633
FXUS63 KDVN 050554
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1154 PM CST Tue Feb 4 2025

.KEY MESSAGES...

- Winter Weather Advisory in effect for the freezing
  drizzle/rain set to impact the area tomorrow, phasing into the
  area from south to north through the day. This will lead to
  travel impacts during the afternoon and evening commute,
  especially on untreated roads.

- Another system is progged to impact the area Friday night into
  Saturday, with similar impacts to what we will see tomorrow.
  All forms of precipitation will be in play, but confidence
  remains low at this time.

- Active pattern remains in place as we go into next week, with
  temperatures remaining near to slightly above normal.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 229 PM CST Tue Feb 4 2025

Surface high pressure well north of the area continues to push east
tonight, with surface winds locally shifting easterly in response.
At the same time, we will start to see a wave develop over the
Central Rockies, progged to eject off Wednesday AM. Although, well
ahead of it, we will see WAA kick into the area tonight. Cloud cover
will slowly increase from the south through the night, continuing
the northerly expansion through the day tomorrow. With that said,
tonight will be the calm/quiet before the approaching storm system,
or dare I say actual storm. More on that below. Although tonight, we
will see temperatures largely in the 20s, with the warmest
temperatures being seen south of I-80.

Tomorrow morning, we will see the upper wave eject off of the
Rockies, with a weak surface low developing over the region. There
are some phasing differences amongst guidance, but much of guidance
continues to bring widespread light precipitation to the area by
noon. Looking at model soundings, the primary precipitation type
will be freezing drizzle or light freezing rain, especially for
areas along and north of the Highway 34 corridor in southern IA.
South of there will still see the chance of freezing drizzle/rain,
but they are expected to see temperatures approach/exceed freezing
in the afternoon. Thus, best chance for the freezing side of things
will be prior to noon and into the early afternoon. Diving deeper
into the soundings, saturation around the I-80 corridor isn`t
expected until around 3pm tomorrow, with the temperature profiles
favoring primarily freezing rain/drizzle through the event. As we
approach Highway 20, these locations will be the last to see the
precipitation move in, but also have the best chance to see light
snow mix in as well. Soundings indicate saturation aloft lasting
well into the afternoon hours, introducing ice into the clouds,
unlike those south of Highway 20. Thus, we can see some light snow
mix in, with the transitions to freezing drizzle in the evening
hours, as dry air moving in aloft depletes the ice content. Between
9pm and midnight local time tomorrow night, we will start to see the
remaining parts of this system push east of the area, leaving us dry
by the Thursday morning commute. An area-wide Winter Weather
Advisory has been issued for the impacts from the freezing
rain/drizzle, especially for our afternoon/evening commutes.

Early tomorrow morning, ahead of the main push of precipitation, we
can see a narrow band of light snow along/north of the Highway 20
corridor, as we have a bout of vorticity move through, with some
weak frontogenesis being seen. Confidence on this remains low, but
figured having Slight PoPs for the chance would be worthwhile.

Now, I know I mentioned the potential for an actual storm above.
Believe it or not, a few CAMs are introducing anywhere from 0-500
MUCAPE, mainly along and south of I-80. Thus, we may have the
potential to see some convective elements work into the area. The
favored location with current guidance would be between the I-80 and
Highway 34 corridors. The significance of these convective elements
isn`t just the slight chance for thunder, but can also result
in a brief period of elevated precipitation rates. If this
occurs while we are seeing freezing rain, this can lead to an
area of higher ice accumulation. Thus, this will be something to
keep an eye on, as we can see these higher ice accumulations
where this occurs. Best timing for thunder moving into these
areas will generally be between 3-9pm local time, as this is
when the best forcing moves through the area.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 229 PM CST Tue Feb 4 2025

Flow will remain largely zonal through the remainder of the week,
with surface high pressure passing through the region. While
cool/dry advection will remain on the back end of the system, we
will see daytime temperatures above normal once again on Thursday.
Otherwise, we will remain dry and quiet through the rest of the
week.

Our attention goes to Friday night and through Saturday, when we
expect the next system to impact the area. WAA kicks in on Friday
night, which hints that the bulk of the precipitation won`t move in
until early Saturday morning. This storm system looks quite similar
to that impacting us this Wednesday, with the northern branch of the
jet stream farther south, bringing more snow potential to the area.
Right now, this seems to be confined to our northern half of the
area, with those in the south seeing the best chance for a wintry
mix or even rain. With that said, there are still many unknowns,
especially regarding the phasing of the northern and southern
streams. With such unknowns, I will refrain from further details.
Rather, I just want to raise awareness on a similar system
impacting the area at the start of the upcoming weekend.

Beyond then, the pattern looks to continue being active. While
guidance has us on the northern end of the storm track currently,
that is due to change, given difference amongst the suite, as well
as there being plenty of time for guidance to shift.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1150 PM CST Tue Feb 4 2025

VFR conditions to begin the TAF period with easterly wind. GOES
16 Nighttime Microphysics RGB channel and surface observations
show some MVFR stratus coming off Lake Michigan that is slowly
moving east. Not anticipating this to reach the MS RVR, but will
continue to monitor for any amendments. Conditions will
deteriorate this afternoon and evening, with widespread MVFR
clouds lifting northeast over the terminals. Model soundings
suggest fzdz will be the dominant ptype late afternoon through
the evening hours, with a light glaze of icing anticipated on
most surfaces. Some IFR/LIFR cigs/vsbys are expected late in the
period, with NBM ceiling probabilities <1kft in the 40-60%
range at the moment.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Weather Advisory from noon to 9 PM CST Wednesday for
     IAZ040>042-051>054-063>068.
     Winter Weather Advisory from 9 AM to 9 PM CST Wednesday for
     IAZ076>078-087>089-098-099.
IL...Winter Weather Advisory from noon to 9 PM CST Wednesday for
     ILZ001-002-007-009-015>018.
     Winter Weather Advisory from 9 AM to 9 PM CST Wednesday for
     ILZ024>026-034-035.
MO...Winter Weather Advisory from 9 AM to 9 PM CST Wednesday for
     MOZ009-010.

&&

$$

SHORT TERM...Gunkel
LONG TERM...Gunkel
AVIATION...Gross