Tornadoes and Hail in Mississippi, February 13, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
925 PM CST MON FEB 12 2007

.DISCUSSION...FORECAST TWEAKED SLIGHTLY FOR MINOR TEMPERATURES
ADJUSTMENT. OTHERWISE NO OTHER SIGNIFICANT CHANGES MADE. LEADING
EDGE OF LARGE AREA OF RAINFALL HAS CROSSED THE MS RIVER THIS EVENING
BUT STRONGER CONVECTION IS HANGING ALONG THE BACK EDGE OF THE RAIN
SHIELD WHERE UPPER FORCING IS MOST PRONOUNCED. SURFACE CONDITIONS
OVER THE ARKLAMISS HAVE BEEN SLOW TO MODERATE WITH DEWPONTS
REMAINING IN THE 30S OVER ERN ZONES WITH 40S AND LOWER 50S OTHER
AREAS. WATER VAPOR PIX SHOW DIGGING TROUGH OVER CENTRAL TX BECOMING
MORE NEGATIVELY TILTED IN NATURE...WHICH WILL AID UPPER FORCING AND
DIVERGENCE ALOFT LATER TONIGHT. ELEVATED CONVECTION WILL INCREASE
LATER TONIGHT...MAINTAINING HAIL AS THE PRIMARY SEVERE RISK TONIGHT
AND EARLY TUESDAY.

&&

.PREV DISCUSSION...SHORT TERM....(TONIGHT THROUGH TUESDAY NIGHT).
LATEST SATELLITE IMAGERY SHOWED A STRONG SOUTHERN STREAM SHORTWAVE
MOVING THROUGH THE SOUTHERN PLAINS TOWARD THE REGION. THERE WAS
ENOUGH STRONG COOL AIR ALOFT WITH STRONG LAPSE RATES FOR SOME GOOD
LIGHTNING ACROSS THE REGION. LATEST RUC ANALYSIS SHOWED A STRONG
SOUTHERN UPPER JET PUNCHING TOWARD THE SOUTHERN PLAINS AT AROUND 150
KNOTS...WHICH AFFECT OUR REGION FOR TONIGHT. LATEST VISIBLE IMAGERY
SHOWED CLOUDS ACROSS MOST OF THE REGION AS GULF MOISTURE WAS
INCREASING. ON THE SURFACE WE WERE GETTING SOME WARM AIR ADVECTION
ACROSS THE REGION IN SOUTHERLY LOW LEVEL FLOW. AS OF 2 PM
TEMPERATURES WERE MOVING TO AROUND 70 DEGREES.

LOOKING AT THE SHORT TERM. WE WILL BE DEALING WITH SOME SEVERE
WEATHER FOR TONIGHT AND TUESDAY IN THE FORM OF TWO ROUNDS ACCORDING
TO THE MODELS. WITH THE UPPER DISTURBANCE SOME GOOD 500 DKM HEIGHT
FALLS WILL PUSH ACROSS THE REGION FROM THE PLAINS(80-100 DKM). THIS
WILL COMBINE WITH GOOD COOLING ALOFT 300 MB -45C AND 500 MB TEMP
-18C TO -21C. THE SHORTWAVE COMING THROUGH THE PLAINS WILL BECOME
NEGATIVELY TILTED AS THE ASSOCIATED SURFACE LOW PUSHES NORTHEAST
ACROSS ARKANSAS DURING THE NIGHT. JET DYNAMICS COME INTO PLAY AS WE
WILL GET INTO THE LEFT FRONT QUAD OF A 160 PLUS KNOT JET BY EARLY
TUESDAY. EXPECT THE CONVECTION TO INCREASE IN COVERAGE AS THE LOWER
AND UPPER LEVEL DYNAMICS EVOLVE DURING THE NIGHT. LAPSE RATES DURING
THE SHORT TERM PERIOD WILL BE AROUND 6-8C. WE WILL ALSO GET INTO THE
LEFT FRONT QUAD OF 70 KNOT JET AT 500 MB. THE COOL TEMPS ALOFT AND
LOW WET BULB ZERO HEIGHTS SPELLS SOME GOOD HAIL RISKS FOR TONIGHT
AND TUESDAY. LOOKING FOR QUARTER TO GOLFBALL SIZE HAIL IN ELEVATED
SUPERCELLS FOR TONIGHT. WE MAY GET TO A LESSER EXTENT SOME DAMAGING
WINDS. IN THE SOUTHWEST IF THE DEWPOINTS RISE INTO THE LOWER 60S
WITH ENOUGH LOW LEVEL SHEAR ISOLATED TORNADOES WILL NOT BE OUT OF
THE QUESTION. EXPECT THE STORMS TO BE GENERALLY ELEVATED SUPERCELLS
WITH LOW DEWPOINTS.

LOOKING AT SURFACE WINDS AS THE AREA OF LOW PRESSURE MOVES NORTHWEST
OF THE REGION THE PRESSURE GRADIENT WILL TIGHTEN ACROSS THE REGION.
GUIDANCE HAD GRIDS OF AROUND 15 KNOTS IN THE DELTA REGION...SO PUT IN
GUST GRIDS OF APPROACHING 25 KNOTS...WHICH WILL BRING US JUST BELOW
LAKE WIND ADVISORY CRITERIA FOR THE DELTA REGION FOR TONIGHT.

