MESO: Mesoscale Discussion 0488

ACUS11 KWNS 141117
SWOMCD
SPC MCD 141117
MSZ000-LAZ000-141245-

MESOSCALE DISCUSSION 0488
NWS STORM PREDICTION CENTER NORMAN OK
0617 AM CDT SAT APR 14 2007

AREAS AFFECTED...LA...MS

CONCERNING...TORNADO WATCH 139...

VALID 141117Z - 141245Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 139 CONTINUES THROUGH
13Z. SEVERE THREAT WILL INCREASE ACROSS AREAS EAST WW 139 TOWARD
MID DAY...POSSIBLY AFTER A TEMPORARY WEAKENING OF ACTIVITY. A NEW
WW MAY NOT BE NEEDED UNTIL LATER THIS MORNING.

VIGOROUS CONVECTIVE DEVELOPMENT PERSISTS NEAR PRE-FRONTAL
CONFLUENCE...NOW MAINLY ALONG A LINE NORTHWEST OF JACKSON MS INTO
THE LAKE CHARLES LA AREA. THIS IS WHERE ACTIVITY APPEARS ROOTED IN
DEEP NEAR SURFACE MOIST LAYER...WITH MOST UNSTABLE CAPE IN EXCESS OF
1000 J/KG. LOW-LEVEL CONFLUENCE ZONE APPEARS LIKELY TO CONTINUE
SLOWLY EASTWARD INTO CENTRAL MISSISSIPPI/SOUTHEAST LOUISIANA THROUGH
THE 12-15Z TIME FRAME. STORMS MAY WEAKEN AFTER DAYBREAK...BEFORE
BOUNDARY LAYER AHEAD OF ACTIVITY BEGINS TO DESTABILIZE WITH DAYTIME
HEATING AND NORTHEASTWARD MOISTURE ADVECTION OFF THE GULF OF MEXICO.
CURRENT INDICATIONS ARE THAT THIS MAY NOT OCCUR UNTIL CLOSER TO
18Z...NORTHEAST OF MCCOMB INTO THE MERIDIAN AREA...WHEN/WHERE
DISCRETE NEW STORMS MAY BEGIN TO DEVELOP AHEAD OF LINE...AND TORNADO
POTENTIAL PROBABLY WILL INCREASE.

CONVECTION BECOMES INCREASINGLY ELEVATED NORTHEASTWARD ACROSS
NORTHERN MISSISSIPPI INTO THE TENNESSEE VALLEY...WHERE IT IS
GRADUALLY WEAKENING. BUT...A RELATIVELY DRY LOW-LEVEL AIR MASS MAY
CONTINUE TO CONTRIBUTE TO SUFFICIENT EVAPORATIVE COOLING TO ENHANCE
DOWNDRAFTS AND POTENTIAL FOR GUSTY SURFACE WINDS ANOTHER COUPLE OF
HOURS.

.KERR.. 04/14/2007

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

ATTN...WFO...MOB...JAN...LIX...LCH...

31949103 32579065 33029007 33158957 33068877 32848845
31538874 30038992 29739073 29839237 30759183

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