000
FXUS63 KDVN 181142
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
642 AM CDT Thu Apr 18 2024

.KEY MESSAGES...

- Widespread chances of showers and a few thunderstorms will
  move through the area today, with perhaps a strong to severe
  storm or two for areas along and south of US Highway 34 this
  afternoon

- Our first of several chilly nights develops tonight, with
  frost/freeze headlines likely needed at times through the
  weekend

- Generally dry conditions expected throughout the long term
  period, with another system moving in for Monday night and
  Tuesday

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 411 AM CDT Thu Apr 18 2024

After a quiet and calm early morning, we are now beginning to see
light rain showers moving into our southwestern areas. This is
associated with a large upper-level trough that is established
across the far northwestern CONUS region. A mid-level shortwave
is just starting to move in, along with a southerly 30 to 40
knot low-level jet nosing into our area. This activity will
continue to expand over the next several hours. So far, there
hasn`t been any evidence of lightning, per the GOES-East GLM
Flash Extent Density imagery. The latest HREF ensemble most-
unstable CAPE progs indicate the instability gradient to remain
to our south well into Missouri, although we could see some
modest instability lifting northward this morning. The latest
CAM guidance is suggesting that this morning`s precipitation
will be one of two rounds of showers and perhaps a few
thunderstorms to move through our area today. The break in
between these two rounds appears to occur right around noon
before a second round moves in this afternoon. This second round
appears to have more support for thunderstorms, thanks to
stronger upward vertical motion and slightly higher surface dew
points. If storms do develop, they are most likely south of
Interstate 80. A tight baroclinic zone will also develop across
our southeast this afternoon, which should establish
frontogenetical forcing to help enhance lift. Instability is
expected to remain quite modest this afternoon, but with the
more favorable shear and aforementioned enhanced lift, storms
could become more robust this afternoon with the second round.
SPC continues to outline areas along and south of US Highway 34
in a Marginal Risk (level 1/5) for a severe storm or two, with
large hail and locally strong winds as the main threats. A
Slight Risk (level 2/5) remains just to our south. Pwat values
between 1 to 1.50 inches will be maximized across our south, so
most locations will see between 0.50 to 1.50 inches of rainfall
in total with today`s rain - a beneficial rainfall for those
areas still impacted by drought.

Precipitation from the second round will come to an end by this
afternoon and early evening, leading to a dry and mostly calm night.
We continue to watch our first potential for frost during the
growing season tonight, and we have temperatures in the 30s
forecast, coolest in northeastern Iowa. The window for frost
potential is a bit short, mainly for after midnight tonight
through sunrise, but winds are expected to quickly taper off
during that time frame with clear skies, supporting frosty
conditions.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 411 AM CDT Thu Apr 18 2024

Friday through Monday will see dry conditions. The main focus for
this time frame will be a few chilly nights Friday, Saturday, and
Sunday nights. Models suggest we will have zonal flow aloft, along
with a large area of high pressure that will settle across the
central CONUS. Confidence in frost Friday night/Saturday morning is
a bit lower, as we will be contending with stronger winds and cloud
cover in some parts of our area, which should inhibit radiational
cooling/frost development. However, confidence is much higher for a
freeze Saturday night/Sunday morning, with more ideal radiational
cooling conditions. In fact, the NBM probabilities of low
temperatures at or below freezing Saturday night/Sunday morning are
between 70 to 100 percent across northeastern Iowa. Be on the
lookout for any frost/freeze headlines issued this weekend!

A mid-level shortwave is progged to move through the area
Monday night and Tuesday. Per the GEFS and ECMWF ensemble low
tracks, an attendant surface low will translate north of our
region during that time, as it pulls some decent moisture
northward. At this time, it appears to be mainly showers with
perhaps some isolated storms with it. After the system passes
through, dry conditions are likely to prevail through mid-week.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 642 AM CDT Thu Apr 18 2024

Light to moderate rain, with an isolated storm or two, will
continue to expand northeastward this morning. This will
actually be one of two rounds of showers/storms to move through
the area today, so there will be a brief respite from activity
late this morning and early afternoon. Confidence is high for
MVFR/IFR ceilings with this activity. There remains uncertainty
on the exact timing and location of any thunderstorms that
develop, but confidence in storms is highest for MLI and BRL. If
any storms move over the terminals, IFR visibilities are
expected. Otherwise, vsbys will be MVFR in the showers. This
activity will come to an end late this afternoon and evening
from west to east, leading to VFR tonight.

&&

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

&&

$$

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