418
FXUS63 KDVN 132344
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
644 PM CDT Sat Jul 13 2024

.KEY MESSAGES...

- A Heat Advisory is in effect until 8 PM this evening for the
  counties roughly along and south of I-80 for peak heat indices
  of 100 to 105 F.

- The heat continues for Sunday and Monday with peak heat
  indices between 100 to 110 F.

- Organized thunderstorms are possible late tonight with a
  cluster of storms moving in from the north/northwest. This
  could bring gusty winds and heavy rainfall. Additional rounds
  of scattered storms are possible Sunday and Monday.

- Moderate to major river flooding continues on the Mississippi
  River with most sites crested or cresting in the coming days.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 230 PM CDT Sat Jul 13 2024

Late This afternoon through Tonight:

SPC mesoanalysis had a mid-level vorticity max over
Minnesota/Wisconsin with a southwesterly LLJ to the south
across the Mid to Upper Mississippi Valley. Warm air advection
on the nose of the 850mb jet has kicked off a few scattered
showers and storms across the far eastern portion of the area,
mainly from near Freeport down toward Princeton. Much of this
activity should shift to the east of the area by the late
afternoon hours. Heading into late this evening and the
overnight, confidence remains low on the potential for
convection. Latest HRRR runs hold the organized storms well to
our north across Minnesota and Wisconsin, while the NAMnest
drops a line of storms in from the north after midnight. Will
maintain 20-40% chances in the forecast through the overnight,
highest across the NE portion of outlook area. If storms do
manage to drop southeastward into the local area tonight, the
primary threats would be strong winds and frequent lightning.
Moderate MUCAPE and modest deep layer shear would be supportive
of strong to severe storms, which is in line with SPC`s Slight
Risk across the north and northeast, and Marginal Risk to the
south.

Sunday:

Low chances for showers and storms will continue through the
day with potential for scattered strong to severe storms
developing during the late afternoon and evening. Confidence is
low on this late PM development; however with a very unstable
air mass due to the hot/humid conditions, presence of any low-
level outflow boundaries, and potential for a mid- level wave to
roll west to east across the area, the threat for at least
scattered strong/severe storms will have to be monitored
closely. Highs in the upper 80s to lower 90s are forecast, with
dewpoints in the lower to mid 70s. Heat indices are forecast in
the upper 90s to near 105 degrees (highest south of I-80).
Through early next week, 850mb temperatures are forecast to be
24 to 27C, which is strongly supportive of excessive heat.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 230 PM CDT Sat Jul 13 2024

The hot weather will continue on Monday with chances for
scattered showers and storms as a cold front gradually drops in
from the north. Models continue to show a strong EML, but the
frontal position could serve to erode that with time, especially
after dark. The ample CAPE over 3000 J/KG would support strong
storms, as would the increasing shear from the westerly flow
aloft. For now, pops are in the 30-60% range by Monday night.

Tuesday is a transition day into the far cooler air in the
extended. Highs will be rather warm, but with decreasing
humidity and gusty winds, the heat stress will be decreasing
through the day.

Wednesday though Saturday continue to look very pleasant, with highs
in the 70s to low 80s, and lows in the 50s!

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 631 PM CDT Sat Jul 13 2024

VFR conditions are forecast through the period. A prob30 group
was placed in the TAFs for both KDBQ and KMLI between 9 and 13z
on Sunday for a potential line of thunderstorms that is forecast
to sink southward across the area during the morning. MVFR
visibilities are possible with this line of storms as it sinks
southward. Winds will turn to the southwest after 15z Sunday
with speeds of 10 to 20 knots.

&&

.HYDROLOGY...
Issued at 938 AM CDT Sat Jul 13 2024

The crest on the Mississippi River is now between Keithsburg,
IL and Gladstone, IL (L/D 18). Upstream of New Boston (L/D 17)
river levels continue to fall. New Boston and Keithsburg are
just starting to show signs of falling. As the broad crest
continues to attenuate, areas from Gladstone downstream to
Gregory Landing should begin a very broad crest over the next
day or two.

Tributary Rivers:

On the lower Cedar River near Conesville, IA, minor flooding
continues. Over the next 24 to 36 hours the flooding is forecast
to end.

The lower Wapsipinicon River near Dewitt, IA will remain in
moderate flood through mid-day Sunday before falling into minor
flood. A fairly rapid drop in water levels will commence Sunday
afternoon and night as backwater effects from the Mississippi
River decrease.

Minor flooding continues on the lower Iowa River at Oakville due
to backwater effects from the Mississippi. With the broad crest
on the Mississippi now just south of Keithsburg, IL, water
levels on the lower Iowa River will slowly fall to and then
remain around flood stage over the next four days.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory until 8 PM CDT this evening for IAZ063>065-067-
     068-076>078-087>089-098-099.
IL...Heat Advisory until 8 PM CDT this evening for ILZ015-016-
     024>026-034-035.
MO...Heat Advisory until 8 PM CDT this evening for MOZ009-010.

&&

$$

SHORT TERM...Uttech
LONG TERM...Ervin
AVIATION...Cousins
HYDROLOGY...08