Alert archive / Colorado / Tornado Watches in 2007
Tornado Watch 511
The Storm Prediction Center issued this tornado watch at Jul 11, 2007, 6:12 PM MDT for 4 states. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 11, 2007, 6:12 PM MDT (00:12 UTC)
- Expired
- Jul 12, 2007, 12:00 AM MDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 23 counties
Adams County, CO, Arapahoe County, CO, Cheyenne County, CO, Kit Carson County, CO, Logan County, CO, Morgan County, CO, Phillips County, CO, Sedgwick County, CO, Washington County, CO, Weld County, CO, Yuma County, CO, Cheyenne County, KS, Greeley County, KS, Sherman County, KS, Wallace County, KS, Banner County, NE, Cheyenne County, NE, Dundy County, NE, Kimball County, NE, Scotts Bluff County, NE, Goshen County, WY, Laramie County, WY, Platte County, WY
The radar
The Cheyenne radar (KCYS), 80 km from the middle of the area, began a volume at 00:13 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
- 30%
- One or more EF2 to EF5 tornadoes
- 10%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 95%
Warnings issued inside it
4 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 11, 7:07 PM MDT | Severe Thunderstorm Warning | BOU | Washington | 24 min |
| Jul 11, 7:52 PM MDT | Severe Thunderstorm Warning | CYS | Laramie | 23 min |
| Jul 11, 8:21 PM MDT | Severe Thunderstorm Warning | CYS | Laramie | 39 min |
| Jul 11, 8:32 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 43 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, 0.2 hours before the alert went out and 122 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
- 320 J/kg
- Mixed-layer CIN
- -152 J/kg
- Mixed-layer LCL
- 2266 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 33 m²/s²
- 0-3 km storm-relative helicity
- 103 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.1
The text
As transmitted, in the capitals the NWS used until 2016.
000
WWUS20 KWNS 120017
SEL1
SPC WW 120017
COZ000-KSZ000-NEZ000-WYZ000-120600-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 511
NWS STORM PREDICTION CENTER NORMAN OK
615 PM MDT WED JUL 11 2007
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
NORTHEAST COLORADO
NORTHWEST KANSAS
SOUTHWEST NEBRASKA
SOUTHEAST WYOMING
EFFECTIVE THIS WEDNESDAY NIGHT FROM 615 PM UNTIL MIDNIGHT MDT.
TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 65 STATUTE
MILES EAST AND WEST OF A LINE FROM 30 MILES WEST NORTHWEST OF
TORRINGTON WYOMING TO 40 MILES SOUTH OF BURLINGTON COLORADO. FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU1).
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.
OTHER WATCH INFORMATION...CONTINUE...WW 509...WW 510...
DISCUSSION...TSTMS/POSSIBLE SUPERCELLS EXPECTED TO INCREASE OVER WW
AREA THIS EVENING AS MOIST SELY UPSLOPE FLOW PERSISTS BENEATH 30-40
KT NWLY MID LVL FLOW. LOW LEVEL DIRECTIONAL SHEAR AND MODEST T/TD
SPREADS SUGGEST A THREAT FOR TORNADOES IN ADDITION TO LARGE
HAIL/WIND. GRADUAL INCREASE IN LOW LVL MOISTURE AND NOCTURNAL
STRENGTHENING OF SSWLY LLJ SUGGEST POSSIBLE UPSCALE GROWTH INTO AN
MCS WITH A CONTINUED THREAT FOR HAIL/WIND ESE INTO KS.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 32025.
...CORFIDISPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 11, 8:38 PM MDT | Mesoscale Discussion | SPC | Cheyenne, Kit Carson, Logan, Morgan, Phillips, Washington and 2 more | 97 min |
| Jul 11, 9:17 PM MDT | Mesoscale Discussion | SPC | Baca, Bent, Crowley, Elbert, El Paso, Huerfano and 7 more | 88 min |
| Jul 12, 12:36 PM MDT | Mesoscale Discussion | SPC | Logan, Phillips, Sedgwick, Weld | 84 min |
| Jul 12, 1:03 PM MDT | Severe Thunderstorm Watch | SPC | Boulder, Larimer, Logan, Morgan, Phillips, Sedgwick and 2 more | 7 hr |
| Jul 12, 3:55 PM MDT | Mesoscale Discussion | SPC | Cheyenne, Elbert, Kit Carson, Lincoln, Washington, Yuma | 95 min |
| Jul 12, 4:19 PM MDT | Severe Thunderstorm Watch | SPC | Adams, Arapahoe, Cheyenne, Elbert, Kit Carson, Lincoln and 1 more | 7 hr |
| Jul 12, 5:36 PM MDT | Mesoscale Discussion | SPC | Boulder, Larimer, Logan, Morgan, Phillips, Sedgwick and 1 more | 54 min |
| Jul 12, 12:31 AM MDT | Mesoscale Discussion | SPC | Barber, Barton, Clark, Comanche, Cowley, Edwards and 21 more | 2 hr |
| Jul 12, 4:34 AM MDT | Mesoscale Discussion | SPC | Barber, Clark, Comanche, Harper, Kingman, Kiowa and 2 more | 2 hr |
| Jul 12, 2:41 PM MDT | Mesoscale Discussion | SPC | Clark, Grant, Haskell, Meade, Morton, Seward and 1 more | 2 hr |
| Jul 12, 4:54 PM MDT | Severe Thunderstorm Watch | SPC | Barber, Clark, Comanche, Edwards, Finney, Ford and 19 more | 7 hr |
Nearby
Tornado Watches in Colorado, 2007Tornado Watches in Nebraska, 2007Tornado Watches in Kansas, 2007Every tornado watch in 2007
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.