Alert archive / Kansas / Tornado Watches in 2009

Tornado Watch 487

June 20, 200912 counties in Kansas

The Storm Prediction Center issued this tornado watch at Jun 20, 2009, 7:56 PM CDT for 12 counties in Kansas. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Jun 20, 2009, 7:56 PM CDT (00:56 UTC)
Expired: Jun 21, 2009, 12:57 AM CDT
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 0.5 in
Strongest gust expected: 60 kt

Counties Chase County, KS, Clay County, KS, Dickinson County, KS, Geary County, KS, Marion County, KS, McPherson County, KS, Morris County, KS, Ottawa County, KS, Pottawatomie County, KS, Riley County, KS, Saline County, KS, Wabaunsee County, KS

The radar

The Topeka radar (KTWX), 93 km from the middle of the area, began a volume at 00:58 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 40%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 20%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 10%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 60%

Warnings issued inside it

8 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Jun 20, 8:00 PM CDT	Tornado Warning	ICT	McPherson	30 min
Jun 20, 8:23 PM CDT	Severe Thunderstorm Warning	ICT	McPherson, Marion	52 min
Jun 20, 8:29 PM CDT	Severe Thunderstorm Warning	ICT	McPherson	18 min
Jun 20, 8:39 PM CDT	Tornado Warning	ICT	Marion	36 min
Jun 20, 8:51 PM CDT	Tornado Warning	TOP	Dickinson	54 min
Jun 20, 9:27 PM CDT	Tornado Warning	TOP	Morris	38 min
Jun 20, 10:31 PM CDT	Flash Flood Warning	TOP	Dickinson, Morris	3 hr
Jun 20, 10:46 PM CDT	Tornado Warning	TOP	Geary	29 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Topeka, KS (KTOP), launched 00:00Z, 0.9 hours before the alert went out and 144 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 1517 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 575 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 139 m²/s²
0-3 km storm-relative helicity: 144 m²/s²
Significant tornado parameter: 1.6
Supercell composite: 6.5

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

102 
WWUS20 KWNS 210054
SEL7  
SPC WW 210054
KSZ000-210400-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 487
NWS STORM PREDICTION CENTER NORMAN OK
755 PM CDT SAT JUN 20 2009

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF 

       A SMALL PART OF CENTRAL AND NORTHEAST KANSAS

EFFECTIVE THIS SATURDAY EVENING FROM 755 PM UNTIL 1100 PM CDT.

TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 40 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 20 MILES SOUTHWEST OF SALINA
KANSAS TO 25 MILES SOUTHEAST OF MANHATTAN KANSAS.  FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU7).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

DISCUSSION...A SMALL MCV AND AN ASSOCIATED THUNDERSTORM CLUSTER HAS
INTENSIFIED IN THE PAST 1-2 HOURS.  THE STORMS ON THE E FLANK OF THE
CLUSTER WILL CONTINUE TO INTERACT WITH THE SURFACE WARM
FRONT...WHERE LOW-LEVEL SHEAR IS STRONGEST AND BOUNDARY LAYER DEW
POINTS ARE IN THE LOW 70S.  DESPITE POOR MID LEVEL LAPSE
RATES...VERTICAL SHEAR AND MOISTURE PROFILES COULD SUSTAIN A TORNADO
AND WIND DAMAGE THREAT IN A NARROW CORRIDOR FOR THE NEXT FEW HOURS.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 23025.


...THOMPSON

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 20, 10:09 PM CDT	Mesoscale Discussion	SPC	Clay, Dickinson, Geary, Morris, Riley	66 min
Jun 21, 12:56 AM CDT	Mesoscale Discussion	SPC	Atchison, Brown, Doniphan, Jackson, Marshall, Nemaha	94 min

Nearby

Tornado Watches in Kansas, 2009 Every tornado watch in 2009

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.