Flash Flood Warning 60, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
324 PM CDT MON JUN 28 2010

.DISCUSSION...

TONIGHT THROUGH WEDNESDAY NIGHT...WATER VAPOR IMAGERY CONTINUES TO
SHOW AN EXPANSIVE MOISTURE PLUME ASSOCIATED WITH TROPICAL STORM
ALEX...WHICH IS CURRENTLY CENTERED IN THE SOUTHWESTERN GULF OF
MEXICO. THIS MOISTURE PLUME CONTINUES TO MOVE NORTHWARD INTO THE
ARKLAMISS REGION AND IS ASSOCIATED WITH PWAT VALUES OF AROUND
2.5 INCHES ACROSS THE WEST CENTRAL GULF OF MEXICO. CURRENTLY...RUC
ANALYSIS INDICATES PWAT VALUES AROUND 2.1 INCHES ENTERING SOUTHERN
PORTIONS OF THE CWA. WITH AFTERNOON TEMPERATURES IN THE LOWER AND
MIDDLE 90S...AND SURFACE DEWPOINTS IN THE LOWER AND MIDDLE 70S...RUC
ANALYSIS INDICATES SBCAPE VALUES OF AROUND 3000-3500 J/KG ACROSS THE
CWA...WHICH IS CONTRIBUTING TO ROBUST CONVECTIVE UPDRAFTS WITH
SCATTERED CONVECTION ACROSS THE CWA. THE CONVECTION IS FURTHER BEING
SUPPORTED BY AN UPPER-LEVEL LOW AND ATTENDANT TROUGH OVER THE
FORECAST AREA...ALONG WITH A SEA BREEZE CONVERGENCE ZONE MOVING NORTH
FROM THE GULF OF MEXICO. ADDITIONALLY...LOW-LEVEL CONVERGENCE
ASSOCIATED WITH A SURFACE COLD FRONT...WHICH IS SLOWLY MOVING
SOUTHEASTWARD FROM THE MID-SOUTH REGION...HAS RECENTLY SHOWN SIGNS OF
INITIATING CONVECTION ACROSS NORTHWESTERN AREAS.

THE FOCUS FOR CONVECTION WILL SHIFT TOWARD CENTRAL AND NORTHERN
PORTIONS OF THE FORECAST AREA INTO THE LATE AFTERNOON AND EVENING
HOURS AS THE FRONT SLIDES SOUTHEASTWARD...WHILE CONVECTION INITIATED
BY THE SEA BREEZE CONVERGENCE ZONE PUSHES NORTHWARD. LATEST RUC
ANALYSIS INDICATES DCAPE VALUES FROM 1000-1200 J/KG ACROSS THE CWA
DUE TO STEEP LOW-LEVEL LAPSE RATES AND SOME DRY AIR IN THE 750-500-MB
LAYER. THUS...DAMAGING WINDS ASSOCIATED WITH WET MICROBURSTS WILL BE
THE MAIN CONCERN WITH THIS ACTIVITY...ALONG WITH TORRENTIAL RAINFALL
DUE TO THE QUANTITY OF DEEP-LAYER MOISTURE ACROSS THE CWA. AS THE
FRONT BECOMES STATIONARY ACROSS CENTRAL AND NORTHERN PORTIONS OF THE
CWA TONIGHT...AND A PRONOUNCED SURFACE DEWPOINT GRADIENT APPROACHES
FROM THE NORTH...ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
WILL PERSIST THROUGH THE OVERNIGHT HOURS ALONG AND NORTHWEST OF A
LINE FROM MERIDIAN TO NATCHEZ. HOWEVER...THE POTENTIAL FOR STRONG TO
SEVERE STORMS WILL DIMINISH DURING THE OVERNIGHT HOURS AS INSTABILITY
DECREASES WITH THE LOSS OF DAYTIME HEATING.

