FXUS63 KDVN 270008
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
708 PM CDT Fri Apr 26 2024

.KEY MESSAGES...

- Active pattern through the weekend with several rounds of 
  showers and thunderstorms with an additional 1-3+ inches of 
  rain likely.

- Flash Flooding is a concern for areas that receive repeated
  rounds of thunderstorms Saturday night. Confidence remains low
  on the placement of the heaviest rainfall.
 
- Severe storm risk exists through the weekend, but there 
  remains uncertainty as prior rounds of convection may impact 
  magnitude/timing/location of any severe weather threat.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 255 PM CDT Fri Apr 26 2024

A large area of light to moderate rain will continue to work 
through the region from SW to NE into the late afternoon hours.
There have been embedded thunderstorms at times mainly 
along/south of I-80, but this heavier activity has diminished 
significantly over the past few hours. On the northern edge of 
the rain shield, across portions of eastern Iowa into northwest
Illinois, we had a period of strong SE winds during the mid to 
late morning with many locations peaking between 40 - 50 mph. 
Cedar Rapids was the outlier, reaching 65 mph! These unexpected 
strong winds occurred in a region of subsidence sufficient to 
mix down momentum tied to a robust southeasterly LLJ. Still 
gusty SE to S winds will continue through this evening into 
tonight, but likely on the order of 30 to 40 mph for peak gusts.

Persistent elevated warm air advection north of a warm front
draped across northern Missouri will likely lead to another 
round of scattered showers and isolated storms developing this 
evening into early tonight. However, coverage with this round 
does not look to be quite as widespread as earlier today. Any 
threat for severe weather remains low as the better moisture is 
forecast to hold south across central Missouri and the stronger 
dynamics to the west near a surface low over western/central 
Iowa. By late tonight, expect mostly dry conditions with breezy 
S to SSW winds.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 255 PM CDT Fri Apr 26 2024

Saturday: 

A lull in convection is anticipated through much of the day as 
low pressure shifts toward Lake Superior with the attendant 
cold front/low-level boundary expected to hold to our west 
across central Iowa. Gusty southerly winds developing tonight 
(Friday night) will last through the day on Saturday and advect 
a warm and humid air mass into the region with highs in the 
upper 70s to low 80s; dewpoints rising into the 60s will make 
it feel rather humid. There is a low chance for isolated storms 
during the early/mid afternoon period; however, confidence is 
low on activity developing that early. The better chance for 
storms is Saturday evening into the nighttime as a mid-level 
wave approaches from the southwest. Confidence remains low on 
the exact placement for this period, but the environment will be
supportive of strong to severe storms with sufficient MUCAPE 
(2000+ J/kg) and deep layer shear (35+ kts).

The primary threat into Saturday night may transition to heavy 
rainfall and localized flash flooding with high PWATs up to 
1.5 inches. There is also the potential for repeated rounds of 
storms as mean 850-300mb flow steers the convection in a SW to 
NE trajectory, as a new area of low pressure organizes over the
Central Plains. The 12Z HREF that grouped several of the CAMs 
output together shows localized amounts over 3 inches in our 
CWA. A Flood Watch may be needed eventually due to the potential
for an additional 1-3+ inches of rainfall through the weekend. 
Held off for now because of the aforementioned low confidence on
placement of the heaviest rainfall. A look at the latest 1 - 3 
hr flash flood guidance shows values approximately in the 1.5 to
3 inch range.

Sunday: The upper low will lift out and take a similar path to 
the previous shortwave from Colorado into the Upper Midwest by 
Monday morning. We'll see widespread showers and storms occur 
Sunday into Sunday night with the warm, moist advection and 
increasing synoptic scale lift then followed by the cold frontal
passage Sunday night into Monday AM. The widespread 
precipitation and cloud cover brings about uncertainty as to the
severe weather potential and magnitude/location, etc. 

Overall, we have 2 surges of PWATs of around 1.5 inches 
the first today into this evening and the second 
Saturday night through Sunday. Those would be the 
periods favored for locally heavy rainfall concerns.
Between both events many areas will see widespread 1 
inch or more (today through Sunday) with areas/swaths of 2 - 4+
inches where rounds of convection occur that will bring a risk 
of isolated flash flooding. 

In the wake of the cold front, the start of next week 
looks to turn quieter and drier. However, there's signs
that an active pattern will return mid to late next week
with the flow becoming semi-zonal shuttling impulses 
across the Midwest from the Pacific along a meandering 
mid level baroclinic zone.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 638 PM CDT Fri Apr 26 2024

Clouds linger across the area this evening with ceilings ranging
from 500ft at KDBQ to 5500ft at KBRL. Showers and potentially
thunderstorm are forecast to redevelop by 2 to 3 UTC and
continue through the overnight but confidence is lower in that
occurring at this time so they were left out of the TAFs
everywhere except CID. Other locations may see drizzle develop  
with MVFR visibilities instead of rain. Look for precipitation 
to end from 8 to 12 UTC across the area and ceilings to gradually
lift from 12 to 18 UTC on Saturday with potential VFR 
conditions by late afternoon area wide. 

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

$$

SHORT TERM...Uttech
LONG TERM...McClure/Uttech
AVIATION...Cousins