553
FXUS63 KDVN 060530
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1230 AM CDT Mon May 6 2024

.KEY MESSAGES...

- The upper level pattern remains active, with periodic chances
  for rain through next week.

- A potent system arriving Monday night into Tuesday will bring
  a risk for strong to severe thunderstorms.

- Scattered storms remain possible on Wednesday before
  temperatures cool off late in the week.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 230 PM CDT Sun May 5 2024

This Evening and Tonight: Quiet weather is expected with high
pressure overhead leading to light winds, dry conditions, and
lows in the 40s to lower 50s.

Monday Morning and Afternoon: The area of high pressure will
begin to shift to the east into the Great Lakes region, setting
up a return flow locally and increasing low-level moisture. It
looks to be another really nice day with highs in the lower 70s
far north to mid/upper 70s central and south.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 230 PM CDT Sun May 5 2024

Monday Night into Early Tuesday Morning

Widespread showers and storms are likely during this period.
Latest NBM rain chances are 70-100%. Models are in agreement on
an organized QLCS moving through central Iowa and north-
central Missouri during the evening to early nighttime hours,
before reaching our far western/southwest outlook area near or
after midnight. The expectation is for this system to gradually
weaken as it pushes eastward into the forecast area as it runs
into a more stable air mass. However, it could still be strong
to severe across the western to central portions of the area
where there is an overlap between sufficient shear and
instability. Moderate low-level shear (~30 kts in the 0-3 km
layer) will help to maintain a balance between the convection
and its associated gust front.

SPC has Scotland County, MO in a Slight Risk (level 2 of 5) for
severe storms with a Marginal Risk to the east and northeast
(level 1 of 5). The primary threats are damaging winds with a
low risk for an isolated tornado (2% within 25 miles of a
point).

This convection will affect most of the area between midnight
and 10 AM Monday night/Tuesday AM. PWAT values near 1.25" are
forecast with strong WAA forcing. Thus, rainfall on the order
of 0.50" to 1" 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 Tue AM.

Tuesday and Wednesday

Nearly all deterministic models suggest that the surface
boundary for active storms will be south of the area Tuesday,
with additional placement of lower coverage showers/storms
closer to the low center near and north of the area. A SPC
forecast of Marginal (level 1 of 5) will be in place over our
Illinois counties. Scattered storm chances continue again on
Wednesday as a warm front lifts into the southern portion of
the outlook area. Confidence is low on the details this far out,
but SPC has a Slight Risk for severe storms across the far
south.

By late in the week, 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 TUESDAY/...
Issued at 1221 AM CDT Mon May 6 2024

Another very quiet VFR period of aviation is expected through
Monday evening, with the high clouds or clear skies and light
southeast winds expected. An increase in speeds is anticipated
Monday evening, with some 14 to 25 kts southeast winds
developing over eastern Iowa as a line of showers and storms
begins to approach the area. These storms are expected to move
through all terminal sites in the 07z to 12Z period Tuesday.
Early indications suggest they will be decreasing in intensity
as they move through.

&&

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

&&

$$

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