SWODY1
SPC AC 090054
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0654 PM CST SUN FEB 08 2009
VALID 090100Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PART OF THE SRN
PLAINS...
...SRN PLAINS...
EARLY EVENING WATER VAPOR IMAGERY SHOWED AN UPPER TROUGH BECOMING
NEGATIVELY TILTED ACROSS THE SWRN U.S./NRN MEXICO. A VIGOROUS SHORT
WAVE TROUGH WITHIN THE BASE OF THE UPPER TROUGH WILL TRACK FROM SRN
NM/NRN CHIHUAHUA THIS EVENING...REACHING NW TX TO SW KS BY 12Z
MONDAY. IN THE LOW LEVELS...AN ELONGATED AREA OF LOW PRESSURE
ACROSS THE SRN HIGH PLAINS WILL CONSOLIDATE AND DEEPEN OVERNIGHT...
REACHING NW KS BY THE END OF THE PERIOD. IN RESPONSE TO THIS
CYCLOGENESIS...SLY LOW LEVEL FLOW ACROSS THE PLAINS WILL STRENGTHEN
ALLOWING A WARM FRONT TO MOVE NWD INTO SRN NEB/NRN MO BY EARLY
MONDAY MORNING...WHILE A PACIFIC FRONT SWEEPS EWD ACROSS THE SRN
PLAINS.
REGIONAL RADARS/LIGHTNING DATA INDICATED A QUASI-LINEAR LINE OF
TSTMS HAD DEVELOPED ACROSS FAR ERN NM LATE THIS AFTERNOON WITHIN A
ZONE OF LOW-LEVEL CONVERGENCE LOCATED EAST OF AN ADVANCING PACIFIC
COLD FRONT. THIS OCCURRED AS THE LEADING EDGE OF ASCENT WITH THE
EJECTING SWRN U.S./NRN MEXICO UPPER TROUGH SPREAD EWD ACROSS THIS
REGION. INSTABILITY IS EXPECTED TO REMAIN WEAKER WITH EWD EXTENT
INTO THE SRN PLAINS OVERNIGHT...WHERE EXTENSIVE CLOUD COVER LIMITED
SURFACE HEATING. 00Z AMA/MAF SOUNDINGS INDICATED A STRONGER CAP
ACROSS WEST TX WHEN COMPARED WITH FORECAST SOUNDINGS VALID FOR 00Z.
HOWEVER...UPPER FORCING INCREASING ACROSS THE SRN PLAINS IN RESPONSE
TO STRONG HEIGHT FALLS /150+ M PER 12 HRS AT 500 MB/ WITH THE
NEGATIVELY TILTED TROUGH SHOULD COMPENSATE FOR THE WEAK INSTABILITY
AND WEAKEN THE CAP SUFFICIENTLY TO MAINTAIN SQUALL LINE STRUCTURE.
ACTIVITY WILL ADVANCE EWD ACROSS W TX THIS EVENING INTO NRN TX...WRN
OK AND SRN KS LATE TONIGHT. WHILE HAIL SHOULD BE ONE OF THE SEVERE
WEATHER THREATS EARLY THIS EVENING GIVEN AXIS OF GREATER INSTABILITY
OVER ERN NM...THE PRIMARY THREAT OVERNIGHT SHOULD BE STRONG GUSTY
WINDS. THE POTENTIAL EXISTS FOR STRONGER LOW LEVEL WINDS WITHIN LLJ
TO BE TRANSPORTED TO THE GROUND WITHIN THE SQUALL LINE. DESPITE
WEAK INSTABILITY...THIS OUTLOOK WILL ALSO MAINTAIN A MARGINAL
TORNADO THREAT...GIVEN STRONG LOW-LEVEL SHEAR /PER STRENGTHENING
LLJ/ IN A MOIST ENVIRONMENT SUPPORTING A POTENTIAL FOR EMBEDDED
CIRCULATIONS WITHIN THE LINE OF STORMS.
..PETERS.. 02/09/2009
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