Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 220859
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
359 AM CDT SUN MAY 22 2016

.SHORT TERM.../Today/
Issued at 327 AM CDT Sun May 22 2016

Temperatures remain the only real concern today with long wave ridge
overhead and little in the way of forcing or moisture. Highs today
should be a little more homogeneous in the upper 70s and lower 80s
rather than the atypical 10 plus degree spread yesterday with lowest
readings southwest and highest northeast. Soundings still suggest
warmest readings northeast, but approaching central plains thermal
ridge should make yesterday`s gradient less pronounced.

.LONG TERM.../Tonight through Saturday/
Issued at 327 AM CDT Sun May 22 2016

we will transition to a much more active pattern beginning tonight
as the upper ridge shifts east and a Southwest flow works into
Western Iowa...possibly as far East as the Western fringe of our
forecast area. However...most of the instability will be found
over Nebraska so not really looking for much in the way of storms
tonight.

On Monday we get more into the Southwest flow and considerably
more moisture advects into Iowa. Modest instability will work into
central Iowa but deep layer shear will be marginal at best. The
frontal boundary remains to our West on Monday so while the
possibility of a strong to severe storm cannot be ruled out...the
best potential will be West and especially South of Iowa.

During the period Tuesday through Friday numerous shortwaves ride
across the region in the Southwest flow but a surface low develops
to the West and pretty much sits there through the period as a
warm front develops and lifts North across the state Tuesday into
Wednesday. The cold front which was across Eastern Nebraska
through Monday will also be edging into Iowa as well so for
Western/Southern Iowa there should be some severe storms in these
areas during this time period. Beyond Tuesday...each days severe
potential will depend on shortwave timing...what the morning
convection does and how quickly we can destabilize as well as
frontal position. We will certainly have enough shear and
instability for strong to severe storms daily across central
Iowa...especially Southern sections but there are a good amount of
uncertainties as well. We will also have to deal with heavy
rainfall and potential flooding as well due to the duration of
the precipitation but this will depend on where repeated areas of
rainfall occur and again is tough to pinpoint at this time.

Friday into next weekend look equally as unsettled but the medium
range models are all over the place with whether a closed low or
an open wave impacts Iowa. Chances for thunderstorms continue
through the period. Severe and heavy rainfall potential and
location become unclear during this period however since models
are in such big disagreement.

&&

.AVIATION.../For the 06Z TAFS through 06Z Sunday night/
Issued at 1138 PM CDT Sat May 21 2016

High pressure will shift to the East through the period keeping a
light Southwest flow and VFR conditions in place over TAF
locations.

&&

.DMX Watches/Warnings/Advisories...
None.
&&

$$

SHORT TERM...Small
LONG TERM...FAB
AVIATION...FAB



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