textproduct: Des Moines

KEY MESSAGES

- Confidence remains high in above normal temperatures this week.

- Monitoring fog potential over melting snowpack tonight into the middle part of this week.

- Limited sunshine Wednesday and Thursday may limit the degree of warming, but still a mild Christmas. Low chances for precipitation (<15%).

DISCUSSION

Issued at 214 AM CST Mon Dec 22 2025

Early morning radar shows light returns over far northern Iowa, but no precipitation has been reported over this area with cloud bases around 9kft. There was a recent mPING near Austin, MN of freezing rain and about an hour ago Fairmont, MN near I-90 reported light rain with a 10 mile visibility so whatever may be falling is extremely light. All of this precipitation is within the strong low level warm air advection (WAA) wing and will be pushing away from our forecast area in the next few hours. Turning attention to the upper level pattern, the ridge can be seen in the plume of water vapor in GOES-East imagery arcing from California into the Montana and then downward into the western Great Lakes. This ridge will be building a bit more poleward and moving eastward through this week with the ridge axis over Iowa on Christmas Day. Confidence continues to remain very high in temperatures being above normal this week in this pattern, though how far above normal is more in question on Christmas Eve and even more so on Christmas itself. Before we get to later this week, today will have breezy winds from the south with gusts between 15 and 25 mph, which will be strongest this morning with the highest gusts in southwest Iowa. Spread in temperatures today remains tight and did increase highs upward given the WAA regime. Wet bulb temperatures should be above freezing for around 12 hours from later today into tonight and this will help to melt the snowpack over northern Iowa. Soundings show an inversion setting up and winds do lessen raising concerns for fog potential over the snowpack after midnight tonight.

Tuesday will have highs several degrees lower as high pressure passing north of the state causes northerly flow and cooler air to arrive. This will be short-lived as the next round of low level WAA surges over Iowa Tuesday night into Wednesday helping to create a low level inversion. Checking around different central Iowa locations, forecast soundings show the depth of moisture trapped beneath this inversion generally a bit less than yesterday at this time with perhaps the exception over our eastern forecast area (e.g GGI). This is where drizzle may still be possible given the weak omega and directional shear as a filament of vorticity passes over the state. Overall though, drizzle chances are looking less likely on Christmas Eve with a cloudy sky across much of Iowa. This cloud cover is looking to linger into Christmas Day, especially over northern and eastern Iowa. This is where soundings show a saturating profile that may allow for light rain later on Christmas as another round of WAA occurs ahead of a weak surface low that will move across the region Thursday night into Friday. The clouds will have an impact on temperatures with the spread between the 25th and 75th percentile growing from 5 to 9 degrees on Wednesday to 6 to 11 degrees on Thursday. Spreads do remain smaller in far southern Iowa on Thursday so temperatures may rise to near 60 degrees, but the ceiling on highs is lowering the longer the clouds linger on Thursday. In the wake of the low on Friday, winds from the northwest will usher in less warm air, but it will still be mild for late December.

While models start to diverge in their evolution of the upper air pattern next weekend, there is a general consensus that a more amplified trough sends a cold front through the state later Saturday or Sunday. There is not much agreement on whether there will be any precipitation with this, but temperatures do look to move back closer to normal and winds could be breezier on Sunday.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1109 AM CST Mon Dec 22 2025

Patchy low to mid-level clouds drift over southern, central and eastern Iowa, producing brief periods of MVFR conditions. Expectation is for this stratus to continue drifting northeastward through the afternoon, although persistent MVFR conditions are not expected. Otherwise breezy southerly winds will become lighter and westerly overnight then northerly by tomorrow morning. A low chance for fog still remains tonight, mainly over northern Iowa. However, recent guidance suggests winds may not calm enough for fog to form so have left out of TAFs with this issuance.

DMX WATCHES/WARNINGS/ADVISORIES

None.