861
FXUS63 KDVN 050734
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
234 AM CDT Sun May 5 2024

.KEY MESSAGES...

- Upper level pattern remains active, with periodic chances for
  showers and storms through next week.

- A potent dynamic system arriving Monday night to Tuesday will
  bring a more significant severe threat in the region, and
  possibly our CWA.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 143 AM CDT Sun May 5 2024

Despite the cool start that looks in store this morning, today
will be a nearly ideal late spring day, with ample sunshine, dry
air, light winds, and highs in the upper 60s to lower 70s. If
you`re able, get out an enjoy this fabulous weather today!

Quiet weather looks to last through tonight and Monday morning,
as surface high pressure keeps the moisture shunted well south
of Iowa. Lows tonight will fall to the 40s again, with lower to
mid 70s expected for highs Monday. Monday will see increasing
humidity through the day, but deep moisture should not spread
into the area until Monday night. This means most all of Monday
now appears dry, with the focus for both rain and severe weather
holding closer to the Plains and Missouri Valley region.
Monday night, in a mature to decaying phase, this forcing and
deep moisture will arrived in our area.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 143 AM CDT Sun May 5 2024

Models are now showing a more consistent signal that Monday
night will be the best chance for widespread rain and
thunderstorms in the coming days. As stated in the short term, a
mature to decaying phase of MCS/QLCS should arrive from the west
during the late evening. This convection will most affect our
entire area between Midnight and 10 AM Monday night/Tuesday AM.
PWAT values over 1.25 are forecast with this strong WAA forcing.
Thus, rainfall on the order of 0.75 to 1.25 is likely where
storms maintain a mature convective signature, while lesser
totals are expected in the east 1/3 where dissipating convection
is more likely very late Monday night/Tue AM.

There will be deep layer shear around 40-50kts overnight, but
little boundary layer instability to work with. Some organized
wind threat seems possible in mature QLCS in our western areas,
but this will probably lose it`s punch as it heads east
encountering more stable air at lower levels. SPC has our
southwest in Marginal (lvl 1 of 5).

Tuesday is questionable with placement of the surface
boundaries. Nearly all deterministic models suggest that the
surface boundary for active storms will be south of the area
Tuesday, with additional placement of storms closer to the low
center located well north of the area. A SPC forecast of
Marginal (lvl 1) will be in place over our Illinois counties.

Beyond this early week busyness, all guidance suggests a broad
deep upper trof will build into the Great Lakes through the end
of the week. This will bring cooler weather, along with
frequent, somewhat diurnally driven shower and thunderstorm
chances through the end of the week. Highs in the 60s are
forecast, but pending cloud cover, we could be limited as low as
the mid 50s in this pattern. Rainfall, while not heavy, could
see daily totals of ~0.25 inch in scattered showers/storms.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1213 AM CDT Sun May 5 2024

A predominantly VFR forecast is in store the next 24 hours in
all sites, as high pressure moves over the region. Light
northwest winds and clear skies will be expected, except near
CID early today. MVFR fog remains possible at
CID early this morning, although a few models aren`t depicting
any to develop, so confidence in MVFR fog is around 50 to 70%,
which is still high enough to include in the CID TAF.

&&

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

&&

$$

SHORT TERM...Ervin
LONG TERM...Ervin
AVIATION...Ervin