re: General Tornado Thread

ANYONE IN MISSISSIPPI.. READ THIS OUTLOOK FROM JACKSON NWS OFFICE PLEASE.. READ IT CLOSELY.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
515 PM CDT SUN APR 27 2014

...SEVERE WEATHER OUTBREAK EXPECTED TONIGHT THROUGH TUESDAY...
...SIGNIFICANT FLOODING POSSIBLE MONDAY INTO EARLY TUESDAY...

.DISCUSSION...

TODAY THROUGH TUESDAY

SEVERAL ROUNDS OF SIGNIFICANT SEVERE WEATHER ARE EXPECTED TO IMPACT
THE REGION LATE THIS AFTN THROUGH TUESDAY NIGHT. THESE ROUNDS AND
THEIR POTENTIALLY LIFE-THREATENING HAZARDS WILL BE FOCUSED IN
DIFFERENT AREAS OVER THIS TIME FRAME. BELOW WILL BE A DISCUSSION
FOCUSING ON THE SPATIAL, TEMPORAL AND HAZARDS SCOPE OF THESE ROUNDS.
IT SHOULD BE NOTED THAT MONDAY LOOK PARTICULARLY DANGEROUS.

OVERALL SYNOPSIS REVEALS A STRONG OCCLUDED H5 CLOSED LOW OVER KS AS
CYCLONICALLY CURVED H7-H3 JET STREAK MAXIMUMS PIVOT AROUND THE
SOUTHERN FRINGE OF THE AN ATTENDANT 983 MB SURFACE LOW ALLOWING FOR
STRONG VERTICAL WIND SHEAR TO SPREAD OVER A LARGE UNSTABLE WARM
SECTOR ACROSS THE ARKLATEX TOWARDS THE DELTA REGION. IT IS THIS SAME
CLOSED LOW THAT WILL BE THE MAIN DYNAMIC FORCING MECHANISM THAT WILL
BRING MORE SEVERE STORMS ESPECIALLY ON MONDAY AND AGAIN TUESDAY.

FOR TODAY...THE GREATEST SEVERE WEATHER CHANCES WILL BE LOCATED IN
THE ARKLAMISS DELTA WHERE THE BEST COMBO OF INSTABILITY /~3000 J/KG
SBCAPE/ DEEP LAYER SHEAR /50-60 KT/ AND 0-1 KM ESRH /300-500 M2/S2/
EXIST. A TIGHT THERMAL GRADIENT IS ALSO NOTED ACROSS THE DELTA
REGION THAT COULD LIKELY SERVE AS A LOW-LVL CONVERGENT FOCUS. STORMS
THAT DEVELOP IN THIS ENVIRONMENT WILL HAVE THE CAPABILITY OF
PRODUCING TORNADOES (SOME STRONG), LARGE HAIL TO SIZE OF GOLF BALLS,
AND DAMAGING STRAIGHT-LINE WINDS. STORMS THAT DEVELOP ACROSS NW MS
AND DELTA REGION SHOULD GROW UPSCALE THROUGH THE EVENING THAT WILL
ENHANCE THE DAMAGING WIND GUST RISK AS IT MOVES INTO NORTH-CENTRAL
AND NORTH MS. THE SHOWERS AND GENERAL TSTORMS IN SW MS WILL CONTINUE
TO MOVE NE AND POSE A MARGINAL STRONG TO SEVERE RISK DUE TO DAYTIME
HEATING BUT THIS ACTIVITY SHOULD SLOWLY DISSIPATE THROUGH THE
EVENING AS TEMPS COOL.

