399
FXUS63 KDMX 081743
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1143 AM CST Wed Jan 8 2025

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- Moderating temps begin today
- Northern stream wave brings light snow Thur Night/early Friday
- Second system Sunday potential for more light snow

&&

.DISCUSSION...
Issued at 300 AM CST Wed Jan 8 2025

.Short Term /Today through Thursday/...

Confidence: Medium to High

Fairly quiet day on the way for today. Weak trough aloft is passing
south early this morning; taking the coldest air at H850 along with
it. Skies have cleared and temps are dropping to the single digits
to lower teens this morning. Today will be sunny with a few clouds
late day. Highs should top out in the lower 20s with a few sites
nearing 25 this afternoon. Winds briefly mix from the west at 10 to
20 mph this afternoon. Tonight will see increasing clouds ahead of
the next upstream wave. Though moisture is still a question mark
with the system for tomorrow into tomorrow evening, we are still
looking at the potential for a period of light snow/flurries mainly
during the afternoon and early evening. Have kept PoPs in the 30 to
40% range with the approach/passage of the trough later tomorrow.
Models indicate a fair amount of saturation at H925/H850, but are
struggling a bit with moisture at H700/H500 as the wave tracks east
through the region. Confidence is not all that high that we will see
any accumulation other than a dusting. There are also some timing
differences between the hires and synoptic solutions; with the hires
models a bit faster. After mins tonight in the lower to mid teens,
highs Thursday will reach the upper 20s to lower 30s.

.Long Term /Thursday Night through Tuesday/...

Confidence: Medium

Most of the precipitation will be out of the region by 06z with
lingering clouds overnight. Clouds will linger into Friday as colder
air and northwest flow build back across the region. Highs Friday
will drop about 3 to 5 degrees over the region. High pressure will
enter the picture for Friday evening with some clearing expected.
Mins should be able to dip to the teens over the region due to some
breaks in the cloud cover. Saturday will see another fast
approaching clipper system from the northwest and plenty of cloud
cover by the afternoon. The deterministic models are now in better
agreement regarding the track/strength of the low with the ensemble
means of both the GFS/EC now projecting a low in central/northern
Iowa by 12z Sunday. Unlike the system tracking through tomorrow
evening, much more forcing will be seen with the Sunday storm.
Though forecast mean precipitation is anticipated to be around 0.10
inches in northern Iowa and 0.10 to 0.25 in south Central MN to
western Wisconsin, there is the potential of an inch or more of
snow north of Highway 18 and perhaps 1 to 3 inches in southern MN.
Northwest winds of 15 to 25 mph behind the low may bring more
significant impacts for travel across far northern Iowa and areas
north. Will be monitoring the evolution of the data over the next
several days to see if any more southerly shift in the track occurs.
With fairly decent consistency in the ensemble guidance, it appears
that only minor tweaking will be needed going forward. Travel
interests should pay attention as this system may outperform where
the heavier snow occurs and winds combine for larger impacts.
Saturday highs should top out in the mid 20s north to the lower 30s
southwest while Sunday will be somewhat cooler north in the lower
20s and around 30 in the south. Arctic high pressure will follow
into Monday and Tuesday with colder temperatures. Highs both day
will range from the lower teens north to the lower 20s in the south.
Lows should be nearing/getting below zero over the north half while
single digits remain in the south for Tuesday morning.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1135 AM CST Wed Jan 8 2025

VFR conditions continue for the period with little to no cloud
cover as seen on satellite. Winds will switch to the southwest
this evening as a surface high pressure departs the area, but
remain at or below 10kts. Will see clouds return late in the
period from west to east as a frontal boundary enters into
western Iowa.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Castillo/Donavon
AVIATION...REV