928
FXUS63 KDVN 151721
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1221 PM CDT Sat Jun 15 2024

.KEY MESSAGES...

- A quiet start to the weekend expected with mostly dry conditions
  through this afternoon.

- Scattered showers and storms are possible tonight into Sunday
  morning, favored across the northwest portion of the forecast
  area.

- Hot weather is expected Sunday through Tuesday with peak heat
  indices between 95 to near 100 degrees. Forecast temperatures
  drop by a few degrees for the middle to end of the week.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 315 AM CDT Sat Jun 15 2024

Today and Tonight

GOES WV imagery showed a shortwave trough over eastern Colorado
and a large MCS across portions of eastern Nebraska into north-
central Kansas. As of early this morning, SPC Mesoanalysis had
the MUCAPE gradient draped across eastern NE into northwest MO
with no instability locally where dewpoints are in the 50s to
upper 40s. CAMs are generally in good agreement on the Central
Plains convective line to weaken as it approaches central to
eastern Iowa. There are low chances for showers and isolated
storms through the day mainly across the west and northwest
counties, but forecast soundings are showing a dry sub-cloud
layer. For this reason, much of the area is expected to stay dry
through the afternoon/evening. Temperatures will range from the
low 80s north to mid/upper 80s central and south, with
comfortable humidity expected.

As the mid-level shortwave glances the area late tonight, a
period of scattered showers and storms is possible, especially
across the northern portion of the forecast area. NBM rain
chances range from near 20% along I-80 to 40-60% north of
Highway 30. The HREF has MUCAPE increasing to near 1000-1500
J/kg with 30+ kts of deep layer shear, which could support a few
strong storms with gusty winds the primary threat. Latest SPC
outlook has a Marginal Risk for severe storms along and west of
a Manchester, IA to Cedar Rapids to Memphis, MO line.

Sunday

Scattered showers and storms may linger north of I-80 during
the morning hours before shifting east and dissipating.
Otherwise, hot and humid conditions are expected with highs in
the low to mid 90s and peak heat indices between 95 to near 100
degrees, highest south of I-80. Subsidence behind the departing
shortwave should result in mainly dry conditions across the
outlook area for the afternoon. A surface low tracking near Lake
Superior will lead to breezy SW winds locally with gusts around
30 mph, providing some relief from the hot conditions. The
resultant boundary layer mixing should hold dewpoints in the
60s and prevent much of the area from reaching Heat Advisory
criteria, aside from on an isolated/brief basis.

EC and GFS ensemble mean 850mb temps near 21 C are in the
95-97th percentile and have a return interval of 1 or more
days per year, suggesting this is not an extremely unusual
event. Fairly confident in highs topping out in the low to mid
90s for most areas; much lower confidence on locations reaching
the upper 90s as shown by the NBM 50th - 75th percentiles.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 315 AM CDT Sat Jun 15 2024

Monday - Tuesday:

Hot weather continues early in the week with forecast highs in
the low to mid 90s (isolated upper 90s possible on Monday).
Dewpoints will be the main player in whether locations hit Heat
Advisory criteria (100 F). The NBM has been consistent with
afternoon dewpoints in the mid/upper 60s, yielding peak heat
indices on Monday between 95 to the lower 100s, and a little
lower on Tuesday. An increasing surface pressure gradient
between low pressure over the central and northern Plains and
high pressure along the East Coast will lead to breezy southerly
winds both Monday and Tuesday afternoon with gusts of 30+ mph,
hopefully providing a little relief from the heat!

Wednesday - Friday:

The core of the upper-level heat dome is forecast to set up
over the Eastern U.S. through the middle to end of the week,
placing eastern Iowa and northwest Illinois on the western
fringe. This may allow a surface boundary to drop in from the NW
leading to occasional chances for showers and thunderstorms.
With the increased chance for occasional rain and slightly
cooler 850mb temps, forecast highs are several degrees cooler
for the mid/late week period, yet remain in the mid 80s to lower
90s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1221 PM CDT Sat Jun 15 2024

Largely VFR conditions are expected through the TAF period. Our
main focus for this set continues to be on a round of showers
and storms expected late tonight. The latest high-resolution
models show quite a bit of spread in the areal coverage of
storms, so confidence is lower on the timing for any storms
that impact local terminals. However, CID and DBQ remain the
most likely terminals to see any storms, so continued the PROB30
groups for them, with brief MVFR/IFR conditions possible under
the heaviest storms. As we get closer to the event, TEMPOs will
likely be needed. Additionally, a 40 to 50 kt southwesterly low-
level jet is expected tonight, so we have introduced LLWS to
the TAFs to account for it. Gusty southerly winds are expected
at times, especially during the daylight hours Sunday.

&&

.CLIMATE...
Issued at 315 AM CDT Sat Jun 15 2024

Record High Temperatures:

June 16:
KMLI: 98/1918

June 17:
KBRL: 98/1944
KMLI: 98/1897

Record Warm Minimum Temperatures:

June 17:
KDBQ: 74/1921
KMLI: 78/2018

June 18:
KDBQ: 74/1921
KMLI: 77/2018

June 19:
KDBQ: 76/1931
KMLI: 78/1953

&&

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

&&

$$

SHORT TERM...Uttech
LONG TERM...Uttech
AVIATION...Schultz
CLIMATE...Uttech/Schultz