SWODY2
SPC AC 120559
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT THU APR 12 2007
VALID 131200Z - 141200Z
..THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF NERN TX INTO
SRN AR AND NRN LA...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF THE SRN PLAINS
INTO THE LWR MS VLY...
..SRN PLAINS TO THE LWR MS VLY REGION...
PRIMARY FEATURE OF INTEREST WILL BE THE UPR LOW THAT WILL DIG INTO
THE DESERT SW TODAY AND THEN TURN EWD TOWARD THE SRN PLAINS ON FRI.
UPR LEVELS WILL BECOME QUITE DIFFLUENT AHEAD OF THIS SYSTEM WITH THE
SUB-TROPICAL JET PEELING OFF ALONG THE GULF COAST AND A SEPARATE
STREAM ROTATING NEWD AROUND THE LOW. A STRONG SLY LLJ OF 50-60 KTS
ORIENTED FROM CNTRL TX/OK EARLY IN THE DAY WILL TRANSLATE EWD INTO
THE LWR MS VLY OVERNIGHT FRIDAY. ELEVATED TSTMS WILL LIKELY BE
ONGOING ACROSS NRN TX AND OK EARLY FRIDAY WHERE THE SLY LLJ IMPINGES
ON THE NW-SE ORIENTED WARM FRONT. A FEW OF THESE STORMS MAY PRODUCE
HAIL AND PERHAPS GUSTY WINDS INTO THE MORNING HOURS.
ATTENTION WILL THEN TURN TO FRI AFTN INTO THE OVERNIGHT WHEN A
SIGNIFICANT AND ACTIVE SEVERE WEATHER EPISODE WILL LIKELY UNFOLD.
WARM AND MOIST AIR MASS...CHARACTERIZED BY MID-UPPER 60S DEW
POINTS...SHOULD ADVECT QUICKLY NWD FRI AFTN AHEAD OF THE DEVELOPING
DRYLINE IN CNTRL TX AND TO THE S OF THE WARM FRONT LIFTING NWD TO
ALONG THE RED RVR VLY...SRN AR AND NRN LA. THIS AIR MASS SHOULD
BECOME UNSTABLE OWING TO STEEP MID-LEVEL LAPSE RATES AND INCREASING
BOUNDARY LAYER MOISTURE.
TSTMS ARE EXPECTED TO GRADUALLY DEVELOP WITHIN THE SLY LLJ AXIS AND
WELL WITHIN THE DEVELOPING WARM SECTOR AWAY FROM THE DRYLINE DURING
THE AFTN. STORMS WILL MOVE RATHER QUICKLY NWD THROUGH ERN TX AND
ENCOUNTER THE BAROCLINIC ZONE ACROSS NERN TX...SWRN AR AND NWRN LA.
AS THEY DO SO...THEY WILL LIKELY BECOME SUPERCELLULAR GIVEN THE
50-60 KTS OF VERTICAL SHEAR. FORECAST LOW-LEVEL HODOGRAPHS WILL BE
QUITE SUPPORTIVE FOR TORNADIC SUPERCELLS... ESPECIALLY NEAR THE WARM
FRONT AND ALONG THE NRN EDGE OF THE RICHER LOW-LEVEL MOISTURE SURGE
DURING THE LATE AFTN/EARLY EVE. VERY LARGE HAIL AND DAMAGING WINDS
CAN ALSO BE EXPECTED. THIS ACTIVITY WILL SHIFT EWD DURING THE
EVENING INTO CNTRL/NRN LA AND SCNTRL/SERN AR.
TO THE WEST OF THIS ACTIVITY...PRIMARY HEIGHT FALLS WILL EMERGE
ACROSS N TX AND OK DURING THE MID-AFTN HOURS...STRENGTHENING THE
MASS CONVERGENCE FROM SWRN/SCNTRL OK INTO CNTRL TX VCNTY THE SFC
LOW/DRYLINE. AS A RESULT...A SECONDARY AREA OF TSTM INITIATION WILL
LIKELY OCCUR. THE MID-UPPER LEVEL FLOW WILL BE BACKING WITH
TIME...AND ACTIVITY HERE MAY VERY WELL EVOLVE INTO LINEAR SEGMENTS
BY EVENING. VERTICAL SHEAR...HOWEVER...WILL BE MORE THAN SUFFICIENT
FOR SUPERCELLS WITH VERY LARGE HAIL. THE LOW-LEVEL WIND FIELDS
ALONG THE DRYLINE WILL BE COMPARATIVELY WEAKER THAN FARTHER E...BUT
ISOLD TORNADOES CANNOT BE RULED OUT.
OVERNIGHT...THE ACTIVITY THAT DEVELOPS ALONG THE DRYLINE WILL LIKELY
PROPAGATE EWD AND MERGE WITH THE STORMS DOWNSTREAM. BACKING OF THE
LOW-MID LEVEL FLOW SUGGEST THAT A SQUALL LINE WILL PROBABLY EVOLVE
LATER AT NIGHT FROM SRN AR INTO LA AND PERHAPS THE UPR TX COAST WITH
POSSIBLE EMBEDDED LEWPS/SUPERCELLS. LARGE HAIL AND DAMAGING WINDS
WILL BE PRIMARY THREATS. BUT...TORNADOES WILL ALSO BE
POSSIBLE...ESPECIALLY ALONG THE NERN PERIPHERY OF THE RETURNING GULF
AIR MASS ACROSS CNTRL/SRN LA INTO SWRN MS.
.RACY.. 04/12/2007
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