FXUS63 KDMX 261850

AFDDMX



Area Forecast Discussion

National Weather Service Des Moines IA

150 PM CDT Thu Jun 26 2025



.KEY MESSAGES...



- Thunderstorms tracking east-southeastward through the state

  this afternoon into evening. Damaging winds and heavy rain are

  the main threats, though a tornado is possible mainly in 

  northeastern Iowa. 



- Thunderstorm activity moves out late tonight with dry

  conditions expected on Friday. 



- Warm temperatures continue this weekend and next week with

  additional rain and thunderstorm chances through the second

  half of the weekend and at times next week. 



&&



.DISCUSSION...

Issued at 109 PM CDT Thu Jun 26 2025



Focus is on the developing activity this afternoon into evening. 

Midday surface analysis has the warm front hanging out over northern 

Iowa near the IA/MN border, continuing to become better defined with 

time. The surface low is ejecting out of eastern SD/NW IA/SE MN and 

will track across far northern IA/southern MN with time through the 

afternoon and evening hours. Adjacent to the low is a cool front 

extending southward through eastern NE and beyond. These features 

will all be drivers of our showers and storms through the afternoon 

and evening with storms having already been bubbling into midday 

over portions of west central Iowa with some showers ongoing in 

portions of northern Iowa and mostly clear skies to the east of the 

bubbling storms/showers. The warm sector south and east of the two 

boundaries is directly over the state where temperatures have warmed 

into the 80s where precipitation is not ongoing, with very moist and 

humid conditions as dew points are near-widespread in the 70s. This 

has translated to instability values (MLCAPE) of 1000-2500 J/kg over 

the area as of midday with soundings showing robust ECAPE values as 

we get into later this afternoon as well. Wind shear over much of 

central to southern Iowa remains weaker, but over north central into 

far northern Iowa bulk wind shear is much better, 30-40 knots. The 

farther north is also where LCLs are lowest and is generally where 

the better tornado environment exists, but is also highly 

conditional with rain ongoing over that same environment as of 

midday. The triple point between the fronts and surface low will

remain a foci for any potential more discrete storms where the 

tornado potential would be highest with initial storm 

development given the low level CAPE and stretching potential in

that vicinity. The caveat is how this environment recovers 

given the activity ongoing around midday. Further south along 

the front, generally expecting more linear convection with more 

broken storms the farthest south you go given the very weak 

shear. For portions of central into northern Iowa, storms along 

the line may pose a damaging wind threat, though will monitor 

for any potential spin ups as well the further north you go 

where the more favorable (though conditional) tornado 

environment exists. Not really expecting much in the way of hail

given the overall environment, but some small, to maybe 

isolated marginally severe hail could be possible if a more 

robust storm is able to develop. Overall, storms are expected to

develop in western Iowa and track east to southeast with time 

through the area, but CAMs are not necessarily capturing current

trends well so confidence is decreased in how convection plays 

out through the afternoon. Besides the conditional tornado 

threat north, and wind threat with the line, will also continue 

to monitor our hydro situation as the environment remains 

favorable for efficient rainfall, as it has the last several 

days. Continue to expect 1-3" with localized higher 3"+ amounts,

though again midday activity may affect how the rest of the 

afternoon/evening progress. 



By late tonight, storms will have cleared the area with a surface 

ridge moving over on Friday. This will bring a much-needed quiet day 

in terms of weather back to the area. Waves moving through our 

otherwise upper zonal flow will bring precipitation chances back to 

the forecast at times later in the weekend (Saturday night into 

Sunday) and again at times next week. Will continue to monitor the 

threat for any severe weather with uncertainty remaining on where 

storms may track into Sunday. Otherwise, temperatures remain warm in 

the 80s to 90s. 



&&



.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...

Issued at 1258 PM CDT Thu Jun 26 2025



Thunderstorms developed over central and western Iowa early 

this afternoon ahead of strengthening low pressure centered over

eastern Nebraska. Expect the individual thunderstorms to move 

generally north-northeastward as the line advances east through 

this evening. Hail and gusty winds are possible at the terminals

as storms pass. Look for IFR ceilings after storms depart 

tonight through late morning Friday.



&&



.HYDROLOGY...

Issued at 109 PM CDT Thu Jun 26 2025



One final round of heavy rainfall and possible flash flooding is 

expected today before at least a short break in precipitation on 

Friday. However, as water is routed through the basins and river 

systems, river flooding concerns will persist well into next week.



A broken line of storms is expected to develop along a cold front 

this afternoon and move from west to east across much of the CWA 

into this evening. As in past days, robust moisture content, high 

freezing levels and ample instability will again lead to efficient 

rain rates. However, this line of storms should be progressive, 

moving eastward around 30 mph. Many of the global models and CAMs 

are indicating widespread 1-2" rainfall amounts, but the progressive 

nature of the storms should prevent rainfall amounts from getting 

out of hand. The 26/12Z HREF 24hr PMM valid from 12z Thu to 12z

Fri shows this nicely, with only sporadic amounts over 3" 

indicated.



Flash flooding is a concern with the rainfall this afternoon into 

tonight however for now we have opted to not issue a flood watch for 

flash flooding because we think the current flash flood guidance 

(FFG) across our CWA is a little too low. Historically the FFG 

starts having a tougher time capturing reality in our region during 

this time of year, due to ag crops taking off in their growth. That 

issue is admittedly tempered with the recent heavy rainfall, however 

we still think the FFG is running a little low. Although some 

isolated flash flooding is possible, at this time we do not believe 

the flash flooding will become scattered (i.e., rise to the level of 

needing a watch). If the storms this afternoon and evening do more 

training than we presently expect, though, then the flash flood risk 

would increase.



In terms of river flooding, we have returned to 24 hrs of QPF in our 

river forecasts. The river forecast updates today do not have any 

significant changes aside from some ups and downs within the same 

category. The main reasons for the forecast changes are mainly QPE 

vs QPF changes from last night was well as shifting of the QPF 

locations for today. It should also be noted that for many locations 

where action stage is forecast, those forecast crests are near flood 

stage.



Due to increased confidence in the river flooding occurring, we have 

issued river flood watches for those locations where river flooding 

is forecast. The larger streams of most concern presently include 

the Cedar, Winnebago and Raccoon Rivers. For some locations, the 

elevated stages and river flooding is expected to continue well into 

next week.



Additional rainfall is in the forecast for the Sunday timeframe. 

This rainfall may be locally heavy and may impact area rivers. 

Depending on the location of the rainfall, this rainfall has the 

potential to result in quicker rises, slightly higher crests or 

slower falls after the crests.



&&



.DMX WATCHES/WARNINGS/ADVISORIES...

None.



&&



$$



DISCUSSION...05

AVIATION...DLH

HYDROLOGY...05/Zogg

