Severe Thunderstorm Warning 658, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
400 PM CDT WED JUL 23 2008

.DISCUSSION...ARKLAMISS REGION REMAINS IN A SQUEEZE PLAY THIS
AFTERNOON BETWEEN MOIST SOUTHERLY FLOW COMING IN FROM THE GULF OF
MEXICO AND DRIER NORTHERLY FLOW ASSOCIATED WITH A WEAK FRONT AND
UPPER LEVEL DISTURBANCE COMING DOWN FROM THE NORTH. SOME OF THE
MENTIONED LOW LEVEL SOUTHERLY FLOW IS AT LEAST SOMEWHAT ATTRIBUTABLE
TO HURRICANE DOLLY (WHICH RECENTLY MADE LANDFALL AT SOUTH PADRE
ISLAND TEXAS). PERSISTENT BAND OF WEST TO EAST ORIENTED SHOWERS AND
THUNDERSTORMS HAVE BEEN PROGRESSING SLOWLY NORTH THROUGH THE
AFTERNOON ACROSS NE LA AND SOUTH MS ALONG THE NORTHERN EDGE OF DEEP
LOW LEVEL SOUTHERLY FLOW. THIS BAND IS NOW STRUGGLING TO PUSH NORTH
OF THE I-20 CORRIDOR AS I WRITE. TO THE NORTH THERE ARE NOW ISOLATED
STORMS DEVELOPING IN THE NORTHERLY FLOW REGIME DUE TO A VERY
MOIST...HOT AND UNSTABLE AIRMASS BEING ACTIVATED BY THE REFERRED TO
DISTURBANCE COMING SOUTH. THERE SHOULD BE A WEST TO EAST BAND OF
ENHANCED CONVERGENCE SET UP BETWEEN HIGHWAY 82 AND I-20 LATE THIS
AFTERNOON INTO THIS EVENING WHERE VIGOROUS THUNDERSTORM GROWTH TAKES
PLACE. THIS EXPECTED ACTIVITY SHOULD BE CAPABLE OF PRODUCING AT
LEAST ISOLATED INCIDENTS OF SEVERE WEATHER (FROM WIND AND HAIL) AND
EXTREMELY HEAVY DOWNPOURS. THE FORECAST AND HWO HIGHLIGHTS THESE
GENERAL AREAS FOR HAVING THE HIGHEST RISK FOR ACTIVE WEATHER AS WE
GO THROUGH THE EVENING HOURS. EXPECT CONCENTRATED SHOWERS AND STORMS
OVER NORTHERN ZONES THIS EVENING TO TAKE SOME TIME TO DIMINISH...BUT
EVENTUALLY ENDING AFTER MIDNIGHT. ELSEWHERE EVENING CONVECTION WILL
BE MORE ISOLATED AND LIKELY QUICKER TO END.

FOR TOMORROW THE MENTIONED CONVERGENCE BAND (LOOSELY ASSOCIATED WITH
AN ACTUAL FRONTAL BOUNDARY) WILL SET UP FROM NORTHWEST TO SOUTHEAST
ACROSS NORTHEAST MISSISSIPPI. MEANWHILE...SOUTHWEST LOW LEVEL FLOW
WEST OF THIS BOUNDARY WILL BE SOMEWHAT DIVERGENT...ALTHOUGH THE
ATMOSPHERE WILL GET RATHER WARM AND UNSTABLE. WITH LITTLE UPPER
LEVEL SUPPORT ANTICIPATED...EXPECT MOST OF THE DAYTIME SHOWER AND
STORM ACTION TO BE ISOLATED AND TENDING BY LATE AFTERNOON TO BECOME
MORE CONCENTRATED IN NORTHEAST ZONES AROUND THE CONVERGENCE ZONE. A
FEW STRONG STORMS WILL BE POSSIBLE...BUT THERE IS NOT EXPECTED TO BE
ENOUGH INSTABILITY OR ATMOSPHERIC FORCING AVAILABLE FOR MUCH IN THE
WAY OF SEVERE WEATHER. HIGHS WILL BE MAINLY IN THE MID 90S (LIKE THE
12Z MAV SUGGESTS).

RIDGING WILL BE BUILDING BACK IN FROM THE WEST RATHER STRONGLY BY
FRIDAY...BUT THE PRESENCE OF THE CONVERGENCE ZONE NEAR THE MS/AL
STATELINE AND A POSSIBLE DISTURBANCE COMING SOUTH FROM THE TN VALLEY
COULD STILL BRING SOME SCATTERED SHOWERS AND STORMS TO AREAS OF MS
EAST OF INTERSTATE 55. OTHERWISE...ANTICIPATE ONLY VERY ISOLATED
DIURNAL SHOWER AND STORM ACTIVITY WITH TEMPERATURES ALONG AND WEST
OF I-55 STARTING TO HEAT BACK UP. WENT LARGELY WITH MAV ADVERTISED
TEMPS (RANGING FROM THE UPPER 90S ALONG AND WEST OF THE BIG RIVER TO
LOW AND MID 90S OVER EASTERN ZONES).

