580
FXUS63 KDVN 142337
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
637 PM CDT Tue Apr 14 2026

.KEY MESSAGES...

- Strong to severe storms are likely (some significant severe
  possible) through the evening, with highest confidence in
  coverage along the Highway 20 corridor and lower confidence on
  the southern extent. We have an Enhanced (level 3/5) Risk for
  Severe Weather for our north, and Slight Risk (level 2/5)
  south.

- Widespread showers and storms are expected Wednesday, with
  multiple rounds possible. Severe weather will be possible
  again, especially in the afternoon and evening. SPC
  highlighted the whole area in a Slight Risk (level 2/5) for
  severe weather.

- A stronger surface low and cold front will work through the
  region on Friday, bringing along another potential bout of
  severe weather. SPC currently has much of our area in an
  Enhanced Risk (level 3/5) for severe weather.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 130 PM CDT Tue Apr 14 2026

An active forecast lies ahead, with current SPC outlooks
highlighting areas along/north of Interstate 80 in an Enhanced
(level 3/5) Risk for severe weather, with a Slight Risk (level
2/5) south. Features that we are watching as potential points
for convective initiation will be subtle outflow boundaries over
the area, resulting from overnight convection. Also, we will
have a stationary boundary draped over/near our northern
counties along Highway 20. This stationary boundary will be the
area of most concern, as it will provide the necessary surface
forcing for convective initiation. Further, we will see the LLJ
increase in magnitude later this afternoon and through the
evening, converging near that boundary. Thus, there will be
plenty of forcing in our north for thunderstorm potential. We
are looking at the potential for discrete supercell storms,
where coverage may increase in the evening hours owing to the
strengthening LLJ. Below, we will dive into timing and
environmental details.

The main forecast challenge lies with the location and timing of
convection, owing to the cap in place over the area. Best chances to
see storms this afternoon/evening will be along and north of the
Highway 20 corridor, where we will see the best forcing to overcome
the cap. Although, our whole outlook is highlighted for severe
weather for a reason. Even though areas south of the Highway 20
corridor are capped, there are ways in which we can break through
that cap. Looking at 12z CAMs, the cap does seem to be a little
weaker than initially forecast, where some CAMs are starting to hint
at late afternoon storms developing farther south than the Highway
20 corridor. Further, the latest runs of the HRRR and other high-res
CAMs are starting to indicate more coverage of potential supercells,
especially closer to the I-80 corridor. This is generally showing
the possibility of a broken line of supercells moving west to east
from mid-afternoon and through the evening. Thus, mesoscale analysis
through the afternoon will be crucial, closely monitoring the extent
of surface heating, moisture, along with any sources of mesoscale
lift. As was mentioned, an outflow boundary from the morning
convection can be in play. This has generally set up along the
Interstate 80 corridor this morning, which may be a potential source
of forcing necessary. This feature has become more diffuse, but
still may serve as a point for initiation, especially with a
strengthening LLJ. Timing wise, we are generally looking at the
potential for storms to develop as early as 3PM and the severe
threat lasting until around 10PM. Storms are expected to move west-
east through the evening.

Now, let`s dive into the environment that we have in place. As was
mentioned, initiation will largely be conditional on surface
forcing, with best forcing in our north along the stationary front.
Along and south of that boundary, the open warm sector is primed for
severe convection, with the cap being the limiting factor. We will
see deep layer shear around 45-55 KTs. This will couple with
instability around 2500-3500+ CAPE, favorable for organized
strong/severe convection. The environment is favoring supercell
thunderstorms as the main convective mode. The decreased upper level
support should help keep these more discrete at least through the
afternoon, with a strengthening LLJ late in the afternoon increasing
coverage. This CAPE profile is also quite large in the hail growth
layer, with midlevel lapse rates of 7.5-8.5 C/km favoring large hail
potential, with some very large hail possible. This increased hail
potential has been noted by the SPC. Otherwise, while the deep layer
shear is moderate-high, much of this will be seen in the lowest 3km,
where the best curvature in model hodographs are seen. Thus, strong
LLVL shear will also be favorable for tornadoes as well, some of
which could be stronger and longer lived. In the end, all hazards
are in play, with hail and tornadoes being the primary threat.

