National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KDVN 171144
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
644 AM CDT Wed Apr 17 2024

.KEY MESSAGES...

- Largely dry conditions today, with only a chance of showers after
  sunrise

- Gusty west to southwest winds today around 25 to 35 mph

- Widespread chances of showers and a few storms south return
  for Thursday

- A few chilly nights are expected for Thursday night through
  the upcoming weekend, which will likely lead to our first
  frost/freeze headlines of the season

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 429 AM CDT Wed Apr 17 2024

A relatively quieter day is on tap weather-wise today, as the
area of low pressure that brought widespread severe weather
yesterday continues to lift northeastward. Early this morning,
we are monitoring a line of showers and storms that formed
along a convergence boundary ahead of an associated mid-level
PVA impulse. This line is rather thin spatially, and doesn`t
appear to have much structure to cause concern for any morning
surprise convection, but it`s possible to see some locally
strong winds and perhaps some small hail with it.

By sunrise, the surface low will be located over the
southeastern MN/west-central WI area. A few embedded PVA maxima
in the mid-levels will likely keep our region clouded over, with
a 20 to 40 percent chance of showers, with no thunderstorms
expected as instability shifts eastward. Winds will shift more
from the west to southwest direction, gusting between 25 to 35
mph for most locations, with perhaps a few isolated gusts to 40
mph. Temperatures will also be closer to seasonal averages, with
highs in the lower 60s north to the upper 60s south.

A surface high pressure ridge axis moves in briefly tonight, leading
to a period of clear and calm conditions, with lows in the 40s.
However, another system moves in for the early Thursday morning
hours. More details in the Long Term section.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 429 AM CDT Wed Apr 17 2024

Thursday starts off with increasing chances of showers across
the area and perhaps a few thunderstorms south of Interstate 80.
This is due to a shortwave trough that is progged to pass
through the area, ahead of a 100+ kt upper-level jet associated
with a higher wavelength upper trough. A 30 to 40 knot low-
level jet will also nose into our region to help enhance
convergence and forcing for ascent. Both the GEFS and ECMWF
ensembles indicate the instability gradient to set up just south
of our forecast area, so pretty limited support for convection.
Pwat values of around 1 to 1.5" will be possible, which is over
the 90th percentile of the SPC sounding climatology, so some
pretty moisture-laden air moving in. CAMs are indicating that
convective initiation will occur before sunrise Thursday morning
over southwestern Iowa, taking the shape of a small MCS, and
then follow the instability gradient southeastward towards St.
Louis. We could be brushed by a thunderstorm or two across our
south, but the bulk of the support for storms will remain out of
the area. As such, SPC has a Marginal Risk, or level 1 out of
5, for severe storms just outside of our forecast area. We will
have to watch to see if this Marginal is adjusted northward.
This system shouldn`t last too long, with precipitation ending
in the afternoon to early evening.

Once the Thursday system exits, attention quickly turns to a more
wintry feel, with a few chilly nights starting Thursday night, going
into the weekend. Despite a few shortwaves moving overhead, dry air
and strong cold air advection will help lead to lows in the 30s. The
coldest nights will be Friday night and Saturday night, with the NBM
chances of lows at or below freezing in the 50 to 80 percent range,
highest over eastern Iowa. This will likely lead to the first
frost/freeze headlines of the growing season.

Dry conditions this weekend will continue into the early part of
next week, with perhaps another chance of showers Monday night and
Tuesday.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 644 AM CDT Wed Apr 17 2024

Expect MVFR and widely scattered showers to move through the
area over the next several hours as an area of low pressure
moves across central Wisconsin. Confidence is low on IFR
ceilings occurring at local TAF terminals, although there have
been a few upstream ob sites that indicate ceilings below 1kft.
Westerly winds, gusting between 25 to 35 knots, are expected.
Eventually, the low pressure system will exit the region later
today, and ceilings will improve back to VFR and clear tonight.
Additionally, winds weaken tonight before another system moves
in Thursday.

&&

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

&&

$$

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