SWODY1
SPC AC 220057
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0757 PM CDT WED APR 21 2010
VALID 220100Z - 221200Z
..THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SERN CO...SWRN
KS...TX/OK PANHANDLES...NW TX...NERN NM...WRN OK...
..SYNOPSIS...
IN MID-UPPER LEVELS...SPLIT-FLOW PATTERN FEATURES REX CONFIGURATION
OVER WRN NORTH AMERICA WITH RIDGING OVER WRN CANADA AND BROAD
CYCLONIC GYRE CENTERED OVER SRN SIERRA NEVADA RANGE. THIS VORTEX
WILL MOVE EWD THROUGH REMAINDER PERIOD. SEVERAL SMALLER-SCALE
PERTURBATIONS AND VORTICITY BANNERS ARE ORBITING THIS CYCLONE...BUT
ITS CENTROID SHOULD BE LOCATED OVER S-CENTRAL NV BY 12Z. AHEAD OF
THIS SLOW-MOVING BUT LARGE CYCLONE...PROLONGED REGIME OF LOW-LEVEL
LEE TROUGHING WILL PERSIST OVER CENTRAL/SRN HIGH PLAINS. LOW-LEVEL
WAA AND MOISTURE TRANSPORT WILL INTENSIFY THIS EVENING AND EARLY
TONIGHT JUST E OF LEE TROUGHING...AS LLJ LIKEWISE STRENGTHENS TO
APPROXIMATELY 40 KT OVER PORTIONS PERMIAN BASIN AND CAPROCK REGIONS
BY 22/06Z.
AT SFC...23Z ANALYSIS INDICATED WARM FRONTAL ZONE ESEWD FROM LOW
OVER SERN UT...ACROSS EXTREME SRN CO...TO SECONDARY LOW NE
TAD...BECOMING DIFFUSE ACROSS EXTREME SERN CO AND OK
PANHANDLE...THEN BETTER-EVIDENT AGAIN OVER NWRN/N-CENTRAL OK.
EXPECT FRONT TO DRIFT NWD ACROSS KS/OK BORDER REGION...BUT MOVE NWD
FASTER OVER SRN CO. BOUNDARY DELINEATING OUTLINE OF MESOSCALE COLD
POOL WAS DAWN FROM WRN UNION COUNTY NM SEWD TO OLDHAM COUNTY
TX...SWD AGAIN TO BETWEEN PVW-CVS...CURVING EWD BETWEEN
PVW-LBB...THEN ENEWD TOWARD CDS. DRYLINE INTERSECTED THIS BOUNDARY
NEAR LBB AND EXTENDED SWD ACROSS PERMIAN BASIN REGION. DRYLINE WILL
RETREAT WWD OVERNIGHT WITH MOIST ADVECTION YIELDING 50S DEW POINTS
ALONG MUCH OF ERN NM/TX BORDER.
..CENTRAL/SRN HIGH PLAINS REGION...
REF SPC WWS 72-73 AND RELATED MESOSCALE DISCUSSIONS FOR COVERAGE OF
SHORT-TERM SVR SITUATION IN AND NEAR THE WWS.
WIDELY SCATTERED TO SCATTERED TSTMS ARE POSSIBLE OVERNIGHT OVER
PANHANDLES....TX SOUTH-PLAINS AREA...NW TX AND WRN OK. SOME
INCREASE IN CONVECTIVE COVERAGE ALSO MAY OCCUR INVOF TX/NM BORDER
NEXT FEW HOURS AS DRYLINE BACKS INTO AREA OF PRE-EXISTING/HIGH-BASED
TSTMS. RELATIVE INCREASE IN COVERAGE ALSO IS POSSIBLE FARTHER N
OVER SERN CO AND SWRN KS...ALONG AND N OF SYNOPTIC WARM
FRONT...WHERE STRONGER ISENTROPIC ASCENT TO LFC WILL BE AVAILABLE
EITHER FOR ERN MOVEMENT OF EXISTING SERN CO CONVECTION OR NEWER
DEVELOPMENT. MUCAPE WILL INCREASE WITH SWD EXTENT...BUT SO WILL
CINH...RENDERING HIGHER-MAGNITUDE BUT MORE CONDITIONAL SVR HAIL
THREAT FROM CONVECTION. WHILE NONZERO...TORNADO POTENTIAL AFTER
DARK WILL DIMINISH WITH DIABATIC COOLING OF SFC LAYER AND WEAKENING
OF SOLENOIDAL CIRCULATIONS RELATED TO BOUNDARIES...AND ALSO...GIVEN
LACK OF ROBUST SFC THETAE UPSTREAM TO MAINTAIN UNEQUIVOCALLY
SFC-BASED INFLOW PARCELS.
CENTRAL/NRN PANHANDLE AREA REMAINS UNDER INFLUENCE OF
PERSISTENT/RELATIVE COLD POOL AND ACCOMPANYING LAYER OF STATIC
STABILITY NEAR GROUND. THIS AIR MASS WILL BECOME MORE
SHALLOW...WITH WEAKENING STABILITY OVERNIGHT...AS RESIDUAL BOUNDARY
LIFTS NWD AND BECOMES MORE DIFFUSE. MODIFIED AMA RAOB AND RUC FCST
SOUNDINGS SUGGEST CONDITIONAL POTENTIAL FOR STG GUSTS GENERATED
ALOFT TO REACH SFC GIVEN DRYNESS OF AIR WITHIN TOP OF STABLE LAYER
AND HIGHER...I.E. AOA 1/2 KM AGL.
..CENTRAL ROCKIES/INTERMOUNTAIN REGION...
AIR MASS NEAR SFC FCST TO STABILIZE SUBSTANTIALLY AFTER DARK...AS
DIABATIC COOLING OCCURS OVER HIGHER TERRAIN. THIS...ALONG WITH
INCREASING COVERAGE OF RELATIVELY STABILIZED/OUTFLOW AIR FROM
CONVECTION NOW SCATTERED ACROSS THIS REGION...WILL RENDER SVR
POTENTIAL MORE MRGL WITH TIME.
.EDWARDS.. 04/22/2010
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