THE SECOND ROUND OF SEVERE WEATHER ON TUESDAY WILL BE ASSOCIATED
WITH THE COLD FRONTAL PASSAGE. DEWPOINTS WILL RISE TO THE LOWER
60S...WHICH WILL CREATE SOME SURFACE BASED STORMS...BUT STILL EXPECT
HAIL TO BE THE PRIMARY RISK. DAMAGING WINDS AND ISOLATED TORNADOES IS
NOT OUT OF THE QUESTION IF WE GET ENOUGH LOW LEVEL SHEAR.

TIMING WISE FOR TONIGHT EXPECT THE BEST CHANCE OF SEVERE WEATHER IN
THE DELTA REGION FROM THE 10 PM TO 3 AM TIME FRAME...THE NATCHEZ
TRACE TO I-55 CORRIDOR TO BE FROM 2 AM TO 5 AM...THEN THE EAST
MISSISSIPPI REGION FROM 5 TO 8 AM TUESDAY MORNING.

FOR THE SECOND ROUND THE BEST CHANCE OF SEVERE WILL BE ALONG AND
NORTH AND EAST OF A GREENVILLE TO JACKSON TO LAUREL LINE. THE TIME
FRAME WILL BE FROM 10 AM TO 4 PM.

AFTER THE SYSTEM MOVES OUT EXPECT ONLY LINGER SHOWERS FOR TUESDAY
EVENING IN THE NORTHEAST...WHICH WILL END BY MIDNIGHT. AS FAR AS
POPS ARE CONCERN KEPT HIGH POPS FOR TONIGHT AND WENT CLOSE TO MAV
GUIDANCE FOR TUESDAY AND TUESDAY NIGHT. MADE SMALL CHANGES TO MAV
GUIDANCE ON TEMPS.

AS FAR AS TEMPS ARE CONCERN MADE SOME SLIGHT ADJUSTMENTS TO
GUIDANCE. WITH POPS WENT CLOSE TO GUIDANCE ON POPS FOR MONDAY AND
MAINTAINED HIGH POPS FOR MONDAY NIGHT.

LONG TERM...(WEDNESDAY THROUGH MONDAY)...THIS LONG TERM PORTION OF
THE FORECAST WILL BE ALL ABOUT THE COLD FOR WED-FRI THEN SOME MINOR
MODERATION OVER THE WEEKEND AS WE TRANSITION AHEAD OF THE NEXT
SYSTEM.

WED WILL START OFF QUITE RAW AS A SOLID SHIELD OF STRATUS WILL EXIST
AND STRONG CAA WILL BE ONGOING. THE AREA WILL START OFF COLD WITH
AROUND 30 N TO 37 SE. WITH STRONG CAA THROUGH THE DAY...TEMPS WILL
NOT MOVE MUCH AND ONLY EXPECT UPPER 30S N TO MID 40S S AT BEST. THIS
COULD ACTUALLY BE A TAD HIGH AS MOST OF THE CWA COULD REALLY
STRUGGLE TO SEE 40 DEGREES. THE STRATUS WILL BREAK A BIT...BUT GIVE
WAY TO OTHER MID/HIGH LEVEL CLOUDS WED N THROUGH THU. TEMPS WILL
SLOWLY FALL WED N WITH MID 20S N TO AROUND 30 SOUTH. CAA WILL STILL
BE QUITE DOMINANT ON THU AND AGAIN...THE REGION AMY STRUGGLE TO SEE
40 DEGREES. THE STRONG CANADIAN SFC HIGH WILL SETTLE OVER THE REGION
THU N UNDER CLEAR SKIES. EXPECT ONE OF THE COLDEST NIGHTS OF THE
YEAR WITH UPPER TEENS TO LOWER 20S AREA WIDE.

SFC HIGH SHIFTS EAST ON FRI AS WE SEE ANOTHER TROUGH APPROACH THE
AREA ON SAT. FRI WILL OFFER A MUCH WARMER DAY THE THE PREV 2...BUT
STILL BE BELOW CLIMO HIGHS. EXPECT LOWER 50S AREA WIDE. ANOTHER SFC
HIGH WILL MOVE IN SAT NIGHT AND KEEP THE AREA ON THE COOL SIDE WITH
BELOW CLIMO READINGS INTO MON./CME/

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&

SHORT TERM...17
LONG TERM...CME
03

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
132048-
ADAMS-ASHLEY-ATTALA-BOLIVAR-CARROLL-CATAHOULA-CHICOT-CHOCTAW-
CLAIBORNE-CLARKE-CLAY-CONCORDIA-COPIAH-COVINGTON-EAST CARROLL-
FORREST-FRANKLIN LA-FRANKLIN MS-GRENADA-HINDS-HOLMES-HUMPHREYS-
ISSAQUENA-JASPER-JEFFERSON-JEFFERSON DAVIS-JONES-KEMPER-LAMAR-
LAUDERDALE-LAWRENCE-LEAKE-LEFLORE-LINCOLN-LOWNDES-MADISON LA-
MADISON MS-MARION-MONTGOMERY-MOREHOUSE-NESHOBA-NEWTON-NOXUBEE-
OKTIBBEHA-RANKIN-RICHLAND-SCOTT-SHARKEY-SIMPSON-SMITH-SUNFLOWER-
TENSAS-WARREN-WASHINGTON-WEBSTER-WEST CARROLL-WINSTON-YAZOO-
248 PM CST MON FEB 12 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL MISSISSIPPI...
NORTHEAST LOUISIANA...AND EXTREME SOUTHEAST ARKANSAS

.DAY ONE...TONIGHT AND TUESDAY...

