983
FXUS63 KDVN 130726
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
226 AM CDT Sat Jul 13 2024

.KEY MESSAGES...

- The Heat builds into the area today, and continues to expand
  through Monday. Heat indices in the lower 100s are possible
  today, and likely 100 to 105 Sunday and Monday.

- Organized thunderstorms are possible tonight, with an MCS moving
southeast/south.  This could bring gusty winds, and heavy rainfall.
The next chance for organized storms is focused on Monday night`s
cold frontal passage.

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

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 222 AM CDT Sat Jul 13 2024

Light winds, temperatures in the lower 70s, and dewpoints rising to
the upper 60s to lower 70s are found across the area early today,
substantially warmer than yesterday at this time. Mid clouds are
noted on satellite over our area, but as of 2 AM, no showers have
developed in this mid level WAA regime. We`ll watch conditions, but
for now, the chances for morning storms remains under 20%.

Today will focus on the building heat and humidity, but all eyes
will be focused north of our area, as we watch southeastward moving
convection in the Dakotas and Minnesota. There are two scenarios
playing out today.  One, the heat builds in, and so does the EML,
resulting in hot, dry conditions through Monday. This is roughly 1/2
of available guidance.   The other, which at the moment is supported
by satellite/radar, shows several convective clusters moving
southeast towards northern Illinois by this evening. This would
generally arrive in our CWA after 7 PM, but could bring a wind gust
threat to our northern counties.  During the evening and overnight,
as a LLJ is aimed directly at our area, around 35 to 45 kts, the
cold pool could slowly propagate southwestward, resulting in a heavy
rain swath over our northern 1/2 of the CWA.  WPC and SPC are both
on board with this second scenario, which is supported by the
northwest flow aloft, diffluent thickness over our area, and LLJ
position.  It`s important to realize, that we often get a
significant convective event as significant heat waves build in, so
this potential should be no surprise.  Cells would continue to move
quickly during the overnight activity southeastward, but the
convective axis of storms would slowly shift southward, thus a
period of training is expected as the line slowly drops south.

Sunday, after any storms move out early, it appears the heat will be
in place through Monday, with only very low chances for thunder in
the far north.  Highs in the upper 80s to lower 90s are forecast,
with dewpoints in the lower to mid 70s. Heat indices both days
are forecast in the 97 to 104 range. Both Sunday and Monday,
850mb temperatures are forecast to be 24 to 27C, which is
strongly supportive of excessive heat.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Issued at 222 AM CDT Sat Jul 13 2024

Monday night, the cold front will move into our area, with storms
possible along it, and just post frontal. 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 30-50% range Monday
night, due to the potential of the EML holding back storm
formation.


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 /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1230 AM CDT Sat Jul 13 2024

Scattered to spotty broken VFR ceilings will continue through
the morning, and some of these clouds might develop into
isolated showers and storms (20% coverage). But confidence on
this remains low, especially given minimal coverage, so do not
have in any of the TAFs. For the afternoon, it`s also another
case of if anything develops it would be low coverage, and looks
to be mainly DBQ issue if there are any storms. South winds
will have occasional gusts in the 16-20 kt range this afternoon.

Storms are becoming more probable over the Minnesota/Wisconsin
border region later this afternoon. The more organized these
storms are, the greater likelihood they will move south-
southeast and affect some of the TAF sites this evening,
including the possibility of gusts exceeding 35 kt. At this
time, confidence of TSRA is only to the level of a PROB30
inclusion.

&&

.HYDROLOGY...
Issued at 1043 AM CDT Fri Jul 12 2024

The crest on the Mississippi River is between New Boston, IL
(L/D 17) and Keithsburg, IL. Areas upstream of New Boston
through the Quad Cities are coming off a a broad crest. From
Keithsburg, IL downstream to Gregory Landing, MO a broad crest
will commence over the next 0.5 to 1.5 days.

Tributary Rivers:

On the lower Cedar River near Conesville, IA, minor flooding
continues as water levels continue to fall.

The lower Wapsipinicon River near Dewitt, IA will remain in
moderate flood through Saturday. A fairly rapid drop in water
levels will commence Saturday 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. Once the broad crest
on the Mississippi gets downstream of Keithsburg, IL, water
levels on the lower Iowa River will slowly begin to fall.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory from 1 PM this afternoon to 8 PM CDT this
     evening for IAZ076>078-087>089-098-099.
IL...Heat Advisory from 1 PM this afternoon to 8 PM CDT this
     evening for ILZ025-026-034-035.
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