000
FXUS63 KDVN 261009
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
509 AM CDT Fri Apr 26 2024

...Updated for 12z Aviation...

.KEY MESSAGES...

- Active pattern through the weekend with rounds of
  showers/storms with areas of heavy rainfall (1-3+
  inches).

- 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 308 AM CDT Fri Apr 26 2024

Active convection was occurring across Nebraska early
this morning ahead of a lifting wave from Colorado.
This wave will eject northeastward into the Upper
Midwest over the next 24+ hours taking on a negative
tilt, while at the surface a warm front will
eventually lift northward through the region later
tonight. Until doing so, we`ll see rounds of showers
develop/lift northward across the region today into
tonight in the low level warm advection, with one
main round evolving from south to north 12z-20z
then a decrease before more scattered activity tonight
between the warm front and nocturnal LLJ which could
result in a few stronger storms tonight. Proxy
forecast soundings show increasing surface inhibition
(CIN) with fairly tall, skinny CAPE profiles and so
marginal severe hail would appear to be the primary
threat. However, remnant surface based convection
that is anticipated to develop to our west this
afternoon could move and/or further develop into
portions of the cwa mainly west/south later this
evening/tonight with aid of glancing ascent from the
lifting shortwave. This activity tonight may also
be accompanied by a marginally severe gusty wind
threat, as negative 0-4km theta-e lapse rates develop
post-warm front.

Highs today will show a wide range, from the lower to
mid 50s north, to the mid 60s far south as the warm
approaches with winds staying brisk/gusty 20-35 mph.

Lows tonight will be steady to rising with the passage
of the warm front.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 308 AM CDT Fri Apr 26 2024

Saturday, a brief lull in convection is anticipated as
weak amplification of mid level ridging occurs in
the wake of the departing shortwave and ahead of the
downstream upper low over the Four Corners region.
This bout of weak subsidence may allow for at least
partial sunshine. This combined with southerly winds
in the warm sector will push highs well into the 70s and
lower 80s. Dew points climbing into the 60s will make
for a more humid feel. The combination will yield MUCAPE
in excess of 1500+ j/kg, while deep layer shear will
be in excess of 35-40 kts. This would support the potential
for organized severe convection, but the challenge is
with the trigger which is initially lacking and barring
no boundaries for PM development we may be waiting
until evening for more robust and better storm coverage
to occur with the increasing nocturnal LLJ. This would
bring a mostly large hail and damaging wind threat.

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 (Friday 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 /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 510 AM CDT Fri Apr 26 2024

Warm advection band of induced showers and a few storms will
lift northward through the terminals from south to
north between 12z and 20z, which was handled with a period
of prevailing SHRA. Thunder mention was omitted due to lower
confidence with limited instability. Conditions will drop
generally into MVFR during the precipitation, then after it
moves through conditions will lower into IFR ahead of a lifting
warm front. Additional showers and storms are possible tonight
that is handled with PROB30 mention. Some improvement to
MVFR is possible after the warm front passes by 06z. E/SE
winds will remain gusty 20-30 kt today. The winds will turn
from the SSW with the passage of the warm front tonight and
remain gusty at 20+ kt. LLWS is possible tonight as the LLJ
strengthens.

&&

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

&&

$$

SHORT TERM...McClure
LONG TERM...McClure
AVIATION...McClure