Flash Flood Warning 100, NWS Jackson, MS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
734 PM CDT SAT AUG 29 2009

.DISCUSSION...A FEW THINGS TO DISCUSS THIS EARLY EVENING...FIRST IS
THE CURRENT ACTIVITY AND HOW THINGS MAY EVOLVE THROUGH THE NIGHT.
LASTLY...WHAT IS EXPECTED ON SUNDAY AND WHAT APPEARS TO BE A
DIMINISHING STRONG/SVR THREAT.

CURRENT STORM ACTIVITY HAS BEEN HOLDING ITS OWN BUT NOT REAL
VIGOROUS. POOR LAPSE RATES ARE THE MAIN CULPRIT FOR THAT AS
INSTABILITY IS IN THE RANGE FOR GENERAL TSRA WITH 2500 J/KG SBCAPE
AND 1500-1800 J/KG MLCAPE. THE ACTIVITY ACROSS THE N FORMED WITHIN
AN AXIS OF -5 TO -6 LIS RIGHT IN THE WEAK SFC TROUGH AXIS. THERE IS
SOME OK ASCENT ALOFT AS A MID LEVEL S/W IS POSITIONED JUST TO OUR NW
AND EXTENDS BACK INTO E TX. THERE IS DECENT JET ENERGY...BUT WE WERE
NOT IN ANY FAVORED REGION...SO THE UPPER DIV WAS NOT FOCUSED AND
MORE MIDDLE OF THE ROAD. DUE TO THE LACK OF STRONG ACTIVITY AND THE
FACT THAT WE WILL BE LOOSING INSTABILITY THIS EVENING...WE HAVE
REMOVED THE RISK OF STRONG STORMS FOR THE AFTERNOON/EVENING.

THE NEXT QUESTION IS HOW WILL THINGS EVOLVE FOR THE REST OF THE
NIGHT. MODEL GUID SUGGESTS THINGS WILL LINGER THROUGH LATE EVENING
AND ACTUALLY EXPAND IN COVERAGE AFTER 08/09Z THROUGH SUN MORNING/MID
DAY. THAT SEEM REASONABLE AS BETTER MID/UPPER SUPPORT WILL SHIFT OUR
WAY. THE UPPER JET WILL TAKE ON MORE OF A COUPLED STRUCTURE WHICH
WILL GREATLY ENHANCE THE UPPER DIV AND DEEP LAYER ASCENT. THE MID
LEVEL S/W AXIS WILL ALSO SHIFT MORE INTO THE CWA WHICH WILL SUPPORT
SOLID MID LEVEL ASCENT. IN THE LOWER LEVELS...WE WILL HAVE LEFT OVER
SFC BOUNDARIES ACROSS THE CENTRAL CWA ALONG WITH THE SFC PRESSURE
TROUGH LOCATED THE TRACE CORRIDOR. ALL THIS SHOULD SUPPORT DECENT
LOW LEVEL CONVERGENCE AND POOLING OF MOISTURE. MY MAIN ISSUED WITH
ACTIVITY DEVELOPING TOWARDS MORNING IS THE LACK OF A LL JET. USUALLY
WE NEED THIS FEATURE TO INCREASE THE LOW LEVEL MOISTURE AND PROVIDE
SOME LOW LEVEL ISENTROPIC ASCENT IN THE WAA REGIME. WITH JUST ONE
NEG ELEMENT...I WILL LEAN TOWARDS MORE ACTIVITY DEVELOPING ACROSS
CENTRAL/S SECTIONS LATER TONIGHT AS IS SHOWN BY NCEP MODELS AS WELL
AS LOCAL HI RES WRF OUTPUT. CURRENT FORECAST HANDLES THIS AND WILL
LEAVE AS IS. I MAY HAVE TO TWEAK THE TIMING OF PRECIP SOME...BUT I
WILL HANDEL THAT A BIT LATER AS THINGS EVOLVE A BIT MORE.

LASTLY...WHAT WILL THE POTENTIAL BE FOR STRONG/SVR ACTIVITY ON SUN.
AT THIS POINT...IM NOT REAL IMPRESSED AND REALLY CONCERNED THAT THE
AREA WILL NOT DESTABILIZE MUCH. MODEL GUID IS ONLY OFFERING HIGH
TEMPS FROM THE LOWER/MID 80S AND THAT WILL NOT OFFER MUCH IN THE WAY
OF INSTABILITY. MODEL GUID IS OFFERING 1500-1800 J/KG OF MLCAPE BUT
ALSO HAS MID/UPPER 70S SFC DEWPTS. THOSE TYPES OF DEWPTS ARE WAY
OVERDONE AND WE SHOULD ONLY SEE VALUES 70-73. ALSO...WITH ACTIVITY
GETTING SUCH AN EARLY START AND LIKELY CONTINUING INTO MID/LATE
MORNING...IT COULD BE TOUGH TO EVEN REACH THE MID 80S WHILE THE BEST
ASCENT IS OVER THE AREA. THERE IS STILL A GOOD BIT OF UNCERTAINTY
AND IF ACTIVITY OVERNIGHT DOES NOT DEVELOP LIKE THE GUID
SHOWS...THEN THERE WILL BE SOME WINDOW FOR THE AREA TO DESTABILIZE
AND SUPPORT SOME STRONGER ACTIVITY. AT THIS TIME...WE WILL TRIM THE
STRONG AND VERY LOW END SVR RISK MORE TO THE SE PORTION.

