Thursday, March 29, 2012

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 291732
SWODY2
SPC AC 291730

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT THU MAR 29 2012

VALID 301200Z - 311200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE OH
VALLEY...

...OH VALLEY AND MID-MS VALLEY...
A SUBTLE SHORTWAVE TROUGH IS FORECAST TO MOVE ESEWD ACROSS THE OH
VALLEY ON FRIDAY AS A SFC LOW GRADUALLY DEEPENS...MOVING EWD ACROSS
IL...IND AND OH DURING DAY. ALONG AND SOUTH OF THE TRACK OF THE
LOW...SFC DEWPOINTS ARE FORECAST TO BE IN THE MID TO UPPER 50S F
WITH MODERATE INSTABILITY DEVELOPING AROUND MIDDAY. MODEL FORECASTS
INITIATE THUNDERSTORMS JUST TO THE NORTH OF THE SFC LOW IN THE
VICINITY OF CHICAGO FRIDAY MORNING WITH THIS ACTIVITY SPREADING
ESEWD ACROSS IND AND OH DURING THE AFTERNOON.

FORECAST SOUNDINGS AT 21Z FRIDAY AT INDIANAPOLIS AND CINCINNATI SHOW
MLCAPE VALUES FROM 1000 TO 1500 J/KG WITH STEEP MID-LEVEL LAPSE
RATES NEAR 7.0 C/KM. IN ADDITION...THE ENTRANCE REGION OF A
MID-LEVEL JET SHOULD MOVE ACROSS THE OH VALLEY HELPING TO ENHANCE
DEEP LAYER SHEAR WITH FORECAST SOUNDINGS SHOWING 0-6 KM SHEAR IN THE
30 TO 40 KT RANGE. THE SHEAR AND THERMODYNAMIC ENVIRONMENT SHOULD
SUPPORT A SEVERE THREAT AS STORMS INCREASE IN COVERAGE FRIDAY
AFTERNOON. THE STORMS MAY DEVELOP INTO A LINE AS A COLD FRONT
ADVANCES ESEWD ACROSS THE REGION. THIS ALONG WITH VEERED LOW-LEVEL
FLOW AND 0-3 KM LAPSE RATES OF 8.5 TO 9.0 C/KM SHOULD BE FAVORABLE
FOR ISOLATED WIND DAMAGE. A THREAT FOR LARGE HAIL SHOULD ALSO EXIST
WITH THE GREATEST THREAT JUST TO THE SOUTH OF THE SFC LOW TRACK
WHERE THE GREATEST COMBINATION OF INSTABILITY AND SHEAR IS FORECAST.


FURTHER TO THE SOUTHWEST IN THE MID MS VALLEY...MODERATE INSTABILITY
WILL BE IN PLACE ACROSS A BROAD CORRIDOR WITH ISOLATED THUNDERSTORM
DEVELOPMENT POSSIBLE FRIDAY AFTERNOON. HOWEVER...LARGE-SCALE ASCENT
AND DEEP LAYER SHEAR SHOULD REMAIN VERY WEAK KEEPING ANY SEVERE
THREAT MARGINAL.

...SRN PLAINS...
A SUBTLE SHORTWAVE TROUGH IS FORECAST TO MOVE SLOWLY SEWD INTO THE
SRN PLAINS FRIDAY. AHEAD OF THE SHORTWAVE TROUGH...A BROAD WARM
SECTOR SHOULD EXIST WITH MODERATE TO STRONG INSTABILITY IN PLACE BY
AFTERNOON. AT THE SFC...A LOW IS FORECAST ACROSS WEST TX WITH A
DRYLINE EXTENDING SWD FROM THE LOW AND A PRONOUNCED MOIST AXIS
EXTENDING NWWD ACROSS ECNTRL TX INTO SW OK. ISOLATED TO SCATTERED
THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE DURING THE LATE AFTERNOON
AS THE CAPPING INVERSION WEAKENS. FORECAST SOUNDINGS ALONG THE WRN
EDGE OF THE MOIST AXIS SHOW MLCAPE VALUES FROM 1000 TO 2000
J/KG...0-6 KM SHEAR IN THE 25 TO 35 KT RANGE ALONG WITH STEEP
MID-LEVEL LAPSE RATES. THIS SHOULD BE SUFFICIENT FOR A SEVERE THREAT
LATE FRIDAY AFTERNOON. HOWEVER...LARGE-SCALE ASCENT SHOULD REMAIN
WEAK ACROSS THE REGION WITH MUCH UNCERTAINTY CONCERNING WHERE THE
GREATEST COVERAGE OF CONVECTION WILL BE. WILL LEAVE A SEE TEXT IN
THE SRN PLAINS ATTM.

..BROYLES.. 03/29/2012

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