Severe Thunderstorm Warning 257, NWS Des Moines, IA

441 
WWUS53 KDMX 281644
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
1144 AM CDT TUE AUG 28 2018

IAC049-281653-
/O.CAN.KDMX.SV.W.0257.000000T0000Z-180828T1715Z/
Dallas IA-
1144 AM CDT TUE AUG 28 2018

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL DALLAS 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 4207 9338 4188 9386 4202 9400 4231 9373
TIME...MOT...LOC 1643Z 228DEG 41KT 4197 9390 

$$

IAC015-079-169-281715-
/O.CON.KDMX.SV.W.0257.000000T0000Z-180828T1715Z/
Story IA-Boone IA-Hamilton IA-
1144 AM CDT TUE AUG 28 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1215 PM CDT
FOR NORTHWESTERN STORY...EASTERN BOONE AND SOUTH CENTRAL HAMILTON
COUNTIES...

At 1143 AM CDT, a severe thunderstorm was located near Boone
Speedway, or near Boone, moving northeast at 45 mph.

HAZARD...Quarter size hail.

SOURCE...Trained weather spotters.

IMPACT...Damage to vehicles is expected.

Locations impacted include...
Ames, Boone, Nevada, Story City, Roland, Gilbert, Iowa State Center,
Boone Speedway, Kelley, Luther, Boone Municipal Airport, Ledges State
Park and Ames Municipal Airport.

People attending Confirmed-- Farm Progress Show should seek safe
shelter immediately!

This includes Interstate 35 between mile markers 112 and 126.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4207 9338 4188 9386 4202 9400 4231 9373
TIME...MOT...LOC 1643Z 228DEG 41KT 4197 9390 

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

Kotenberg

256 
WWUS53 KDMX 281706
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
1206 PM CDT TUE AUG 28 2018

IAC015-079-169-281716-
/O.EXP.KDMX.SV.W.0257.000000T0000Z-180828T1715Z/
Story IA-Boone IA-Hamilton IA-
1206 PM CDT TUE AUG 28 2018

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN STORY...EASTERN
BOONE AND SOUTH CENTRAL HAMILTON COUNTIES WILL EXPIRE AT 1215 PM
CDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However small hail
is still possible with this thunderstorm.

LAT...LON 4207 9338 4188 9386 4202 9400 4231 9373
TIME...MOT...LOC 1706Z 228DEG 43KT 4214 9365 

$$

Kotenberg

Area Forecast Discussion
National Weather Service Des Moines IA
639 AM CDT Tue Aug 28 2018

.SHORT TERM.../Today through Tonight/
Issued at 357 AM CDT Tue Aug 28 2018

At 3 AM a cold front was nosing into far northwest Iowa while aloft
several weak impulses were traversing north central and northwest
Iowa and locations to the west.  Moderate instability exists across
the northwest Iowa and locations north and west of the frontal
boundary along with sufficient deep shear to the continuation of
thunderstorms through the early morning hours.  Soundings appear to
indicate an elevated warm layer above the cold front and this is
likely where storms are initiating.  As long as the shear remains,
the threat for large hail...along with some wind threat will
persist.  Somewhat troubling is that the CAM models have recently
weakened or delayed the moving of these storms into the forecast
area until 12Z or later.  Radar imagery is not confirming this as
robust storms are just a few counties away.  Movement however does
indicate that they may just graze our northwest/northern counties.
Either way, the trend is for storms to gradually weaken as the low
level jet weakens through mid morning but not before a few severe
storms make their way across northern Iowa.

Later today and especially this afternoon and evening, instability
will be very strong along and ahead of the cold front and ongoing
storms are expected to become more widespread and intensify. Further
south, in an area of warm advection ahead of the front, additional
storms will break out mid to late morning.  It is unclear at this
point if the southern area will see much convection but if they do
develop the resultant convective debris may lessen the severe threat
at least initially.  The latest CAM models suggest that even if
storms initiate in the warm sector, there will be some clearing and
time for destabilization before the front comes through later this
afternoon and evening across the southeast.  Bottom line is that is
will be a stormy day today with a severe threat far north early this
morning then southeast during peak heating into the early evening.
QPF pretty impressive as well with over an inch forecast and higher
amounts possible in stronger storms.  Not really concerned with
flash flooding at this point as higher QPF amounts progged over D1
to D3 drought areas and with crops still capable of absorbing quite
a bit of water.

