DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 281254
SWODY1
SPC AC 281251

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0751 AM CDT MON OCT 28 2013

VALID 281300Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS KS...

...SYNOPSIS...
PRINCIPAL UPPER-AIR INFLUENCE ON CONVECTIVE POTENTIAL THIS PERIOD
WILL BE LARGE/WELL-DEFINED CYCLONE...NOW CENTERED OVER NRN CA/NV
BORDER. THIS FEATURE IS DECELERATING MARKEDLY ATTM...BASED ON
MOISTURE-CHANNEL SATELLITE ANIMATIONS. RELATED 500-MB LOW IS FCST
TO PIVOT ENEWD ACROSS NRN NV TO NV-ID BORDER REGION THROUGH
REMAINDER PERIOD. AS THIS OCCURS...SFC LOW IS FCST TO DEVELOP
WITHIN LEE-SIDE TROUGHING ALREADY ANALYZED OVER SRN/CENTRAL HIGH
PLAINS. THIS LOW LIKELY WILL RESULT FROM MERGER OF WEAK EXISTING
LOW NEAR LHX WITH FRONTAL ZONE NOW MOVING SWD ACROSS ERN CO AND NWRN
KS. BY 00Z...SFC LOW SHOULD BE LOCATED OVER SERN CO...WITH FRONT
QUASISTATIONARY AND EXTENDING ENEWD OVER PORTIONS WRN/NRN KS. SFC
CYCLONE IS FCST TO EJECT NEWD ACROSS SWRN/W-CENTRAL KS
TONIGHT...WITH BOUNDARY TO ITS NE LIFTING NWD AS WARM FRONT ACROSS
NRN KS.

SFC DRYLINE CURRENTLY EXTENDS FROM TX BIG BEND REGION NWD BETWEEN
INK-HOB...THEN BECOMING DIFFUSE NEWD ACROSS TX SOUTH-PLAINS REGION.
DRYLINE SHOULD BECOME BETTER-DEFINED WITH NWD EXTENT TODAY FROM TX
PANHANDLE TO EXTREME SWRN KS/EXTREME SERN CO AREA AS MOIST ADVECTION
CONTINUES TO BOOST BOUNDARY-LAYER MOISTURE TO ITS E.

CONDITIONAL BUT MULTI-MODAL SVR RISK IS EVIDENT FOR ANY SFC-BASED
CONVECTION THAT CAN FORM NEAR DRYLINE AND FRONT THIS AFTN AND EARLY
EVENING...FOLLOWED BY MORE CERTAIN SVR-HAIL POTENTIAL ASSOCIATED
WITH INCREASING TSTM COVERAGE OVER KS TONIGHT.

...CENTRAL HIGH PLAINS...DAYTIME...
LOW-LEVEL CONVERGENCE IS EXPECTED TO BE MAXIMIZED THIS AFTN JUST NE
AND SE OF SFC LOW ALONG THOSE BOUNDARIES...WITH POTENTIAL FOR
DRYLINE BULGE INTO PARTS OF OK PANHANDLE AND SWRN KS. PRIMARY
LIMITING FACTOR FOR TSTM COVERAGE...AND POSSIBLY FOR SFC-BASED
INITIATION OF ANY KIND BEFORE DARK...WILL BE STG CAPPING ATOP
BOUNDARY LAYER STILL CHARACTERIZED BY IMMATURE RETURN-FLOW REGIME.
LACK OF SUBSTANTIAL MID-UPPER LEVEL SUPPORT ALSO IS EVIDENT...AND
WEAK HEIGHT RISES ARE EXPECTED THROUGH MOST OF DAYLIGHT HOURS OVER
THIS REGION. FCST SOUNDINGS SUGGEST SUFFICIENT HEATING TO BOOST
MLCAPE INTO 1000-1500 J/KG RANGE IN NARROW PLUME OF SUSTAINED
SUNSHINE ACROSS HIGHER ELEVATIONS OF PANHANDLES AND WRN KS...WHILE
SFC DEW POINTS RISE INTO 50S IMMEDIATELY E OF DRYLINE/FRONT.

ANY SUSTAINED AND RELATIVELY DISCRETE TSTM THAT DEVELOPS IN THIS
ENVIRONMENT COULD BECOME SUPERCELLULAR...GIVEN FCST SOUNDINGS THAT
DEPICT FAVORABLE DEEP SHEAR AND SUFFICIENTLY ENLARGED/CURVED
LOW-LEVEL HODOGRAPHS. HOWEVER...APPARENTLY SFC-BASED DEVELOPMENT IN
MOST OPERATIONAL AND HI-RES/CONVECTION-ALLOWING MODELS IS SCANT
BEFORE 00Z. MAIN REASON FOR THIS APPEARS TO BE LACK OF MORE ROBUST
BOUNDARY-LAYER THETAE...GIVEN EARLY-STAGE CHARACTER OF RETURN-FLOW
REGIME AND PRESENCE OF SELY TRAJECTORIES FROM CONTINENTAL
ANTICYCLONE MORE THAN ABOUT 100 NM E OF AFOREMENTIONED BOUNDARIES.

...CENTRAL PLAINS AFTER DARK...
DEEPENING LOW-LEVEL CYCLONE WILL FURTHER STRENGTHEN ANTECEDENT
LOW-LEVEL WAA/MOISTURE-TRANSPORT REGIME THROUGHOUT EVENING...AMIDST
BROAD/45-55 KT LLJ. RESULTING STG ISENTROPIC FORCING TO LFC WILL
CONTRIBUTE TO INCREASING AMOUNT OF ELEVATED TSTMS LATE THIS EVENING
AND TONIGHT...SHIFTING ENEWD ACROSS CENTRAL/ERN KS. TSTM COVERAGE
SHOULD BECOME SCATTERED-NUMEROUS IN CLUSTERS BETWEEN 06Z-12Z. MOST
INTENSE OF THIS CONVECTION WILL PRODUCE LARGE HAIL...SUPPORTED BY
COMBINATION OF 45-55 KT EFFECTIVE SHEAR MAGNITUDES AND MUCAPE
LOCALLY EXCEEDING 1500 J/KG.

..EDWARDS/COHEN.. 10/28/2013

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