Alert archive / Colorado / Severe Thunderstorm Watches in 2009
Severe Thunderstorm Watch 511
The Storm Prediction Center issued this severe thunderstorm watch at Jun 25, 2009, 1:30 PM MDT for 10 counties in Colorado; 8 counties in Nebraska; Goshen County, Laramie County, Platte County, Wyoming. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 25, 2009, 1:30 PM MDT (19:30 UTC)
- Expired
- Jun 25, 2009, 8:00 PM MDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 21 counties
Adams County, CO, Arapahoe County, CO, Denver County, CO, Douglas County, CO, Elbert County, CO, Lincoln County, CO, Logan County, CO, Morgan County, CO, Washington County, CO, Weld County, CO, Banner County, NE, Box Butte County, NE, Cheyenne County, NE, Dawes County, NE, Kimball County, NE, Morrill County, NE, Scotts Bluff County, NE, Sioux County, NE, Goshen County, WY, Laramie County, WY, Platte County, WY
The radar
The Cheyenne radar (KCYS), 51 km from the middle of the area, began a volume at 19:31 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
- 20%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 30%
- 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
- 80%
Warnings issued inside it
3 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 25, 2:05 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Arapahoe, Denver | 40 min |
| Jun 25, 2:48 PM MDT | Flash Flood Warning | BOU | Adams, Arapahoe, Denver | 2 hr |
| Jun 25, 3:30 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 44 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 12:00Z, 7.5 hours before the alert went out and 190 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
- 60 J/kg
- Mixed-layer CIN
- -255 J/kg
- Mixed-layer LCL
- 2125 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 4 m²/s²
- 0-3 km storm-relative helicity
- 25 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
614
WWUS20 KWNS 251929
SEL1
SPC WW 251929
COZ000-NEZ000-WYZ000-260200-
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 511
NWS STORM PREDICTION CENTER NORMAN OK
130 PM MDT THU JUN 25 2009
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
NORTH CENTRAL INTO NORTHEAST COLORADO
NEBRASKA PANHANDLE
SOUTHEAST WYOMING
EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 130 PM UNTIL
800 PM MDT.
HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70
STATUTE MILES EAST AND WEST OF A LINE FROM 55 MILES NORTH OF
TORRINGTON WYOMING TO 10 MILES SOUTHWEST OF LIMON COLORADO. FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU1).
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 508...WW 509...WW 510...
DISCUSSION...STRONG TO SEVERE THUNDERSTORM DEVELOPMENT WILL CONTINUE
ALONG THE FRONT RANGE FROM CENTRAL CO INTO SERN WY...WITH STORMS
SHIFTING EWD INTO MODERATE INSTABILITY THROUGH THE EVENING. SHEAR
WILL BE SUFFICIENT FOR SUPERCELLS...ESPECIALLY WITH INITIAL STORMS
LATE TODAY. HOWEVER...EVOLUTION INTO CLUSTERS/LINES SHOULD OCCUR
WITH SEVERE THREAT PERSISTING OVER THE HIGH PLAINS INTO THE MID
EVENING. ALTHOUGH A BRIEF TORNADO MAY OCCUR...OVERALL THREATS
SHOULD BE FROM LARGE HAIL AND DAMAGING WINDS...ALONG WITH HEAVY
RAIN.
AVIATION...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 26015.
...EVANSSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 25, 1:06 PM MDT | Mesoscale Discussion | SPC | Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas and 13 more | 54 min |
| Jun 25, 4:22 PM MDT | Mesoscale Discussion | SPC | Adams, Arapahoe, Broomfield, Denver, Douglas, Elbert and 5 more | 53 min |
| Jun 25, 5:50 PM MDT | Mesoscale Discussion | SPC | Adams, Arapahoe, Broomfield, Denver, Douglas, Elbert and 5 more | 55 min |
| Jun 24, 9:53 PM MDT | Mesoscale Discussion | SPC | Boyd, Cedar, Dixon, Holt, Knox, Pierce | 97 min |
| Jun 24, 10:53 PM MDT | Severe Thunderstorm Watch | SPC | Antelope, Boone, Boyd, Burt, Cedar, Colfax and 23 more | 5 hr |
| Jun 25, 1:13 AM MDT | Mesoscale Discussion | SPC | Cedar, Dakota, Dixon, Wayne | 92 min |
| Jun 25, 3:49 PM MDT | Mesoscale Discussion | SPC | Crook | 56 min |
Nearby
Severe Thunderstorm Watches in Colorado, 2009Severe Thunderstorm Watches in Nebraska, 2009Severe Thunderstorm Watches in Wyoming, 2009Every severe thunderstorm 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.