020 
FXUS63 KDMX 240917
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
317 AM CST Tue Jan 24 2023

.DISCUSSION.../Today through Monday/
Issued at 316 AM CST Tue Jan 24 2023

Take Home Points:

*Some fog/freezing fog this morning, mainly west
*Active pattern with multiple mainly light snow opportunities
*Normal temps rest of work week, giving way to prolonged cold period

Discussion: 

To begin, seemingly a rinse and repeat when it comes to fog/freezing 
fog with light surface flow, lingering low level moisture, and 
mostly clear skies. Mainly affecting portions of western into 
central Iowa, primarily limiting visibilities. Some deposition onto 
roadway surfaces will be possible in areas of dense fog, and cause
some slick patches. As that subsides by around mid-morning, the 
remainder of the day will be seasonable with temperatures in the 
upper 20s to mid 30s across the state. 

The overall upper level pattern will take on relatively low-
amplitude/semi-zonal look through the central conus, allowing the 
region to be influenced by compact shortwaves within the flow or 
being clipped by larger amplitude waves traversing through Canada. 
As such, an active pattern will dominate much of the rest of the 
forecast and provide multiple opportunities for light to moderate 
wintry precipitation. 

Round 1 will take place late tonight through Wednesday as a pair of 
shortwaves converge over the region. A southern stream compact 
cutoff upper low will slide NE today out of the New Mexico/West Texas 
area, concurrent with a northern steam open wave sliding SE out of 
southern Canada. The wild card here tends to remain how the two 
waves may/may not phase with one another and recent runs do not 
suggest full phasing, keeping the overall PoP progression a bit 
disjointed. Long story short, most impactful snowfall looks to 
remain just south of the state, with near advisory worthy snowfall 
possible in the SE where going forecasts are for 2-3 inches through 
the first half of Wednesday. The northern wave, much more moisture 
starved, may provide a widespread general light snowfall of under an 
inch as it slides in on the heels of the southern wave through the 
remainder of Wednesday into early Thursday. 

Round 2 comes down out of Canada late Thursday into Friday, though 
strongest and best phased lift will remain centered north of the 
area into Minnesota, waning as you work southward. Northern third 
of Iowa remains the most likely to see accumulations of an inch or 
greater, but should again struggle to do too much more than that 
with a broad lack of moisture. The more notable aspect of this wave 
will likely be the notable cold air that will filter in as the wave 
exits eastward. Buckle up for a prolonged period of cold 
temperatures, more on that in a minute. 

Round 3 work in Saturday and has the look of a potentially sneaky 
event. As this shortwave comes off the Rockies and induces Lee 
Cyclogenesis, banded snowfall may be the result over the area. There 
does appear to be marginally more moisture with this round than the 
previous two, and it would not be a big surprise if a narrow area of 
moderate snowfall results. Given the time frame, it remains too 
early to try and really hone in on an area of greatest concern, but 
something to keep a casual eye on.  

Rounds 4+ may be possible into next week, though at this point model 
consensus begins to diverge more rapidly and confidence in details 
becomes mostly futile. But there is something to latch onto in 
general... a period of prolonged cold.

While the flow pattern is not expected to be highly amplified over 
the central conus through the going forecast period and beyond, 
broad troughing across southern Canada into the northern US will 
allow cold air to infiltrate this weekend and largely remain in 
place. Depicted temperatures generally 15 to 20+ degrees below 
normal resulting in highs single digits to teens above zero and lows 
single digits below to single digits above zero. Euro/GFS 
extended/long range forecasts depict little disruption to the large 
scale pattern, preventing notable warming through the first week of 
February, before giving way mid-February with a return towards 
normal.   


&&

.AVIATION.../For the 06Z TAFS through 06Z Tuesday night/
Issued at 1136 PM CST Mon Jan 23 2023

Clearing into central sections as expected with patchy fog
developing west central near ADU; as well over northwest Iowa.
Though some indications of less widespread fog overnight, have
maintained some 3-5sm at FOD,DSM, and OTM with MVFR cigs filling
in again toward 10-12z as stratus reforms in these areas.
Confidence on coverage of dense fog still somewhat low. /rev


&&

.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...REV
DISCUSSION...Curtis
AVIATION...REV