditions is expected from northwest to
southeast this afternoon into this evening as winds from the
northwest and north-northwest prevail at 10 to 20 knots with
gusts of 20 to 30 knots before diminishing into tonight.

&&

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

&&

$$

DISCUSSION...Ansorge
AVIATION...Ansorge