SWODY1
SPC AC 041955
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0155 PM CST FRI MAR 04 2011
VALID 042000Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS ERN OK/MO/NWRN AR AND
VICINITY...
...ERN OK/MO/NWRN AR AND INTO THE LOWER MS VALLEY...
FAIRLY WIDESPREAD SHOWERS AND THUNDERSTORMS CONTINUE TO DEVELOP
ACROSS PRIMARILY WRN MO...ALONG NWRN FRINGES OF THE AXIS OF GREATEST
INSTABILITY. STEEP LAPSE RATES AND AMPLE SHEAR -- BEING PROVIDED BY
A SHORT-WAVE TROUGH CROSSING INTO WRN MO FROM ERN KS -- WILL
CONTINUE TO SUPPORT CONVECTIVE DEVELOPMENT THIS AFTERNOON AND
EVENING. STORMS SHOULD INCREASE SSWWD INTO ERN OK WITH TIME...WITH
ALL OF THIS ACTIVITY TO MOVE ENEWD THROUGH EVENING.
WHILE LIMITED CAPE REMAINS AN ISSUE WITH RESPECT TO ROBUST
CONVECTION/MORE WIDESPREAD SEVERE STORMS...AMPLE INSTABILITY EXISTS
TO SUPPORT A FEW STRONGER/SEVERE CELLS. SLIGHT RISK HAS BEEN
SHIFTED SLIGHTLY NWD THIS FORECAST...WITH HEATING ALLOWING CAPE TO
BE SLIGHTLY HIGHER THAN FORECAST INTO CENTRAL MO.
OTHERWISE...THREAT FOR SOME HAIL - AND PERHAPS ISOLATED DAMAGING
WINDS -- CAN BE EXPECTED THROUGH THIS EVENING.
..GOSS.. 03/04/2011
.PREV DISCUSSION... /ISSUED 1015 AM CST FRI MAR 04 2011/
..SYNOPSIS...
TROUGH APPROACHING PLAINS WITH LEAD S/WV NOW WRN KS FOLLOWED BY A
SECONDARY VORT MAX VICINITY 4 CORNERS THIS MORNING. COLD FRONT FROM
NRN MO SWWD INTO SWRN OK PUSHES SEWD TO NEAR A STL-SGF-SPS LINE BY
00Z.
AN ELEVATED MIX LAYER WITH LAPSE RATES AOA 7.5C/KM CURRENTLY
SPREADING EWD ACROSS CENTRAL/SRN PLAINS WILL CAP MUCH OF WARM SECTOR
THIS AFTERNOON...HOWEVER IT WILL PROVIDE THERMODYNAMIC SUPPORT FOR A
SEVERE THREAT ONCE STORMS CAN INITIATE. LIMITING THE SEVERE
THUNDERSTORM POTENTIAL ARE BOTH THE LIMITED AVAILABLE LOW LEVEL
MOISTURE RETURN FROM THE GULF...LESS THAN 1 INCH PWAT...AND MODEST
ASCENT WITH BOTH UPPER TROUGHS.
...SERN KS/WRN MO...
COMBINATION OF ASCENT WITH LEAD S/WV MOVING EWD ACROSS KS AND LIFT
PROVIDED ALONG AND BEHIND COLD FRONT SHOULD LEAD TO PRIMARILY
ELEVATED THUNDERSTORM DEVELOPMENT DURING THE AFTERNOON SERN KS INTO
MO. ALTHOUGH MUCAPE WILL BE LIMITED...GENERALLY MUCH LESS THAN 1000
J/KG...THE COLD AIR ALOFT/STEEP LAPSE RATES COUPLED WITH FORCED
ASCENT ALONG AND N OF THE FRONT WILL LEAD TO A FEW STRONG/SEVERE
THUNDERSTORMS. SEVERE THREAT SHOULD BE CONFINED TO LARGE HAIL ON
COLD SIDE OF FRONT WITH EVENTUALLY A LOW THREAT OF SUPERCELL/WIND
DAMAGE BY THIS EVENING SRN MO NEARER THE FRONT AS DEEP LAYER SHEAR
INCREASES AND SFC CINH WEAKENS IN THE WARM SECTOR.
...OK/TX/AR/SRN MO...
BY TONIGHT...THE SECOND AND STRONGER UPPER TROUGH WILL AMPLIFY AND
MOVE ESEWD INTO TX AND SRN OK. THIS SYSTEM IS FORECAST TO BE
POSITIVELY TILTED AND SLOW TO EJECT ACROSS THE PLAINS.
ALSO...CAPPING INVERSION WILL LIMIT CONVECTIVE DEVELOPMENT.
PRESENT INDICATIONS ARE THAT A COMBINATION OF INCREASING LARGE SCALE
FORCING...THE APPROACHING COLD FRONT...AND DAYTIME HEATING WILL HELP
TO INITIATE ISOLATED THUNDERSTORMS BY LATE AFTERNOON FROM SWRN MO
INTO EASTERN OK. WHILE THE COVERAGE WILL NOT BE PARTICULARLY
HIGH...THOSE STORMS THAT DO FORM WILL BE IN AN ENVIRONMENT OF STEEP
MID LEVEL LAPSE RATES...8C/KM... AND 35-45 KNOTS OF EFFECTIVE SHEAR.
SUPERCELL STRUCTURES WILL BE POSSIBLE WITH LARGE HAIL THE MAIN
THREAT. LOCALLY DAMAGING WINDS WILL ALSO BE POSSIBLE THROUGH THE
EVENING AS STORMS GROW UPSCALE IN LINES AND CLUSTERS.
LATE TONIGHT...CONVERGENCE ALONG THE FRONT AND CONTINUED BOUNDARY
LAYER MOISTENING WILL LIKELY RESULT IN SCATTERED THUNDERSTORMS OVER
EAST TX. A STRONGER CAPPING INVERSION SHOULD LIMIT UPDRAFT STRENGTH
WITH ONLY LOW PROBABILITIES OF HAIL CURRENTLY FORECAST.
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