MESO: Mesoscale Discussion 0847

ACUS11 KWNS 200631
SWOMCD
SPC MCD 200630
OKZ000-200800-

MESOSCALE DISCUSSION 0847
NWS STORM PREDICTION CENTER NORMAN OK
0130 AM CDT SUN MAY 20 2012

AREAS AFFECTED...SRN AND CNTRL OK

CONCERNING...SEVERE THUNDERSTORM WATCH 284...

VALID 200630Z - 200800Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 284
CONTINUES.

SUMMARY...AN ISOLATED SEVERE THREAT WILL LIKELY CONTINUE ACROSS WW
284 AND EWD ACROSS CNTRL OK FOR A FEW MORE HOURS. HAIL AND A FEW
DAMAGING WIND GUSTS WILL BE POSSIBLE BUT THE THREAT IS EXPECTED TO
BECOME INCREASINGLY MARGINAL WITH TIME.

DISCUSSION...A CLUSTER OF STRONG TO SEVERE THUNDERSTORMS IS ONGOING
ACROSS WRN AND CNTRL OK ALONG A CORRIDOR OF MODERATE INSTABILITY
WHERE SBCAPE VALUES ARE ESTIMATED IN THE 1000 TO 1500 J/KG RANGE.
THE ACTIVITY IS LOCATED NEAR THE NOSE OF THE LOW-LEVEL JET SHOW BY
MESOANALYSIS WITH 20 TO 30 KT OF LOW-LEVEL FLOW. THIS ALONG WITH 40
KT OF FLOW NEAR 500 MB IS CREATING MODERATE DEEP LAYER SHEAR
PROFILES FAVORABLE FOR SEVERE STORMS. THE INSTABILITY COMBINED WITH
STEEP MID-LEVEL LAPSE RATES APPROACHING 8.0 C/KM AT 500 MB EVIDENT
ON FORECAST SOUNDINGS SHOULD BE SUPPORTIVE OF HAIL WITH THE STRONGER
CORES. ALTHOUGH THE NEAR SFC LAYER IS SOMEWHAT STABLE ESPECIALLY TO
THE EAST OF THE WATCH...MATURE SHORT LINE SEGMENTS COULD ALSO POSE
AN ISOLATED WIND DAMAGE THREAT. AS THE STORMS MOVE EWD INTO
INCREASINGLY STABLE AIR...THE SEVERE THREAT SHOULD GRADUALLY BECOME
MARGINAL EARLY THIS MORNING.

..BROYLES.. 05/20/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...TSA...OUN...

LAT...LON 35439931 34699918 34369835 34229757 34359681 34869624
36009632 36069776 35439931

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