Hail and Damaging Wind in Iowa, April 15 to 16, 2017

Area Forecast Discussion
National Weather Service Des Moines IA
407 AM CDT Sat Apr 15 2017

.SHORT TERM.../Today through Tonight/
Issued at 406 AM CDT Sat Apr 15 2017

Convection is ongoing across the far West/Northwest ahead of a
frontal boundary in a broad area of theta-e advection and some
forcing.  A couple of weak shortwaves will pass Northeast into
Minnesota and Wisconsin and keep the showers/storms going across
this area through the morning.

The cold front will gradually push across Iowa today and be out of
the area by 09Z tonight.  The cold front will be the focus for
storms today into the evening hours.  There will be plenty of
moisture in place and soundings show a favorable shear profile for
strong updrafts.  This combined with 2000+J/Kg of CAPE across the
Southeast half of so of the state during peak heating and we will
see some strong storms this afternoon.  Large hail and damaging wind
will be the main threats. Current SPC Outlook did bring the threats
further North into Iowa but depending on the speed of the front, may
need to be brought back further West in later updates.

The front will be in the Southeast portion of the state this evening
and the severe potential will continue into the evening, though it
will be waning.  Looking for storms to be ending between 03Z and 06Z
with some lingering precip until 09Z or so. Behind the front cooler
air will begin to move in.  Lows will be in the upper 30's to mid
40's across the North.

.LONG TERM.../Sunday through Friday/
Issued at 406 AM CDT Sat Apr 15 2017

High pressure will move into the state on Sunday and will result
in a very pleasant day. Monday will be a transition day as return
flow develops as the area of high pressure moves east and lee side
cyclogenesis commences in response to an intense PV anomaly
crossing the Rockies. High temperatures on Monday will again be in
the mid 60s north to the low to mid 70s south. Kinematic forcing
associated with the PV anomaly will arrive late Monday night into
Tuesday. The surface low pressure is expected to move to the north
across South Dakota and Minnesota during this period and will drag
a cold front through Iowa by Tuesday afternoon and potential near
the peak of diurnal heating. A few severe storms will be possible
with the frontal passage.

The progressive weather pattern will continue through much of the
extended forecast. High pressure ridge will follow for early
Wednesday though theta-e advection aloft will already be ongoing
in advance of another strong short wave though will bring
increasing chances for precipitation by the afternoon and into the
overnight hours. This system could bring rainfall in excess of
one inch to portions of the state. More uncertainty exists in the
extended with a closed upper low moving across the southwest
CONUS and into the Oklahoma and Kansas regions. Currently still
have precipitation chances into northern Iowa though general
trends are further south with this system will drier air moving
into portions of Iowa. Temperatures will be mild early in the
period with highs in the 60s and 70s then falling into the 50s and
60s Wednesday through Friday.

&&

.AVIATION.../For the 06Z TAFS through 06Z Saturday night/
Issued at 1159 PM CDT Fri Apr 14 2017

Delayed the onset of MVFR ceilings as convection looks to be
slowed to develop later Saturday morning. There is some
diminishing convection in eastern Nebraska that may impact FOD and
MCW towards 10-12z Saturday and have VCTS mentioned. Otherwise,
have the MVFR ceilings introduced during the afternoon with the
main trough/cold front tracking across the state.

&&

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

SHORT TERM...FAB
LONG TERM...Donavon
AVIATION...Podrazik

Hazardous Weather Outlook
National Weather Service Des Moines IA
548 AM CDT Sat Apr 15 2017

IAZ026>028-036>039-046>050-057>062-070>075-081>086-092>097-161100-
Franklin-Butler-Bremer-Hamilton-Hardin-Grundy-Black Hawk-Greene-
Boone-Story-Marshall-Tama-Audubon-Guthrie-Dallas-Polk-Jasper-
Poweshiek-Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-Union-
Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne-
Appanoose-Davis-
548 AM CDT Sat Apr 15 2017

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

A few severe storms are possible mainly this afternoon and
evening. Damaging wind gusts to 60 mph, ping pong sized hail and
an isolated tornado are all possible.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Strong to severe thunderstorms are possible Tuesday afternoon and
evening. Large hail will be the primary threat, with damaging
winds a secondary threat. Additional thunderstorms are possible by
Wednesday afternoon and night. Locally heavy rainfall is possible
with each event.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is possible this afternoon and evening.

IAZ004>007-015>017-023>025-033>035-044-045-161100-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Sac-Calhoun-Webster-Crawford-Carroll-
548 AM CDT Sat Apr 15 2017

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

Isolated severe thunderstorms are possible today with damaging
wind gusts to 60 mph and quarter sized hail possible.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Strong thunderstorms are possible again late Monday night into Tuesday
morning. Isolated thunderstorms are possible by Wednesday
afternoon and evening. Locally heavy rainfall is possible with
each event.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.