Sunday, September 23, 2012

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 231730
SWODY2
SPC AC 231728

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT SUN SEP 23 2012

VALID 241200Z - 251200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
ALTHOUGH A RATHER LARGE CLOSED LOW/VORTEX WILL BE MAINTAINED ACROSS
ERN CANADA THROUGH DAY 2...THE CENTER OF THIS SYSTEM WILL HAVE
SHIFTED NWD TO NRN QUEBEC/HUDSON BAY. THIS WILL RESULT IN WEAK
HEIGHT RISES ACROSS THE SERN STATES...AND IN COMBINATION WITH THE
EXPECTED GRADUAL WEAKENING OF THE WRN NORTH AMERICA RIDGE SHOULD
SUPPORT A MORE ZONAL FLOW PATTERN FROM THE ROCKIES EWD THIS FORECAST
PERIOD.

...MID SOUTH /NERN AR...SERN MO TO WRN TN AND FAR NRN MS/...
A FEW ELEVATED TSTMS MAY BE ONGOING AT THE START OF DAY 2 ACROSS
NERN AR...WITH THIS ACTIVITY DEVELOPING EWD INTO FAR SERN MO AND WRN
TN/FAR NRN MS MON MORNING. THIS ACTIVITY WILL BE LOCATED WITHIN A
LOW LEVEL WAA REGIME BENEATH THE ERN EXTENT OF STEEP MIDLEVEL LAPSE
RATES. WEAK EFFECTIVE BULK SHEAR AND INSTABILITY ARE EXPECTED TO
PRECLUDE A SEVERE WEATHER THREAT WITH THESE ELEVATED STORMS...BUT
SMALL/SUB-SEVERE HAIL CANNOT BE RULED OUT.

...INTERMOUNTAIN WEST/GREAT BASIN TO ROCKIES/CENTRAL HIGH PLAINS...
A COMPACT LOW/TROUGH...CURRENTLY LOCATED OVER OREGON...SHOULD EVOLVE
INTO MORE OF AN OPEN WAVE ON MON AS IT MOVES SEWD THROUGH THE GREAT
BASIN TOWARD THE FOUR CORNERS REGION. SIMILAR TO DAY 1...THE
COMBINATION OF DIABATIC HEATING AND OROGRAPHIC ASCENT WILL LIKELY
RESULT IN HIGH BASED CONVECTION ALONG AND E OF THE TRACK OF THE
UPPER TROUGH. THIS COMBINED WITH STEEP MIDLEVEL LAPSE RATES SHOULD
SUPPORT SOME TSTM DEVELOPMENT...THOUGH OVERALL MEAGER MOISTURE...AND
WEAK INSTABILITY/SHEAR PARAMETER SPACE WILL PRECLUDE A SEVERE
WEATHER THREAT.

...LOWER MO/MID MS AND LOWER OH VALLEYS...
LATEST MODEL CONSENSUS SUGGESTS LATE DAY 2 ELEVATED TSTM DEVELOPMENT
SHOULD ALSO OCCUR A LITTLE FARTHER DOWNSTREAM INTO MORE OF THE LOWER
OH VALLEY...AND THUS THIS OUTLOOK UPDATE EXTENDS THE GENERAL TSTM
AREA INTO MORE OF CENTRAL IND TO SWRN OH/ERN KY. A STRENGTHENING
MIDLEVEL JET STREAK FROM THE LOWER MO TO LOWER OH VALLEYS MON
AFTERNOON/EVENING WILL SUPPORT LOW LEVEL MASS RESPONSE AND AN
INCREASE IN A SWLY LLJ INTO THESE SAME REGIONS. ASCENT ATTENDANT TO
THESE FEATURES AND LOW LEVEL MOISTURE/WARM AIR ADVECTION WILL LIKELY
RESULT IN A CORRIDOR OF ELEVATED TSTMS FROM CENTRAL/NRN MO TO THE
LOWER OH VALLEY. WEAK DEEP LAYER SHEAR WILL PRECLUDE A SEVERE HAIL
THREAT...THOUGH SMALL HAIL WILL BE POSSIBLE GIVEN AN INCREASE IN
INSTABILITY/MIDLEVEL LAPSE RATES.

..PETERS.. 09/23/2012

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