Interesting. SPC has upgraded day 2 to include a moderate risk around the Texas/Oklahoma borders again.
SPC AC 221731
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1231 PM CDT SUN APR 22 2007
VALID 231200Z - 241200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF WRN OK AND NORTH
TX...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...CNTRL PLAINS...HIGH PLAINS AND WRN OZARKS...
...SIGNIFICANT SEVERE THUNDERSTORM EVENT EXPECTED ACROSS PARTS OF
THE SRN PLAINS MONDAY AFTERNOON AND EVENING...
...SRN PLAINS...
LATEST WATER VAPOR IMAGERY SHOWS AN UPPER-LEVEL TROUGH ALONG THE
WEST COAST TODAY AND THIS FEATURE WILL MOVE EWD INTO THE FOUR
CORNERS REGION MONDAY. A WELL-DEFINED 80 TO 90 KT MID-LEVEL JET
ROUNDING THE BASE OF THE TROUGH AND A SRN STREAM JET OVER NRN MEXICO
AND CNTRL TX WILL BEGIN TO AFFECT THE REGION MONDAY AFTERNOON. THESE
FEATURES ALONG WITH SUBTLE LEAD SHORTWAVE TROUGH ACTIVITY WILL
PROVIDE STRONG LIFT SUPPORTING SCATTERED THUNDERSTORM CLUSTERS
ACROSS THE REGION MONDAY AFTERNOON. AS VERTICAL SHEAR INCREASES DUE
TO THE INFLUENCE OF THIS COMPLEX JET STRUCTURE ASSOCIATED WITH THE
UPPER-LEVEL TROUGH...A VERY HIGH POTENTIAL FOR SEVERE THUNDERSTORMS
WILL EXIST ACROSS THE REGION MONDAY AFTERNOON AND EVENING.
FORECAST SOUNDINGS FOR MONDAY AFTERNOON ACROSS THE REGION SHOW 0-6
KM SHEAR VALUES IN THE 40 TO 50 KT RANGE INCREASING INTO THE 50 TO
60 KT RANGE DURING THE EVENING. CONSIDERING MODERATE INSTABILITY
SHOULD BE PRESENT FROM THE RIO GRANDE VALLEY EXTENDING NWD INTO
NORTH TX AND OK...THE SHEAR WILL BE FAVORABLE FOR SUPERCELLS.
LOW-LEVEL SHEAR PROFILES ON FORECAST SOUNDINGS ALSO APPEAR FAVORABLE
FOR TORNADOES AND A SIGNIFICANT TORNADO THREAT MAY DEVELOP AS
SUPERCELLS MATURE LATE MONDAY AFTERNOON. A CLUSTER OF TORNADOES
APPEARS LIKELY ACROSS PARTS OF THE MODERATE RISK AREA WHERE STRONG
LOW-LEVEL SHEAR PROFILES WILL EXIST. IN ADDITION...A PLUME OF VERY
STEEP LAPSE RATES IS FORECAST TO MOVE EWD INTO NORTH TX AND SRN OK
BY LATE AFTERNOON ASSOCIATED WITH THE EXIT REGION OF THE MID-LEVEL
JET. THIS WILL PROVIDE SUPPORT FOR NUMEROUS LARGE HAIL EVENTS WITH
SUPERCELLS DURING THE LATE AFTERNOON AND EVENING. THE ATMOSPHERE
SHOULD ALSO BE SUPPORTIVE OF VERY LARGE HAIL WITH THE MOST INTENSE
STORMS. ISOLATED WIND DAMAGE WILL ALSO BE LIKELY WITH SUPERCELLS AND
BOW ECHOES ESPECIALLY AS MCS ORGANIZATION TAKES PLACE IN THE
EVENING.
...CNTRL PLAINS/HIGH PLAINS...
WATER VAPOR IMAGERY SHOWS AN UPPER-LEVEL TROUGH OVER THE WEST COAST
AND THIS FEATURE WILL MOVE EWD INTO THE FOUR CORNERS REGION MONDAY.
