Alert archive / Colorado / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 784
The Storm Prediction Center issued this severe thunderstorm watch at Aug 17, 2011, 6:37 PM MDT for 6 counties in Colorado. It took effect at Aug 17, 2011, 7:09 PM MDT. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 17, 2011, 6:37 PM MDT (00:37 UTC)
- In effect from
- Aug 17, 2011, 7:09 PM MDT
- Expired
- Aug 17, 2011, 10:00 PM MDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 65 kt
Counties Baca County, CO, Bent County, CO, Kiowa County, CO, Las Animas County, CO, Otero County, CO, Prowers County, CO
The radar
The Pueblo radar (KPUX), 107 km from the middle of the area, began a volume at 00:37 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
- 10%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
1 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 17, 6:53 PM MDT | Severe Thunderstorm Warning | PUB | Bent, Crowley, Kiowa, Otero, Prowers | 52 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
Denver, CO (KDNR), launched 00:00Z, 0.6 hours before the alert went out and 218 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.
- Mixed-layer CAPE
- 6 J/kg
- Mixed-layer CIN
- -104 J/kg
- Mixed-layer LCL
- 4056 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- -4 m²/s²
- 0-3 km storm-relative helicity
- 59 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
226
WWUS20 KWNS 180036
SEL4
SPC WW 180036
COZ000-180400-
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 784
NWS STORM PREDICTION CENTER NORMAN OK
635 PM MDT WED AUG 17 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
SOUTHEAST COLORADO
EFFECTIVE THIS WEDNESDAY EVENING FROM 635 PM UNTIL 1000 PM MDT.
HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 55
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES SOUTHWEST
OF LA JUNTA COLORADO TO 40 MILES EAST SOUTHEAST OF LAMAR
COLORADO. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.
OTHER WATCH INFORMATION...CONTINUE...WW 783...
DISCUSSION...STORMS ARE BECOMING BETTER ORGANIZED INTO AN ARCING
LINE APPROACHING THE AR RIVER VALLEY AS CONVERGENCE INCREASES ALONG
INTERSECTING OUTFLOW BOUNDARIES. MOIST UPSLOPE LOW LEVEL FLOW AND A
DEEP WELL-MIXED BOUNDARY LAYER WILL ENHANCE POTENTIAL FOR DAMAGING
WIND GUSTS AND OCCASIONAL HAIL AS THE LINE MOVES SEWD OVER THE NEXT
SEVERAL HOURS.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 29020.
...WEISSSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 17, 6:19 PM MDT | Mesoscale Discussion | SPC | Baca, Bent, Crowley, Kiowa, Otero, Prowers | 56 min |
| Aug 17, 9:17 PM MDT | Mesoscale Discussion | SPC | Baca, Prowers | 58 min |
Nearby
Severe Thunderstorm Watches in Colorado, 2011Every severe thunderstorm watch in 2011
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.