OVERALL MODEL CONSENSUS CONTINUES TO SUGGEST THE UPPER RIDGE
CENTERED JUST TO OUR WEST WILL BE THE MAIN WEATHER STORY FOR THE
ARKLAMISS THIS WEEKEND. SHOWER AND THUNDERSTORM ACTIVITY SHOULD
MAINLY BE ISOLATED AT BEST WITH 850 MB TEMPS FROM 20 TO 22 DEGREES C
TRYING TO BUILD INTO AREAS WEST OF THE NATCHEZ TRACE. LATEST 12Z MEX
GUIDANCE FOR THESE DAYS HAS COME IN HOTTER AND HAVE LARGELY FOLLOWED
(AND EVEN INCREASED IN WESTERN ZONES A BIT). RIGHT NOW OUR FORECAST
ADVERTISES A RANGE OF HIGHS NEAR 100 WEST AND IN THE MID 90S EAST
FOR BOTH DAYS...AND OUR FORECAST COULD EASILY BE TOO COOL. THERE IS
ALSO THE EXPECTATION OF ENOUGH LOW LEVEL MOISTURE REMAINING IN PLACE
TO DELIVER HEAT INDEX VALUES UP AROUND 105 IN AT LEAST WESTERN
ZONES. MODELS SUGGEST THE RIDGE INFLUENCE WILL CONTINUE INTO AT
LEAST EARLY NEXT WEEK AND HEAT MAY BUILD FURTHER. HOWEVER...THERE IS
A LITTLE UNCERTAINTY IN THIS ASSUMPTION AS THE BREAKDOWN OF THIS
RIDGE IS LIKELY BY THE LATTER PORTION OF NEXT WORK WEEK AND HOW
QUICKLY THIS WILL OCCUR IS QUESTIONABLE. OUR CURRENT FORECAST
ADVERTISES HIGHS MAINLY IN THE MID AND UPPER 90S MONDAY AND TUESDAY
AND WE DEFINITELY MAY BE TOO COOL IF THE RIDGE BREAKDOWN DOES NOT
OCCUR QUICKLY. BUT WITH GIVEN UNCERTAINTIES AND POSSIBLE PRECIP
IMPLICATIONS (IN MAINLY NORTHERN AND EASTERN ZONES)...I WILL LEAVE
THE GOING FORECAST ALONE AND WAIT FOR INCREASED CONFIDENCE. /BB/

&&

.AVIATION...ALL TAF SITES HAVE MOVED INTO VFR STATUS AND WILL LIKELY
REMAIN THAT WAY UNTIL THIS AFTERNOON. ONCE AGAIN THE BIGGEST CONCERN
TODAY WILL BE CONVECTION. ACROSS THE SOUTH(HBG) SHRA AND TSRA COULD
BEGIN EARLY THIS AFTERNOON BUT ELSEWHERE CONVECTION WILL LIKELY HOLD
OFF UNTIL LATE THIS AFTERNOON AND SHOULD PERSIST WELL INTO THE
EVENING. SOME OF THESE STORMS COULD BE POTENT AND BESIDES FREQUENT
LIGHTNING AND HEAVY RAIN THERE COULD BE SOME RATHER STRONG WIND
GUSTS. STRONG TO SEVERE STORMS WILL BE POSSIBLE ACROSS THE ENTIRE
AREA BUT THE GREATEST RISK LOOKS TO BE ALONG AND NORTH OF I 20 LATE
THIS AFTERNOON AND THIS EVENING. AS WITH ANY TSRA...VISBIES AND
CEILINGS WILL BOTH DETERIORATE DOWN TO MVFR AND IFR AT TIMES. ALSO
LOOKS FOR WINDS GUSTS IN EXCESS OF 40KTS AND POSSIBLY SOME SMALL
HAIL WITH THE STRONGEST STORMS. CONVECTION SHOULD START TO FINALLY
SLACK OFF AFTER MIDNIGHT WITH ALL CONVECTION DONE WELL BEFORE
SUNRISE. /CAB/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       71  94  73  95 /  38  14  11  16
MERIDIAN      70  92  71  92 /  38  20  14  35
VICKSBURG     72  95  74  96 /  40  13   9   9
HATTIESBURG   70  94  72  94 /  20  23  10  24
NATCHEZ       71  92  74  94 /  20  25   8   8
GREENVILLE    72  92  74  97 /  54  13  12   9
GREENWOOD     72  93  73  96 /  54  14  14  16

&&

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

BB/CAB

HAZARDOUS WEATHER OUTLOOK...CORRECTION
NATIONAL WEATHER SERVICE JACKSON MS
236 PM CDT WED JUL 23 2008

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
241945-
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-
SIMPSON-SMITH-JASPER-CLARKE-JEFFERSON-ADAMS-FRANKLIN MS-LINCOLN-
LAWRENCE-JEFFERSON DAVIS-COVINGTON-JONES-MARION-LAMAR-FORREST-
236 PM CDT WED JUL 23 2008