EAST OF THE UPPER-TROUGH...A DIFFLUENT UPPER-LEVEL PATTERN WILL
EXIST ACROSS THE HIGH PLAINS AND CNTRL PLAINS. ALTHOUGH THE JET
ENERGY ASSOCIATED WITH THE TROUGH WILL REMAIN SOUTH OF THE
REGION...THE DIFFLUENCE WILL BE FAVORABLE FOR SCATTERED THUNDERSTORM
DEVELOPMENT ALONG AN INSTABILITY AXIS LOCATED FROM SRN KS EXTENDING
NWWD INTO ERN CO. THUNDERSTORMS SHOULD INITIATE ALONG THE
INSTABILITY AXIS AND MOVE EWD INTO THE CNTRL PLAINS LATE MONDAY
AFTERNOON INTO THE EVENING.
FORECAST SOUNDINGS ACROSS THE REGION LATE MONDAY AFTERNOON SHOW 0-6
KM SHEAR VALUES IN THE 40 TO 50 KT RANGE LARGELY DUE TO STRONG
DIRECTIONAL TURNING BELOW 500 MB. THIS SHOULD BE SUFFICIENT FOR
SUPERCELLS ESPECIALLY IF POCKETS OF MODERATE INSTABILITY DEVELOP
ALONG THE MOIST AXIS MONDAY AFTERNOON. STEEP LAPSE RATES...STRONG
VERTICAL SHEAR AND COLD MID-LEVEL TEMPS SHOULD BE FAVORABLE FOR
LARGE HAIL. IN ADDITION...SFC DEWPOINTS ALONG THE MOIST AXIS ARE
FORECAST TO BE DRIER THAN AREAS FURTHER SOUTH WITH MAINLY 50S F
ACROSS KS AND ERN CO. THIS SHOULD BE CONDUCIVE FOR WIND DAMAGE WITH
SUPERCELLS AND BOW ECHOES ESPECIALLY ASSOCIATED WITH SHORT LINE
SEGMENTS. ALTHOUGH...LCL HEIGHTS WILL BE HIGHER THAN AREAS FURTHER
SOUTH...A TORNADO THREAT MAY ALSO EXIST WITH SUPERCELLS DUE TO THE
BACKED SFC WINDS AND ESPECIALLY WITH SUPERCELLS THAT CROSS ANY
PRE-EXISTING BOUNDARIES.
...MS VALLEY/OH AND TN VALLEYS...
AT THE SFC...A SLOW MOVING COLD FRONT SHOULD BE PRESENT FROM OZARK
REGION EXTENDING ENEWD INTO THE OH VALLEY. ALTHOUGH A FLAT
UPPER-LEVEL RIDGE IS FORECAST ACROSS THE REGION MONDAY...LOW-LEVEL
CONVERGENCE SHOULD BE SUPPORTIVE OF SCATTERED THUNDERSTORM
DEVELOPMENT ACROSS THE REGION MONDAY AFTERNOON AND EVENING. ALTHOUGH
THE SHEAR ENVIRONMENT IS NOT FORECAST TO BE THAT STRONG...ENOUGH
INSTABILITY MAY DEVELOP ALONG AND AHEAD OF THE FRONTAL BOUNDARY FOR
A MARGINAL SEVERE THREAT. HAIL AND STRONG GUSTY WINDS MAY ACCOMPANY
THE STRONGER THUNDERSTORMS ESPECIALLY NEAR PEAK HEATING.
FURTHER SOUTH THE SRN OZARKS AND WRN PART OF THE TN VALLEY...MODEL
FORECASTS DEVELOP INSTABILITY AND SCATTERED THUNDERSTORMS. IF THIS
OCCURS...VERTICAL SHEAR PROFILES SHOULD BE SUPPORTIVE OF MARGINALLY
SEVERE THUNDERSTORMS FROM THE LATE AFTERNOON TO EARLY EVENING.
..BROYLES.. 04/22/2007