...THUNDERSTORMS...
SEVERE WEATHER WILL BE POSSIBLE FOR TONIGHT INTO TUESDAY. OVER
THE REGION WE ARE EXPECTING TWO ROUNDS OF SEVERE WEATHER. THE
FIRST ONE WILL OCCUR FOR TONIGHT. THE SECOND ROUND WILL OCCUR
DURING LATE TUESDAY MORNING INTO TUESDAY AFTERNOON ACROSS THE
NORTH AND EASTERN PORTIONS OF THE FORECAST AREA.

FOR THE FIRST ROUND A STRONG LOW PRESSURE SYSTEM WILL TRACK
NORTHEAST...JUST NORTH OF THE REGION TONIGHT INTO THE PREDAWN
HOURS TUESDAY. THIS WILL HELP TO DRAW NORTHWARD WARM AND MOIST
AIR. THIS WILL COMBINE WITH VERY COLD TEMPERATURES ALOFT
PROVIDING STEEP LAPSE RATES AND SUFFICIENT INSTABILITY FOR SEVERE
THUNDERSTORMS. A STRONG UPPER DISTURBANCE WILL ACCOMPANY THE LOW
PRESSURE SYSTEM AND PRODUCE THE TRIGGER TO GENERATE THESE STORMS.
AT THIS TIME THE PRIMARY RISK OF SEVERE WEATHER LOOKS TO BE
HAIL...SOME AS LARGE AS QUARTER TO GOLF BALL SIZE. HOWEVER
ISOLATED TORNADOES IN THE SOUTHWEST DURING THE NIGHT AND DAMAGING
WINDS ELSEWHERE IS NOT OUT OF THE QUESTION. AS FAR AS TIMING IS
CONCERNED...10 PM TO 3 AM IN THE DELTA REGION...2 AM TO 5 AM IN
THE NATCHEZ TRACE/INTERSTATE 55 CORRIDOR THEN 5 TO 8 AM IN THE
EAST. OVERALL...THE BEST CHANCE OF SEVERE WEATHER WILL BE ALONG
AND WEST OF INTERSTATE 55 WITH AND ENHANCED AREA ACROSS THE
PARISHES OF LOUISIANA SOUTH OF INTERSTATE 20.

THE SECOND ROUND OF SEVERE STORMS WILL BE POSSIBLE FROM 10 AM TO
4 PM TUESDAY AS COLDER TEMPERATURES ALOFT MOVE OVERHEAD AND THE
ACTUAL COLD FRONT CLASHES WITH 70 DEGREE AIR TEMPERATURES. ONLY A
PORTION OF THE FORECAST AREA WILL BE UNDER THE RISK WITH THE
SECOND ROUND OF SEVERE STORMS. AREAS ACROSS THE SOUTH WILL SEE A
LOW LEVEL CAP DEVELOP AND POSITIONED UNDERNEATH A STRONG JET
STREAM. AT THIS TIME AREAS NORTH AND EAST OF A GREENVILLE TO
JACKSON TO LAUREL LINE WILL BE UNDER THE PRIMARY RISK OF SEVERE
WEATHER. A MORE ENHANCED RISK WILL EXIST FOR AREAS EAST OF A
EUPORA TO FOREST LINE. THIS ENHANCED AREA WILL BE UNDER THE
GREATEST INSTABILITY AND IN A LOCATION WHERE STORMS WILL HAVE
TIME TO MATURE. MOST OF THE SEVERE WEATHER WILL BE IN THE FORM OF
QUARTER TO GOLFBALL SIZE HAIL. A SMALLER RISK WILL EXIST IN THE
FORM OF DAMAGING WINDS AND POSSIBLY EVEN A TORNADO IF THE LOW
LEVEL SHEAR CAN BECOME STRONGER.

EVERYONE IS URGED TO STAY ABREAST TO THE LATEST OUTLOOKS AND
STATEMENTS CONCERNING THE HAZARDOUS WEATHER EVENT.

.DAYS TWO THROUGH SEVEN...TUESDAY NIGHT THROUGH MONDAY...

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER CALL TO ACTION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS WILL LIKELY BE NEEDED TONIGHT AND TUESDAY. OTHERWISE
ACTIVATION IS NOT ANTICIPATED THROUGH NEXT MONDAY.

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.SRH.NOAA.GOV/JAN. THIS INCLUDES THE GRAPHICAL HAZARDOUS
WEATHER OUTLOOK.