[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 200556
SWODY1
SPC AC 200554

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1154 PM CST SUN MAR 19 2006

VALID 201200Z - 211200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF MS AND AL...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE LOWER TO
MID MS VALLEY...TN VALLEY AND SRN PLAINS...

...LOWER TO MID MS VALLEY...
A POTENT UPPER-LEVEL TROUGH WILL ORGANIZE AND BEGIN TO ACCELERATE 
EWD INTO THE SRN PLAINS TODAY. THE TROUGH WILL BECOME NEGATIVELY
TILTED AND SPREAD STRONG UPPER-LEVEL DIFFLUENCE ACROSS THE LOWER MS
AND TN VALLEYS. INCREASING LARGE-SCALE ASCENT COMBINED WITH MOISTURE
ADVECTION AND STRONG VERTICAL SHEAR WILL SUPPORT A WIDESPREAD SEVERE
WEATHER EVENT TODAY AND TONIGHT ACROSS THIS REGION.

AN MCS SHOULD BE ONGOING AT THE BEGINNING OF THE PERIOD NEAR THE
TX-LA STATE-LINE. THIS STORM COMPLEX WILL MOVE EWD ACROSS LA AND NRN
MS TODAY HELPING TO SHARPEN A WARM FRONT LIFTING NWD ACROSS MS...AL
AND GA. THE FRONT SHOULD BE LOCATED FROM CNTRL MS EXTENDING EWD
ACROSS CNTRL AL BY LATE AFTERNOON. STRONG MOISTURE ADVECTION AHEAD
OF THE APPROACHING SYSTEM SHOULD BRING SFC DEWPOINTS INTO THE MID TO
UPPER 60S F ACROSS THE SRN HALF OF MS AND AL. CURRENT THINKING IS
THAT THE INITIAL MORNING MCS WILL TRACK ENEWD ALONG THE COOL SIDE OF
THE BOUNDARY ALLOWING MODERATE INSTABILITY TO DEVELOP ACROSS SCNTRL
MS AND CNTRL AL BY LATE AFTERNOON. AS THE UPPER-TROUGH APPROACHES
AND AN ASSOCIATED 100 KT MID-LEVEL JET PUNCHES INTO THE LOWER MS
VALLEY...STORM INITIATION APPEARS LIKELY ACROSS SERN LA OR SWRN MS
DURING THE AFTERNOON WITH A SEVERE MCS DEVELOPING AND MOVING NEWD
ACROSS CNTRL MS AND NCNTRL AL.

FORECAST SOUNDINGS SHOW IMPRESSIVE SHEAR PROFILES ACROSS THE
MODERATE RISK AREA TODAY WITH 0-6 KM SHEAR VALUES OF 60-70 KT
SUGGESTING SUPERCELLS WILL BE LIKELY WITH STORMS THAT REMAIN
DISCREET. LARGE LOOPED HODOGRAPHS DUE TO THE STRONG LOW-LEVEL JET
WILL CREATE 0-1 KM SRH VALUES AROUND 300 M2/S2 SUGGESTING
SIGNIFICANT TORNADOES WILL BE POSSIBLE. THE BEST TORNADO THREAT
SHOULD EXIST WEST OF THE LOW-LEVEL JET MAX FROM SCNTRL MS EXTENDING
NEWD ACROSS MOST OF ERN MS INTO WRN AND NRN AL. IF MODERATE
INSTABILITY DEVELOPS AS FORECAST...A FEW LONG TRACK STRONG TORNADOES
WOULD BE POSSIBLE WITH SUPERCELLS THAT PARALLEL THE FRONTAL
BOUNDARY. LARGE HAIL AND WIND DAMAGE SHOULD ALSO ACCOMPANY
SUPERCELLS AND/OR BOW ECHOES. IF CELLS GRADUALLY MERGE AND A LINEAR
MCS DEVELOPS THIS EVENING...THE WIND DAMAGE THREAT WOULD ALSO BE
ENHANCED ACROSS THE REGION. THE SEVERE WEATHER THREAT SHOULD
GRADUALLY DIMINISH OVERNIGHT AS A DRY SLOT PUNCHES EWD ACROSS THE
REGION AND THE MCS MOVES AWAY FROM THE INSTABILITY AXIS.

...SRN PLAINS/OZARK PLATEAU...
A POTENT UPPER-LOW WILL MOVE EWD INTO THE SRN AND CNTRL PLAINS
TODAY. STRONG MOISTURE ADVECTION AHEAD OF THE SYSTEM WILL INCREASE
SFC DEWPOINTS ACROSS AR AND OK THIS AFTERNOON ALLOWING FOR
SUFFICIENT INSTABILITY FOR THUNDERSTORM DEVELOPMENT. THE COLD AIR
ALOFT AND WARMING SFC TEMPS WILL CREATE VERY STEEP LAPSE RATES WHICH
COMBINED WITH STRONG VERTICAL SHEAR SHOULD BE FAVORABLE FOR
SUPERCELLS WITH LARGE HAIL. THE GREATEST THREAT FOR VERY LARGE HAIL
SHOULD EXIST FROM FAR ERN OK ACROSS THE AR RIVER VALLEY. THE SEVERE
THREAT SHOULD GRADUALLY DIMINISH DURING THE EVENING AS INSTABILITY
DECREASES ACROSS THE REGION.

..BROYLES.. 03/20/2006