SWODY2
SPC AC 161730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT FRI SEP 16 2011
VALID 171200Z - 181200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE SRN AND
CNTRL HIGH PLAINS...
...SYNOPSIS...
A LOW AMPLITUDE PROGRESSIVE SYNOPTIC PATTERN WILL PREVAIL SATURDAY.
UPPER TROUGH WITH EMBEDDED VORTICITY MAXIMA CURRENTLY OVER THE WRN
U.S. WILL MOVE INTO THE PLAINS BY LATE AFTERNOON. THE EXPANSIVE CP
HIGH PRESSURE AREA WILL CONTINUE THROUGH THE ERN U.S. WHILE A LEE
TROUGH BECOME ESTABLISHED OVER THE HIGH PLAINS. IN RESPONSE TO THE
INCREASING SLY LOW LEVEL FLOW ACCOMPANYING THE LEE TROUGH A WARM
FRONT WILL DEVELOP NWD THROUGH OK AND KS WITH A DRYLINE OR PACIFIC
FRONT BECOMING ESTABLISHED ACROSS THE SRN HIGH PLAINS.
...CNTRL/SRN HIGH PLAINS...
ELEVATED STORMS MAY BE ONGOING EARLY SATURDAY WITHIN ZONE OF
ISENTROPIC LIFT NORTH OF WARM FRONT ACROSS PORTIONS OF OK/KS INTO
THE MID-LOWER MS VALLEY. THE WARM FRONT SHOULD SHIFT NWD THROUGH OK
INTO SRN KS AS SURFACE RIDGE RETREATS AND THE LEE CYCLONE AND SLY
FLOW STRENGTHEN WITHIN ZONE OF HEIGHT FALLS AND INCREASING WLY FLOW
OVER THE HIGHER TERRAIN ASSOCIATED WITH PROGRESSIVE UPPER TROUGH.
NWD ADVECTION OF LOW-MID 60S DEWPOINTS THROUGH NWD EXPANDING WARM
SECTOR BENEATH 7-7.5 C/KM MID LEVEL LAPSE RATES ALONG WITH DIABATIC
WARMING SHOULD CONTRIBUTE TO AXIS OF 1000-1500 J/KG MLCAPE OVER THE
SRN/CNTRL HIGH PLAINS. A FEW STORMS MAY DEVELOP WITHIN ZONE OF
INCREASING CONVERGENCE ALONG DRYLINE OR PACIFIC FRONT...POSSIBLY
AIDED BY VORTICITY MAXIMA EMBEDDED WITHIN THE UPPER TROUGH. FLOW
ALOFT IS NOT EXPECTED TO BE PARTICULARLY STRONG WITH 20-30 KT AT 500
MB...BUT VERTICAL SHEAR WILL UNDERGO A MODEST INCREASE AS THE TROUGH
APPROACHES SUPPORTING 30-35 KT EFFECTIVE SHEAR FROM LATE AFTERNOON
INTO THE EVENING. THIS ENVIRONMENT WILL BE SUPPORTIVE OF STORMS WITH
AT LEAST MARGINAL SUPERCELL STRUCTURES AND BOWING LINE SEGMENTS WITH
ISOLATED LARGE HAIL AND DAMAGING WIND POSSIBLE THROUGH EARLY
EVENING. HODOGRAPHS WILL UNDERGO SOME ENHANCEMENT TOWARD EVENING AS
LOW LEVEL JET STRENGTHS...BUT WILL BE COINCIDENT WITH A STABILIZING
BOUNDARY LAYER...SUGGESTING THE WINDOW FOR A BRIEF TORNADO OR TWO
SHOULD REMAIN SMALL.
..DIAL.. 09/16/2011
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