National Weather Service Raw Text Product

103 
FXUS63 KDMX 141746
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1145 AM CST Wed Feb 14 2018

.SHORT TERM.../Today through Tonight/
Issued at 338 AM CST Wed Feb 14 2018

Southerly flow continued across Iowa overnight and while a large
area of high pressure remained over the far eastern CONUS.
Overnight temperatures remained in the 20s to low 30s across much
of central Iowa though a few locations across the state completely
dropped off into the teens and had fog develop, including Ames and
Iowa City to the east. Warm advection overnight around 925 mb has
created a significant inversion across the state. The inversion
will create a challenge with temperature forecasts for today as it
will be difficult to mix through much of the inversion with the
existing snow cover. Temperatures warmed better than expected on
Tuesday however, the mixing was also better than it will be today.
Therefore, have kept highs below guidance and mainly in the mid to
upper 30s north to mid to upper 40s south.

The primary challenge overnight will be fog potential. Higher dew
points will continue to advect northward. Dew points in the 30s over 
the central and south moving over the current snow cover, combined 
with additional moisture from the snow melt that will be trapped by 
the inversion, should help lead to fog development. The fog could 
potentially become dense.

.LONG TERM.../Thursday through Tuesday/
Issued at 338 AM CST Wed Feb 14 2018

The fog may linger into Thursday ahead of a boundary that will move 
through the state late in the day and into the evening. High 
temperatures will remain mild and in the 30s and 40s. The boundary 
will move through and bring a chance of light snow far north in the 
evening. Gusty northwest winds will follow with gusts over 30 mph 
likely. Friday will be much colder with highs in the teens and 20s. 
Warm advection will return this weekend with highs back into the 30s 
for Saturday then the 30s and 40s for Sunday. The next system to 
impact the state arrives Sunday night and Monday. Very mild air may 
remain across central and southeast Iowa Sunday night. Have 
increased Monday morning low temperatures but likely will need to 
raise several more degrees if this pattern holds.
This system could bring a wide variety of precipitation to Iowa.
Precipitation could range from showers and a few thunderstorms to 
snow northwest. The cooler air will remain into Tuesday with some 
precipitation chances lingering east.

&&

.AVIATION.../For the 18Z TAFS through 18Z Thursday afternoon/
Issued at 1145 AM CST Wed Feb 14 2018

IFR conditions will move into central and southern IA as low clouds 
and fog advect northward out of MO.  Still some question as to how 
far north the IFR conditions will make it but for now I have it shy 
of the highway 20 corridor.  Conditions to become MVFR aft 15Z as 
winds begin to shift to a northerly direction.

&&

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

$$

SHORT TERM...Donavon LONG TERM...Donavon AVIATION...FAB