SWODY2
SPC AC 101728
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT THU SEP 10 2009
VALID 111200Z - 121200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
12Z MODELS REMAIN CONSISTENT INDICATING THE SHORTWAVE TROUGH
AMPLIFYING SEWD INTO THE NRN PLAINS TODAY WILL EVOLVE INTO A CLOSED
LOW FRIDAY AND TRACK SWWD TOWARD THE CENTRAL/NRN HIGH PLAINS. THIS
PATTERN CHANGE WILL RESULT IN A REX BLOCK AS SPLIT FLOW REGIME OVER
WRN CANADA BREAKS DOWN AND A RIDGE BUILDS N/NEWD INTO WRN/CENTRAL
CANADA. WEAK SURFACE LOW ATTENDANT TO THE CLOSED LOW SHOULD OCCLUDE
OVER THE ERN DAKOTAS BEFORE UNDERGOING FURTHER WEAKENING. TRAILING
FRONT WILL ADVANCE SWD THROUGH THE CENTRAL PLAINS. MEANWHILE...THE
OH VALLEY UPPER LOW WILL DRIFT SLOWLY TOWARD THE MID ATLANTIC
REGION.
...CENTRAL PLAINS TO MID MO VALLEY...
UPPER 50S TO LOW 60S DEWPOINTS WILL PERSIST IN WARM SECTOR FROM THE
CENTRAL AND SRN PLAINS THROUGH THE MS VALLEY. MUCH OF THE MOIST
WARM SECTOR WILL HAVE SHIFTED EAST OF THE STEEPER LAPSE RATES WITH
WEAK INSTABILITY LIKELY. THE EXCEPTION REMAINS OVER THE CENTRAL
HIGH PLAINS WHERE A PLUME OF RELATIVELY STEEP LAPSE RATES WILL EXIST
ALONG WRN PERIPHERY OF LOW LEVEL MOISTURE RESULTING IN THE POTENTIAL
FOR MODERATE INSTABILITY.
AT 12Z FRIDAY...TSTMS ARE EXPECTED TO BE ONGOING ALONG THE SURFACE
FRONT FROM NRN NEB THROUGH THE ERN DAKOTAS TO NWRN MN. ADDITIONAL
STORMS WILL LIKELY REDEVELOP ALONG THE CONVECTIVELY ENHANCED FRONT
AS IT MOVES EWD AND SEWD DURING THE DAY. MODELS CONTINUE TO
INDICATE STRONG DEEP LAYER SHEAR WILL REMAIN WNW OF THE FRONT.
THUS...WEAK VERTICAL SHEAR CO-LOCATED WITH STRONGER INSTABILITY OVER
THE CENTRAL PLAINS SHOULD RESULT IN A RATHER LIMITED SEVERE WEATHER
THREAT.
..PETERS.. 09/10/2009
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