Area Forecast Discussion
Issued by NWS Des Moines, IA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KDMX 171748

National Weather Service Des Moines IA
1248 PM CDT Mon Oct 17 2016

Issued at 1247 PM CDT Mon Oct 17 2016

Have left the early morning forecast unchanged for the most part
but have lowered highs a tad NW where persistent clouds should
keep temps down. The precip forecast is unchanged with only slight
chances far north into the early evening hours. Several convection
allowing models continue to suggest convection developing soon, if
not already, but moisture aloft seems insufficient to produce
anything elevated at the moment and surface based development
holding off until convergence and reduced inhibition can phase
north of the border into Minnesota.


.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 18Z TAFS through 18Z Tuesday/
Issued at 1247 PM CDT Mon Oct 17 2016

MVFR to IFR conditions will continue to affect roughly the
northern half of IA through the afternoon, but with gradual improvement
to mainly MVFR north by 21z. There is a low chance of convection
toward KMCW but certainly not great enough for any mention. Winds
may also gust to 30kts or more southeast toward KOTM this
afternoon during peak mixing. Confidence is medium in VFR
conditions through the end of the period with winds becoming
northwest into Tue with the passage of a cold front.





SHORT TERM...Podrazik
AVIATION...Small is the U.S. government's official web portal to all federal, state and local government web resources and services.