SWODY1
SPC AC 191950
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0150 PM CST MON DEC 19 2011
VALID 192000Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF CENTRAL/EAST
TX...
CURRENT FORECAST SEEMS ON TRACK...WITH FEW ADJUSTMENTS MADE.
WIDESPREAD CLOUDS IN THE WARM SECTOR HAVE SUPPRESSED DAYTIME HEATING
AND DESTABILIZATION. THIS IS ADDING UNCERTAINTY TO WHETHER
SUFFICIENT INSTABILITY CAN DEVELOP FOR ORGANIZED SEVERE STORMS.
NEVERTHELESS...STRONG AND INCREASING WIND FIELDS COUPLED WITH
FAVORABLE LARGE SCALE ASCENT WILL POSE A RISK OF A FEW STRONG OR
ISOLATED SEVERE STORMS THROUGH THE NIGHT ACROSS PARTS OF TX.
..HART.. 12/19/2011
.PREV DISCUSSION... /ISSUED 1025 AM CST MON DEC 19 2011/
...SYNOPSIS...
EWD-MOVING UPPER LOW CENTERED NEAR EPZ WILL TURN MORE NEWD THIS
PERIOD IN RESPONSE TO THE PROGRESSION OF 80-90 KT MIDLEVEL JET
STREAK FROM NRN MEXICO INTO NRN TX/ERN OK. THIS EVOLUTION WILL
RESULT IN A CORRIDOR OF 12-HR HEIGHT FALLS /500 MB/ AOA 100 M
SPREADING FROM ERN NM/WRN TX INTO KS/OK. IN THE LOW LEVELS...
SURFACE LOW OVER ERN NM WILL DEVELOP ACROSS THE SRN TX PNHDL THIS
AFTERNOON INTO CNTRL OK BY 20/12Z. THIS LOW PRESSURE WILL BE
ACCOMPANIED BY A PACIFIC FRONT THAT WILL ADVANCE EWD ACROSS
WRN/CNTRL TX AND SWRN/S-CNTRL OK.
...SRN PLAINS...
SCATTERED ELEVATED TSTMS OVER PARTS OF W-CNTRL/NWRN TX INTO
WRN/CNTRL OK WILL MOVE/DEVELOP EWD/NEWD TODAY IN CONJUNCTION WITH A
LEAD VORTICITY MAXIMUM EJECTING NEWD IN ADVANCE OF PRIMARY
UPPER-LEVEL SYSTEM. LIMITED ELEVATED INSTABILITY SHOULD PRECLUDE A
SEVERE HAIL THREAT WITH THIS ACTIVITY.
BY MID/LATE AFTERNOON...LATEST CONVECTION-ALLOWING AND MESOSCALE
MODEL GUIDANCE INDICATES AN INCREASED LIKELIHOOD FOR SURFACE-BASED
TSTM DEVELOPMENT ALONG PACIFIC FRONT INVOF OF THE I-35 CORRIDOR OF
NRN/CNTRL TX. HERE...INCREASING BOUNDARY LAYER MOISTURE CONTENT
WILL BE OFFSET TO A DEGREE BY WIDESPREAD CLOUDS WITH MLCAPE VALUES
RISING TO 500-1000 J/KG. BUT...GIVEN THE STRONG FORCING FOR ASCENT
AND STRENGTHENING LOW- AND DEEP-LAYER SHEAR /I.E. ESRH OF 200-300 M2
PER S2 AND EBS OF 45-55 KT/...THE SETUP WILL FAVOR THE DEVELOPMENT
OF ORGANIZED STORM MODES INCLUDING SUPERCELLS WITH A RISK FOR A FEW
TORNADOES...DAMAGING WINDS AND HAIL.
ELSEWHERE...ISOLATED...LOW-TOPPED TSTMS WILL BE POSSIBLE THIS
AFTERNOON OVER THE SRN TX PNHDL INTO FAR SWRN OK BENEATH MIDLEVEL
COLD CORE AND INVOF OCCLUDING SURFACE LOW. HERE...STEEPENING LAPSE
RATES WILL YIELD WEAK CONVECTIVE INSTABILITY WITH THE STRONGEST
STORMS CAPABLE OF SOME HAIL...POSSIBLY APPROACHING SEVERE LEVELS.
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