Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 170426
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1126 PM CDT Mon Oct 16 2017

.SHORT TERM.../Tonight through Tuesday/
Issued at 350 PM CDT Mon Oct 16 2017

Very quiet this forecast period with relatively dry airmass in
place.  There will be forcing across the state this evening with the
continued warm advection but with very little moisture, the lifting
will result in very few clouds.  Thereafter, subsidence is expected
overnight into Tuesday keeping the threat of clouds and
precipitation limited.  Surface winds will remain from the southwest
to south overnight but will decrease as mixing subsides. With
thermal ridging building into the state tonight into Tuesday,
temperatures will be a good 10 degrees warmer overnight than this
morning.  The mixing on Tuesday will also help boost temperatures to
70-75 in most locations by afternoon.

.LONG TERM.../Tuesday night through Monday/
Issued at 350 PM CDT Mon Oct 16 2017

Little change in long term forecast thinking from previous shifts.
The period from Tuesday night through Friday remains quiet with
dry, mostly clear, and mild weather the rule. Only weather of note
within the seven days is associated with the passage of a deep
trough moving across the central U.S. over the weekend. The
initial shortwave on the leading flank of the trough will move
overhead late Friday, but with a relative lack of moisture in
fairly dry southerly low-level flow, only an increase in mid-level
clouds and perhaps a few sprinkles are anticipated around Friday
night. The primary trough axis will move through sometime around
Saturday night, with deeper moisture and precipitable water values
well above seasonal norms. GFS/EC/GEM all indicate sufficient
instability for thunderstorms, with a potential for locally heavy
rainfall though the system should be progressive enough to
mitigate this potential. Directional shear and overall
flow/forcing fields are not terribly supportive of severe weather
and that threat remains low. Behind the late Saturday surface
front the airmass will be modified Pacific, so once rain clears
out early Sunday temperatures will only be perhaps 10 degrees
cooler than they were on Friday, ahead of the system.

&&

.AVIATION.../For the 06Z TAFS through 06Z Tuesday night/
Issued at 1126 PM CDT Mon Oct 16 2017

Low level wind shear is the primary aviation hazard overnight with
a steep low level inversion in place. Otherwise VFR conditions
with south to southwest winds forecast. Any clouds will be AOA 20
kft.

&&

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

$$

SHORT TERM...Cogil
LONG TERM...Lee
AVIATION...Donavon



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