DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 101225
SWODY1
SPC AC 101223

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0723 AM CDT THU OCT 10 2013

VALID 101300Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL/SRN HIGH
PLAINS...

...SYNOPSIS...
HIGH-AMPLITUDE SYNOPTIC PATTERN IS FCST TO PERSIST. WHILE REMAINING
EMBEDDED WITHIN ERN MEAN RIDGE...MID-UPPER LEVEL CUT-OFF CYCLONE NOW
OVER VA IS EXPECTED TO DRIFT ERRATICALLY THROUGH PERIOD. TROUGHING
WILL DOMINATE UPPER-AIR PATTERN OVER WRN CONUS...ANCHORED BY CYCLONE
NOW PIVOTING EWD ACROSS LOWER CO RIVER AREA. HEIGHT FALLS ARE FCST
OVER NRN ROCKIES...AHEAD OF SHORTWAVE TROUGH NOW EVIDENT IN MOISTURE
CHANNEL IMAGERY OVER BC. AS THAT OCCURS...SWRN 500-MB CYCLONE WILL
TURN NEWD ACROSS GREAT BASIN. ACCOMPANYING TROUGH SHOULD REACH ERN
PORTIONS UT/AZ AND WRN WY BY 00Z. BY 12Z...CYCLONE SHOULD BECOME
MORE COMPACT AND REACH BLACK HILLS AREA...WITH VORTICITY LOBE
ARCHING SEWD THEN SWD ACROSS NEB/KS. WEAK TROUGHING WILL EXTEND
FROM THERE SWWD OVER NM.

11Z SFC CHART SHOWED WEAK LOW OVER SERN CO...WITH LEE TROUGHING
SSWWD ACROSS ERN NM. DRYLINE WAS DEVELOPING OVER TX/OK PANHANDLES
ALONG WRN FRINGE OF MRGL MOISTURE RETURN...BECOMING BETTER-DEFINED
SWD INVOF TX/NM BORDER TO LOWER PECOS VALLEY. QUASISTATIONARY FRONT
EXTENDED FROM LOW NEWD ACROSS NERN SD. LATTER BOUNDARY SHOULD REMAIN
NEARLY STATIONARY...EXCEPT FOR SOME MESOSCALE RETREAT NWWD
IMMEDIATELY AHEAD OF CYCLONE TRACK. LOW WILL DEEPEN WITH APCH OF
MID-UPPER LEVEL WAVE AND MOVE TO NERN CO/SWRN NEB AREA BY 00Z...THEN
STRENGTHEN FURTHER AND MOVE TO SWRN SD BY 12Z. COLD FRONTOGENESIS
IS EXPECTED S OF SFC LOW...WITH FRONT REACHING SERN CO AND ERN NM BY
00Z. BY 12Z...COLD FRONT WILL HAVE OVERTAKEN MOST OF DRYLINE AND
SHOULD ARC FROM LOW ACROSS CENTRAL NEB...CENTRAL KS...NWRN OK/ERN TX
PANHANDLE AREA...AND TX SOUTH-PLAINS/TRANS-PECOS REGIONS.

...CENTRAL/SRN HIGH PLAINS...
SCATTERED TO LOCALLY NUMEROUS TSTMS...IN CELLS THEN BANDS...ARE FCST
ACROSS OUTLOOK AREA LATE THIS AFTN AND EVENING...MOVING RAPIDLY NEWD
WITH PRIMARY RISK OF DAMAGING GUSTS. LARGE HAIL ALSO IS
POSSIBLE...ESPECIALLY FROM ANY RELATIVELY DISCRETE SUPERCELLS.
TORNADO POTENTIAL WILL BE SUBSTANTIALLY MITIGATED BY
HIGH-BASED/HIGH-LCL NATURE OF ANY RELATIVELY DISCRETE
CONVECTION...AND COLD-POOL-DRIVEN/FORWARD-PROPAGATIONAL
CHARACTERISTICS OF ONE OR MORE SQUALL LINES.

MAIN LIMITING FACTOR FOR MORE INTENSE/SIGNIFICANT EVENT APPEARS TO
BE LACK OF RICH MOISTURE. HOWEVER...EXPECT STEEPENING DEEP-LAYER
LAPSE RATES RELATED FIRST TO DIABATIC AFTN HEATING THEN STG COOLING
ALOFT...LATTER BEING RELATED TO VIGOROUS DCVA AND LOW-MIDLEVEL
FRONTOGENETIC PROCESSES. MLCAPE 300-800 J/KG IS EXPECTED TO DEVELOP
WITH SFC DEW POINTS 40S/LOW 50S F ALONG/AHEAD OF DRYLINE. DESPITE
DIABATIC SFC COOLING...SFC-BASED EFFECTIVE INFLOW PARCELS MAY BE
MAINTAINED AHEAD OF CONVECTION FOR SEVERAL HOURS THIS
EVENING...AIDED BY FORCED ASCENT...AS REGIME TRANSLATES NEWD ACROSS
KS/NEB. OVER SRN HIGH PLAINS...SVR THREAT SHOULD BE SHORTER IN
DURATION AND...WITH SWD EXTENT...MORE ISOLATED/MRGL.

HIGH-RES/CONVECTION-ALLOWING GUIDANCE INDICATES EVENT MAY BE
BIMODAL. THIS SCENARIO APPEARS REASONABLE BASED ON PRESENCE OF TWO
INITIALLY DISTINCT PROCESSES THAT MAY SUPPORT SVR CONVECTION IN
OVERLAPPING AREAS...
1. TSTMS NEAR DRYLINE...LATE AFTN INTO EARLY EVENING...INITIALLY
DISCRETE THEN PERHAPS FORMING AT LEAST BKN LINE. THIS ACTIVITY WOULD
POSE LOWER WIND THREAT BUT POTENTIALLY GREATER HAIL RISK THAN NEXT
REGIME...
2. INTENSE DEEP-LAYER FORCING LEADING TO TSTM INITIATION OVER CO AND
NRN NM BEHIND DRYLINE...PERHAPS AS FAR W AS MTNS/FOOTHILLS. THIS
ACTIVITY SHOULD BECOME MORE CONCENTRATED...DEEPER AND
BETTER-ORGANIZED AS IT MOVES INTO GREATER PW OVER ERN CO AND WRN
KS...DELIVERING DAMAGING OUTFLOW. WEAKENING AND S-N EROSION OF
CONVECTIVE BAND SHOULD OCCUR TONIGHT AS IT ENCOUNTERS PROGRESSIVELY
MORE STABLE BOUNDARY LAYER WITH TIME AND EWD EXTENT.

..EDWARDS/LEITMAN.. 10/10/2013

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