443 
FXUS63 KDMX 042000
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
300 PM CDT Mon Sep 4 2023

.DISCUSSION.../Tonight through Monday/
Issued at 300 PM CDT Mon Sep 4 2023

Key Messages:

- One more hot day on Tuesday with heat index values of 95 to 
  slightly over 100. 
- A few storms later Tuesday afternoon/evening with a few stronger
  storms.
- Cooler to end the week with relatively pleasant temperatures. 

The higher dewpoints from earlier today have slowly decreased into 
this afternoon as mixing has deepened.  Heat index values are 
topping out from 95 to 100 once again with a robust south breeze 
over the state.  The decent south flow persists into tonight ahead 
of a shortwave passing through the northern Plains.  This keeps 
overnight temperatures quite warm in the 70s for much of the area 
along with higher dewpoints.  Larger scale models and CAMs have both 
indicated the possibility for isolated elevated storms moving into 
the south later tonight on strong low level flow and have continued 
the low PoPs for this potential.  

The shortwave continue to press east on Tuesday arriving in 
Minnesota by evening. Isolated morning showers/storms may linger in 
the southeast, otherwise Iowa remains in the warm sector for another 
day with breezy south winds and one more day with widespread highs 
in the 90s. Given the higher dewpoints ahead of the system, heat 
index values are forecast to be slightly higher than today with 
values mostly from 95 to 102 across the area. The surface boundary 
approaches northwest Iowa by afternoon and slides into the forecast 
area by early evening.  Decent instability is expected ahead of the 
front across the area, but a robust cap remains in place for much of 
the day.  This cap begins to weaken later in the day as kinematics 
from the upper system allow for erosion.  Most model output suggests 
convection remains isolated in Iowa during the late afternoon to 
evening ahead of the front with the more widespread activity farther 
north where better forcing leads to complete cap erosion.  Storms 
that do develop in our area may be quite strong given the 
instability and may produce some near severe wind gusts given the 
inverted-v nature of soundings.  Hail may also occur given the 
decent instability as well.  

The bulk of any threat is expected to diminish with the passage of 
the front by midnight on Tuesday night with cooler air arriving into 
Wednesday and Thursday.  A weak shortwave passing through the area 
late Thursday into early Friday may produce a few showers in 
southwest Iowa, but much of the area remains tranquil into Saturday 
with pleasant temperatures/humidity. 

&&

.AVIATION.../For the 18Z TAFS through 18Z Tuesday afternoon/
Issued at 1243 PM CDT Mon Sep 4 2023

Widespread VFR conditions with breezy south to southwest winds for
much of the forecast. Visibilities remain unrestricted with any
ceilings at or above 20kft.  

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE. 

&&

$$

DISCUSSION...Cogil
AVIATION...Cogil