665
FXUS63 KDVN 041043
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
543 AM CDT Thu Jul 4 2024

.KEY MESSAGES...

- Tricky forecast today with potentially strong to severe
  thunderstorms, that could impact 4th of July celebrations.

- A rather active pattern still looks to be on tap through the
  longer range, with near daily chances for precipitation
  somewhere in or near our forecast area. Saturday may be the
  best chance at a dry day, with slight-chance PoPs daily from
  there.

- Moderate to Major River Flooding continues, with further
  changes to river forecasts expected as we transition from
  predicted rainfall to observed rainfall over the next 36 hrs.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 300 AM CDT Thu Jul 4 2024

A complex, mesoscale driven day is expected today as questions
about what happens this evening with showers and storms remains
front and center. Convection south of the area this morning
should move east of the area after 18z. At the same time another
wave is expected to move towards the area from the NW. A cold
front is expected to be dragged across the area by this wave
later in the afternoon and into the evening. How the AM storms
evolve will greatly affect the afternoon and evening storms. We
may see some showers associated with the convectively enhanced
wave/MCV moving south of us this AM. The clouds/showers this AM
will determine whether or nature provides the fireworks tonight
or not.

So CAMs are all over the place, recent HRRR runs buy into a
clearing this afternoon and redevelopment of showers and storms
this afternoon that approach the area this evening, likely
affecting firework displays. We need to keep an eye on the
clouds, if we see decent clearing I think storms, that are
strong to severe are plausible from 23z to 06z. If we don`t
clear, there is enough largescale ascent that we could see
isolated showers between 02z and 06z with the fropa. If we do
get PM storms due to clearer skies, we do have a prime
environment for severe weather. SPC has the area in a marginal
risk, which is likely continent on the clearing skies. We do
have 40-50kt deep layer shear that is perpendicular to the
forcing boundary suggesting supercells are possible. Decent
flow aloft may keep these storms supercellular instead of
developing cold pools and forming lines. Think hail and damaging
winds are main threat as llvl shear is not all that impressive.
That said, I never count a supercell out on ability to produce a
tornado, so there remains that threat as well.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 300 AM CDT Thu Jul 4 2024

To start the long term, an upper level low/trof is expected to
swing through the area into Saturday AM. We could see some
showers associated with this low on Friday. With the clouds
associated with this low, we could see highs only in the 70s.
Saturday into Sunday we continue to see an active flow with
overall trofing across the area. A series of waves through this
flow could bring pop chances to the area. Model guidance still
suggests that Saturday will be the best chance for dry day this
weekend. Early next week, a high amplitude ridge to our west
builds. We see a deeper trof across our area that would lead to
some scattered showers and storms. With the NW flow we should
see temps be more seasonable if not slightly below normal.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 535 AM CDT Thu Jul 4 2024

VFR conditions are expected through much of the TAF period,
with brief moments of MVFR cigs/vis when heavier showers pass
through this morning and then again this evening. Showers are
currently moving into the area, impacting much of the area by
12z. The showers will be mainly light, with the heavier showers
and storms possible near/after 00z for most. Confidence remains
low on thunderstorm coverage this evening and tonight. Thus,
have opted to message the potential with a PROB30 group right
now. Winds at the beginning of the period will be light and
variable, increasing to near 10 KTs out of the southeast by
15-18z. From there, a cold front will pass through this evening,
shifting winds westerly between 03-06z.

&&

.HYDROLOGY...
Issued at 1211 PM CDT Wed Jul 3 2024

The forecasts along the Mississippi River havn`t changed much from
the previous ones, with many forecast points cresting into the
weekend. Locations from Dubuque to Keokuk are still expected to
crest over their respective Major Flood Stage levels. At Gregory
Landing, a crest in the Moderate category is forecast. The crest is
forecast near Dubuque and Bellevue on July 4th and 5th, with sites
from Fulton to Keokuk seeing a crest between July 6th and 8th.

On the Maquoketa at Manchester, the heavy rains and training
thunderstorms to produce them did not materialize and shifted to the
south of that basin. Thus it is no longer expected to reach the
minor flood stage and the warning has been cancelled.

Also with the rainfall amounts not being quite as high or widespread
as earlier anticipated in some of the more northern basins, several
tributary forecasts have been toned down some. Ongoing river flood
watches and warnings on the Cedar, Iowa, Wapsi, Skunk, and Maquoketa
Rivers have been adjusted accordingly to the rainfall reports from
this morning. But with a few other areas indeed receiving torrential
rainfall a bit further south, the river flood watches for the North
Skunk River near Sigourney and English River at Kalona have been
upgraded to river flood warnings.

Current projections for additional rainfall over the next few days
through the end of the week look more spotty with widespread heavy
rain not likely. This should help maintain the current forecasts
from deviating too much from the most recent forecasts.

&&

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

&&

$$

SHORT TERM...Gibbs
LONG TERM...Gibbs
AVIATION...Gunkel
HYDROLOGY...12