420
FXUS63 KDVN 201143
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
643 AM CDT Sun Apr 20 2025

.KEY MESSAGES...

- A strong storm system will impact the area today and tonight
  bringing widespread rainfall and possibly a few severe storms
  south of I-80.

- Temperature warming into the 70s this upcoming week with
  periodic chances for showers and storms.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 315 AM CDT Sun Apr 20 2025

Models rather consistent with the storm system to impact the
area today and tonight. Noticed the rainfall amounts in the NBM
has increased to 2 inches in our western counties. SPC maintains
the SLGT and MRGL risks pretty much from yesterday.

Today and Tonight: A longwave upper-level trough is expected to
move out of the Rockies and approach our region for Easter
Sunday, becoming more negatively-tilted with time. A potent mid-
level vort max should pivot through the area, supporting large-
scale forcing for ascent. An attendant surface low pressure
system will lift northward from the southern Great Plains
towards eastern Iowa by Sunday evening. This will support
widespread rain (80-100% chance) and a few thunderstorms. The
rain will spread south to north this morning. Heavy downpours
at times will be the main story with this system, as instability
will be more limited. However, abundant moisture is expected,
with Pwat values progged around 1 to 1.5 inches, as well as
integrated water vapor transport per the ECWMF ensemble
percentiles giving values over 97% of climatology. NBM
exceedance probabilities of one inch of total rainfall for
Sunday through Sunday night range from 40 to 80% (east to west
through the outlook area), so around an inch of total rainfall
appears likely for much of the forecast area, with some spots
recieving 1.50 to 2.00 inches of rain.

Severe potential: SPC continues with a Marginal Risk (level 1
of 5) for strong to severe storms up to I-80, and a Slight Risk
(level 2 of 5) is in place along and south of Highway 34. The
Enhanced (3 of 5) is still just to the south of the forecast
area. These outlooks may be adjusted more so continue to monitor
the latest trends. The main threats as of now appear to be
damaging wind and large hail but a tornado or two is possible in
the SLGT risk area, with the greatest threat farther to our
south. CAM`s depict a broken line of thunderstorms, possibly
some severe, quickly moving northeast across the forecast area
between 5 pm and 10 pm this evening.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 315 AM CDT Sun Apr 20 2025

Monday through Saturday: the pattern remains somewhat active
despite zonal flow aloft. Periodic shortwaves will translate
through the region, which could spark off some additional
showers and storms, but exact timing and location details remain
uncertain this far out. Temperatures are expected to gradually
warm up into the 70s for much of this time-frame, cooling into
the 60s on Saturday.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 640 AM CDT Sun Apr 20 2025

Low pressure tracking out of the southern Plains will bring
widespread MVFR to IFR ceilings. Numerous showers will spread
from south to north during the morning hours with MVFR/lcl IFR
conds. There remains some uncertainty on the exact timing of a
break in the shower activity by the afternoon, around 2-4 hours
in duration, before the heaviest wave of showers and
thunderstorms moves quickly northeast across the taf sites from
late this afternoon through the evening hours. Some of these
storms could be severe, mainly south of I-80. Have also
mentioned LLWS this evening as the surface low tracks from OK
into eastern IA.

&&

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

&&

$$

SHORT TERM...Haase
LONG TERM...Haase
AVIATION...Haase