232
FXUS63 KDVN 130558
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1258 AM CDT Mon May 13 2024

.KEY MESSAGES...

- Periods of showers and storms are likely Monday into Monday
  night with the heaviest rainfall amounts along and south of
  Interstate 80.

- Active weather will continue over the next 7 days as zonal
  flow remains in place across the CONUS.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 211 PM CDT Sun May 12 2024

A cold front sits to our northwest and stretches from Duluth to
Rochester to Sioux Falls South Dakota then west southwestward
into northeast Colorado. Temperatures at 2 PM ranged from 80
degrees Sterling Rock Falls to 85 degrees at Macomb. Scattered
showers and storms have developed across northern Iowa early
this afternoon. Stronger deep layer shear sits to the northeast
in Wisconsin at 30 to 40 knots with 1000 to 1500 J/KG of
surrface based CAPE to our north. These showers and storms are
forecast to sink slowly southeastward through this evening and
gradually dissipate. Model soundings show an inverted-V profile
and think that winds in storms gusting up to 40 to 50  MPH are
the main threat.

The cold front to our northwest is forecast to move into
northern Iowa by 12 UTC on Monday. CAMs show showers and storms
along the front sinking into the area this evening and gradually
dissipating before moving into our area.

A vertically stacked storm system is forecast o trudge from
central Nebraska and Kansas border tonight and into western
Illinois by 12 UTC on Tuesday. Moisture advection head of this
system will slowly saturate the atmosphere with the best lift
and moisture spreading into far northeast Missouri and southeast
Iowa by 12 UTC on Monday and slowly spread northeastward
through the day. This will bring periods of rain showers and
storms through the period. Models show 1.25 to 1.50 inches of
precipitable water through the day on Monday into Monday night
which is 100 to 150 percent of normal. Heavy rain will be
possible as this storm system moves across the area especially
south of Interstate 80. Rainfall amounts will range from up to
0.5 inches north of Interstate 80 to up to an inch south with
isolated higher amounts.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 211 PM CDT Sun May 12 2024

A split zonal flow is forecast to be in place across the CONUS
through the long term period. This will result in a series of
troughs and ridges moving across the area through next weekend.
Models begin to diverge later in the week on the timing and
placement of different features.

Tuesday: Shower chances will continue at least through the morning
hours as the vertically stacked system tracks across central and
southern Illinois. Otherwise, we`ll have breezy NE winds and
seasonable temps in the upper 60s to low 70s.

Wednesday - Saturday: Ridging aloft and surface high pressure is
forecast to build in later Tuesday into Wednesday, leading to a
break in the wet weather. The next system to impact the region
arrives by late Wednesday into Thursday, bringing another round of
widespread rain to the outlook area. Once again there is uncertainty
on how quickly this system pushes to our east. The NBM has a chance
for rain (30-40%) continuing through Friday which is reasonable
given the model discrepancies. Forecast temperatures late in the
week are near to slightly above normal.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1245 AM CDT Mon May 13 2024

Isolated showers and storms are possible tonight into early
Monday AM, mainly at DBQ. Coverage of showers and storms is
forecast to increase later Monday AM into the afternoon/evening
which could lead to periods of MVFR ceilings and visibilities.
The atmosphere will become more humid on Monday, increasing the
potential for heavy downpours and brief IFR conditions. Right
now, confidence is low on where the heaviest rain will fall but
TEMPO groups may be needed in later updates to account for
periods of moderate to heavy rain.

&&

.HYDROLOGY...
Issued at 946 PM CDT Sun May 12 2024

New forecast by the River Forecast Center this evening showed
little to no change for the Wapsipinicon River near DeWitt. The
river should reach flood stage before 7am tomorrow morning and
slowly rise to 11.4 feet over the next 3 days. Depending on
where additional rainfall on Monday falls, more rises may be
possible. However, at this time the highest totals are expected
south of the Wapsi basin. The flood warning was continued with
this forecast issuance.

The forecasts for the Cedar and Iowa Rivers have come in lower
this evening. The Iowa River at Marengo now is expected to not
reach flood stage and as a result, I have cancelled the watch
here. The Cedar River near Conesville forecast was kept just at
flood stage for now due to the incoming QPF uncertainty. For
this reason, have kept the flood watch going there.

Taking a deeper dive into the QPF, widespread rainfall in the
0.5" to 1" range is expected in the next 24 hours, with some
localized higher amounts. The 12z HREF probability-matched mean
QPF values through Tuesday morning are painting a swath of
rainfall in excess of one inch, with some isolated amounts over
two inches slightly northward closer to the downstream portions
of the Iowa and Cedar River basins. This QPF placement and how
much runoff occurs will be very important to whether additional
rises are seen and if warnings will be needed.

&&

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

&&

$$

SHORT TERM...Cousins
LONG TERM...Cousins/Uttech
AVIATION...Uttech
HYDROLOGY...Gross