THE NEXT, AND POTENTIALLY MOST SIGNIFICANT ROUND OF SEVERE WEATHER
COULD DEVELOP AS EARLY AS DAYBREAK MONDAY AND THEN LAST THROUGH THE
DAY AS STORMS PROGRESS EAST ACROSS THE ENTIRE REGION. BY 7AM
MONDAY...A BRISK S/WV TROUGH LOOKS TO EJECT OFF THE MAIN CYCLONIC
GYRE WHILE THE GYRE CONTINUES TO DEEPEN. INDUCED LIFT FROM HEIGHT
FALLS AND 90 KT H5 JET IN AR IN PRESENCE OF 1000-1500 MLCAPE AND
NEAR 7 C/KM H7-H5 LAPSE RATES COULD SUPPORT SEVERE CONVECTION
SHORTLY AFTER DAY BREAK ALONG AND WEST OF THE MS RIVER. DEPENDING ON
WHERE THIS ACTIVITY SETS UP AND HOW IT EVOLVES WILL BE CRITICAL FOR
HOW THE REST OF THE PLAYS OUT. ONE SCENARIO COULD BE FOR COLD
POOLING FROM THIS POSSIBLE STORM CLUSTER TO LEAD TO A BOUNDARY
SETTING UP NORTH I-20. ALONG AND SOUTH OF THIS POSSIBLE BOUNDARY, A
CONCERNING ENVIRONMENT OF AMPLE MLCAPE, MODEST 0-1 KM SRH AND STRONG
DYNAMIC LOW-LVL CONVERGENCE AND UPPER LEVEL LIFT WILL PROVIDE A
IMPETUS FOR SEVERE STORM DEVELOPMENT CLOSE TO THE NATCHEZ TRACE
CORRIDOR. A SECOND SCENARIO IS THAT AS THE INITIAL WAVE LIFTS OFF TO
THE NE AND LITTLE/NO COLD POOLING OCCURS DUE TO STRONG SOUTHERLY
INFLOW AND STRONG MIXING. THE CLUSTER MAY SLOW AND EVOLVE INTO MORE
DISCRETE CELLS/SUPERCELLS THROUGH THE AFTN WHILE RENEWED UPPER LEVEL
DIVERGENCE IMPINGES ON THE VOLATILE ENVIRONMENT PRESENT IN THE LOW-
LVLS. STRONG AND POSSIBLY LONG TRACK TORNADOES WILL BE POSSIBLE
TOMORROW AFTN WITH ANY DISCRETE SUPERCELL THAT DEVELOPS GIVEN CIPS
ANALOGS AND FORECAST ENVIRONMENT. LARGE HAIL TO SIZE OF GOLFBALLS TO
EGG SIZE COULD ALSO BE POSSIBLE ALONG WITH DAMAGING STRAIGHT-LINE
WINDS. AS THE COMPLEX EVOLVES THROUGH THE LATE AFTN AND NIGHT, HEAVY
RAIN AND FLASH FLOODING WILL ALSO BECOME A SIGNIFICANT CONCERN FOR
CENTRAL AND NORTH MS AS AMPLE MOISTURE FLUX WILL CONTINUALLY FEED
INTO THE REGION. SIGNIFICANT RIVER RISES COULD OCCUR WHERE PRECIP
MAXIMUM OCCURS.

THIS HEAVY RAIN COMPLEX WILL MOVE ACROSS EAST MS THROUGH TUESDAY
MORNING WITH THE DRYLINE/BOUNDARY SET-UP NEAR THE MS RIVER. THERE IS
STILL SOME DISCREPANCY AS TO WHERE THE NORTH TO SOUTH ORIENTED
BOUNDARY WILL BE SET UP BETWEEN THE EC/GFS/NAM. AREAS ALONG AND EAST
OF THE LINE (LIKELY I-55 AND EAST) WILL REMAIN UNDER AN ELEVATED
RISK OF SEVERE STORMS INCLUDING TORNADOES, HAIL, STRAIGHT-LINE
WINDS, AND MORE HEAVY RAIN. TUESDAY EVOLUTION WILL REVOLVE AROUND
RECOVERY FROM MONDAY AND MORE DETAILS WILL BE ADDED AS WE APPROACH
THAT TIME FRAME.

IT SHOULD BE STRESSED THAT TOMORROW..MONDAY...LOOKS VERY CONCERNING
AND SEVERE ACTION PLANS SHOULD BE COMPLETED BY TONIGHT IN
PREPARATION. /ALLEN/