Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 171132

National Weather Service Des Moines IA
632 AM CDT Mon Oct 17 2016

...Updated Aviation Discussion...

.SHORT TERM.../Today/
Issued at 402 AM CDT Mon Oct 17 2016

Fog looks to persist over western to northwest portions of
the forecast area through sunrise. Weak WAA has developed over the
remainder of the forecast area and has inhibited any further fog
development this morning. Even locations within the advisory,
visibility is not quite reaching criteria for an extended time
frame, but restrictions continue to be variable from clear to 1/4
mile and only trimmed off a few of the southern counties. Will
continue to monitor and likely be able to trim off some of the
eastern edges of the advisory prior to 12z.

The other concern was focused on winds and temperatures today, along
with the low potential for convection in northern Iowa. First, warm
front looks to surge northward throughout the day as the surface low
over eastern Kansas transitions east. There is some mid-level Theta-
E advection riding the strong WAA b/t 17-23z today and may spawn a
few thunderstorms over far northern Iowa. However, MCW to FRM
soundings are strongly capped (+16C at around 750mb) and have low
confidence with anything significant breaking this cap today. Thus,
lowered pops to only the northwest portion of the forecast area.

Nudged up maximum temperatures today with the strong mixing and
seemingly enough sunshine over the southern half of the CWA.
Reintroduced near record high mention as a result south of
Interstate 80.  It will be breezy today with the strong pressure
gradient and fairly deep mixing across the south.

.LONG TERM.../Tonight through Sunday/
Issued at 402 AM CDT Mon Oct 17 2016

Main upper system will pass north of the state tonight as surface
low near the twin cities this evening pulling into the upper Great
Lakes by Tuesday morning. Given the track of both surface and
upper system, best forcing will be north of the state tonight with
little threat of precipitation in Iowa. Temperatures will
initially be quite warm as thermal ridge will linger across the
state this evening. However, cold advection will intensify after
midnight as surface boundary passes through the state and
northwest winds increase. Temperatures will be 10 to 15 degrees
cooler on Tuesday but still above normal for this time of year.

Next concern will be upper trof passing through the state late
Wednesday into early Thursday. Euro is slightly more
amplified/stronger then GFS and has a few more showers across the
state than the weaker GFS. In either case, any precipitation will
be light as moisture will be limited across the state.
Temperatures will be cool into Thursday as thermal trof grazes the
northeast but warm advection will intensify later Thursday night
and continue into the weekend as thermal ridging builds toward the


.AVIATION.../For the 12Z TAFS through 12Z Tuesday morning/
Issued at 626 AM CDT Mon Oct 17 2016

LIFR fog to continue impacting MCW through around 14z this
morning. Otherwise, strong southerly winds look to develop mid to
late this morning and increase throughout the afternoon. Nudged up
wind gusts for DSM, ALO, and OTM this afternoon. Cold front
through tonight will bring some gusty winds behind the front and
introduced wind gusts to over 20 knots past 05z tonight.
Other than MCW, expecting VFR conditions through the entire TAF


Dense Fog Advisory until 9 AM CDT this morning for IAZ004-005-



SHORT TERM...Podrazik
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