Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 142351
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
651 PM CDT Thu Sep 14 2017

.SHORT TERM.../Tonight through Friday/
Issued at 238 PM CDT Thu Sep 14 2017

Upper ridging will be continuing to build across the eastern half
of the country as a western trof deepens into Friday. This will
continue the warm advection across the central US including Iowa
during this period. Temperatures remain well above normal during
the day with good south to southwest winds mixing nicely by
midday. GFS is by far most bullish in trying to produce
precipitation tonight into Friday morning across central Iowa.
Almost no other models display this extent of precipitation and
with forcing in generally waning overnight, the GFS seems
overdone. Have left some very low pops across the northwest
overnight, otherwise the forecast will be dry. This will persist
into Friday as the state will be in the warm sector of the system
with generally capped conditions.

.LONG TERM.../Friday night through Thursday/
Issued at 238 PM CDT Thu Sep 14 2017

Western trof will begin translating eastward on Friday night into
Saturday. The main focus for storm on Friday night will likely
remain west of the forecast area although they may begin to
impinge on western area toward daybreak. Much of the forecast area
will remain in the warm sector on Saturday ahead of an approaching
cold front. Temperatures will once again be well above normal with
strong southerly flow across the state. The front will advance
through central Iowa on Saturday night with the best threat of
storms during this time with stronger convergence along the front
and better kinematics. Flow is quite unidirectional and
instability is decent for mid September. There may be some limited
severe weather threat in the evening hours but this should pass
quickly as the storms advance quickly north and east.

Broad southwest flow continues to be advertised by both the GFS
and Euro into next week with a series of waves moving toward the
Midwest. There will be ongoing chances of storms during this time
but at various intervals that are hard to time out at this point.
This will likely lead to a forecast that sounds worse than what
will really occur. Temperatures will also remain above normal
during this time given the southwest flow aloft and near the
surface.

&&

.AVIATION.../For the 00Z TAFS through 00Z Friday evening/
Issued at 651 PM CDT Thu Sep 14 2017

There is high confidence in VFR conditions through the period with
essentially nothing beyond scattered mid clouds. The only items of
concern would be very brief high based showers near KOTM early
this evening /VCSH/ and then LLWS potential north and west
overnight due to an increasing low level jet ahead of the NE/SD/MN
frontal boundary, which has been added at KFOD and KMCW.

&&

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

&&

$$

SHORT TERM...Cogil
LONG TERM...Cogil
AVIATION...Small



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