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

.DAY ONE...TONIGHT AND THURSDAY

SCATTERED STRONG TO SEVERE STORMS WILL STILL BE POSSIBLE LATE THIS
AFTERNOON MAINLY NORTH OF INTERSTATE 20. THE PRIMARY RISK FROM THESE
STORMS WILL BE WINDS UP TO 60 MPH AND NICKEL SIZED HAIL. AFTERNOON
HEATING AND ABUNDANT MOISTURE HAVE LED TO A HIGHLY UNSTABLE
ENVIRONMENT. COMBINE THAT WITH THE APPROACHING WEAK FRONT FROM THE
NORTH AND THUNDERSTORMS WILL BEGIN TO DEVELOP THIS LATE AFTERNOON.
THESE STORMS WILL BE ABLE TO BECOME QUITE POTENT RATHER QUICKLY. IN
ADDITION TO THE SEVERE RISK...INTERACTING OUTFLOW BOUNDARIES COULD
FOCUS STORMS IN A FEW LOCATIONS TO PRODUCE VERY HEAVY RAINFALL OF 1
TO 2 INCHES IN LESS THAN ONE HOUR...ESPECIALLY ACROSS NORTHEASTERN
MISSISSIPPI.

.DAYS TWO THROUGH SEVEN...THURSDAY NIGHT THROUGH TUESDAY

VERY HOT CONDITIONS MAY START TO MOVE BACK INTO THE REGION AS EARLY
AS FRIDAY. THE ENTIRE OUTLOOK AREA WILL HAVE THE POTENTIAL TO SEE
TEMPERATURES CLIMB NEAR OR SLIGHTLY ABOVE THE CENTURY MARK LATE THIS
WEEKEND AND INTO THE EARLY PARTS OF NEXT WEEK...ESPECIALLY AREAS
ACROSS THE WEST. PLEASE STAY TUNED TO FURTHER UPDATES REGARDING THIS
POSSIBLE HEAT WAVE.

.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 LATE THIS AFTERNOON AND THIS EVENING.

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

24

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
253 PM CDT WED JUL 23 2008

MSZ058-232040-
CLARKE MS-
253 PM CDT WED JUL 23 2008

A STRONG THUNDERSTORM CAPABLE OF PRODUCING PEA TO DIME SIZE HAIL AND
40 TO 50 MPH WINDS WAS LOCATED 4 MILES WEST OF QUITMAN AT 253 PM
CDT...MOVING SOUTHEAST AT 9 MPH.

VERY HEAVY RAIN ALONG WITH CONTINUOUS CLOUD TO GROUND LIGHTNING ARE
ALSO POSSIBLE WITH THIS STORM.

PEOPLE IN CLARKE COUNTY SHOULD MONITOR THIS STORM CLOSELY.

BANNAN

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
341 PM CDT WED JUL 23 2008

MSZ066-232050-
JONES MS-
341 PM CDT WED JUL 23 2008

A STRONG THUNDERSTORM CAPABLE OF PRODUCING VERY HEAVY RAIN WAS
LOCATED 4 MILES EAST OF SANDERSVILLE AT 341 PM CDT. THE STORM WAS
NEARLY STATIONARY.

HEAVY RAINFALL BETWEEN 2 AND 3 INCHES IS POSSIBLE WITH THIS STORM.
IF THE STORM CAN HOLD TOGETHER OVER THE NEXT 30 MINUTES...A FLASH
FLOOD WARNING MAY BE NEEDED AS AN ADDITIONAL 2 PLUS INCHES MAY OCCUR.

PEOPLE IN NORTHEASTERN JONES COUNTY SHOULD MONITOR THIS STORM
CLOSELY.

CME

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
524 PM CDT WED JUL 23 2008

MSZ046-232235-
KEMPER MS-
524 PM CDT WED JUL 23 2008

...STRONG THUNDERSTORM OVER KEMPER COUNTY...

A STRONG THUNDERSTORM CAPABLE OF PRODUCING 40 TO 50 MPH WINDS WAS
LOCATED 4 MILES SOUTHWEST OF DE KALB AT 524 PM CDT...MOVING SOUTH AT
14 MPH.

VERY HEAVY RAIN ALONG WITH CONTINUOUS CLOUD TO GROUND LIGHTNING ARE
ALSO POSSIBLE WITH THIS STORM.

HIGH WINDS CAN BRING DOWN TREES AND LARGE LIMBS RESULTING IN SERIOUS
INJURY OR PROPERTY DAMAGE. EXERCISE EXTREME CAUTION WHEN OUTDOORS
DURING SUCH STRONG WINDS...AND BE ESPECIALLY AWARE OF OLDER TREES.

PEOPLE IN CENTRAL KEMPER COUNTY SHOULD MONITOR THIS STORM CLOSELY.

OLB

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