FXUS63 KDMX 272345

AFDDMX



Area Forecast Discussion

National Weather Service Des Moines IA

645 PM CDT Mon Oct 27 2025



 ...Updated for the 00z Aviation Discussion...



.KEY MESSAGES...



- Definite (90-100%) widespread rain for much of Tuesday and

  Tuesday night. Thunder chances low (<10%). Rainfall amounts up

  to 1.5" possible, though most areas will receive around an

  inch.



- Windy conditions in Western Iowa Tuesday night/Wednesday

  morning. 40mph wind gusts possible (75% confidence).



- Next best chance for precipitation Friday night.



&&



.DISCUSSION...

Issued at 244 PM CDT Mon Oct 27 2025



A strong Pacific jet continues to move in today, bringing in Pacific 

moisture across the Rockies and into the Plains (seen best in water 

vapor imagery). Moisture is rounding the trough base and ejecting 

northeastward, following a closed upper low embedded in the main 

trough. A coastal trough will dig into the Pacific northwest, 

locking the inland jet into a NW-to-SE orientation. Meanwhile, a

stubborn high pressure region residing over the Great Lakes and

into Ontario/Quebec will lock the northern stream pattern into 

place. This will give time for the upper jet to enhance the 

trough at its base, developing a closed low in the next 36 

hours. It will affect Iowa during that intensification process, 

but the better height falls as well as the more thorough 

saturation will be kept south of the state. We've seen a lag in 

low level moisture due to the closed low that has been sitting 

over the Ozarks/Mid South and that will remain the case as the 

same system pulls most of the Gulf moisture with it into the 

coastal southeast. Dry air in our area continues to fight off 

boundary layer saturation thanks to the easterly winds off of 

the aforementioned high.



Despite the factors inhibiting rainfall amounts, the duration of 

rainfall from the slowed pattern will keep 1 inch QPF in the 

forecast for much of the area. Thunder chances remain very low 

(<10%) for the area, evidenced by CAPE < 100J/kg and little in the 

way of negative theta-e lapse rates. High likelihood of rain for 

much of Tuesday and Tuesday night (90-100%) with widespread coverage 

of rain expected. Hourly rainfall rates will remain under a half 

inch per hour due to the lack of convective processes.



As the low closes off and deepens, its passage will become 

increasingly dynamic. The immediate aftereffects will be winds on 

Wednesday on the western half of the inverted trough. 925mb winds 

over 40kts will be found over portions of southwest Iowa, closest to 

the MO River valley. CAA and 5mb height rises will persist after 

midnight Tuesday night and before noon Wednesday. Cloud cover will 

insulate temperatures overnight, keeping mixing in play without a 

nocturnal inversion. The favorable wind setup will migrate over 

southern Iowa Wednesday morning. Current thinking is wind gusts up 

to 40mph will be possible in the far western and southern parts of 

the state (75% confidence) which warranted a boost in winds from NBM.



In the extended, highs will be in the 50s. The lows will begin to 

consistently settle in the 30s once skies can clear. Northwest flow 

remains across the region through the weekend, leaving the region 

susceptible to additional waves propagating in from Canada. The

first of which will be late Friday. Moisture return won't 

recover by this point, so precipitation amounts will be light.



&&



.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...

Issued at 634 PM CDT Mon Oct 27 2025



VFR conditions prevail over all sites, but stratus has begun to

work it's way into the state ahead of the approaching system and

eventual rainfall. Much of the MVFR ceilings are away from TAF

sites in the southwest portion of the state. The current 

steering flow would suggest it should stay that way until the 

larger scale system (and associated rainfall) begins to move 

farther east into the state through Tuesday morning. Rain will 

initially begin fairly light and sporadic in the morning, then 

becoming more persistent into the afternoon and evening hours. 

Ceilings will match this, steadily lowering as heavier rain 

makes it's way eastward. Current TAFs have mostly MVFR ceilings 

with the rain tomorrow, but a stretch of IFR conditions is 

possible with the heaviest part of the system toward the end of

the current TAF period. Therefore, will be evaluating the 

need for IFR mention in TAFs for Tuesday afternoon/evening in 

future issuances.



&&



.DMX WATCHES/WARNINGS/ADVISORIES...

None.



&&



$$



DISCUSSION...Jimenez

AVIATION...Dodson