575
FXUS63 KDVN 150901
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
301 AM CST Fri Nov 15 2024

.KEY MESSAGES...

- Dense fog this morning, especially along and west of the
  Mississippi River.

- Quiet start to the weekend with slightly warmer temperatures

- Active pattern from Saturday night on with the return of
  precipitation to the area, especially Monday night.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 301 AM CST Fri Nov 15 2024

Fog is the main concern in the short term. Stratus deck has
quickly eroded from west to east this morning. Temperatures
dropped to near the dewpoint leading to rapid dense fog
development, especially right after the clouds clear. Have
expanded the dense fog advisory further east and north. Could
see further extension to the river before the sun comes up. We
could see some of the vsbys go up and down, especially the
closer you get the river. There is a better trof/convergence
zone to the west of of a CID to Kahoka, MO line. This the
preferred area for longer lasting dense fog. This fog will drive
the short term weather as well as we are going into the season
of fog/clouds busting forecasts during the day.

How fast does the fog burn off is always a question this time of
year with lower sun angles and shorter days. Looking at our 00z
sounding, there are two inversions that could keep the fog/low
clouds from burning off. In fact, the HREF has lower temps today
in a nod to this scenario. Currently believe the cloud/fog
burnoff will be slow and forecast reflects this. If they do
burnoff quicker then temps will have to be raised for the day.
Winds will be stronger tonight, so fog is not expected tonight
across the area.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 301 AM CST Fri Nov 15 2024

Upper level ridging will give way to southwest flow to start the
period. A shortwave will move north of the area Saturday night
into Sunday bringing with it a slight chance for rain (15-20%).
Into the start of next week, an upper level low SW of the area
will move over the area, swinging negatively tilted as it moves
through the area. This looks to be the first decent midlatitude
system since the beginning of the month. As this low fills
another wave interacts with it from the west. Guidance shows a
large cutoff low across the area to end next week. Models do
poorly with this setup, so confidence is low in any single
solution that far out.

Looking to the first chance for precip, Saturday evening into
the overnight. Overall QPF looks light, mainly a couple of
hundredths as the main forcing will remain north of the area.
Latest NBM had removed pops from this period. The operational
runs of the the GFS/NAM/ECM/GEM all had some light QPF. As such
added slight chance to chance POPs (15-25%) into the forecast.

All attention turns to the strong system Monday and Monday
night. The main low and occluding surface low will be west of
the forecast area. That said, a strong H85 jet of 50-60 knots
will move over the area after 00z Tuesday. Warm front rain will
affect most of the area Monday. Monday evening and overnight,
the warm sector is expected to move into portions of the area.
With the surface low west of the area, the better QPF will be
across Iowa. Looking NBM prob exceedance for QPF, all of the
area will see some QPF with probabilities of exceeding half an
inch in 24 hrs ranging from 90% across the western CWA to 50% in
the eastern CWA. This should do little to affect rivers across
the area and is welcome rain to say the least.

Diving more into Monday evening, there looks to be a low end
chance for strong to severe storms in the warm sector. The GFS
has some SBCAPE (<200 J/kg) with a strongly curved low level
hodograph. CSU Machine learning severe probs brings a 5% risk of
severe storms to the area. This looks like another HSLC tornado
setup. These events are hard to predict because small changes in
the guidance can have large affects on the potential outcome. We
will have to keep an eye on this as both the ECM/GFS have
surface temps in the upper 50s to low 60s in the warm sector
that evening with an advancing warm front.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1040 PM CST Thu Nov 14 2024

Satellite imagery continues to show a large area of MVFR
stratus over eastern Iowa and northwest Illinois, with the back
edge moving closer to BRL and CID. As high pressure continues to
build in, the stratus deck will gradually break up late tonight
into early Friday AM from west to east. Clearing skies and
light winds may lead to fog development at CID and potentially
near BRL (lower chance), which could become dense for several
hours Friday morning and lead to LIFR/VLIFR conditions. After
the fog dissipates by mid Friday morning, VFR should prevail
through the afternoon.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Dense Fog Advisory until 9 AM CST this morning for IAZ076-087-
     098.
IL...None.
MO...Dense Fog Advisory until 9 AM CST this morning for MOZ009-010.

&&

$$

SHORT TERM...Gibbs
LONG TERM...Gibbs
AVIATION...Uttech