[MCD] SWOMCD

[Mesoscale Convective Discussions]

ACUS11 KWNS 212252
SWOMCD
SPC MCD 212251 
ARZ000-LAZ000-TXZ000-OKZ000-220045-

MESOSCALE DISCUSSION 1996
NWS STORM PREDICTION CENTER NORMAN OK
0551 PM CDT THU SEP 21 2006

AREAS AFFECTED...NCNTRL/NERN TX...SERN OK AND WRN AR

CONCERNING...TORNADO WATCH 783...

VALID 212251Z - 220045Z

22Z MESOANALYSIS PLACES A 985 MB LOW OVER NCNTRL KS WITH A DRYLINE
EXTENDING SWD THROUGH CNTRL OK AND INTO NCNTRL TX JUST WEST OF KABI.
 A DOUBLE STRUCTURE WARM FRONT EXISTED ACROSS THE ARKLATEX. THE
NRN-MOST FEATURE EXTENDING FROM THE LOW SEWD ACROSS NERN OK INTO
SWRN AR.  A MARINE WARM FRONT...A DEMARCATION OF MORE QUALITY
TROPICAL MSTR...WAS LIFTING NWD THROUGH NERN TX AND SWRN LA.  

WATER VAPOR IMAGERY SUGGESTS THAT A WEAK MID-LEVEL JETLET MAY BE
MIGRATING INTO THE RED RVR REGION ALONG THE BASE OF THE UPPER LOW. 
MESOANALYSIS TIME SERIES SHOWS THAT A REGION OF MODEST PRESSURE
FALLS HAS PERSISTED ACROSS THE METROPLEX AND MAY BE A REFLECTION OF
THIS MID-LEVEL JETLET. THOUGH THE CUMULUS ALONG THE DRYLINE APPEAR
FLAT...WARM ADVECTION HAS BEEN INCREASING ACROSS SERN OK AND NERN TX
WHERE CONVECTIVE CLOUDS HAVE BEEN GROWING.  IN FACT...A FEW TSTMS
WERE BEGINNING TO DEVELOP IN THIS REGION.  

LATEST RUC IS SIMILAR TO PREVIOUS MODEL RUNS IN INCREASING TSTMS
FROM EXTREME NERN TX NEWD INTO WRN AR THROUGH LATE EVENING.  MORE
QUALITY MSTR WAS LAGGING SOMEWHAT SOUTH OF THE REGION...BUT COULD
BECOME A FACTOR IN FURTHER DESTABILIZATION LATER ON.  TSTMS THAT CAN
MANAGE TO BECOME ROOTED INTO THIS ENVIRONMENT COULD BECOME
SUPERCELLULAR GIVEN FAVORABLE VERTICAL SHEAR.  RIGHT-MOVING STORMS
WILL HAVE ACCESS TO 250+ M2/S2 0-1KM STORM RELATIVE HELICITY...
INCREASING THE RISK OF TORNADOES.  THIS WILL BE ESPECIALLY THE CASE
FOR STORMS THAT CAN DEVELOP VCNTY THE RED RVR IN NERN TX AND SERN OK
EWD INTO SWRN AR...OR ALONG THE NRN EDGE OF THE RETURNING  TROPICAL
ENVIRONMENT.

..RACY.. 09/21/2006

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

ATTN...WFO...LZK...SHV...TSA...FWD...OUN...

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