A quick look at our 18z sounding would indicate higher instability
is in place, with CAPE around 4000+, along with shear nearing 50
KTs. Thus, a supercell environment is in place. Along with that, our
lapse rates are around 9.5 just above the cap, which is more than
favorable for severe hail, some of which may be significantly
severe. Now, as was forecast, a cap does remain in place. Although,
it is not a strong cap, with CIN sitting around -50. Any further
heating and mesoscale forcing should be able to overcome this cap.
This has been hinted in latest runs in CAMs, showing an increased
coverage of storms later this afternoon and evening.

Tonight, we will continue to see the potential for showers/storms as
the LLJ remains overhead and better forcing aloft moves in. Cloud
cover will remain through the night, moderating temperatures in the
60s. While the overall severe threat will be lower overnight, some
guidance hints at some wind/hail potential, but confidence is low.

Tomorrow, we will see another chance for severe weather, with a
Slight Risk (level 2/5) for the whole area. A similar
environment will be in place tomorrow, but a little less on the
instability owing to more cloud cover. Although, it will remain
sufficient for convection. The main difference tomorrow will be
the surface low and associated cold front passing through. Thus,
plenty of surface forcing and better upper level support moving
in. With such forcing in play, we are expecting more coverage
of storms, especially in the afternoon and evening hours. Storm
mode looks to be mixed, with initial supercells eventually
growing upscale into line segments, with the main line of
convection coming with the cold front that evening/night.
Overall, with such forcing, the radar presentation tomorrow may
look quite messy through the day. Showers/Storms may be possible
through the day, but the better severe threat seems to be the
afternoon and evening. All hazards will be in play, but hail and
wind seem to be the primary threats at this time.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 130 PM CDT Tue Apr 14 2026

Upper wave that brought impacts to the area on Wednesday will have
since pushed east of the area on Thursday, with weak upper ridging
moving in. With this, we will see a surface high pass through the
area, resulting in a quiet weather day. We should be geared to have
quite a pleasant day, with temperatures increasing into the 70s, a
westerly breeze, and decreasing cloud cover.

This break of quiet weather will be short-lived though, as Thursday
night into Friday, strong southwesterly flow sets up ahead of the
next shortwave trough. Strong vort max will approach the area Friday
afternoon and evening, with a surface low dragging a seasonally
strong cold front through the area. Thus, plenty of forcing in play
for storms. A brief look at the environment would indicate
sufficient shear and instability in place ahead of the front,
favorable for organized convection, some of which could be strong to
severe. Environment would be favorable for supercell thunderstorms
being the initial storm mode, which may be discrete. Although, as
the day goes on and the strongest part of the LLJ core moves in
ahead of the cold front, upscale growth is likely. This would lead
to a QLCS event for the late afternoon and evening on Friday, where
all hazards will be possible. Will refrain from further details, as
much can change between now and then. SPC also has their eyes on
this system, highlighting much of our area in a 15% or 30% risk for
severe weather, which equates to a Slight/Enhanced Risk (level 2/3
of 5) for severe weather.

A look ahead to the upcoming weekend shows a drier pattern
developing for Saturday and Sunday as upper-level ridging develops
to the west. A cold front should bring notably cooler and more
seasonal temperatures to the area on the heels of strong, gusty
northwest winds. This could bring our first bout of frost/freeze
conditions during this growing season, possibly Saturday night,
though winds may stay up to limit this to just a freeze
potential for parts of the area, while Sunday night could bring
about more widespread freeze and frost with lighter winds as
high pressure builds in.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 629 PM CDT Tue Apr 14 2026

Convection across eastern Iowa will move into southern Wisconsin
by 03z/15 followed by a brief lull. After 06z/15 the next round
of convection will develop/move into eastern Iowa and eventually
northern Illinois through 14z/15. A period of LLWS will be
observed along/east of the Mississippi river through 06z/15.
Potential for IFR conditions with any convection. After 15z/15
quiet conditions with diurnal convection developing after 18z/15
across mainly northern Illinois but also into eastern Iowa.

&&

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

&&

$$

SHORT TERM...Gunkel
LONG TERM...Gunkel/McClure
AVIATION...08

NWS DVN Office Area Forecast Discussion