Severe Thunderstorm Warning 54, NWS Quad Cities, IA

021 
WWUS53 KDVN 160108
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
808 PM CDT SAT APR 15 2017

IAC011-113-160200-
/O.CON.KDVN.SV.W.0054.000000T0000Z-170416T0200Z/
Benton IA-Linn IA-
808 PM CDT SAT APR 15 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM CDT
FOR BENTON AND LINN COUNTIES...

At 808 PM CDT, a severe thunderstorm was located near Newhall, or 7
miles southeast of Vinton, moving east at 30 mph.

HAZARD...60 mph wind gusts and quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees. 

Locations impacted include...
Cedar Rapids, Vinton, Marion, Hiawatha, Robins, Belle Plaine, Center
Point, Fairfax, Atkins, Central City, Springville, Palo, Shellsburg,
Newhall, Blairstown, Van Horne, Alburnett, Keystone, Norway and
Garrison.

This includes Interstate 380 between mile markers 16 and 38.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4215 9230 4223 9138 4201 9136 4195 9137
      4186 9207 4186 9230
TIME...MOT...LOC 0108Z 256DEG 24KT 4206 9196 

HAIL...1.00IN
WIND...60MPH
 
$$

ERVIN

292 
WWUS53 KDVN 160114
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
814 PM CDT SAT APR 15 2017

IAC011-113-160200-
/O.CON.KDVN.SV.W.0054.000000T0000Z-170416T0200Z/
Benton IA-Linn IA-
814 PM CDT SAT APR 15 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM CDT
FOR BENTON AND LINN COUNTIES...

At 814 PM CDT, a severe thunderstorm was located over Shellsburg, or
8 miles southeast of Vinton, moving east at 30 mph.

HAZARD...60 mph wind gusts and quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees. 

Locations impacted include...
Cedar Rapids, Vinton, Marion, Hiawatha, Robins, Belle Plaine, Center
Point, Fairfax, Atkins, Central City, Springville, Palo, Shellsburg,
Newhall, Blairstown, Van Horne, Alburnett, Keystone, Norway and
Garrison.

This includes Interstate 380 between mile markers 16 and 38.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4215 9230 4223 9138 4201 9136 4195 9137
      4186 9207 4186 9230
TIME...MOT...LOC 0114Z 253DEG 26KT 4209 9188 

HAIL...1.00IN
WIND...60MPH
 
$$

ERVIN

161 
WWUS53 KDVN 160118
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
818 PM CDT SAT APR 15 2017

IAC011-113-160200-
/O.CON.KDVN.SV.W.0054.000000T0000Z-170416T0200Z/
Benton IA-Linn IA-
818 PM CDT SAT APR 15 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM CDT
FOR BENTON AND LINN COUNTIES...

At 818 PM CDT, a severe thunderstorm was located over Palo, or 10
miles northwest of Cedar Rapids, moving east at 30 mph.

HAZARD...60 mph wind gusts and quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees. 

Locations impacted include...
Cedar Rapids, Vinton, Marion, Hiawatha, Robins, Belle Plaine, Center
Point, Fairfax, Atkins, Central City, Springville, Palo, Shellsburg,
Newhall, Blairstown, Van Horne, Alburnett, Keystone, Norway and
Garrison.

This includes Interstate 380 between mile markers 16 and 38.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4215 9230 4223 9138 4201 9136 4195 9137
      4186 9207 4186 9230
TIME...MOT...LOC 0118Z 259DEG 25KT 4206 9184 

HAIL...1.00IN
WIND...60MPH
 
$$

ERVIN

462 
WWUS53 KDVN 160125
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
825 PM CDT SAT APR 15 2017

IAC011-113-160200-
/O.CON.KDVN.SV.W.0054.000000T0000Z-170416T0200Z/
Benton IA-Linn IA-
825 PM CDT SAT APR 15 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM CDT
FOR BENTON AND LINN COUNTIES...

At 824 PM CDT, a severe thunderstorm was located over Toddville, or 7
miles northwest of Cedar Rapids, moving east at 30 mph.

HAZARD...60 mph wind gusts and quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees. 

Locations impacted include...
Cedar Rapids, Vinton, Marion, Hiawatha, Robins, Belle Plaine, Center
Point, Fairfax, Atkins, Central City, Springville, Palo, Shellsburg,
Newhall, Blairstown, Van Horne, Alburnett, Keystone, Norway and
Garrison.