FOR TUESDAY INTO WEDNESDAY NIGHT...THE STATIONARY BOUNDARY WILL
BECOME DIFFUSE YIELDING A REMNANT SURFACE CONFLUENCE AXIS ALONG THE
INTERSTATE 20 CORRIDOR. HOWEVER...THE FRONT WILL BECOME REINFORCED
BY THE DEWPOINT GRADIENT MOVING SOUTH INTO THE REGION.
ADDITIONALLY...THE UPPER-LEVEL HEIGHT GRADIENT BETWEEN A BROAD
UPPER-LEVEL RIDGE OVER THE SOUTHEAST CONUS AND A TROUGH OVER THE
NORTHEAST CONUS WILL INTENSIFY AND SUPPORT A JET STREAK NORTH OF
INTERSTATE 20. THE RIGHT ENTRANCE REGION OF THIS FEATURE WILL PROVIDE
ADDITIONAL LARGE-SCALE ASCENT TO THE CWA THROUGH THE PERIOD.
MEANWHILE...DEEP-LAYER MOISTURE ASSOCIATED WITH TROPICAL STORM ALEX
WILL CONTINUOUSLY FEED INTO THE REGION WITH PWAT VALUES CLIMBING TO
THE 2.1 TO 2.3 INCH RANGE...WHICH WILL BE 130 TO 150 PERCENT OF
NORMAL VALUES. THESE FACTORS WILL PROVIDE THE SET-UP FOR NUMEROUS
SHOWERS AND THUNDERSTORMS ACROSS THE CWA FOR TUESDAY AND
WEDNESDAY...PARTICULARLY DURING THE AFTERNOON AND EVENING HOURS.
GIVEN THE DEGREE OF DEEP-LAYER MOISTURE...THE STORMS WILL BE CAPABLE
OF PRODUCING HEAVY RAINFALL. ADDITIONALLY...A FEW STRONG STORMS WILL
BE POSSIBLE DURING THE AFTERNOON AND EVENING HOURS ON TUESDAY AND
WEDNESDAY. HOWEVER...THE POTENTIAL FOR SEVERE STORMS WILL BE
MITIGATED BY FAIRLY WIDESPREAD CONVECTIVE OVERTURNING AND LIMITED
INSOLATION ASSOCIATED WITH NUMEROUS SHOWERS AND STORMS. THIS WILL
KEEP TEMPERATURES FROM RISING AS WARM AS THEY WOULD WITHOUT THE
CONVECTION...AND HIGH TEMPS FOR TUESDAY WERE LOWERED A DEGREE OR TWO
BELOW MAV GUIDANCE.

WITH REGARD TO THE LATEST ON TROPICAL STORM ALEX...ALEX WAS CENTERED
AROUND 535 MILES SOUTHEAST OF BROWNSVILLE TEXAS AT 28/1800 UTC...WITH
AN ESTIMATED MINIMUM CENTRAL PRESSURE OF 990 MB AND MAXIMUM SUSTAINED
WIND SPEEDS OF 60 MPH. PLEASE SEE THE LATEST NHC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. ALEX IS
FORECAST TO MOVE NORTHWESTWARD DURING THE NEXT FEW DAYS WHILE
STRENGTHENING. THE CONSENSUS AMONGST NHC MODELS IS FOR THE TRACK OF
THE CENTER OF ALEX TO REMAIN WELL WEST OF THE CWA. HOWEVER...ALEX IS
FORECAST TO BRING A LARGE PLUME OF MOISTURE TO MUCH OF THE CENTRAL
AND WESTERN GULF STATES. THE SOUTHWESTERN PART OF THE CWA COULD BE
CLOSE ENOUGH PROXIMITY TO THE TRACK OF ALEX FOR THE POTENTIAL OF
ENHANCED FLASH FLOODING. HOWEVER...DUE TO UNCERTAINTIES IN THE TRACK
OF ALEX AND POSITIONS OF THE AFOREMENTIONED BOUNDARIES...MENTION OF
HEAVY RAINFALL AND FLOODING IS CURRENTLY BEING WITHHELD FROM THE
HAZARDOUS WEATHER OUTLOOK. /COHEN/

THURSDAY THROUGH MONDAY...THE EXTENDED FORECAST DEPENDS HEAVILY ON
THE EVENTUAL TRACK OF THE REMAINS OF TROPICAL SYSTEM ALEX AND MODEL
SOLUTIONS DIFFER SIGNIFICANTLY FOR LOCAL WEATHER LATER IN THE WEEK
INTO THE WEEKEND. WILL LEAN CLOSER TO THE EURO SOLUTION AS FAR AS THE
TRACK OF THE TROPICAL SYSTEM IS CONCERNED...THIS SOLUTION MAY BE A
BIT FASTER COMPARED TO THE OFFICIAL NHC FORECAST FOR ALEX BUT IT
SHIFTS THE SYSTEM MORE TO THE WEST ACROSS NRN MEXICO WHILE THE GFS
MOVES THE SYSTEM NWD ALONG THE WRN GULF LATER THIS WEEK. BY
SATURDAY...MODEL DIFFERENCES BECOME EVEN MORE SIGNIFICANT WHEN THE
GFS DRAGS THE REMNANTS OF ALEX NWD ACROSS ERN TX FRI NIGHT THROUGH
SAT WHEN THE EURO PLACES THE AREA UNDER A STRENGTHENING RIDGE WITH
ALEX LONG GONE ACROSS MEXICO.

