SWODY1
SPC AC 081954
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0254 PM CDT FRI OCT 08 2010
VALID 082000Z - 091200Z
...NO SVR TSTM AREAS FORECAST...
...CENTRAL AND NRN HIGH PLAINS...
VERY LITTLE CHANGE REQUIRED THIS FORECAST...AS SHOWERS AND
THUNDERSTORMS CONTINUE TO DEVELOP OVER THE ROCKIES...AND ARE
EXPANDING EWD INTO THE CENTRAL HIGH PLAINS ATTM. MODEST INSTABILITY
PREVAILS -- BUT WITH SOME OFFSET BEING PROVIDED BY AMPLE SHEAR
ACROSS THE REGION...A FEW STRONGER STORMS WILL BE POSSIBLE INTO THIS
EVENING. ALONG WITH LIMITED THREAT FOR MARGINAL HAIL WITH THE
STRONGEST STORMS...RELATIVELY DRY/DEEP BOUNDARY LAYER MAY ALSO
PRODUCE LOCALLY GUSTY WINDS.
..GOSS.. 10/08/2010
.PREV DISCUSSION... /ISSUED 1124 AM CDT FRI OCT 08 2010/
...CENTRAL/NRN HIGH PLAINS THIS AFTERNOON/EVENING...
NO SIGNIFICANT CHANGES TO PRIOR OUTLOOK REASONING. THE MIDLEVEL LOW
OVER THE NRN ROCKIES WILL PROGRESS SLOWLY EWD TO THE NRN AND CENTRAL
HIGH PLAINS BY EARLY SATURDAY...WHILE THE PRIMARY BELT OF WLYS
REMAINS TO THE N OVER CANADA. THE MIDLEVEL LOW WILL BE ACCOMPANIED
BY A WEAK SURFACE CYCLONE WHICH IS EXPECTED TO MOVE EWD INVOF THE
SD/ND BORDER THROUGH TONIGHT. REGIONAL SURFACE OBSERVATIONS...12Z
SOUNDINGS...AND GOES PW IMAGERY ALL SHOW A RATHER DRY ENVIRONMENT
ACROSS THE CENTRAL/NRN PLAINS WARM SECTOR WITH BOUNDARY LAYER
DEWPOINTS IN THE UPPER 40S TO LOWER 50S AND PW VALUES LESS THAN AN
INCH. THE BOUNDARY LAYER WILL LIKELY REMAIN CAPPED THROUGH THE
PERIOD ACROSS THE LOWER PLAINS OF THE DAKOTAS/NEB...WITH
THUNDERSTORM DEVELOPMENT MORE PROBABLE FARTHER TO THE W ALONG THE
LEE TROUGH AND COLD FRONT WHERE DEEPER MIXING WILL RESULT IN WEAKER
CONVECTIVE INHIBITION.
THE MARGINAL MOISTURE AND DEEP MIXING WILL RESULT IN INVERTED-V TYPE
PROFILES WITH WEAK BUOYANCY /MUCAPE GENERALLY AOB 750 J PER
KG...PERHAPS ROOTED NEAR 700 MB IN THE RESIDUAL MIDLEVEL MOISTURE
PLUME/. EFFECTIVE BULK SHEAR WILL BE SUFFICIENT FOR ORGANIZED STORM
STRUCTURES...BUT THE WEAK INSTABILITY WILL TEND TO LIMIT THE OVERALL
SEVERE STORM THREAT. A FEW STRONG OUTFLOW GUSTS APPEAR TO BE THE
MAIN CONCERN WITH HIGH-BASED CONVECTION...THOUGH MARGINALLY SEVERE
HAIL CANNOT BE RULED OUT GIVEN THE STEEP LAPSE RATES AND COOLING
TEMPERATURE PROFILES WITH THE APPROACH OF THE MIDLEVEL LOW.
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