Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 171956
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
256 PM CDT Fri Mar 17 2017

.SHORT TERM.../Tonight through Saturday/
Issued at 255 PM CDT Fri Mar 17 2017

Main concern in shorter term will be status and its affect on
temperatures overnight. Currently, breezy northwest surface winds
across the state this afternoon with mild temperatures in most
locations. Push of cooler air is arriving in northern Iowa this
afternoon with status from South Dakota and Minnesota. These
clouds will drop down into the northern half of the state by this
evening and should linger through much of the night. This will
also help keep winds mixed in the north and limit cooling.
However, some shorter term guidance would suggest clearing by
daybreak which would allow readings to drop nicely prior to
sunrise. Therefore, will remain near guidance for lows overnight
given the uncertainty in cloud cover. Otherwise, some gradual
clearing in the northeast is expected on Saturday with surface
ridge entering the west by afternoon. Nice temperature gradient
will exist across the state by afternoon with southwest areas into
the upper 50s with the northeast holding near 40.

.LONG TERM.../Saturday night through Friday/
Issued at 255 PM CDT Fri Mar 17 2017

Warm advection will intensify Saturday night into Sunday as
surface ridge slides to the east and southerly winds strengthen.
Thermal ridge will push into the west by afternoon and anticipate
readings near 70 in the west with 50s in the northeast with any
remaining snowpack quickly dissipating. Surface front will advance
into the state late Sunday afternoon into the evening and will
initially be dry. However, some convection is expected to develop
by mid evening across the southeast half of the state where cap
weakens allowing storms to form. While instability isn`t overly
strong, sufficient shear may allow a few to produce some
marginally severe hail during the evening.

Cooler air then spreads into the state Sunday night into Monday
behind the surface front with cooler readings into early next
week. However, models continue to indicate a western trof ejecting
toward the central United States in the later half of the work
week. Warm advection will increase ahead of this system with
moisture streaming northward. Current indications are Iowa will
be in the warm sector of this system with mainly rain and
thunderstorms chances. However, some track adjustment remains
likely and will continue to monitor for any changes that may
complicate the precipitation type for later in the week.

&&

.AVIATION.../For the 18Z TAFS through 18Z Saturday afternoon/
Issued at 255 PM CDT Fri Mar 17 2017

Main concern will be status deck dropping into northern Iowa this
afternoon and lingering through the night. Have continued with
widespread VFR conditions at northern sites overnight with some
improvement after daybreak. Visibilities will be unrestricted for
the duration of the forecast with brisk northwest surface winds
overnight but beginning to weaken toward the end of the period as
surface ridging approaches.

&&

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

&&

$$

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



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