937
FXUS63 KDVN 102338
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
638 PM CDT Fri May 10 2024

.KEY MESSAGES...

- Brief gusty winds are possible this evening with scattered
  showers behind a cold front. Thunderstorm potential is quickly
  diminishing.

- Clouds will quickly clear after 9 pm this evening, possibly
  allowing for a viewing of the northern lights.

- Warmest day in the next week will be Sunday with highs in the
  80s.

- Active long term as a series of waves makes its way through
  the area.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 224 PM CDT Fri May 10 2024

Mostly to party sunny skies were found across the area this
afternoon. Temperatures in the mid to upper 60s were found
area-wide. North of the area, another wave started moving into
MN and N WI. A cold front with this wave was being pulled south
into the area. This will serve as the main forecast problem in
the short term.

Two main things of interest are the chances for showers and
thunderstorms this evening and how fast do clouds clear out
after the cold front. Cold front timing and shower/storm timing
have been rather consistent. Expect most of the showers/storms
to enter the area between 01 and 02Z and exit our southeast by
05z to 07z. Clouds should clear quickly after the front moves
through as drier air moves into the area. We currently have a
clear forecast and I expect that to continue. That said, some
CAA CU over MN behind the front does make me a little nervous,
especially if it decides to turn to stratus, we could be out of
luck with sky cover tonight. I do not see this happening, but we
need to keep an eye on it as it would be the only way we aren`t
clear.

This evening, CAPE does build ahead of the front as dewpoints in
the 50s start to pool ahead of it. This will help to develop
thunderstorms, as the front moves south, cooling after the
sun sets, should lead to a decrease in overall CAPE. This means
the best chance for thunder will be across the far north as the
showers and storms enter. With dry low levels, inverted V
soundings are indicative of gusty winds with these showers. Wind
gusts to 45 mph cannot be ruled out. With a decrease in CAPE
overall risk for severe weather is so low that it doesn`t
warrant a mention in the HWO.

After this, a quiet Saturday is expected with similar
temperatures to today.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 224 PM CDT Fri May 10 2024

Period will start out with short-lived ridging as a SW wave
pulls warmer air into the area for Sunday. Temperatures into the
low 80s are currently forecast. After this, guidance slowly
brings this nearly cut-off SW wave across the area leading to an
increase in rain and thunderstorm chances. Sunday afternoon we could
see scattered showers and storms. While CAPE up to 2000 J/kg
are possible, the shear is rather weak at 20-25 kts of deep
layer. This suggests a multicell type of thunderstorm
environment with strong storms. With the large T/Td spread could
possibly see some strong to near severe gusts, especially if we
can get that 2000 CAPE to develop.

Tuesday On: There is uncertainty on how fast the rain moves out
with most of the models lingering it across the south through
Tuesday morning. Generally, we`ll be looking at a more tranquil
pattern later Tuesday into Wednesday as a backdoor cold front
advects in a cooler and drier air mass from the NE. NBM highs
may be too warm for Wednesday, and latest trends in the
deterministic models is to delay the next round of showers and
storms until Wednesday night into Thursday.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 635 PM CDT Fri May 10 2024

VFR conditions are expected through the TAF cycle. A cold front
will push through this evening and bring brief gusty winds over
25 kts along with scattered rain showers to areas north of
I-80. High pressure builds into the region Saturday, with mostly
sunny skies and some gusty northwest winds in the late morning
and afternoon hours.

&&

.HYDROLOGY...
Issued at 846 PM CDT Thu May 9 2024

Changes...

The flood watch for the Wapsipinicon River near De Witt
has been changed to a flood warning.

Discussion:Active period again with periodic rounds of showers
and thunderstorms as another deep trough comes out of the
Rockies and into the middle of the country. However, way too
early to determine severe threats or rainfall amounts. Highs
will be well into the 70s to around 80.

The Cedar, Iowa and Wapsipinicon Rivers continue to rise as a
result of the rainfall over the past 30 hours. The forecast for
De Witt has not changed much over the past 24 hours, thus
confidence has increased that it will reach flood stage within
the next 24 hours.

The overall situation with the Cedar and Iowa Rivers is more
uncertain. While there is a better accounting of the overall
runoff compared to 24 hours ago, the forecast for Marengo on the
Iowa river is just barely above flood stage. Since the flood
crest will gradually attenuate due to gravity as it moves
downstream, there is a 30 to 40 percent chance that the crest at
Marengo may occur just below flood stage.

On the Cedar River near Conesville the flood crest will also
attenuate as it moves downstream. However, the crest is further
above flood stage which means there is a 50 percent chance of
reaching flood stage.

Rainfall over the next 72 hours and where it occurs will be the
deciding factor as to whether or not the Cedar and Iowa Rivers
will reach flood stage near Conesville and at Marengo
respectively. If the rainfall is lighter than expected then
river forecasts may be lowered. However, if rainfall is heavier
than expected then river forecasts may be raised.

&&

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

&&

$$

KEY MESSAGES...Gross/Gibbs
SHORT TERM...Gibbs
LONG TERM...Gibbs
AVIATION...Gross
HYDROLOGY...08