[MCD] SWOMCD

Wed Dec 14 19:09:42 UTC 2005

ACUS11 KWNS 141905
SWOMCD
SPC MCD 141904 
LAZ000-TXZ000-142030-

MESOSCALE DISCUSSION 2559
NWS STORM PREDICTION CENTER NORMAN OK
0104 PM CST WED DEC 14 2005

AREAS AFFECTED...UPPER TX COAST/FAR SERN TX INTO SWRN LA

CONCERNING...TORNADO WATCH 894...

VALID 141904Z - 142030Z

CONTINUE VALID PORTIONS OF WW AS TORNADO THREAT WILL CONTINUE. 
BROKEN LINE OF INTENSE THUNDERSTORMS CONTINUES TO EVOLVE JUST WEST
OF THE HOU METRO AREA ATTM.  THIS ACTIVITY IS TRACKING EWD AT AROUND
35 KT AND SHOULD MOVE ACROSS GALVESTON BAY BY 20Z AND INTO FAR SWRN
LA JUST AFTER 21Z IF IT MAINTAINS CURRENT FORWARD MOTION.

VWP FROM HOU INDICATES EXTREME LOW LEVEL SHEAR WITH 0-1 KM SRH IN
EXCESS OF 350 M2/S2...ALONG WITH 60+ KT OF SFC-6 KM SHEAR.  PRIMARY
CONCERN CONTINUES TO CENTER AROUND WEAK LOW LEVEL LAPSE RATES AND
SUBSEQUENT MAINTENANCE OF SURFACE-BASED STORMS.  MODIFIED HOURLY RUC
SOUNDINGS INDICATE CONVECTION NEAR AND SOUTH-SOUTHWEST OF HOU IS
VERY NEARLY SURFACE-BASED WITH SURFACE TEMPERATURES IN THE LOWER 70S
AND DEW POINTS IN THE MID/UPPER 60S.  IN ADDITION...STRONG SURFACE
PRESSURE FALLS WILL ALSO ENHANCE LIFTING WITHIN THE BOUNDARY LAYER
AND FURTHER INCREASE THE RISK OF INGESTING SURFACE-PARCELS.  WITH
SUCH EXTREME SHEAR...SUPERCELLS WILL CONTINUE TO SUPPORT A RISK OF
TORNADOES GIVEN THE NEAR SURFACE-BASED NATURE OF THE STORMS.  LARGE
HAIL...DAMAGING WINDS AND VERY HEAVY RAINFALL RATES ARE ALSO
EXPECTED.

SLY LLJ IS FORECAST TO REMAIN ANCHORED INTO THE UPPER TX COAST
THROUGH 21Z...SO FURTHER DEVELOPMENT WEST OF ONGOING STORMS MAY
OCCUR NEAR THE SURFACE COLD FRONT INTO THE EARLY EVENING. 
HOWEVER...PRIMARY SEVERE THREAT SHOULD SHIFT INTO SWRN LA BETWEEN
21-00Z AS LLJ DEVELOPS INTO SWRN LA.  AS DEW POINTS INCREASE INTO
THE MID 60S AND LLJ DEVELOPS EWD...ADDITIONAL WATCH MAY BE NEEDED
INTO SWRN LA PRIOR TO 20-21Z.

..EVANS.. 12/14/2005

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

ATTN...WFO...LIX...LCH...HGX...CRP...EWX...

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