Alert archive / Arkansas / Tornado Watches in 2011
Tornado Watch 878
The Storm Prediction Center issued this tornado watch at Nov 8, 2011, 7:04 PM CST for 19 counties in Arkansas; Dunklin County, Pemiscot County, Missouri. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Nov 8, 2011, 7:04 PM CST (01:04 UTC)
- Expired
- Nov 8, 2011, 9:26 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
All 21 counties
Clay County, AR, Craighead County, AR, Crittenden County, AR, Cross County, AR, Faulkner County, AR, Greene County, AR, Jackson County, AR, Lee County, AR, Lonoke County, AR, Mississippi County, AR, Monroe County, AR, Phillips County, AR, Poinsett County, AR, Prairie County, AR, Pulaski County, AR, Saline County, AR, St. Francis County, AR, White County, AR, Woodruff County, AR, Dunklin County, MO, Pemiscot County, MO
The radar
The Little Rock radar (KLZK), 92 km from the middle of the area, began a volume at 01:07 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
- 20%
- Ten or more severe wind reports
- 10%
- One or more gusts of 65 knots or more
- 5%
- Ten or more severe hail reports
- 5%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 30%
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Little Rock, AR (KLZK), launched 00:00Z, 1.1 hours before the alert went out and 138 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
- 682 J/kg
- Mixed-layer CIN
- -21 J/kg
- Mixed-layer LCL
- 797 m above ground
- 0-6 km bulk shear
- 62 kt
- 0-1 km storm-relative helicity
- 351 m²/s²
- 0-3 km storm-relative helicity
- 396 m²/s²
- Significant tornado parameter
- 1.9
- Supercell composite
- 7.2
The text
As transmitted, in the capitals the NWS used until 2016.
218
WWUS20 KWNS 090107
SEL8
SPC WW 090107
ARZ000-MOZ000-090700-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 878
NWS STORM PREDICTION CENTER NORMAN OK
705 PM CST TUE NOV 8 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
EASTERN ARKANSAS
THE MISSOURI BOOTHEEL
EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 705 PM
UNTIL 100 AM CST.
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 55 STATUTE
MILES EAST AND WEST OF A LINE FROM 25 MILES SOUTHEAST OF LITTLE
ROCK ARKANSAS TO 50 MILES EAST NORTHEAST OF WALNUT RIDGE
ARKANSAS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).
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 876...WW 877...
DISCUSSION...THREAT FOR ISOLD TORNADOES AND LOCALLY DMGG WIND MAY
EXTEND NEWD FROM CNTRL AR INTO THE DELTA REGION AS EXISTING
SUSTAINED STORMS NOW W AND N OF LIT ENCOUNTER STRENGTHENING LLJ /
ASCENT ASSOCIATED WITH OK UPR TROUGH. WEAK LOW LVL LAPSE RATES WILL
LIMIT COVERAGE...BUT OBSERVED AND FCST HODOGRAPHS SUGGEST POTENTIAL
FOR TORNADOES GIVEN A SUSTAINED STORM.
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
400. MEAN STORM MOTION VECTOR 23035.
...CORFIDISPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Nov 8, 6:43 PM CST | Mesoscale Discussion | SPC | Craighead, Crittenden, Cross, Independence, Jackson, Lonoke and 6 more | 62 min |
| Nov 8, 9:21 PM CST | Mesoscale Discussion | SPC | Ashley, Bradley, Chicot, Desha, Drew, Lincoln | 84 min |
Nearby
Tornado Watches in Arkansas, 2011Tornado Watches in Missouri, 2011Every tornado 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.