315
FXUS63 KDVN 151150
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
650 AM CDT Mon Jul 15 2024

.KEY MESSAGES...

- The heat continues for today and Monday with peak heat indices
  between 100 to 110 F. A Heat Advisory is in effect area-wide
  today until 8 PM but afternoon relief is possible north if
  storms arrive.

- An Enhanced Risk (Level 3 of 5) for severe storms across the
  outlook area. Damaging winds are the primary hazard, but
  tornadoes will also be possible today.

- Moderate to major river flooding continues on the Mississippi
  River with most sites crested. The Rock River is now expected
  to see flooding due to the heavy rains upstream in the past 24
  hours.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 316 AM CDT Mon Jul 15 2024

Today is another day to closely monitor forecasts and warnings!

Our area is set to be impacted by a damaging line of storms
this afternoon and evening, with an abundance of observational
and model data supporting the apex of a severe bowing line,
moving through eastern Iowa and northwest Illinois. SPC has our
area in Enhanced, level 3 of 5, today, focusing primarily on
damaging winds, but also noting a 5% tornado risk, and a low 2%
hail risk.

Today will be hot and humid, and while that will get handled by
an advisory today (though some values may reach warning criteria
in the south), the focus needs to be on severe weather during
the afternoon and evening. This heat will be the pool of energy,
CAPE we need to supply another round of severe storms. However,
this time, we`re dealing with a strong trigger (mid level jet
streak), focusing mechanism (front), and significant shear over
40 kts, and PWAT values over 2 inches and all those factors
really add up to a potential high end event.

The activity in eastern ND early today, will likely drop
southeast into MN, but could trigger a few elevated cells into
eastern Iowa and northern Illinois. Some CAMs do create a
separate event from this activity, but that seems unlikely.
Instead, it looks like air mass recovery will occur quickly
today, with winds becoming southeast and increase to 10 to 15
mph. This is especially true over northern areas, where the
mesohigh from last evening`s storms will be decaying.

I expect storms to fire in central Iowa by mid afternoon, and
will rapidly spread east and southeast. Damaging wind will be a
threat from the onset, but with the backed winds in eastern Iowa
and northern Illinois, STP values may exceed 2 in locations
north of Interstate 80, supporting supercells and tornadoes
during the afternoon and early evening.

By early evening, an established bowing storm segment should be
formed, moving east, with a comma head, and trailing line of
cells. This will lay out a swath of heavy rainfall and wind,
with guidance most supportive of this falling roughly along the
Interstate 80 corridor, then sinking south during the evening.

While the exact position is looking to go through our area, this
event will fall into line once we know the position of backed
winds and initial storms that trigger in central Iowa/northeast
Iowa today. Once they are, the axis of most significant storms
can be identified and communicated.

After 9 PM, the mode of storms looks to become primarily heavy
rain producing multicells storms, with the axis of heavy rain
gradually sinking south through the late evening and overnight.

Rainfall amounts of 1-2 inches will be common with this event,
with some amounts in the late evening training supporting and
additional 1" where training storms occur. Thus, this event
could again impact rivers, especially with any amounts over
northern Illinois, which is dealing with back to back heavy
rainfall events in the past 36 hours.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 316 AM CDT Mon Jul 15 2024

Cooler and less humid air will move into the region behind a
cold front by Tuesday and last through the end of the week.
Overnight lows in the 50s are forecast on several nights, giving
our air conditioning a bit of a break.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 650 AM CDT Mon Jul 15 2024

Patchy shallow fog will dissipate across the area by 13-1330Z.
Southerly winds will increase with occasional gusts today,
especially at airports along/south of I-80 where gusts as high
as 25 kt may occur this afternoon. Isolated showers or storms
(20-30 percent coverage) may sprout in the northeast quarter of
Iowa, including near CID and DBQ between 16Z and 22Z, but
confidence is low on this.

The main story with the TAF is the high likelihood of growing
storms into a quickly-moving storm complex expected late this
afternoon through mid-evening over the area. These storms and
especially the complex will be capable of severe winds, and
likely will have temporary LIFR visibility in very heavy
rainfall. Tried to incorporate that into two hour TEMPOs within
the TAF, but naturally there is some uncertainty still with
timing. Behind the storms later tonight, there could be again
some fog/low cigs.

&&

.HYDROLOGY...
Issued at 316 AM CDT Mon Jul 15 2024

A broad crest on the Mississippi River is occurring from
Gladstone, IL (L/D 18) down through Gregory Landing, MO. This
crest will last up to two days. Upstream of Keithsburg, IL
river levels are falling.

Tributary Rivers:

The Cedar River near Conesville, IA fell below flood stage last
evening and will continue falling over the next week.

The lower Wapsipinicon River near Dewitt, IA is expected to fall
below flood stage around sunrise Monday morning. The rate of
fall on the river has slowed down due to locally heavy rainfall
overnight.

Backwater effects from the Mississippi River continue to lessen
on the lower Iowa River. The Iowa River at Oakville, IA is
forecast to drop just below flood stage this evening but then
remain near flood stage through the remainder of this week.

River flood warning have been issued for Joslin and Moline
given the additional 1-3 inch heavy rain falling on the basin
this past evening following the 2 to 5 inch rainfall event just
the night before.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory from 1 PM this afternoon to 8 PM CDT this
     evening for IAZ040>042-051>054-063>068-076>078-087>089-
     098-099.
IL...Heat Advisory from 1 PM this afternoon to 8 PM CDT this
     evening for ILZ001-002-007-009-015>018-024>026-034-035.
MO...Heat Advisory from 1 PM this afternoon to 8 PM CDT this
     evening for MOZ009-010.

&&

$$

SHORT TERM...Ervin
LONG TERM...Ervin
AVIATION...Friedlein
HYDROLOGY...08