Note:
The expiration time in the watch graphic is amended if the watch is
replaced, cancelled or extended.
Note: Click for
Watch Status Reports.
SEL8
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 218
NWS STORM PREDICTION CENTER NORMAN OK
755 PM CDT THU APR 30 2009
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
CENTRAL AND NORTHWEST OKLAHOMA
EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 755 PM
UNTIL 100 AM CDT.
HAIL TO 3 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 40
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES SOUTH
SOUTHWEST OF GAGE OKLAHOMA TO 20 MILES SOUTHEAST OF CHANDLER
OKLAHOMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).
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 217...
DISCUSSION...SCATTERED THUNDERSTORMS HAVE BEGUN TO FORM OVER
NORTHWEST OK ALONG A WEAK OUTFLOW BOUNDARY. THESE STORMS MAY TRACK
SOUTHEASTWARD INTO CENTRAL OK THROUGH THE EVENING. A VERY
MOIST/UNSTABLE AIRMASS AND SUFFICIENT EFFECTIVE SHEAR SUGGEST A RISK
OF SUPERCELLS CAPABLE OF VERY LARGE HAIL AND DAMAGING WINDS.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 28025.
...HART
Note:
The Aviation Watch (SAW) product is an approximation to the watch area.
The actual watch is depicted by the shaded areas.
SAW8
WW 218 SEVERE TSTM OK 010055Z - 010600Z
AXIS..40 STATUTE MILES NORTH AND SOUTH OF LINE..
25SSW GAG/GAGE OK/ - 20SE CQB/CHANDLER OK/
..AVIATION COORDS.. 35NM N/S /23S GAG - 52E OKC/
HAIL SURFACE AND ALOFT..3 INCHES. WIND GUSTS..60 KNOTS.
MAX TOPS TO 500. MEAN STORM MOTION VECTOR 28025.
LAT...LON 36529994 36099656 34939656 35389994
THIS IS AN APPROXIMATION TO THE WATCH AREA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE WOUS64 KWNS
FOR WOU8.
Watch 218 Status Report Message has not been issued yet.
Note:
Click for Complete Product Text.
Tornadoes
Probability of 2 or more tornadoes
|
Low (20%)
|
Probability of 1 or more strong (F2-F5) tornadoes
|
Low (5%)
|
Wind
Probability of 10 or more severe wind events
|
Mod (30%)
|
Probability of 1 or more wind events > 65 knots
|
Mod (30%)
|
Hail
Probability of 10 or more severe hail events
|
Mod (50%)
|
Probability
of 1 or
more hailstones > 2 inches
|
Mod (30%)
|
Combined Severe Hail/Wind
Probability of 6 or more combined severe hail/wind events
|
High (80%)
|
For each watch, probabilities for particular events inside the watch
(listed above in each table) are determined by the issuing forecaster.
The "Low" category contains probability values ranging from less than 2%
to 20% (F2-F5 tornadoes), less than 5% to 20% (all other probabilities),
"Moderate" from 30% to 60%, and "High" from 70% to greater than 95%.
High values are bolded and lighter in color to provide awareness of
an increased threat for a particular event.
weather.gov 
