National Weather Service Raw Text Product

812 
FXUS63 KDMX 030447
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1147 PM CDT Sat Jul 2 2022

...Updated for the 06z Aviation Discussion...

.DISCUSSION.../Tonight through Saturday/
Issued at 406 PM CDT Sat Jul 2 2022

Key Messages:
-Quiet and Dry through Sunday 
-Shower and Storm Chances Starting Early Monday Morning
-Warm Temperatures Possible Monday and Tuesday

Convection today has mostly split the state to the north and south, 
with only a few areas near the northern and southern borders 
experiencing any precipitation. For most of central Iowa, 
Independence Day weekend has started out fairly quiet and looks to 
remain that way through most of the day Sunday as guidance continues 
to keep the area dry through the weekend. 

Our quiet weekend comes to an end late Sunday night as a shortwave 
propagates through the upper level ridge to our west and develops a 
Mesoscale Convective System (MCS) across NE and SD. Models continue 
to struggle with the location of this system and seem to more 
frequently highlight areas north of highway 30 as the most favorable 
path for heavy precipitation. However, early CAM guidance as well as 
the 12z GFS and NAM imply that storms could stretch as far as the 
southern border. Due to this large spread in location, have decided 
to still focus higher pops to the north but also extend lower pops 
to the south. Also decided to slow the precip down a bit, with most 
guidance suggesting convection wont make it into central Iowa until 
around 06z and after on Monday. 

Severe weather risk for this system looks low, with the more 
favorable environment further to the west with the initial 
convection in NE and SD. Damaging winds associated with the 
development of a strong cold pool will likely be the greatest severe 
risk. However, the approaching air mass has no lack of moisture, 
with PWATs over 2 inches and warm cloud depths in the 14k to 15k ft 
range. This bodes well for locally heavy rainfall, but shouldn't 
create much impact in way of flooding with mostly dry soils across 
the state and diminishing rain chances prior to this system. 

Following the initial MCS Monday, more uncertainty continues in the 
forecast. Warm air associated with the approaching ridge could push 
heat indices into advisory level across the southern half of the 
area on Monday and Tuesday. However, longevity of Monday's system, 
as well as potential convective redevelopment Monday night into 
Tuesday morning, will have a lot of control over how high 
temperatures can get. If cloud cover is unable to clear due to 
storms Monday and Tuesday, we may struggle to reach the highs 
forecasted. On the other hand, if the warm air at the lower levels 
can hold off the convection Monday night through Tuesday morning, it 
is likely that an advisory will be needed Tuesday. The NBM currently 
favors the warmer temperatures, but the spread amongst model 
guidance is large, so will continue to monitor in future forecasts. 
Following Tuesday, active weather and predominantly warm to seasonal 
temperatures continue through the rest of the forecast period.

&&

.AVIATION.../For the 06Z TAFS through 06Z Sunday night/
Issued at 1137 PM CDT Sat Jul 2 2022

VFR conditions are expected this period. Clear skies and light
southeast winds are expected overnight. Will likely see diurnal 
cumulus after 17Z Sunday along with breezy SE winds. There is 
potential for thunderstorms Sunday night but the latest guidance 
indicates impacts will be after this period. 

&&

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

$$

DISCUSSION...Dodson/Krull
AVIATION...Fowle