Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 231715
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1215 PM CDT Sat Mar 23 2024

.KEY MESSAGES...

- Chance (20-40%) for light snow tonight across portions of
  eastern Iowa and northwest Illinois.

- Active weather is expected Sunday through Tuesday morning,
  with widespread precipitation and strong winds.

- Potential for thunderstorms Sunday night and Monday with a few
  strong storms possible on Monday.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 337 AM CDT Sat Mar 23 2024

Dry and cooler than normal conditions are on tap today, as surface
high pressure ridging builds into the area. Despite sunshine,
highs will be limited in the 30s in the snow covered areas
north with highs around 40 to the mid 40s elsewhere. This afternoon
will bring an increase in mid/high cloudiness ahead of our next
system.

Tonight, a longwave trough will advance through the Intermountain
West. This will lead to low pressure developing along the Lee
of the Rockies. A lead shortwave embedded within the developing
broad southwesterly flow aloft is progged to eject across the
region overnight through Sunday morning. The combination of the
two will foster a strengthening low level warm advection regime.
Initially low level moisture will be limited with a
strengthening east-southeast flow from the departing surface
ridge. Thus, any precipitation with this wave will be fighting
the lower level dry air, but there is some signal in the
guidance that top down saturation may be sufficient for some
light snow to develop across portions of eastern Iowa into
northwest Illinois later this evening and overnight. Due to
saturation concerns have kept PoPs in the 20-40% range. Accums
up to around an inch are possible. Then, late tonight with a
veering low level jet there is also a signal for potentially a
few showers (20-30% and mainly rain) to develop on the back
side of the warm advection wing into SE Iowa, NE Missouri and
WC Illinois. Temperatures look to bottom out by mid to late
evening from the mid 20s to mid 30s from north to south, then
hold steady to rise a bit overnight in the warm advection, as
winds turn gusty at times from the E/SE.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 337 AM CDT Sat Mar 23 2024

The aforementioned upper level trough and attendant surface
cyclone will eject northeastward Sunday night into Tuesday,
bringing eventual widespread rain. Initially, the main moist
conveyor and theta-e fetch and forcing for ascent will be
focused to our west through the Central/Northern Plains. Some
precipitation may brush west/north sections of the service area
on Sunday, of which could be light snow or a rain/snow mix
before thermal profiles have warmed enough to support rain by
late Sunday PM. Any additional snow accums would be light and
an inch or less our portions of the north/west.

The main window for widespread precipitation /rain/ looks to
develop by late Sunday night through Monday night, as the
synoptic scale ascent ramps up ahead of the ejecting trough
and interacts with Gulf moisture and a PWAT feed of around
1 inch. This will bring rounds of showers and even a few
embedded thunderstorms. There is also the potential for some
strong storms by Monday afternoon ahead of the surface low.
Strengthening wind fields will lead to plenty of deep-layer
shear. The uncertainty lies with how much instability will be
present. Some of the guidance is suggesting potential for
SBCAPEs on the order of 500-1000 j/kg in the evolving warm
sector, more than enough to support a few organized storms in
a HSLC environment, mainly west of the Mississippi River ahead
of the triple point. This potential will continue to be
evaluated over the next couple of days, so stay tuned!

Bouts of windy conditions are also on tap Sunday night through
Monday in the strengthening surface pressure gradient.
GFS and EC ensembles don`t show much in the way of probability
of gusts exceeding 34 kt, and the BUFR soundings from
deterministic guidance shows generally 25 to 30+ kt through
the mixed layer. Stronger winds 40-45+ kt are noted further
aloft, but uncertainty on whether those can be readily tapped
due to clouds and precipitation. Another bout of stronger winds
arrives by Tuesday in the cold advection in the wake of the
departing system. This will lead to a period of below normal
temperatures midweek. However, another system developing in
the west by late next week will lead to southwesterly flow aloft
and a warming trend heading into Easter weekend. It also looks
to bring a return of active/unsettled weather.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1213 PM CDT Sat Mar 23 2024

Good flying conditions expected into this evening, with light
winds.

Tonight, strengthening warm advection will bring lowering
ceilings still predominantly VFR, with a low chance (20-40%) of
MVFR ceilings at DBQ developing after 04z. There will also
be a chance of light snow/flurries at DBQ, CID, MLI by late
evening into the overnight, while a rain shower/sprinkles will
be possible at BRL. This potential is handled with PROB30
mention. Winds tonight will increase from the E/SE at around
10-15+ kt.

By sunrise Sunday, increased surface winds from the southeast at
15 to 25 kts are expected, with generally VFR cigs around
8000-10000 ft.


&&

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

&&

$$

SHORT TERM...McClure
LONG TERM...McClure
AVIATION...Ervin


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