Front passes through late tonight ending the threat of storms/heavy
rainfall.  The bulk of the storms should be done by 06Z with
lingering showers and a few storms through 09Z.  Cooler and less
humid air will arrive by 12Z Wednesday.

.LONG TERM.../Wednesday through Monday/
Issued at 357 AM CDT Tue Aug 28 2018

Westerly flow aloft to be in place Wednesday with the cold front
expected to bring storms chances to the area today to have pushed to
the south of the state with an area of high pressure building into
the state. This will bring dry and cool conditions as h85 temps
falling to around +10C aloft. The area of high pressure will remain
in place into Thursday before return flow sets back up and
WAA/moisture advection returns to the state Thursday night into
Friday. A weak shortwave trough will push east through the broader
westerlies aloft and bring chances for storms back to the area
Thursday night. Broad lift will remain in place into Friday/Saturday
with a broad upper level trough across the central US and a sfc
trough axis in place across the state. This will allow for continued
chances for storms to end the week and into the weekend. The weakly
defined surface boundary to linger across the south into Sunday with
high pressure sliding across the northern portion of the state. This
should confine the better chances for precip to the central/south
late in the weekend. The boundary to then lift back to the north
into early next week with continued chances for storms with general
troughiness in the western US and westerly to southwesterly flow
aloft across Iowa.

Temperatures will initially be cooler across the state Wednesday
with the cool airmass in place aloft with highs expected to top out
in the low to mid 70s and lows in the 50s. Slightly warmer
conditions into Thursday with highs in the mid 70s to around 80,
with a return to mainly low to mid 80s expected for late this week
and into the weekend. Humidity will return to the area Friday and
beyond as dewpoints climb back into the upper 60s to lower 70s.

&&

.AVIATION.../For the 12Z TAFS through 12Z Wednesday morning/
Issued at 639 AM CDT Tue Aug 28 2018

Cold front to slowly move across TAF locations today.  Strong
thunderstorms with large hail possible across far northern Iowa this
morning before weakening some.  Additional strong storms tied to
frontal boundary in the afternoon with peak heating across eastern
TAF locations possibly impacting KDSM as well...especially early on.
Front to move out of the state after 09Z with improving conditions.

&&

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

&&

SHORT TERM...FAB
LONG TERM...Beerends
AVIATION...FAB

Hazardous Weather Outlook
National Weather Service Des Moines IA
405 AM CDT Tue Aug 28 2018

IAZ028-037>039-048>050-059>062-070>075-081>086-092>097-291100-
Bremer-Hardin-Grundy-Black Hawk-Story-Marshall-Tama-Dallas-Polk-
Jasper-Poweshiek-Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-
Union-Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne-
Appanoose-Davis-
405 AM CDT Tue Aug 28 2018

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

Strong to severe thunderstorms will be possible by mid to late
afternoon into tonight. The primary threats are damaging winds
and large hail, but an isolated tornado or two cannot be ruled
out. Locally heavy rainfall is also possible.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Periodic chances for storms return Thursday night through
Monday. The threat of severe weather is low at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters are likely to be needed this afternoon into tonight.

IAZ004>007-015>017-023>027-033>036-044>047-057-058-291100-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Franklin-Butler-Sac-Calhoun-Webster-
Hamilton-Crawford-Carroll-Greene-Boone-Audubon-Guthrie-
405 AM CDT Tue Aug 28 2018

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

Thunderstorms are possible today into tonight. A strong to
possibly severe storm is possible early this morning. Large
hail or damaging wind gusts are the main threat early this
morning. Otherwise a strong storm may be possible with gusty
winds and small hail from late morning through this evening.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Periodic chances for storms return Thursday night through
Monday. The threat of severe weather is low at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed early this morning, otherwise
it is not anticipated.

