SWODY1
SPC AC 081247
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0647 AM CST SUN FEB 08 2009
VALID 081300Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTERNOON INTO
TONIGHT FOR THE SRN HIGH PLAINS...
...SRN HIGH PLAINS THIS AFTERNOON INTO TONIGHT...
AN INITIALLY CLOSED MID-UPPER LOW OVER THE LOWER CO RIVER VALLEY/NRN
BAJA WILL EVOLVE INTO AN OPEN WAVE AND EJECT EWD TO NM/W TX BY THIS
EVENING AND NEWD OVER NW TX/OK/KS OVERNIGHT...IN RESPONSE TO AN
UPSTREAM TROUGH WHICH WILL MOVE INLAND TONIGHT OVER CA/ORE. LEE
CYCLOGENESIS WILL OCCUR IN ADVANCE OF THIS WAVE ACROSS ERN NM INTO
ERN CO...WITH A SURFACE CYCLONE EXPECTED TO DEVELOP BY TONIGHT FROM
E CENTRAL CO INTO NW KS AS THE MID LEVEL WAVE EJECTS OVER THE SRN
HIGH PLAINS. A TRAILING PACIFIC COLD FRONT WILL FOCUS CONVECTIVE
DEVELOPMENT THIS AFTERNOON THROUGH TONIGHT ACROSS THE HIGH PLAINS.
MOISTURE RETURN IN ADVANCE OF THIS SYSTEM HAS BEEN LIMITED BY A VAST
PRIOR FRONTAL INTRUSION THROUGH THE GULF/CARIBBEAN BASINS. A SLOW
CHANGE IN LOW-LEVEL TRAJECTORIES FROM NELY TO ELY ACROSS THE ERN
GULF AND ASSOCIATED GRADUAL AIR MASS MODIFICATION IS NOW SUPPORTING
LOW 60S DEWPOINTS ACROSS THE WRN GULF OF MEXICO. LESSER BOUNDARY
LAYER MOISTURE EXTENDS FARTHER INLAND ACROSS THE SRN PLAINS...WITH
LOW-MID 50S DEWPOINTS FROM SRN OK INTO CENTRAL TX. SOME OF THIS
MOISTURE WILL CONTINUE TO SPREAD NWWD TODAY ACROSS THE SRN PLAINS
BENEATH A WARM ELEVATED MIXED LAYER. THE COMBINATION OF 45-50 F
DEWPOINTS AND AFTERNOON SURFACE TEMPERATURES AT LEAST IN THE 60S
WILL CONTRIBUTE TO WEAK INSTABILITY /SBCAPE APPROACHING 500 J/KG/
THIS AFTERNOON INVOF THE TX/NM BORDER.
THUNDERSTORM DEVELOPMENT IS EXPECTED BY MID-LATE AFTERNOON ACROSS
ERN NM AS THE PACIFIC COLD FRONT AND AN ASSOCIATED BAND OF DEEP
ASCENT SPREAD E OF THE MOUNTAINS. DEEP LAYER FLOW/SHEAR LARGELY
PARALLEL TO THE FRONT...AS WELL AS STRONG LINEAR FORCING FOR ASCENT
AND A PRONOUNCED CAP E OF THE FRONT...SHOULD LEAD TO A QUICK
TRANSITION TO A SQUALL LINE ALONG THE FRONT THIS EVENING. THE
SQUALL LINE WILL THEN SWEEP EWD ACROSS W/NW TX...WRN OK...AND SW KS
OVERNIGHT. EVEN THOUGH INSTABILITY IS EXPECTED TO REMAIN RATHER
WEAK...STRONG AMBIENT FLOW IN THE LOW-MID LEVELS COULD BE
TRANSPORTED TO THE GROUND WITHIN THE SQUALL LINE. COOL MID LEVEL
TEMPERATURES WILL ALSO SUPPORT A THREAT FOR MARGINALLY SEVERE HAIL
WITH THE INITIAL ACTIVITY NEAR THE TX/NM BORDER. THE TORNADO THREAT
WILL BE MARGINAL GIVEN THE VERY WEAK INSTABILITY EXPECTED LATER THIS
EVENING AND OVERNIGHT...THOUGH STRONG LOW-LEVEL SHEAR IN A MOIST
ENVIRONMENT COULD SUPPORT EMBEDDED CIRCULATIONS WITHIN THE LINE OF
STORMS.
..THOMPSON.. 02/08/2009
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