625
FXUS63 KDVN 280549
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1249 AM CDT Sun Apr 28 2024

.KEY MESSAGES...

- Active period continues into the overnight and also into
  Sunday.

- Flash flooding remains a concern overnight into Sunday morning
  for areas that will have received repeated rounds of storms
  south of I-80, and this is where a Flood Watch continues.

- Scattered severe weather remains possible, mainly well south
  of I-80 overnight, but also into Sunday although prior
  convection may have an impact on the magnitude/timing/location
  of severe weather Sunday PM.

- Unsettled weather continues through next week, with periodic rain
  chances.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 140 PM CDT Sat Apr 27 2024

Late morning surface analysis shows a surface low centered
across eastern Minnesota and western Wisconsin, with a cold
front draped to its south across east central Iowa and northwest
Missouri. Off to our southwest, another surface low with a
warm front and dry line was centered over the Oklahoma
panhandle, with storms ongoing along this and ahead of a
shortwave in the same location. This shortwave will progress
northeast over the next few hours, and will be the driver of our
weather over the next couple of hours.

The overall forecast remains on track for the area, with shower and
storm coverage expected to increase over the next few hours. The
first round should be focused along the stalled cold front draped
across east central Iowa as we destabilize and reach our
convective temperature in the upper 70s. Latest CAMs focus the
threat mainly along and northwest of the HWY 151 corridor. Ample
0-6km shear and steep mid-level lapse rates pushing CAPEs
around 1000-2000 J/kg may lead to storms capable of large hail
initially.

The second round of storms will come this evening as the
aforementioned shortwave rides the front and drives additional
lift across the area. A renewed LLJ will also ensure ample lift
and increased vertical shear. There remains some uncertainty as
to where storms will initiate and track, which is likely tied to
early PM convection and how much it stabilizes that warm sector
air in eastern Iowa. Regardless, HREF ensembles continue to
paint areas mainly south of Interstate 80 with high POPs. Severe
storms will also be possible with mainly a large hail and
damaging wind threat with near straight hodographs and cold pool
dynamics in play. While low, can`t rule out a tornado threat in
the QLCS and with any remnant boundaries from early PM storms.
Look for this threat to wane by midnight, with concerns turning
more towards a heavy rain/flash flood risk.

Speaking of which, we will need to keep a close eye on flash
flooding potential with these storms. LLJ will advect in a rather
robust PWAT feed across the region with values approaching 1.75" by
midnight. Where storms do train, latest CAMs show QPF by Sunday
morning approaching 2-4 inches. This looks to be favored mainly
in southeast Iowa, west central Illinois and northeast Missouri,
where a Flood Watch is now in effect through Sunday morning.

Heading into Sunday, scattered showers and storms will persist
through the morning and early afternoon, with a renewed round of
more widespread linear showers and storms expected by the
evening ahead of another robust shortwave ejecting out of the
Rockies. There is potential for this activity to become severe,
with the Storm Predication Center advertising a Level 1 to 2
risk for the area. The primary threats with storms will be
damaging winds and large hail, with a secondary tornado threat
if low-level shear can materialize.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 140 PM CDT Sat Apr 27 2024

Post cold front passage, we will be in for a dry start to the
week with high pressure moving across the central Plains and
mid-Mississippi River Valley. By mid to late week, a renewed
round of showers and storms is expected for the area as a trough
in the Rockies ejects several shortwaves across the Plains and
Midwest.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1243 AM CDT Sun Apr 28 2024

Showers and storms will continue through the night and Sunday,
resulting in periods of MVFR to IFR conditions. Some locations
are currently seeing VFR, but we will see these conditions
frequently changing through the night. In heavier showers and
storms, cigs may drop between 1000-3000 ft, with vis between 3-5
SM. Winds will remain light and out of the southeast tonight,
increasing through the morning. After 12z, cigs are forecast to
plummet to below 1000 ft at CID and DBQ. Currently, we are
forecasting cigs between 700-900 ft, but some brief periods
lower than that are possible.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch until 10 AM CDT this morning for IAZ087>089-098-
     099.
IL...Flood Watch until 10 AM CDT this morning for ILZ025-026-034-
     035.
MO...Flood Watch until 10 AM CDT this morning for MOZ009-010.

&&

$$

SHORT TERM...Friedlein
LONG TERM...Speck
AVIATION...Gunkel