This includes Interstate 380 between mile markers 16 and 38.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4215 9230 4223 9138 4201 9136 4195 9137
      4186 9207 4186 9230
TIME...MOT...LOC 0124Z 259DEG 27KT 4207 9174 

HAIL...1.00IN
WIND...60MPH
 
$$

ERVIN

691 
WWUS53 KDVN 160130
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
830 PM CDT SAT APR 15 2017

IAC011-113-160200-
/O.CON.KDVN.SV.W.0054.000000T0000Z-170416T0200Z/
Benton IA-Linn IA-
830 PM CDT SAT APR 15 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM CDT
FOR BENTON AND LINN COUNTIES...

At 830 PM CDT, a severe thunderstorm was located over Luzerne, or 10
miles northwest of Marengo, moving northeast at 35 mph.

HAZARD...60 mph wind gusts and quarter size hail. 

SOURCE...Trained weather spotters. 

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees. 

Locations impacted include...
Cedar Rapids, Vinton, Marion, Hiawatha, Robins, Belle Plaine, Center
Point, Fairfax, Atkins, Central City, Springville, Palo, Shellsburg,
Newhall, Blairstown, Van Horne, Alburnett, Keystone, Norway and
Garrison.

This includes Interstate 380 between mile markers 16 and 38.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4215 9230 4223 9138 4201 9136 4195 9137
      4186 9207 4186 9230
TIME...MOT...LOC 0130Z 245DEG 30KT 4192 9218 

HAIL...1.00IN
WIND...60MPH
 
$$

ERVIN

265 
WWUS53 KDVN 160137
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
837 PM CDT SAT APR 15 2017

IAC011-113-160200-
/O.CON.KDVN.SV.W.0054.000000T0000Z-170416T0200Z/
Benton IA-Linn IA-
837 PM CDT SAT APR 15 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM CDT
FOR BENTON AND LINN COUNTIES...

At 836 PM CDT, a severe thunderstorm was located over Luzerne, or 10 
miles northwest of Marengo, moving northeast at 35 mph. Other severe 
thunderstorms are located over portions of Linn County, near 
Alburnett through Marion.

HAZARD...60 mph wind gusts and quarter size hail. 

SOURCE...Trained weather spotters. 

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees. 

Locations impacted include...
Cedar Rapids, Vinton, Marion, Hiawatha, Robins, Belle Plaine, Center
Point, Fairfax, Atkins, Central City, Springville, Palo, Shellsburg,
Newhall, Blairstown, Van Horne, Alburnett, Keystone, Norway and
Garrison.

This includes Interstate 380 between mile markers 16 and 38.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4215 9230 4223 9138 4201 9136 4195 9137
      4186 9207 4186 9230
TIME...MOT...LOC 0136Z 243DEG 29KT 4194 9215 

HAIL...1.00IN
WIND...60MPH
 
$$

ERVIN

335 
WWUS53 KDVN 160141
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
841 PM CDT SAT APR 15 2017

IAC011-113-160200-
/O.CON.KDVN.SV.W.0054.000000T0000Z-170416T0200Z/
Benton IA-Linn IA-
841 PM CDT SAT APR 15 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM CDT
FOR BENTON AND LINN COUNTIES...

At 840 PM CDT, a severe thunderstorm was located near Belle Plaine,
or 13 miles east of Toledo, moving east at 45 mph.

HAZARD...60 mph wind gusts and quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees. 

Locations impacted include...
Cedar Rapids, Vinton, Marion, Hiawatha, Robins, Belle Plaine, Center
Point, Fairfax, Atkins, Central City, Springville, Palo, Shellsburg,
Newhall, Blairstown, Van Horne, Alburnett, Keystone, Norway and
Garrison.

This includes Interstate 380 between mile markers 16 and 38.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4215 9230 4223 9138 4201 9136 4195 9137
      4186 9207 4186 9230
TIME...MOT...LOC 0140Z 260DEG 41KT 4196 9232 

HAIL...1.00IN
WIND...60MPH
 
$$

ERVIN

121 
WWUS53 KDVN 160147
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
847 PM CDT SAT APR 15 2017

IAC011-113-160200-
/O.CON.KDVN.SV.W.0054.000000T0000Z-170416T0200Z/
Benton IA-Linn IA-
847 PM CDT SAT APR 15 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM CDT
FOR BENTON AND LINN COUNTIES...

At 847 PM CDT, a severe thunderstorm was located over Keystone, or 14
miles northwest of Marengo, moving east at 45 mph.

HAZARD...60 mph wind gusts and quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees. 

Locations impacted include...
Cedar Rapids, Vinton, Marion, Hiawatha, Robins, Belle Plaine, Center
Point, Fairfax, Atkins, Central City, Springville, Palo, Shellsburg,
Newhall, Blairstown, Van Horne, Alburnett, Keystone, Norway and
Garrison.

