Severe Thunderstorm Warning 50, NWS Des Moines, IA

127 
WWUS53 KDMX 152139
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
439 PM CDT SAT APR 15 2017

IAC025-161-152200-
/O.CON.KDMX.SV.W.0050.000000T0000Z-170415T2200Z/
Sac IA-Calhoun IA-
439 PM CDT SAT APR 15 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 500 PM CDT
FOR SOUTHEASTERN SAC AND SOUTHWESTERN CALHOUN COUNTIES...

At 438 PM CDT, a severe thunderstorm was located near Black Hawk
Lake, or 9 miles southeast of Sac City, moving northeast at 25 mph.

HAZARD...Quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Damage to vehicles is expected. 

Locations impacted include...
Lake City, Auburn and Yetter. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4223 9496 4232 9498 4245 9471 4230 9463
TIME...MOT...LOC 2138Z 247DEG 21KT 4231 9489 

HAIL...1.00IN
WIND...<50MPH
 
$$

Cogil

816 
WWUS53 KDMX 152150
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
450 PM CDT SAT APR 15 2017

IAC161-152200-
/O.CAN.KDMX.SV.W.0050.000000T0000Z-170415T2200Z/
Sac IA-
450 PM CDT SAT APR 15 2017

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN SAC COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area.  Therefore, the warning has been cancelled.

LAT...LON 4227 9485 4238 9485 4245 9471 4230 9463
TIME...MOT...LOC 2150Z 245DEG 31KT 4235 9476 

$$

IAC025-152200-
/O.CON.KDMX.SV.W.0050.000000T0000Z-170415T2200Z/
Calhoun IA-
450 PM CDT SAT APR 15 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 500 PM CDT
FOR SOUTHWESTERN CALHOUN COUNTY...

At 450 PM CDT, a severe thunderstorm was located near Lake City, or 7
miles southwest of Rockwell City, moving northeast at 35 mph.

HAZARD...Quarter size hail. 

SOURCE...Trained weather spotters. 

IMPACT...Damage to vehicles is expected. 

Locations impacted include...
Yetter.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4227 9485 4238 9485 4245 9471 4230 9463
TIME...MOT...LOC 2150Z 245DEG 31KT 4235 9476 

HAIL...1.00IN
WIND...<50MPH
 
$$

Cogil

769 
WWUS53 KDMX 152202
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
502 PM CDT SAT APR 15 2017

IAC025-152211-
/O.EXP.KDMX.SV.W.0050.000000T0000Z-170415T2200Z/
Calhoun IA-
502 PM CDT SAT APR 15 2017

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN CALHOUN COUNTY
HAS EXPIRED...
        
A new warning has been issued downstream from this warning, 
therefore the warning is allowed to expire. 

LAT...LON 4227 9485 4238 9485 4245 9471 4230 9463
TIME...MOT...LOC 2201Z 244DEG 23KT 4238 9468 

$$

Cogil

Area Forecast Discussion
National Weather Service Des Moines IA
353 PM CDT Sat Apr 15 2017

.SHORT TERM.../Tonight through Sunday/
Issued at 353 PM CDT Sat Apr 15 2017

Message of the Day: Strong to Severe Thunderstorm Potential
Hazards: Lightning, Large Hail, Damaging Winds
Confidence: Medium

