000
ACUS11 KWNS 190203
SWOMCD
SPC MCD 190203
OKZ000-TXZ000-190300-

MESOSCALE DISCUSSION 0685
NWS STORM PREDICTION CENTER NORMAN OK
0903 PM CDT SAT MAY 18 2013

AREAS AFFECTED...WRN AND CNTRL OKLAHOMA AND NW TEXAS

CONCERNING...TORNADO WATCH 171...

VALID 190203Z - 190300Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 171 CONTINUES.

SUMMARY...SVR TSTMS ARE ONGOING ACROSS PORTIONS OF SWRN OKLAHOMA AND
NW TEXAS. THESE TSTMS SHOULD PERSIST THROUGH THE EVENING...INTO THE
OVERNIGHT...POSING A THREAT FOR LARGE HAIL...STRONG DAMAGING
WINDS...AND POSSIBLE TORNADOES.

DISCUSSION...AT 0145 UTC...RADAR OBSERVATIONS SHOWED A LARGE CLUSTER
OF TSTMS LOCATED ACROSS SWRN OKLAHOMA AND A COUPLE OF MORE ISOLATED
TSTMS IN FAR NW TEXAS. THE TSTMS ACROSS SWRN OKLAHOMA HAVE DEVELOPED
IN A VERY UNSTABLE ENVIRONMENT /MUCAPE VALUES AOA 3000 J/KG/ AND
MODEST DEEP-LAYER SHEAR /AROUND 35-40 KTS/. ALTHOUGH SEVERAL OF
THESE WRN OK TSTMS ARE CURRENTLY SUPERCELLS...RECENT RADAR TRENDS
INDICATES A CONGEALING OF COLD POOLS WHICH WOULD SUGGEST THAT
UPSCALE GROWTH TO MCS MAY BE UNDERWAY. THIS DEVELOPING MCS SHOULD
BEGIN TO MOVE EWD THROUGH THE EVENING AND WILL BEGIN TO AFFECT THE
OKC METRO IN THE NEXT 1-2 HRS. GIVEN THE INCREASING 0-1 KM AND 0-3
KM HELICITIES...ONGOING VIGOROUS UPDRAFTS...AND AN ENVIRONMENT
CONDUCIVE FOR SUSTAINING VIGOROUS UPDRAFTS...LARGE HAIL...STRONG
DAMAGING WINDS...AND TORNADOES CANNOT BE RULED OUT.

FARTHER S...ACROSS NW TX...MORE ISOLATED SUPERCELLS ARE MOVING NNE
INTO SWRN OKLAHOMA AND WILL CONTINUE TO POSE A THREAT OF LARGE
HAIL...DAMAGING WINDS...AND POSSIBLE TORNADOES. THESE SUPERCELLS
SHOULD MERGE INTO THE DEVELOPING OKLAHOMA MCS OVER THE COURSE OF THE
NEXT SEVERAL HRS.

..MARSH.. 05/19/2013

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

ATTN...WFO...TSA...FWD...OUN...SJT...LUB...AMA...MAF...

LAT...LON   36970094 36969665 34889675 33459799 33379895 31459909
            31700082 34730040 36970094