DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 120059
SWODY1
SPC AC 120057

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0757 PM CDT THU OCT 11 2012

VALID 120100Z - 121200Z

...THERE IS A SLGT RISK OF SVR TSTMS KS/OK BORDER REGION TO EXTREME
WRN PORTIONS TN/KY...

...SYNOPSIS...
UPPER-AIR PATTERN WILL CONTINUE TO BE DOMINATED BY SPLIT
FLOW...FEATURING NRN-STREAM RIDGING OVER PAC NW AND PAC COAST OF
CANADA...AND PRONOUNCED CYCLONE OVER SRN CA AND ADJACENT WATERS. CA
LOW IS FCST TO MOVE INLAND AND ENEWD THROUGH REMAINDER
PERIOD...REACHING SERN SIERRAS. MEANWHILE...ASSOCIATED CYCLONICALLY
CURVED 500-250 MB SPEED MAXIMA WILL STRENGTHEN SOMEWHAT AND SHIFT
EWD ACROSS ERN/SRN AZ. SEPARATE/NRN-STREAM PERTURBATION WILL MOVE
EWD ACROSS UPPER GREAT LAKES...WHILE RELATED MID-UPPER JET MAX
SHIFTS ESEWD ACROSS MID MS RIVER VALLEY AND LOWER OH VALLEY REGIONS.

23Z SFC ANALYSIS SHOWED COLD FRONT FROM SRN LOWER MI SWWD ACROSS
NWRN MO AND CENTRAL KS TO OK PANHANDLE...ARCHING NWWD THROUGH WEAK
LOW OVER SERN CO. WRN SEGMENT OF THIS FRONT IS FCST TO DECELERATE
OVERNIGHT...DRIFTING SWD ACROSS SRN KS...NWRN OK...NRN TX PANHANDLE
AND NERN NM. MEANWHILE REMAINDER OF FRONT SHOULD REACH SRN
NY...LOWER OH VALLEY...OZARKS AND CENTRAL/ERN PORTIONS KS/OK BORDER
REGION. FROM OZARKS WWD...THIS BOUNDARY WILL OVERTAKE NNEWD-MOVING
WARM FRONT THAT WAS ANALYZED FROM S-CENTRAL KS SEWD ACROSS CENTRAL
AR AND NRN MS. DIFFUSE DRYLINE WAS DRAWN FROM NWRN/N-CENTRAL TX
PANHANDLE SWWD ACROSS E-CENTRAL NM THEN GENERALLY SWD OVER
TRANS-PECOS REGION. DRYLINE MAY RETREAT SLIGHTLY NWWD
OVERNIGHT..WHERE NOT OVERTAKEN BY COLD FRONT.

...KS/OK BORDER REGION TO EXTREME WRN PORTIONS TN/KY...
SCATTERED TSTMS ARE STILL EXPECTED TO DEVELOP IN BAND FROM SWRN
KS/NWRN OK EWD ACROSS OZARKS...ERN PORTION OF WHICH SHOULD AFFECT
PORTIONS WRN TN/KY BEFORE END OF PERIOD. MAIN CONCERN WILL BE
LOW-END SVR HAIL...WITH POTENTIAL COVERAGE THEREOF MRGLLY SUPPORTING
15% PROBABILITY CORRIDOR. FRONTAL TRENDS AND LATEST HIGH-RESOLUTION
NUMERICAL GUIDANCE SUGGESTS RELATIVELY NARROW ZONE OF GREATEST
OVERNIGHT CONVECTIVE POTENTIAL...THOUGH THERE ARE SOME PROGGED PHASE
DIFFERENCES WITH RESPECT TO N-S PLACEMENT OF TSTM AXIS. THIS REGION
WILL LIE BENEATH RIGHT-ENTRANCE REGION AND ASSOCIATED
SUBSYNOPTIC/AGEOSTROPHIC ASCENT...JUXTAPOSED WITH LOW-LEVEL MOISTURE
TRANSPORT AND WAA ACCOMPANYING 30-40 KT 850-MB FLOW ON GULF-ORIGIN
TRAJECTORIES. PARCELS WILL BE LIFTED ISENTROPICALLY TO LFC WITH
ELEVATED MUCAPE RANGING FROM 1500-2000 J/KG OVER KS/OK BORDER
REGION...DIMINISHING TO 500-1000 J/KG RANGE IN ERN PORTIONS OUTLOOK
AREA...ALL AMIDST 35-45 KT EFFECTIVE SHEAR MAGNITUDES.

...SWRN CONUS...
TRIANGULAR AREA OF SCATTERED TO WIDELY SCATTERED TSTMS WAS EVIDENT
BETWEEN SERN AZ...SWRN UT AND SRN PORTIONS SIERRA NEVADA. THIS
ACTIVITY WAS ASSOCIATED WITH LOW LEVEL WAA/MOISTURE TRANSPORT PLUME
WRAPPING THROUGH ERN CONVEYOR OF MID-UPPER CYCLONE...AS WELL AS
LOW-LEVEL FRONTAL/CONVERGENCE ZONE. 00Z RAOBS AND MODIFIED MODEL
SOUNDINGS SUGGEST INCREASE N LAPSE RATES/BUOYANCY AND DECREASE IN
DEEP-LAYER SHEAR WITH NWWD EXTENT THROUGH THIS PLUME...THOUGH SHEAR
OVER SRN NV CONVECTIVE AREA APPEARS AT LEAST MRGLLY FAVORABLE FOR
ORGANIZED MULTICELLS AND TRANSIENT SUPERCELL STRUCTURES. POTENTIAL
FOR ISOLATED LARGE HAIL OR STG-SVR GUSTS SHOULD CONTINUE FOR ANOTHER
FEW HOURS BEFORE DIABATIC SFC COOLING APPRECIABLY DIMINISHES TSTM
INTENSITY AND COVERAGE.

...SRN HIGH PLAINS...
OVERNIGHT CONVECTIVE DEVELOPMENT INVOF DRYLINE AND BENEATH RIDGING
ALOFT IS MORE UNCERTAIN AND CONDITIONAL...THOUGH NSSL AND ARW WRF
PROGS STILL INDICATE THIS POSSIBILITY OVER WRN NM AFTER 06Z. PRIND
SVR POTENTIAL WITH ANY SUCH ACTIVITY WILL BE MRGL AT
MOST...PRIMARILY IN FORM OF ISOLATED HAIL.

..EDWARDS.. 10/12/2012

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