Experimental GOES 16 vis/water vapor data picking up on small-scale
MCV across northern Iowa...moving out of our area. Though uncapped,
not enough energy/instability to push storms to severe levels across
our north in the near-term. Clouds associated with this MCV have
helped gunk up the warm sector all day...effectively nullifying any
differential heating support. Subjective 20z sfc analysis places
the initial trough axis boundary across NW Iowa into SE
Nebraska...and shows another meso-low located over SE Nebraska. It
is almost starting to appear as if any threat for severe wx will
be driven by this low. SPC Mesoanalysis showing the best support
of svr wx being drawn up with the instability axis associated
low. 0-6km MUCAPE values reach around 2500 J/kg and there appears
to be a pocket of 40 to 50 kt effective bulk shear being drawn
into far southern/SW IA. Additionally, SPC mesoanalysis shows a
surge of 8 to 8.5 C/km mid-level lapse rates. Low-level lapse
rates are generally minimal...struggling to exceed 6 to 7 C/km.
DCAPE values touch 1000 J/KG, and SPC Mesoanalysis points to
elevated 0-1km effective helicity...though LCL heights are close
to 1000m which is borderline. In all, am really focusing on far
southern/SW Iowa for any severe threat. All modes cannot be ruled
out, though large hail easily seems to be the primary threat.

By 09z Sun, precip generally looks to be east of our area, with high
pressure, notable dry air entrainment, and large-scale subsidence
being ushered in advance of this sfc high. Sunday looks to be a very
sunny day, with temperatures solidly in the 60s and gradually
decreasing winds.

.LONG TERM.../Sunday night through Saturday/
Issued at 353 PM CDT Sat Apr 15 2017

Zonal flow Sunday night will evolve to weak ridging on Monday,
which will provide for plenty of sunshine and above normal
temperatures. Stayed close to initial guidance for highs with
850mb temperatures ranging from 7 to 10C with return southerly
flow winds across the state. Meanwhile, a shortwave trough that
arrived on the Northwest Coast Sunday night will move eastward
across the northern Rockies and be nearing the Red River of the
North by early Tuesday. At the surface, a cold front will approach
from the west. All models show that the cold front will pass
through the area on Tuesday likely in the afternoon or evening. If
it does pass during peak heating, this gives the best
opportunity for severe weather as there are steep low-level lapse
rates that would allow for strong updrafts along with low
freezing and wet bulb zero heights for possible hail growth.

While this cold front will clear rain chances for about 24 hours or
so, another potent shortwave will begin to approach late Wednesday
and early Thursday bringing showers and storms back into the state.
Rain amounts will average between 0.5 and 1.5 inches. This shortwave
will depart as a more amplified trough enters the Rockies and moves
onto the Plains late this week and early next weekend. Timing and
placement of the surface low differ between the Euro, GFS, and
Canadian with the consensus at this point being that the low
should stay south of Iowa. The best chance for any additional
rain, therefore, looks to be over the southeastern half of the
state. With continued chances of rain through next week, rivers
will continue to be monitored for possible rises that may
necessitate river flood watches and/or warnings. As for
temperatures, above normal temperatures early in the week will
transition in the wake of Tuesday's cold front downward and may be
below climatological values by late next week and early next
weekend.

&&

.AVIATION.../For the 18Z TAFS through 18Z Sunday afternoon/
Issued at 1237 PM CDT Sat Apr 15 2017

Boom or bust TAF period as VFR conditions may ensue if
thunderstorms miss TAF sites. Overall confidence low-medium. Major
concern will be CIGs if TAF sites take direct hit. May need TEMPO
for IFR conditions for an hour or so during storms. VSBYs may also
drop to 1 mile or less during heavier storms. Right now,
confidence not high enough to include IFR at any site...beyond the
next hour or so at KFOD. On the backside between 06z and 12z
Sun...will need to watch for timing of clearing skies and
VFR...which should persist for the remainder of the TAF period.

&&

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

SHORT TERM...Kotenberg
LONG TERM...Ansorge
AVIATION...Kotenberg

Hazardous Weather Outlook
National Weather Service Des Moines IA
355 PM CDT Sat Apr 15 2017

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-162100-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun-
Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford-Carroll-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-
355 PM CDT Sat Apr 15 2017

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

A few severe thunderstorms are possible late this afternoon and
into this evening. The primary threat is ping pong sized hail with
a lesser threat being damaging wind gusts to 60 mph and perhaps
an isolated tornado. Localized flash flooding is also a threat
where rainfall from Friday and Saturday morning have created
saturated soils, which could lead to increased runoff rates.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Strong thunderstorms are possible again early Tuesday into
Tuesday night. Additional thunderstorms are possible by later
Wednesday into early Thursday. Locally heavy rainfall is possible
with each event.

