181
FXUS63 KDVN 161910 CCA
AFDDVN

Area Forecast Discussion...CORRECTED
National Weather Service Quad Cities IA IL
210 PM CDT Fri Aug 16 2024

.KEY MESSAGES...

- Chances of showers and storms will accompany an upper-level
  low that will remain anchored over the western Great Lakes
  through late Saturday

- A Marginal Risk for strong to severe storms remains over far
  northwest Illinois this afternoon and early evening

- A dry pattern develops for next week, with seasonal
  temperatures

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 205 PM CDT Fri Aug 16 2024

After abundant sunshine this morning, we are beginning to see some
diurnal cumulus clouds percolating over our region, particularly
across our northern areas as a PVA maxima dives southeastward
towards our area on the southern side of a vertically stacked upper-
level low currently over northern Wisconsin. The main concern with
this approaching trough will be increasing chances of showers and
thunderstorms this PM, especially for areas north of Interstate 80.
Convective parameter space appears to be less favorable for strong
to severe storms compared to yesterday, with MLCAPE values up to
1000 J/kg and 0-6 km shear 25 to 35 knots progged, so a more
marginal environment for strong storms. SPC has maintained a
Marginal Risk (level 1 of 5) for severe storms later on over far
northwestern Illinois, mainly for a wind/hail threat. This activity
should linger into the evening hours before dissipating due to
increasing atmospheric stability.

Calmer conditions are expected tonight once any lingering showers
and storms diminish, but the aforementioned upper low will slowly
slide southeastward toward Lake Michigan Saturday, leading to
increasing clouds tonight and more chances of showers and storms on
Saturday. With the closer proximity of the upper low, there is a low
potential for funnel cloud development from some of the showers. RAP
NST values are fairly meager, with values no greater than 1, which
suggests a pretty low risk of funnels. However, I wouldn`t rule it
out entirely of seeing some funnels under the stronger
showers/storms. Otherwise, instability and shear appears to be more
meager compared to today, so we are not outlooked for any
strong/severe storms. Temperatures are looking pretty seasonal
overall tonight and Saturday, with highs Saturday in the upper 70s
to lower 80s and tonight`s lows in the lower to middle 60s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 205 PM CDT Fri Aug 16 2024

Although there will be lingering chances of showers and a few
thunderstorms Saturday evening, much of the long-term forecast
period should rather quiet and seasonal.

The upper-level low over the western Great Lakes will finally exit
the region to the east Saturday night, which will lead to a quieter
pattern for us. The WPC cluster analysis indicates a very consistent
signal among the GEFS, EPS, and CMCE ensembles that a large upper-
level omega blocking pattern will develop on Sunday over the central
CONUS and linger through at least Thursday. Upper-level ridging will
become established over the Front Range of the Rockies, placing our
region under an area of subsidence. This will keep our pattern dry
and quiet. Additionally, temperatures will remain seasonal, with
daytime highs in the upper 70s to lower 80s, and overnight lows in
the 50s to lower 60s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1223 PM CDT Fri Aug 16 2024

VFR conditions were observed across the area as of TAF issuance.
We are tracking an approaching trough of low pressure
from the northwest, which will bring increasing chances of
showers and perhaps a few storms, mainly for areas north of the
Highway 30 corridor. At this time, it appears most likely for
DBQ to see some showers, but confidence is a bit lower on
thunderstorm coverage, so we have kept that out of the DBQ TAF
for now. If storm coverage becomes greater than expected, a
TEMPO group for the storms would likely be needed. Otherwise,
some gusty westerly winds and increasing cloud cover are
expected this afternoon. As the system approaches from the
north, expect ceilings to lower tonight into Saturday morning,
with MVFR/IFR cigs likely. Some patchy fog can`t be ruled out
late tonight, but confidence remains low on coverage at this
time.

&&

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

&&

$$

SHORT TERM...Schultz
LONG TERM...Schultz
AVIATION...Schultz