480
FXUS63 KDVN 062356
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
656 PM CDT Sat Jul 6 2024

...00z Aviation Update...

.KEY MESSAGES...

- Showers and storms return later tonight and last through at
  least Monday.

- Near normal temperatures through much of next week.

- Could Beryl have an impact on our weather next week? Time will
  tell.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 155 PM CDT Sat Jul 6 2024

A tranquil afternoon is taking place over the region, with
widespread mid 70s to lower 80s in our area. Dewpoint
temperatures are in the lower 60s, providing a summer feel to
the air, without much of any heat stress. Some spotty sprinkles
are taking place over northern Illinois today, in the cumulus
field, but I`m inclined to keep the forecast dry given the very
isolated and light nature of them.

Looking to the west, there is an upper low pressure centered
over north central South Dakota, with short wave trof
locations in central Nebraska and eastern Montana. These two
short waves will bring the forcing for two many chances for
rainfall over the area through Monday, as they bring lift to a
air mass that is forecast to have PWAT values of 1.5 to 1.75".

The first short wave will move through Iowa tonight, with an
elevated/high based shower and thunderstorms expected to move
from eastern Nebraska into central Iow this evening, then
gradually into eastern Iowa generally after midnight. The focus
for storms appears rather diffuse, so this may be a festering
area of weak convection and rain as it arrives, with QPF mainly
under 0.40"

With mostly cloud skies, temperatures will fall to the mid 60s
area wide.

&&

.LONG TERM /SUNDAY THROUGH SATURDAY/...
Issued at 155 PM CDT Sat Jul 6 2024

A quasi-omega block related to this Midwestern upper low will
remain through early next week, with a the second of the main
shortwaves traversing along the SW to NE oriented mid/upper flow
ahead of a mean upper trough over the Upper Mississippi Valley
Sunday night and Monday.  PoPs will be high at times (60+%),
with the main placement along the location of a wavering
surface frontal boundary. Deep layer shear looks generally
marginal as typical for July and thus any organized severe
weather threat appears low at this time. However, will have to
keep an eye out for any augmentation of the deep layer wind
fields by any shortwaves, which could foster a severe weather
threat if juxtaposed with favorable diurnal timing and
sufficient instability. The threat for widespread heavy or
excessive rainfall also appears low at this time, with 00z GEFS
indicating probabilities of >1 inch of total QPF through 12z
Tuesday at 30-50% and ECE at just 20-30%. This would be good
news for area rivers. We are monitoring the track of Tropical
Storm Beryl, which is currently moving into the south central
Gulf of Mexico. According to the latest NHC forecast it is
expected to intensify into a Hurricane before reaching the lower
and middle Texas coast late Sunday and Monday, then weaken to a
Tropical Depression while reaching the Lower Mississippi Valley
by Wednesday evening. The GFS Vertically Integrated Water Vapor
Transport (IVT) plots does suggest the potential for at least
some connection of moisture from the remnants of Beryl poleward
into the existing moist conveyor ahead of the front in the
region. That being said, the strongest IVT does show to remain
disconnected and closer to remnant low center, but nonetheless
this will be worth monitoring for any potential for a deeper
connection leading to a more widespread heavy rain threat ahead
of the frontal boundary draped across the area. Otherwise, the
general consensus of the ensemble guidance beyond mid next week
keeps the remnants of Beryl well south/east of the area into the
Ohio/Tennessee Valleys. It is possible being on the northwest
flank of this system that subsidence could increase enough to
give us several days of dry weather from Wednesday through
Friday and possibly deeper into next weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 650 PM CDT Sat Jul 6 2024

A VFR TAF period through late evening and into the over night
with light and variable or light southeasterly sfc winds.
Isolated to sctrd showers and thunderstorms, elevated in nature,
are then expected to move in from the west after midnight, and
get into the VCNTY of most of the TAF sites except maybe BRL.
Have timed TEMPO and PROB30 groups for the most likely windows
of activity into Sunday morning. The more substantial storms
may still produce passing bouts of MVFR CIGs and rain-reduced
VSBYs. Then much of the day Sunday may be VFR clouds with sctrd
patches of MVFR CIGs with showers and possible thunderstorms.
Southerly sfc winds should increase to 5-10 KTS, but still may
show variable tendencies around the showers/storms.

&&

.HYDROLOGY...
Issued at 110 PM CDT Sat Jul 6 2024

Rainfall amounts were less than expected. Therefore, the Mississippi
River is currently cresting at and upstream of Bellevue, IA. The
crest may take 1 to as much as 3 days to pass.  Fulton and Camanche
are forecast to begin cresting Sunday afternoon, with Le Claire,
Rock Island, and Gladstone seeing the crest begin late on Monday.
The remainder of the sites south of the Quad Cities are
expected to crest Tuesday through Friday. Major flooding is
occurring or expected to occur along the Mississippi River from
Dubuque to Keokuk.

Tributary Rivers:

Moderate flooding will continue on the Wapsipinicon River at Dewitt
through Tuesday. It is forecast to briefly drop into Minor Flood
Category midweek, before rising back to Moderate Flood stage on
Thursday.

On the Cedar River at Conesville, minor flooding will continue. It
will see a secondary crest near 14.5 feet late this coming week.

The Iowa River at Oakville is seeing high water levels due to
backwater affects from the Mississippi River. It is forecast to
remain near 11.8 through midweek and then rise to near 12 feet.

A flood watch remains in effect for the Cedar River at Cedar Rapids.
It is forecast to briefly reach the 12 foot flood stage late Monday
afternoon. Confidence remains low.

&&

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

&&

$$

SHORT TERM...McClure
LONG TERM...McClure
AVIATION...12
HYDROLOGY...14