795
FXUS63 KDVN 161800
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
100 PM CDT Tue Jul 16 2024

...Midday Hydrology Update...

.KEY MESSAGES...

- Today will be a transition day from the heat/humidity to a
  much cooler air mass.

- Thunderstorms appear to be just south of our counties today.

- Moderate to major river flooding continues on the Mississippi
  River. The Rock River is now expected to see major flooding
  due to the heavy rains upstream in the past 48 hours.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 217 AM CDT Tue Jul 16 2024

The widespread storms that brought rather significant wind
damage, heavy rains, and likely a few tornadoes has moved well
to the east overnight. The front has not moved very far south,
and remains positioned from Kirksville to Quincy, and it
continues to be dealing with persistent training storms just
south of Hancock and McDonough counties. These storms likely
brought flash flooding earlier tonight in Henderson and
McDonough, with 2-4 inches falling in that area.


Today will be the transition day as we slowly advect in drier
air, and eventually, cooler air. To start the day, some shallow
fog is again possible, especially over eastern Iowa where skies
have been clear. As the day progresses, dew points will
gradually fall into the mid to upper 60s, and while not dry air,
it should feel much more comfortable outside with temperatures
peaking in the lower 80s north to mid 80s central and south.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 217 AM CDT Tue Jul 16 2024

Much cooler weather looks to be in place through the weekend,
with an upper trof building into the Great Lakes. Dry weather
will persist through the end of the work week, followed by some
very low pops for activity potentially on the western side of
the upper trof as we approach the weekend. Highs in the upper
70s to lower 80s are forecast through the weekend, followed by
a slight increase to the lower to mid 80s for early next week.

We`re all looking forward to this break in the non-stop heat-
humidity-violent-heavy storms of the past week. Good riddance!

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1210 PM CDT Tue Jul 16 2024

VFR conditions are anticipated through Wednesday. Occasional
high clouds will give way to mostly clear skies tonight into
Wednesday. Northwest winds will average 4 to 8 kts.

&&

.HYDROLOGY...
Issued at 1257 PM CDT Tue Jul 16 2024

Swaths of heavy rain and resultant run-off produced by severe
thunderstorms Monday and Monday night across the area are
aggravating ongoing river flooding or producing new flooding
situations.

The Mississippi River has crested at all sites now, but several will
experience stalled falls or steady trends over the next several days
due to recent bouts of heavy rain, local run-off, and tributary
input. L&D 19 at Keokuk and Gregory Landing will even experience
secondary rises into the weekend.

Tributary Rivers:

Very heavy rainfall on the upper reaches of the Rock River basin
over the past several days, as well as some localized run-off may
produce Major Flooding near Joslin and at Moline by Friday. The
river flood warnings for this have been posted, but there is some
uncertainty that they will actually get that high and Moderate
flooding may be more in line for these sites. The Rock at Como will
be in Minor flood through Saturday evening.

The Pecatonica River basin also received heavy rain, and the site
at Freeport IL is expected to rise well into Minor flood by Friday.

The lower Wapsipinicon River near Dewitt, IA is experiencing
localized run-off from the heavy rainfall last night of 1-2 inches.
It is actually jumping back above flood stage due to this process
and a new warning for that site has been issued this morning. Water
levels are expected to fluctuate around the flood stage through
Thursday night before falling off and maintaining the fall.

Backwater effects from the Mississippi River will keep the lower
Iowa River just below flood stage for the remainder of the week.

Further south, torrential rainfall and run-off from last night may
produce a large rise to action stage on the La Moine River near
Colmar in west central IL. But the extent and speed is still
somewhat uncertain and will have to watch river rise trends through
Thursday.

&&

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

&&

$$

SHORT TERM...Ervin
LONG TERM...Ervin
AVIATION...CN
HYDROLOGY...12