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FXUS63 KDMX 151731

Area Forecast Discussion
National Weather Service Des Moines IA
1131 AM CST Sun Dec 15 2019

.DISCUSSION.../Today through Saturday/
Issued at 341 AM CST Sun Dec 15 2019

Only concern wrt to precipitation this week is the incoming 
shortwave to bring light snow to far southern Iowa today into this
evening. Otherwise, temperatures return mild by mid to late week 
and conditions remain dry. 

Light snow looks to continue to develop over portions of Nebraska 
and spread east into western Iowa later this morning. Saturation 
throughout the entire column looks questionable the further north 
of Interstate 80 you go. Even though there is ice introduction 
for several hours over portions of west to northwest CWA, there 
remains a fairly deep dry layer below 850mb to the surface to 
contend with for any snow to reach the surface. Plus the forcing 
isn't great within the dendritic layer and certainly not enough to
overcome the dry layer. Thus, not expecting much accumulation 
across the aforementioned location. However, potentially could 
see a few snowflakes make it through the dry layer this morning 
through the early afternoon and have a high pop/low QPF scenario 
going for west-central to northern portions of the forecast area.
Further south, mainly along and south of Highway 34 to the 
Missouri border, has better shot at receiving some snow 
accumulation. For instance at Lamoni, the column becomes 
completely saturated by mid-afternoon as the dry layer is 
overcome by the snow due to a bit better forcing within the 
dendritic layer and decent mid-level moisture advection. Have an 
inch or two going along the far south to southeast portions of the
CWA by tonight. By around 06z and after, the column begins to lose
ice introduction from west to east and with some linger forcing 
and enough low level moisture, have mention of fzdz across the 
south. Low confidence with any significant ice amounts as 
shouldn't last long with the forcing moving east fairly quickly.

Monday through Saturday...large and slow moving surface high 
pressure builds into the region Monday and gradually shifts east 
through mid-week.  Monday will remain cool before temperatures 
rebound by Tuesday and Wednesday to above normal.  Only system to 
keep an eye on is a weak shortwave progged to move across the
state late Thursday into Friday. ECMWF and GFS are in decent 
agreement with the timing and location of the surface low that 
develops and the upper low. Plus, both agree this system is 
significantly moisture starved, so likely only a wind shift and 
slightly cooler temperatures Friday.


.AVIATION.../For the 18Z TAFS through 18Z Monday afternoon/
Issued at 1131 AM CST Sun Dec 15 2019

Light snow and low ceilings will spread across southern Iowa this
afternoon into early tonight, resulting in a period of MVFR
ceilings/visibility at DSM and OTM, and perhaps intermittent IFR
conditions at OTM, as covered in TEMPO groups. Further north any
snow will be much lighter with only VFR conditions expected into
tonight, however, early Monday morning low MVFR ceilings will move
in from Minnesota and affect MCW and likely FOD, with IFR ceilings
possible for a period at MCW but with lower confidence at this
range. Winds will be light and variable through the TAF period.




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