This includes Interstate 380 between mile markers 16 and 38.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4215 9230 4223 9138 4201 9136 4195 9137
      4186 9207 4186 9230
TIME...MOT...LOC 0147Z 260DEG 41KT 4197 9221 

HAIL...1.00IN
WIND...60MPH
 
$$

ERVIN

116 
WWUS53 KDVN 160152
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
852 PM CDT SAT APR 15 2017

IAC011-113-160200-
/O.CON.KDVN.SV.W.0054.000000T0000Z-170416T0200Z/
Benton IA-Linn IA-
852 PM CDT SAT APR 15 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM CDT
FOR BENTON AND LINN COUNTIES...

At 851 PM CDT, a severe thunderstorm was located over Keystone, or 13
miles north of Marengo, moving east at 45 mph.

HAZARD...Quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Damage to vehicles is expected. 

Locations impacted include...
Cedar Rapids, Vinton, Marion, Hiawatha, Robins, Belle Plaine, Center
Point, Fairfax, Atkins, Central City, Springville, Palo, Shellsburg,
Newhall, Blairstown, Van Horne, Alburnett, Keystone, Norway and
Garrison.

This includes Interstate 380 between mile markers 16 and 38.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4215 9230 4223 9138 4201 9136 4195 9137
      4186 9207 4186 9230
TIME...MOT...LOC 0151Z 260DEG 41KT 4198 9215 

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

ERVIN

213 
WWUS53 KDVN 160159
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
859 PM CDT SAT APR 15 2017

IAC011-113-160208-
/O.EXP.KDVN.SV.W.0054.000000T0000Z-170416T0200Z/
Benton IA-Linn IA-
859 PM CDT SAT APR 15 2017

...THE SEVERE THUNDERSTORM WARNING FOR BENTON AND LINN COUNTIES WILL
EXPIRE AT 900 PM CDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore the warning will be allowed to expire.  However heavy rain
is still possible with this thunderstorm.

LAT...LON 4215 9230 4223 9138 4201 9136 4195 9137
      4186 9207 4186 9230
TIME...MOT...LOC 0158Z 259DEG 26KT 4199 9210 

$$

ERVIN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
622 PM CDT Sat Apr 15 2017

...AVIATION UPDATE...

.UPDATE...
Issued at 448 PM CDT Sat Apr 15 2017

I have increased pops to likely much earlier in the period to
account for the thunderstorms developing over the northwest 1/2 of
the CWA. These storms by elevated nature, will primarily bring a
small hail threat, and an isolated severe hail threat.
ERVIN

&&

.SYNOPSIS...
Issued at 315 PM CDT Sat Apr 15 2017

Analysis at 2 45 PM CDT shows initial convection just starting to fire
near Missouri River Valley in Western Iowa. Pressure falls and moisture
pooling supports this to congeal and develop into a asymmetrical line
next 3-4+ hours across western Iowa and NW Missouri and move across
forecast area between 7 and 12 PM. Instabilities of 1500-2000 J/KG
with surface dewpoints upper 50s to around 60F supports severe hail
risk and bowing segments by evening with 60+ MPH winds. Upstream energy
supports a near seasonal high pressure system to migrate into region
Sunday into Monday with nice spring weather.

&&

.SHORT TERM...(This Evening through Sunday)
ISSUED AT 315 PM CDT Sat Apr 15 2017

Short term forecast confidence assessment...fair or average with main
issue locations and timing of convective elements across the region,
mainly this evening with some severe in form of hail and damaging straight
line winds.

Tonight...have likely POPS with timing from metwatch and genesis of
storms still TBD with current trend suggesting risk of strong to severe
storms passing between 7 and 12 PM. Local tools suggest hail up to
the size of ping pong balls or 1.5 inches may occur until early evening
and then lower to inch or less as bowing segments of a line take over
by mid evening. Local techniques also support instability and momentum
transfer with bowing segments to support areas of 50 to 60 MPH with
isolated 70 MPH possibly until late evening. Rainfall totals most locations
should tend to be mostly below a half inch with areas of .75 to 1+
inches where strongest cells develop with low chance of training of
storms suggested. Clearing late with cooler air support mins near 50F
far NW with near 60F far SE sections.

Sunday...High pressure to bring fair skies and nice April weather with
highs upper 60s to lower 70s and low humidity. Northwest winds of 10
to 15+ MPH to result in near ideal conditions for outside activities.

