Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 242347

National Weather Service Des Moines IA
642 PM CDT Mon Oct 24 2016

Issued at 353 PM CDT Mon Oct 24 2016

Quiet weather is expected overnight as surface ridging continues
to depart. Initially, airmass will be quite dry across the state
but warm advection and Theta-e advection increase substantially
overnight in response to the approaching shortwave. Temperatures
will fall quickly this evening in the weak wind and relatively clear
skies but level off overnight with the increasing warm advection and
cloud cover. The leading edge of the moisture axis will be into the
southwest portion of the forecast area by Tuesday morning lifting
northeast with time. As forcing increases, a few showers are
expected to develop near this leading edge during the morning and
spread northeast with time. However, the main show with this system
is expected late afternoon into Tuesday night as the bulk of QG
forcing and surface low traverses the state.

Instability will increase during the afternoon into western IA
ahead of the approaching surface low. Convection will develop as
forcing increases by late afternoon in the west ahead of the low
and also in the north near the baroclinic zone. The instability will
be strongest just south and west of the forecast area where a few
marginally severe storm may occur on Tuesday evening. However,
given the limited instability farther east, a few strong storms
may occur in the forecast area but severe weather is not expected.
Farther north nearer the baroclinic zone, a steadier rain is
expected north of Highway 20 in the evening into the overnight
hours as strong low level moisture transport bring ample moisture
into the area. Upwards of two inches of rainfall may occur in the
north and northeast portions of the forecast area by Wednesday
morning but the recent dry conditions should limit the possibility
of flooding. The system will exit to the east of Wednesday with a
morning threat of showers, primarily east of Interstate 35 with
little precipitation after midday.

Cooler temperatures are expected on the backside of the system
into Thursday but a nice push of warmer air is expected later
Thursday into Friday as thermal ridging pushes from the Rockies
into the Missouri River Valley. There is little threat of
precipitation during this time with main jet axis and storm track
north of the state.


.AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/
Issued at 642 PM CDT Mon Oct 24 2016

Low level moisture will move into TAF locations after 09Z and lower
cigs through the morning.  As moisture increases in the afternoon
cigs will lower further as will vsbys in -RA.  Thunderstorms are
most probable over southern TAF locations aft 21Z.





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