MJB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1047 AM CDT TUE AUG 28 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0806 AM     HAIL             GARNER                  43.10N 93.60W
08/28/2018  M3.00 INCH       HANCOCK            IA   PUBLIC

            DELAYED REPORT, TIME ESTIMATED - VIA
            BROADCAST SOCIAL MEDIA.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1105 AM CDT TUE AUG 28 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0755 AM     HAIL             WESLEY                  43.09N 93.99W
08/28/2018  E2.50 INCH       KOSSUTH            IA   TRAINED SPOTTER

            DELAYED REPORT.

&&

Special Weather Statement
National Weather Service Des Moines IA
1109 AM CDT TUE AUG 28 2018

IAZ058-059-071-072-281645-
Guthrie IA-Adair IA-Madison IA-Dallas IA-
1109 AM CDT TUE AUG 28 2018

...Penny to Dime Size Hail Possible...

At 1108 AM CDT, Doppler radar was tracking a strong thunderstorm near
Greenfield, moving northeast at 45 mph.

Dime size hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
West Des Moines, Winterset, Adel, Stuart, Earlham, De Soto, Van
Meter, Redfield, Dexter, Diamondhead Lake, Winterset-Madison County
Airport and Badger Creek State Park.

LAT...LON 4128 9446 4171 9416 4147 9379 4143 9379
      4120 9432
TIME...MOT...LOC 1608Z 225DEG 41KT 4130 9435

Kotenberg

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1125 AM CDT TUE AUG 28 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1114 AM     HAIL             8 ENE GREENFIELD        41.36N 94.32W
08/28/2018  E0.75 INCH       ADAIR              IA   AMATEUR RADIO

            AROUND 4 MINUTES OF DIME TO PENNY SIZED
            HAIL.

&&

SS

Special Weather Statement
National Weather Service Des Moines IA
1125 AM CDT TUE AUG 28 2018

IAZ036-047-048-059-281715-
Hamilton IA-Story IA-Boone IA-Dallas IA-
1125 AM CDT TUE AUG 28 2018

...Dime to Nickel Size Hail Possible...

At 1125 AM CDT, Doppler radar was tracking a strong thunderstorm over
Perry, moving northeast at 55 mph.

Nickel size hail will be possible with this storm.

Locations impacted include...
Ames, Boone, Perry, Nevada, Madrid, Gilbert, Woodward, Iowa State
Center, Boone Speedway, Minburn, Kelley, Bouton, Luther, Perry
Municipal Airport, Boone Municipal Airport, Ledges State Park and
Ames Municipal Airport.

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.

&&

LAT...LON 4204 9341 4186 9378 4186 9382 4185 9382
      4171 9410 4182 9422 4226 9375
TIME...MOT...LOC 1625Z 231DEG 47KT 4184 9410

Kotenberg

Special Weather Statement
National Weather Service Des Moines IA
1127 AM CDT TUE AUG 28 2018

IAZ017-026-027-281715-
Cerro Gordo IA-Franklin IA-Butler IA-
1127 AM CDT TUE AUG 28 2018

...Dime to Nickel Size Hail Possible...

At 1127 AM CDT, Doppler radar was tracking a strong thunderstorm 8
miles west of Hampton, moving northeast at 45 mph.

Nickel size hail and winds in excess of 30 mph will be possible with
this storm.

Rainfall amounts up to one inch will be possible with this storm.

Locations impacted include...
Hampton, Sheffield, Rockwell, Latimer, Coulter, Alexander, Chapin,
Aredale, Dougherty, Hampton Municipal Airport and Beeds Lake State
Park.

LAT...LON 4291 9303 4291 9283 4264 9336 4274 9350
      4280 9350 4315 9302
TIME...MOT...LOC 1627Z 226DEG 41KT 4279 9336

Kotenberg