.LONG TERM...(Sunday Night through Saturday)
ISSUED AT 315 PM CDT Sat Apr 15 2017

An active weather regime will once again set up over the area from
mid to late week.  A couple of shortwaves in nearly zonal flow will
move across the region Monday night through Thursday.  The first
impulse will drive a cold front through the region Tuesday and
Tuesday night.  This system will have to be watched for severe
potential with the boundary moving through the DVN CWA during the
afternoon and evening.  Moisture return ahead of the front may be
questionable with surface ridge in place over the south
central/southeast u.s.

The cold front will stall just to the south of Iowa/nrn IL
Wednesday, then another s/w will moving out of the Rockies will
track east through the plains.  This feature will send  a surface
wave along the boundary through Ia Wednesday night spreading more
showers and storms through the region.

Models suggest a brief break in the action late Thursday then bring
more showers and isolated storms into the region a ahead of a major
trof through Friday.  Most model solutions are keeping the mid/upper
Mississippi Valley on the cool side of this system which should
limit thunderstorm coverage.

temperatures through most of the period will be typical for mid
April.  Although if the late week system tracks to the south,
clouds/rain and easterly surface flow will keep temperatures below
normal.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
ISSUED AT 620 PM CDT Sat Apr 15 2017

A cold front will bring widespread thunderstorms to eastern Iowa
and northwest Illinois through around midnight, followed by VFR
conditions behind the front. Storms will bring temporary IFR
visibility, small hail, and gusty winds. A line of storms along
the front may bring near 50KT winds as it moves through mid
evening.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

UPDATE...Ervin
SYNOPSIS...Nichols
SHORT TERM...Nichols
LONG TERM...DLF
AVIATION...ERVIN

Hazardous Weather Outlook
National Weather Service Quad Cities IA IL
1211 PM CDT Sat Apr 15 2017

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-161715-
Buchanan-Delaware-Dubuque-Benton-Linn-Jones-Jackson-Iowa-Johnson-
Cedar-Clinton-Muscatine-Scott-Keokuk-Washington-Louisa-Jefferson-
Henry IA-Des Moines-Van Buren-Lee-Jo Daviess-Stephenson-Carroll-
Whiteside-Rock Island-Henry IL-Bureau-Putnam-Mercer-Henderson-
Warren-Hancock-McDonough-Scotland-Clark-
1211 PM CDT Sat Apr 15 2017

This Hazardous Weather Outlook is for portions of north central
Illinois...northwest Illinois...west central Illinois...east
central Iowa...northeast Iowa...southeast Iowa and northeast
Missouri.

.DAY ONE...THIS AFTERNOON AND TONIGHT

Thunderstorms are expected this afternoon and tonight with the
most likely time period from 4 PM to midnight.

The main threats are large hail up to the size of 1.5 inches or
the size of ping pong balls initially, then hail and strong winds
up to 60 to 70 MPH this evening. An isolated, brief tornado is
possible, but atmospheric conditions are marginal for this to
occur.

The Storm Prediction Center has a slight risk of severe storms for
the area.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

Thunderstorms are expected at times from Tuesday into Thursday.
However, it is too early to determine the potential for severe
weather and heavy rainfall.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is expected late this afternoon and evening.
Any reports of hail and damaging winds would be appreciated.

Nichols

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
725 PM CDT SAT APR 15 2017

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

0722 PM     HAIL             3 NNE DYSART            42.21N 92.30W
04/15/2017  M0.25 INCH       BENTON             IA   TRAINED SPOTTER

&&

PETERS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
726 PM CDT SAT APR 15 2017

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

0715 PM     HAIL             S MILLERSBURG           41.57N 92.16W
04/15/2017  E0.25 INCH       IOWA               IA   EMERGENCY MNGR

&&

GROSS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
741 PM CDT SAT APR 15 2017

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

0741 PM     HAIL             4 N MARENGO             41.85N 92.07W
04/15/2017  M0.25 INCH       IOWA               IA   TRAINED SPOTTER

&&

PETERS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
748 PM CDT SAT APR 15 2017

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

0705 PM     HAIL             KESWICK                 41.46N 92.24W
04/15/2017  M1.75 INCH       KEOKUK             IA   BROADCAST MEDIA

            RELAYED FROM KCRG, TIME ESTIMATED

&&

PETERS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
749 PM CDT SAT APR 15 2017

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

0749 PM     HAIL             SW CEDAR RAPIDS         41.97N 91.67W
04/15/2017  M0.25 INCH       LINN               IA   PUBLIC

&&

PETERS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
754 PM CDT SAT APR 15 2017

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

0738 PM     HAIL             5 S URBANA              42.15N 91.88W
04/15/2017  M1.00 INCH       BENTON             IA   TRAINED SPOTTER

            TIME ESTIMATED FROM RADAR.

&&

GROSS