DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 130102
SWODY1
SPC AC 130059

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0759 PM CDT FRI OCT 12 2012

VALID 130100Z - 131200Z

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

...SYNOPSIS...
SPLIT-FLOW PATTERN WILL BE MAINTAINED OVER WRN HALF OF CONUS THROUGH
REMAINDER OF PERIOD...AS PREVIOUSLY CUT-OFF CYCLONE ACCELERATES
ENEWD ACROSS UT/NRN AZ. 500-MB LOW SHOULD REACH CO ROCKIES BY END
OF PERIOD...ACCOMPANIED BY HIGH-AMPLITUDE/POSITIVE-TILT SHORTWAVE
TROUGH EXTENDING SWWD ACROSS WRN NM AND SERN AZ.

AT SFC...QUASISTATIONARY FRONTAL ZONE WAS DRAWN OVER SERN/S-CENTRAL
KS THEN SWWD ACROSS N-CENTRAL/SWRN OK...BETWEEN CDS-LBB...WWD TO ERN
NM VICINITY CVS...AND INTO HIGHER TERRAIN S OF I-40.
OLDER...SOMEWHAT DIFFUSE WARM FRONT WAS DRAWN IN WNW-ESE ALIGNMENT
ACROSS S-CENTRAL/SERN OK. THIS BOUNDARY IS EXPECTED TO SHIFT NWD
ACROSS NRN OK AND SERN KS...AND BECOME MORE SHALLOW/ILL-DEFINED WITH
TIME -- AS WILL OK/TX/NM SEGMENT OF OTHER FRONTAL ZONE.

...SRN HIGH PLAINS REGION...
SEVERAL WIDELY DISTRIBUTED AREAS OF STG-SVR CONVECTION ARE
EVIDENT...OVER SRN PANHANDLE/S-PLAINS REGION OF TX...SERN
NM...N-CENTRAL/NERN NM NEAR I-25...AND NRN PORTIONS TX/NM BORDER.
REF WW 660 AND RELATED MESOSCALE DISCUSSIONS FOR LATEST NEAR-TERM
GUIDANCE ON SVR THREAT OVER THIS REGION.

CONVECTIVE COVERAGE IS EXPECTED TO GROW THROUGH REMAINDER EVENING
HOURS. SUPERCELLS STILL WILL BE POSSIBLE AMIDST 50-70 KT EFFECTIVE
SHEAR MAGNITUDES AND ENLARGING LOW-LEVEL HODOGRAPHS...ALONG WITH
INCREASING POTENTIAL FOR BOW/LEWP STRUCTURES. TORNADO POTENTIAL
WILL REMAIN IN AND S OF SFC FRONTAL ZONE FOR ANOTHER 2-3 HOURS UNTIL
NEAR-SFC LAYER SUFFICIENTLY COOLS TO ELEVATE EFFECTIVE INFLOW
PARCELS AGL. WITH FRONTAL ZONES EXPECTED TO BE MORE DIFFUSE AMIDST
STG/BROAD WAA PLUME...GRADATION BETWEEN SFC-BASED AND ELEVATED
INFLOW PARCELS LIKEWISE WILL SHIFT NWD IN INCREASINGLY NEBULOUS
FASHION.

...CENTRAL PLAINS TO MO VALLEY LATE TONIGHT...
SCATTERED TO WIDELY SCATTERED NON-SVR TSTMS IN CLUSTERS ARE ONGOING
FROM PORTIONS ERN KS NNEWD ACROSS NWRN MO AND SRN IA. ADDITIONAL
CONVECTION IS EXPECTED TO DEVELOP FARTHER W ACROSS PORTIONS KS...NEB
AND PERHAPS SWRN IA...LEADING TO NET INCREASE IN TSTM COVERAGE
OVERNIGHT IN SSW-NNE PLUME. TSTM INCREASE WILL OCCUR AS LOW-LEVEL
WAA AND MOISTURE ADVECTION/TRANSPORT BOOSTS 850-700 MB LAYER
THETAE...AMIDST BROAD...STRENGTHENING...SSWLY LLJ. GIVEN LITTLE
CHANGE IN LAPSE RATES ALOFT AWAY FROM CONVECTION...THIS PROCESS WILL
BOOST ELEVATED BUOYANCY...LEADING TO CORRIDOR OF MUCAPE RANGING FROM
AROUND 1800 J/KG OVER CENTRAL KS TO ABOUT 1000 J/KG OVER WRN IA.
EFFECTIVE SHEAR MAGNITUDES FOR ELEVATED TSTMS SHOULD REMAIN
MODEST...I.E. 30-35 KT...INDICATING ISOLATED/MRGL HAIL RISK. A FEW
STG GUSTS COULD REACH SFC OVER AREAS FROM CENTRAL KS SWWD TO
CATEGORICAL RISK AREA WHERE NEAR-SFC STABLE LAYER BECOMES RELATIVELY
SHALLOW. THAT WOULD BE RELATED MORE TO PRECIP LOADING THAN
EVAPORATIVE DRYING...GIVEN HIGH-RH CHARACTER OF SUBCLOUD LAYER.

..EDWARDS.. 10/13/2012

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