SWODY3
SPC AC 150728
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0228 AM CDT THU SEP 15 2011
VALID 171200Z - 181200Z
...SYNOPSIS...
A PROGRESSIVE/LOW-AMPLITUDE LONGWAVE PATTERN WILL PREVAIL OVER THE
CONUS ON SATURDAY. HIGHLIGHTED WITHIN THIS REGIME...A SHORTWAVE
TROUGH IS EXPECTED TO STEADILY PROGRESS EASTWARD OVER THE PACIFIC
NORTHWEST/NORTHERN INTERMOUNTAIN REGION...AND REACH THE NORTHERN
HIGH PLAINS BY EARLY SUNDAY.
...CENTRAL/SOUTHERN PLAINS...
THE SOUTHERN INFLUENCE OF THE AFOREMENTIONED EASTWARD-ADVANCING
NORTHERN HIGH PLAINS TROUGH WILL COINCIDE WITH CONTINUED NORTHWARD
MOISTURE RETURN AND INCREASINGLY PREVALENT SURFACE TROUGHING ACROSS
THE CENTRAL/SOUTHERN PLAINS ON SATURDAY. AFTER WARM ADVECTION-DRIVEN
EARLY DAY SHOWERS/TSTMS ACROSS THE SOUTH-CENTRAL PLAINS/LOWER MO
VALLEY...THE POTENTIAL WILL EXIST FOR ISOLATED TO SCATTERED SURFACE
BASED TSTM DEVELOPMENT SATURDAY AFTERNOON IN VICINITY OF THE SURFACE
TROUGH...INCLUDING A GENERAL SSW-NNE CORRIDOR FROM WEST/SOUTHWEST TX
TO WESTERN OK AND KS.
IF/WHERE MOISTURE RETURN INDEED OCCURS /ON THE ORDER OF LOWER TO
PERHAPS MIDDLE 60S F SURFACE DEWPOINTS/...THE COMBINATION OF
1000-1500 J/KG MLCAPE AND SUFFICIENT VERTICAL SHEAR /30-35 KT/ WILL
EXIST FOR SUSTAINED/SEMI-ORGANIZED STORMS POTENTIALLY INCLUDING
SUPERCELLS /IN SPITE OF A FORECAST MID-LEVEL FLOW WEAKNESS/. SEVERE
HAIL/WIND WOULD BE THE PRIMARY CONCERNS. SATURDAY NIGHT...STORMS
SHOULD INCREASE/SPREAD EASTWARD TOWARD THE LOWER MO VALLEY VICINITY
AMID A STRENGTHENING WARM ADVECTION REGIME...WITH SOME OF THE
STRONGER STORMS POTENTIALLY CAPABLE OF HAIL.
UNCERTAIN DETAILS REGARDING MOISTURE RETURN/DESTABILIZATION...AND
LARGE SCALE FORCING COINCIDENT WITH THE MOIST SECTOR...PRECLUDE A
CATEGORICAL SLIGHT RISK AT THIS TIME...ALTHOUGH SUCH MAY ULTIMATELY
BE WARRANTED FOR PORTIONS OF KS/OK/NORTHWEST TX.
...NORTHERN INTERMOUNTAIN WEST/NORTHERN GREAT BASIN...
TIED TO THE EXPECTED EASTWARD-PROGRESSIVE SHORTWAVE TROUGH/SPEED
MAX...SHOWERS/TSTMS ARE LIKELY ALONG/AHEAD OF AN ADVANCING COLD
FRONT ACROSS THE REGION. SOME TSTMS MAY YIELD CONVECTIVELY ENHANCED
WIND GUSTS AMID A STRONG TROPOSPHERIC WIND PROFILE AND A STEEP LAPSE
RATE ENVIRONMENT...ESPECIALLY SATURDAY AFTERNOON/EARLY EVENING.
HOWEVER...WILL NOT INTRODUCE SEVERE PROBABILITIES AT THIS TIME DUE
TO UNCERTAINTY REGARDING THE DEGREE OF AVAILABLE BUOYANCY/FRONTAL
TIMING.
..GUYER.. 09/15/2011
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