SWODY3
SPC AC 060827
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0227 AM CST FRI FEB 06 2009
VALID 081200Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS LATE SUN AFTN/EVE ACROSS PARTS
OF THE SRN HIGH PLAINS....
...SYNOPSIS...
SHORT TO MEDIUM RANGE MODELS REMAIN SIMILAR CONCERNING SHORT WAVE
DEVELOPMENTS WITHIN THE LARGE-SCALE PATTERN ACROSS THE U.S. DURING
THIS FORECAST PERIOD. IN THE SOUTHERN BRANCH OF THE SPLIT POLAR
WESTERLIES...A SIGNIFICANT SHORT WAVE TROUGH IS EXPECTED TO
ACCELERATE OUT OF THE SOUTHERN U.S./NORTHWEST MEXICAN PLATEAU
REGION...AS ANOTHER UPSTREAM IMPULSE DIGS TOWARD THE CALIFORNIA
COAST. THE LEAD SYSTEM...LIKELY ACCOMPANIED BY A 90+ KT 500 MB JET
STREAK...IS PROGGED TO SUPPORT FAIRLY STRONG SURFACE CYCLOGENESIS TO
THE LEE OF THE CENTRAL ROCKIES...AND THE DEVELOPMENT OF A 50-70 KT
SOUTHERLY LOW-LEVEL JET THROUGH MUCH OF THE CENTRAL AND SOUTHERN
PLAINS BY LATE SUNDAY NIGHT.
A RETURN FLOW OFF THE WESTERN GULF OF MEXICO MAY ALREADY BE UNDERWAY
BY SUNDAY MORNING. HOWEVER...IN THE WAKE OF A SERIES OF RECENT COLD
INTRUSIONS INTO THE GULF OF MEXICO...AIR MASS MODIFICATION WILL
STILL BE ONGOING...AND THE QUALITY OF THE LOW-LEVEL MOISTURE RETURN
IS IN CONSIDERABLE DOUBT. THIS WILL HAMPER DESTABILIZATION...AND
PROBABLY WILL LIMIT THE CONVECTIVE POTENTIAL ASSOCIATED WITH THE
EVOLVING SYNOPTIC SYSTEM.
...SOUTHERN PLAINS...
MODELS ARE SUGGESTIVE THAT LOW CLOUDS ASSOCIATED WITH THE WEAK
MOISTURE RETURN BENEATH A DRY CAPPING ELEVATED MIXED LAYER WILL
RESTRICT SURFACE HEATING SUNDAY...AS FAR WEST AS THE TEXAS SOUTH
PLAINS AND PANHANDLE REGION. HOWEVER...FORECAST SOUNDINGS ACROSS
THE HIGH PLAINS INDICATE STEEP ENOUGH MID-LEVEL LAPSE RATES FOR CAPE
ON THE ORDER OF 500+ J/KG...EVEN WITH SURFACE TEMPERATURES IN THE
UPPER 50S AND DEW POINTS IN THE 40S. THIS SHOULD BE SUFFICIENT TO
SUPPORT VIGOROUS THUNDERSTORM ACTIVITY...AS STRONG FORCING FOR
UPWARD VERTICAL MOTION DEVELOPS ALONG/AHEAD OF A PACIFIC COLD FRONT
ADVANCING ACROSS THE REGION LATE SUNDAY AFTERNOON OR SUNDAY EVENING.
IF STORMS COULD DEVELOP IN A DISCRETE MANNER...LARGE CLOCKWISE
CURVED LOW-LEVEL HODOGRAPHS BENEATH STRONG SOUTH SOUTHWESTERLY
MID/UPPER FLOW WILL BE FAVORABLE FOR SUPERCELLS WITH A RISK FOR
TORNADOES. HOWEVER...RAPID EVOLUTION OF A NARROW SQUALL LINE
APPEARS MUCH MORE LIKELY...WITH DAMAGING WINDS THE PRIMARY SEVERE
THREAT...THOUGH SOME HAIL IS ALSO POSSIBLE...PARTICULARLY IN THE
EARLY STAGES OF THE STORM DEVELOPMENT.
CONVECTION IS EXPECTED TO SPREAD WITH THE STRONGER FORCING TOWARD
PARTS OF SOUTH CENTRAL KANSAS...CENTRAL OKLAHOMA AND NORTH CENTRAL
TEXAS THROUGH 12Z MONDAY. HOWEVER...BASED ON PROGGED WARMING OF
LIFTED PARCEL EQUILIBRIUM LEVELS...WHILE STRONG GUSTY WINDS MAY
PERSIST WITH ACTIVITY THROUGH THE NIGHT...LIGHTNING MAY NOT.
..KERR.. 02/06/2009
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