SWODY3
SPC AC 150751
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0151 AM CST SUN FEB 15 2009
VALID 171200Z - 181200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
PROGRESSIVE BUT COMPLEX UPPER PATTERN WILL REMAIN ACROSS MOST OF THE
COUNTRY TUESDAY. PRIMARY UPPER FEATURE OF INTEREST WILL BE A STRONG
UPPER JET FORECAST TO EJECT FROM BASE OF UPPER LOW CURRENTLY
SITUATED OFF THE WRN U.S. COAST. THIS FEATURE WILL REACH THE SRN
PLAINS TUESDAY AFTERNOON AND THE MID-LOWER MS VALLEY REGION TUESDAY
NIGHT. CYCLOGENESIS WILL COMMENCE OVER THE CNTRL PLAINS DURING THE
DAY AS THE UPPER JET CROSSES THE ROCKIES. AS THE SURFACE LOW LIFTS
NEWD INTO THE MID MS VALLEY REGION...A COLD FRONT WILL ACCELERATE
SWD THROUGH THE CNTRL PLAINS. FARTHER SOUTH...A WARM FRONT WILL
ADVANCE NWD THROUGH ERN TX AND THE LOWER MS VALLEY.
...ERN TX THROUGH THE LOWER MS AND TN VALLEY REGIONS...
SLY LOW LEVEL JET WILL STRENGTHEN TUESDAY IN RESPONSE TO DEVELOPING
CYCLONE OVER THE PLAINS AND CONTRIBUTE TO THE NWD TRANSPORT OF
PARTIALLY MODIFIED GULF AIR THROUGH TX AND THE LOWER MS VALLEY. WLY
MID-UPPER FLOW WILL ADVECT STEEPER LAPSE RATES EWD THROUGH THIS
REGION ABOVE THE RETURNING MOIST AXIS. THESE PROCESSES WILL RESULT
IN MARGINAL ELEVATED INSTABILITY. ISENTROPIC LIFT AND THETA-E
ADVECTION ABOVE A STABLE SURFACE LAYER ASSOCIATED WITH THE STRONG
SWLY LOW LEVEL JET WILL LIKELY BECOME SUFFICIENT TO SUPPORT THE
DEVELOPMENT OF ELEVATED THUNDERSTORMS OVERNIGHT. STORMS APPEAR MOST
PROBABLE FROM THE LOWER MS VALLEY EWD THROUGH THE TN VALLEY REGION
WHERE DEEPER ASCENT AND COOLER MID LEVEL TEMPERATURES WILL EXIST.
THE ENVIRONMENT MIGHT BECOME SUFFICIENT FOR AT LEAST A MARGINAL
THREAT OF HAIL WITH STRONGER UPDRAFTS...ESPECIALLY GIVEN PRESENCE OF
STRONG EFFECTIVE SHEAR. HOWEVER...MORE THAN 5% PROBABILITIES DO NOT
APPEAR WARRANTED AT THIS TIME.
IT APPEARS MUCH OF ERN TX MIGHT REMAIN CAPPED TO DEEPER CONVECTION
WHERE WARMER TEMPERATURES IN THE 850-700 MB LAYER WILL EXIST. BEST
CHANCE FOR THUNDERSTORMS IN TX MAY BE ACROSS NERN PORTION OF THE
STATE LATE TUESDAY NIGHT ALONG ADVANCING PACIFIC FRONT.
..DIAL.. 02/15/2009
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