FXUS63 KDMX 191717
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1217 PM CDT Tue May 19 2026

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- Much cooler today through the end of the week with highs in 
  the upper 50s to low 60s. Temperatures tonight reach the mid 
  to upper 30s in northern Iowa with patchy frost possible 
  there. 

- Rain chances return late Thursday into Friday. 

-Warming trend this weekend with 80s returning by Sunday 
 through early next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 220 AM CDT Tue May 19 2026

The surface low continues to move east across the area with 
associated rain pushing into eastern Iowa early this morning. 
While the bulk of the rainfall has come to an end, some wrap 
around light sprinkles may be possible in northern Iowa through 
today as the low continues to slide east. Today will be markedly
cooler as much cooler air filters in behind the cold front. 
Temperatures early this morning are in the mid 40s across 
northwest Iowa with 50s central and southeast Iowa still in the 
mid 60s. That cooler air northwest will continue to spread 
across the state today and highs will remain in the upper 50s to
low 60s. Winds will also be brisk out of the northwest at 20-30
mph owed to a modestly enhanced pressure gradient across the 
area from the departing low and incoming high pressure, along 
with subsidence and cold air advection. Skies clear through the 
day as high pressure settles across the state. Will clear skies 
and light wind overnight temperatures are expected to fall off 
quickly overnight. Low temperatures in northern Iowa will fall 
to the mid to upper 30s which may result in patchy frost, which 
would impact those with sensitive plants.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 1250 PM CDT Mon May 18 2026

By Tuesday evening a large surface high pressure area will be 
building down the northern High Plains and on Tuesday night 
will settle across Iowa and Minnesota. This will lead to 
rapidly diminishing winds around sunset Tuesday and much cooler
temperatures Tuesday night as winds go light or calm and skies 
clear out, especially near the Minnesota border closer to the 
center of the high and where chances for high cirrus clouds are 
lowest. The result is forecast low temperatures early Wednesday 
morning in the mid-to- upper 30s in our northern and western 
counties, but any frost potential will be dependent on skies 
remaining clear and winds becoming calm. This possibility will 
be better assessed tonight and tomorrow.

From Wednesday through the end of this week a weak 500 MB low 
will meander across southwestern Canada, with cyclonic flow 
extending down across the U.S. Rockies and near Iowa. A series 
of shortwave impulses moving through the flow will result in a 
return of rain chances for our forecast area. Initially, on 
Wednesday, the proximity of the slowly departing surface high 
pressure area and associated dry air will inhibit any 
precipitation chances. By Thursday atmospheric moisture and 
instability will be gradually increasing however, and around 
Thursday night and Friday the most pronounced 500 MB trough 
will move overhead and bring higher rain chances (50-70%). In 
wake of that trough, next weekend, weak subsidence may follow 
along with weak surface riding, supporting mostly dry weather 
and much lower rain chances (10-20%). Also of note is a 
consistent signal for some degree of thermal ridging around 
Sunday into early next week, especially from the EC and GEM, 
lending confidence to warmer temperatures at the end of the 
current 7-day forecast. Climate Prediction Center outlooks also
support a likelihood of warmer than normal temperatures heading
into next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1217 PM CDT Tue May 19 2026

Low stratus clouds are blanketing the area with MVFR ceilings
this afternoon. These will slowly rise this afternoon and
eventually clear out late today or early tonight, though timing
of the clearing is uncertain. Have indicated these trends in the
18Z TAFs, but amendments are possible as the day progresses
based on satellite and surface observations. Once ceilings break
up and/or rise above FL030, VFR conditions are then forecast for
the remainder of the TAF period.

&&

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

&&

$$

SHORT TERM...Hagenhoff
LONG TERM...Lee
AVIATION...Lee