882
FXUS63 KDVN 111948
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
248 PM CDT Sat May 11 2024

.KEY MESSAGES...

- Quiet weather through Sunday morning. Clear skies expected
  tonight.

- Sunday will be the warmest day of the next seven with highs in
  the lower 80s. Isolated to scattered storms are possible late
  Sunday afternoon into Sunday night.

- Zonal flow across the CONUS will result in active weather
  continuing through the next week.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 206 PM CDT Sat May 11 2024

Confluent flow aloft over Upper Midwest this afternoon as 500 MB
ridging builds into the area at the surface and aloft. Visible
satellite imagery is showing some areas of diurnally driven
cumulus developing across Illinois and parts of Iowa. The KDVN
sounding showed a convective temperature of 69 degrees.
Temperatures at 2 PM ranged from 69 degrees at Freeport and
Dubuque to 76 degrees at Macomb. Northwest winds have been
gusting up to 35 MPH at times this afternoon but in general
winds are gusting up to 25 MPH.

High pressure will move southeastward across the area at the
surface and aloft through Sunday morning. This will bring quiet
weather to the area overnight The HRRR and HREF have been
showing some thinning high clouds moving across the area this
evening but do not expect widespread cloud overnight with dry
air in place. Winds will diminish tonight and become light and
variable. Low temperatures will generally be around 50 north of
a Independence to Clinton to Princeton Illinois line with lower
to mid 50s south.

On Sunday, the ridge axis will push to the southeast during the
morning as one shortwave dives into Michigan. The ECWMF is the
faster and farther south of the different solutions with the
cool front approaching the area by 00 UTC Sunday. CAMs do have
isolated to scattered showers and storms developing across the
area from 20 UTC (3 PM) along the Highway 20 corridor. Model
soundings show that brief gusty winds will be the main threat
but moisture is very limited and soundings are showing
inverted-V or onion sounding characteristics. Temperatures on
Sunday will be in the lower 80s. Forecast soundings show the
potential for gusty winds once again with a few gusts especially
across northwest Illinois and far eastern Iowa near 25 MPH.

Models have slowed precipitation moving into the area on Sunday
in association with a closed upper level low moving from
Colorado into eastern Kansas by 12 UTC Monday. The better
chances of 30 to 40 percent will remain west of the Mississippi
River overnight. Rainfall amounts will be light and range from
one to two tenths.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 206 PM CDT Sat May 11 2024

The 500 MB flow will remain zonal through the upcoming week
with an active northern (polar) and southern (sub tropical)
branches of the jet streams across the continental US. This will
result in several more chances for showers and storms. High
temperatures will be in the lower to mid 70s through mid week
before a warming trend beings into next weekend.

Monday: An upper low on the northern periphery of the
subtropical jet is forecast to slowly track from the Southern
Rockies to the Lower to Mid Mississippi Valley early in the
week. This will keep the local area on the cooler and more
stable side of the surface low. Rain is likely to spread in
from SW to NE during the morning and afternoon. NBM chances for
measurable rain range from near 50% in the far NW corner of the
outlook area to ~90% south of I-80. The 24 hour probability for
0.50" or more of rain reaches 50-70% south of I-80 and drops
down to 20% near Highway 20. The NBM may still be running too
warm for max temps due to the likelihood for widespread clouds
and rain; these may need to be lowered by several degrees in
later updates.

Tuesday - Friday: There remains uncertainty with how fast the
rain moves out on Tuesday. The ECMWF lingers the rain through
the morning across the south half of the outlook area, while
the GFS/CMC shift it to the SE more quickly. Our current
forecast is leaning towards the latter scenario. Then it looks
like we will get a break from the rain later Tuesday through
Wednesday before the next shortwave trough and associated cold
front arrive by Wednesday night into Thursday. Late week temps
are forecast to be slightly above normal in the low/mid 70s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1228 PM CDT Sat May 11 2024

High pressure will bring quiet weather and VFR flying conditions
to the area through the TAF period. Currently, gusty northwest
winds are forecast to diminish during the early evening hours.
Winds will turn to the south after midnight as another storm
system approaches the area.

&&

.HYDROLOGY...
Issued at 955 PM CDT Fri May 10 2024

The Flood Warning continues for the Wapsipinicon River near De
Witt. The initial crest has come in considerably lower and
below flood stage, so the river is now expected to go into
Minor flooding on the evening of Monday, May 13th when the
second crest due to routed flow occurs. Given how the initial
crest was lower and attenuation of routed flow confidence is
dropping a bit on the river reaching flood stage.

The overall situation with the Cedar and Iowa Rivers is more
uncertain. Flood watches remain in effect for Marengo on the
Iowa river, and the Cedar River near Conesville. The Iowa
River at Marengo is forecast to go into Minor flooding Sunday
evening May 12, while the Cedar River near Conesville is
forecast to go into Minor flooding early Tuesday morning, May
14.

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.

&&

$$

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