&&

.AVIATION...MAIN FOCUS IN TRYING TO TIME THE POTENTIAL ACTIVITY
LATER TONIGHT. AT THIS TIME...LOOKS LIKE STORM ACTIVITY WILL EXPAND
IN COVERAGE ACROSS CENTRAL AND S SECTIONS FROM 08-09Z THROUGH
15-18Z. LOOK FOR VFR CONDITIONS FOR A FEW MORE HRS THIS EVENING
BEFORE CONDITIONS DROP TO MVFR. DUE TO THE THICKER MID/UPPER LEVEL
CLOUDS IT MAY BE TOUGHER FOR SITES TO DROP BELOW 6SM AS TEMPS STAY A
TAD WARMER THAN PREV MORNINGS. HOWEVER...SFC DEWPTS ARE A BIT HIGHER
SO THAT MAY MAKE UP THE DIFFERENCE. FOR SUN MORNING THROUGH EARLY
AFTERNOON...AREAS ALONG AND S OF I-20 WILL SEE THE MAJORITY OF THE
ACTIVITY AND THAT IS WHERE RESTRICTED CONDITIONS WILL BE. LOOK FOR
VFR CONDITIONS ACROSS THE N AS DRIER AIR MOVES IN.

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       90  70  85  63 /  37  53  67  11
MERIDIAN      91  69  84  64 /  24  52  71  32
VICKSBURG     90  69  86  61 /  25  53  51   9
HATTIESBURG   91  73  86  67 /  44  40  81  37
NATCHEZ       90  70  85  65 /  46  48  67   9
GREENVILLE    89  67  83  58 /  20  28  27   9
GREENWOOD     90  68  83  59 /  23  35  48   9

&&

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

CME

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
554 PM CDT SAT AUG 29 2009

MSZ055>058-062>066-072>074-302300-
SIMPSON-SMITH-JASPER-CLARKE-LINCOLN-LAWRENCE-JEFFERSON DAVIS-
COVINGTON-JONES-MARION-LAMAR-FORREST-
554 PM CDT SAT AUG 29 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH AND EAST MISSISSIPPI.

.DAY ONE...TONIGHT AND SUNDAY

A FEW STRONG THUNDERSTORMS COULD BE POSSIBLE SUNDAY...PARTICULARLY
SOUTH AND EAST OF A LINE FROM BROOKHAVEN TO QUITMAN. AS A COLD FRONT
SINKS SOUTH...STORMS COULD DEVELOP AHEAD OF THIS FRONT AND MAY BECOME
STRONG GIVEN ENOUGH DAYTIME HEATING. AN ISOLATED SEVERE STORM IS
POSSIBLE AS WELL WITH THE MAIN RISK BEING FROM DAMAGING WINDS.
LOCALLY HEAVY RAINFALL WILL ALSO BE POSSIBLE IN THIS AREA ON SUNDAY.

.DAYS TWO THROUGH SEVEN...SUNDAY NIGHT THROUGH FRIDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER CALL TO ACTION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS...MAY BE NEEDED SUNDAY. OTHERWISE...ACTIVATION IS NOT
EXPECTED THROUGH NEXT FRIDAY.

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>054-059>061-
302300-
ASHLEY-CHICOT-MOREHOUSE-WEST CARROLL-EAST CARROLL-RICHLAND-
MADISON LA-FRANKLIN LA-CATAHOULA-TENSAS-CONCORDIA-BOLIVAR-
SUNFLOWER-LEFLORE-GRENADA-CARROLL-MONTGOMERY-WEBSTER-CLAY-LOWNDES-
CHOCTAW-OKTIBBEHA-WASHINGTON-HUMPHREYS-HOLMES-ATTALA-WINSTON-
NOXUBEE-ISSAQUENA-SHARKEY-YAZOO-MADISON MS-LEAKE-NESHOBA-KEMPER-
WARREN-HINDS-RANKIN-SCOTT-NEWTON-LAUDERDALE-CLAIBORNE-COPIAH-
JEFFERSON-ADAMS-FRANKLIN MS-
554 PM CDT SAT AUG 29 2009

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

.DAY ONE...TONIGHT AND SUNDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.DAYS TWO THROUGH SEVEN...SUNDAY NIGHT THROUGH FRIDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER CALL TO ACTION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS...IS NOT EXPECTED THROUGH NEXT FRIDAY.

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

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