586
FXUS63 KDVN 130552
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1252 AM CDT Tue Aug 13 2024

...06z Aviation Update...

.KEY MESSAGES...

- There will be the potential for dense fog tonight through
  much of the area, which may lead to AM commute impacts if it
  becomes widespread. River valleys and low-lying areas remain
  the areas with the best chance.

- Active stretch of weather ahead of us, with near daily chances
  for precipitation somewhere in our area. Best chances for more
  widespread showers/storms will be midweek and beyond.

- Temperatures trending near normal by midweek, with most in the low-
  mid 80s.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 155 PM CDT Mon Aug 12 2024

Aside from the remnant showers being seen in the south, we are
geared up for a quiet and dry 24-48 hours. As this wave pushes out
this evening, we will start to see weak ridging and high pressure
work into the area. With LLVL moisture still around, along with
recent rainfall, we may see fog for some. Areas that are cloudless
tonight are expected to drop into the mid 50s, with those socked in
clouds sticking around 60.

Tomorrow, a beautiful day is ahead of us. A weak surface high
pressure will pass through tonight and tomorrow AM, with LLVL winds
shifting southeasterly. So, we will start to see some more
seasonable temperatures work in tomorrow, with much of the area in
the low-mid 80s. Areas in the south may still be fighting cloud
cover, which would make them slighly cooler than the remainder of
the area, generally keeping them closer to 80. In all, much of the
area will be mostly clear and dry, with the clouds decreasing in the
south through the afternoon.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 155 PM CDT Mon Aug 12 2024

An active period of weather is likely Wednesday into Thursday as an
upper-level trough approaches the area. Though models disagree on
exact timing and location, widespread showers and storms are likely
to impact our area during the Wednesday night/Thursday timeframe.
Wednesday itself will feature comfortable temperatures and humidity
levels with scattered rain chances, highest east. Attention then
turns to Wednesday night as the low-level jet begins to ramp up,
increasing moisture and theta-e transport into the area. Guidance
agrees on a strong shortwave approaching overnight, favoring the
development of an MCS. Most guidance develops impressive moisture by
this time, with PWATs at or above 2.00". Given our past rainfall
events this summer, confidence is low on exceeding that 2.00" PWAT,
as we have typically underperformed compared to guidance prior. That
being said, unseasonably high moisture in the column (PWATs greater
than the 90th percentile) would certainly support heavy and
efficient rainfall with any thunderstorms. When all is said and
done, we`re looking at a healthy swath of 1 to 2 inches of rainfall
across the area, with higher amounts in areas that see repeating
thunderstorms. Because of this, the WPC Day 3 ERO (12z Wednesday
through 12z Thursday) highlights the southwest two-thirds of our CWA
in a slight risk for excessive rainfall, with the remainder of the
area in a Marginal risk. With the first part of August being quite
dry compared to normal along with negative soil moisture anomalies,
the area is in generally good shape to handle a widespread soaking.
However, with such great forcing and moisture transport into our
area, localized flash flooding is definitely a possibility with any
training thunderstorms.

Showers and thunderstorms once again are possible on Thursday and
into Thursday evening, though confidence is lower on how Thursday
will evolve with the potential for remnants/boundaries from early
morning convection to complicate things. There exists the potential
for a triple point severe threat on Thursday, though confidence
is low in this at this range. Guidance diverges on temperatures
for Thursday, with confidence being tied to convective
evolution. With dew points in the 70s and temperatures likely in
the 80s, it is possible we could see some heat indices pushing
90-100F in our southern CWA on Thursday.

Looking ahead to Friday and through the weekend, the GFS and ECMWF
both cut the upper low off over the Great Lakes region which would
put us into a quieter northwest flow pattern. As a result, CAA
should keep temperatures to near normal with humidity moderating.
There will be a few slim chances for wrap-around precipitation
(<30%) over the weekend from the cut-off low, with the best chances
on Saturday.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1245 AM CDT Tue Aug 13 2024

VFR level stratocu continues to hang on along and south of I-80
and may do so through dawn. This may limit the fog in these
areas, but with some holes possible and ongoing light/variable
sfc wind regime will still advertise at least MVFR fog in these
areas. Elsewhere where there is less cloud cover, MVFR to IFR
fog pockets still possible toward dawn but the situation is a
bit uncertain. As Tuesday progresses, after any fog or temporary
low CIGs from fog lift or low stratus seep from central IA clear
out, expect a mainly VFR day into Tue evening. The light and
variable to calm sfc wind regime will trend to the southeast at
4-7 KTs by Tue afternoon.

&&

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

&&

$$

SHORT TERM...Gunkel
LONG TERM...Gunkel
AVIATION...12