.SPOTTER INFORMATION STATEMENT...

Spotter may be needed later this evening. Reports of any severe
weather and rainfall amounts and their impacts would be greatly
appreciated.

Ansorge

Special Weather Statement
National Weather Service Des Moines IA
1203 PM CDT SAT APR 15 2017

IAZ033>035-044-045-151745-
Calhoun IA-Sac IA-Webster IA-Carroll IA-Crawford IA-
1203 PM CDT SAT APR 15 2017

...Rapidly developing line of storms may produce dime size hail...

At 1201 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Rockwell City to near Denison. Movement
was east at 30 mph.

Dime size hail and winds in excess of 30 mph will be possible with
these storms.

Locations impacted include...
Fort Dodge, Denison, Rockwell City, Lake City, Manson, Lake View,
Black Hawk Lake, Fort Dodge Regional Airport, South Twin Lake, North
Twin Lake, Wall Lake, Arcadia, Breda, Vail, Twin Lakes, Auburn,
Westside, Deloit, Barnum and Knierim.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Des Moines .

&&

LAT...LON 4204 9562 4258 9440 4259 9405 4201 9516
TIME...MOT...LOC 1701Z 257DEG 26KT 4244 9457 4210 9534

Kotenberg

Special Weather Statement
National Weather Service Des Moines IA
126 PM CDT SAT APR 15 2017

IAZ034-045-151900-
Calhoun IA-Carroll IA-
126 PM CDT SAT APR 15 2017

...Rapidly intensifying storm may produce dime to nickel size
hail...

At 125 PM CDT, Doppler radar was tracking a strong thunderstorm over
Lake City, or 10 miles south of Rockwell City, moving northeast at 40
mph.

Nickel size hail will be possible with this storm.

Locations impacted include...
Lake City, Lohrville, Somers and Rinard.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Des Moines .

&&

LAT...LON 4220 9490 4221 9488 4221 9486 4222 9486
      4243 9445 4236 9440 4230 9440 4222 9467
      4212 9488
TIME...MOT...LOC 1825Z 240DEG 34KT 4225 9468

Kotenberg

Special Weather Statement
National Weather Service Des Moines IA
357 PM CDT SAT APR 15 2017

IAZ046-152130-
Greene IA-
357 PM CDT SAT APR 15 2017

...Penny to Nickel hail is Expected...

At 356 PM CDT, Doppler radar was tracking a strong thunderstorm near
Jefferson, moving northeast at 40 mph.

Nickel size hail will be possible with this storm.

Locations impacted include...
Jefferson, Grand Junction, Scranton, Paton, Dana and Jefferson
Municipal Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4221 9438 4221 9422 4205 9416 4193 9451
      4202 9459
TIME...MOT...LOC 2056Z 235DEG 36KT 4202 9449

Cogil

Special Weather Statement
National Weather Service Des Moines IA
405 PM CDT SAT APR 15 2017

IAZ033-034-152145-
Calhoun IA-Sac IA-
405 PM CDT SAT APR 15 2017

...Penny to Nickel Hail Expected...

At 404 PM CDT, Doppler radar was tracking a strong thunderstorm near
Lake View, or 11 miles southwest of Sac City, moving northeast at 30
mph.

Nickel size hail will be possible with this storm.

Locations impacted include...
Sac City, Lake City, Lake View, Black Hawk Lake, Wall Lake, Auburn,
Lytton, Yetter, Wall Lake Municipal Airport, Sac City Municipal
Airport and Blackhawk Lake State Park.

LAT...LON 4250 9484 4229 9469 4221 9495 4221 9517
      4230 9524
TIME...MOT...LOC 2104Z 241DEG 25KT 4227 9510

Cogil