WITH SUCH DIVERGENT MODEL SOLUTIONS...THE PLACEMENT OF THE REMNANTS
OF THE BOUNDARY THAT WILL DROP INTO THE AREA WILL BE VERY DIFFICULT.
THE EURO IS NOW STALLING WHAT'S LEFT OF THE BOUNDARY ACROSS THE AREA
AND HAS FLIPPED TO BECOME ONE OF THE WETTER AS FAR AS DEWPOINTS ARE
CONCERNED WHILE THE GFS IS SUGGESTING THAT 50 DEG DEWPOINTS WILL
DROP INTO THE AREA LATER IN THE WEEK. HAVE GENERALLY FOLLOWED THE
LOWEST ENSEMBLE MEMBERS FOR POPS FOR THE EXTENDED PERIOD...
MAINTAINING THE BEST RISK OF CONVECTION OVER SRN ZONES WHERE BETTER
MOISTURE WILL REMAINS IN PLACE.

THE AREA WILL SEE THE EFFECTS OF THE REMAINS OF THE SURFACE BOUNDARY
ON THU AND WILL BE POSITIONED IN AN AREA OF WEAK UPPER FLOW BETWEEN
THE SRN FRINGES OF A BROAD TROUGH TO THE N AND ALEX TO THE SW WED.
THE MODELS AGREE THAT WEAK GENERAL ASCENT WILL DEVELOP AND THE LOWEST
GFS ENSEMBLE POPS HOVER AROUND 50-60% EC/SERN ZONES. THE AIR MASS
WILL REMAIN SOMEWHAT UNSTABLE BUT NOT TO THE EXTENT IT IS NOW WITH
COOLER TEMPS IN PLACE. WILL FOLLOW LIKELY MAV MOS POPS FOR ERN ZONES.
EXPECT AFTERNOON CONVECTION WED BUT NOT CONVINCED THAT COVERAGE WILL
BE TO THAT EXTENT SO WILL CUT WRN POPS TO A HIGH END SCT COVERAGE FOR
WED AFTERNOON. ALSO CUT MAV MOS POPS FOR THU WHEN DRIER AIR BEGINS TO
FILTER IN. DIFFICULT TO TRY TO PLACE ANY BOUNDARY REMNANTS/SURFACE
CONVERGENCE FOR LATER IN THE WORK WEEK. FORECAST SOUNDINGS SHOW MUCH
DRIER AIR FILTERING INTO NRN ZONES BY FRIDAY WITH LITTLE IN THE WAY
OF CAPE FOR NRN AREAS. /03/

&&

.AVIATION...SCATTERED THUNDERSTORMS HAVE DEVELOPED OVER SOUTHEAST
MISSISSIPPI MAINLY ASSOCIATED WITH AN OUTFLOW BOUNDARY THAT WILL
MOVE INTO CENTRAL MS. ELSEWHERE ISOLATED TO SCATTERED THUNDERSTORMS
WERE BREAKING OUT. OUTSIDE OF THUNDERSTORM AREAS...VFR CONDITIONS
WERE BEING REPORTED AND WL PREVAIL. CONVECTIVE COVERAGE WILL
DIMINISH THIS EVENING BUT IS STILL XPCTD N OF I-20...THROUGH 12Z
TUESDAY AS THE FRONTAL BOUNDARY STALLS ACROSS THE AREA. MVFR VSBY WL
BE PSBL ALL AREAS NEAR SUNRISE TUES MORNING. SCATTERED TO NUMEROUS
COVERAGE OF STORMS IS EXPECTED AGAIN TUESDAY. /22/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       74  92  73  88 /  41  71  49  69
MERIDIAN      72  92  71  90 /  41  75  51  70
VICKSBURG     72  92  73  88 /  40  66  47  67
HATTIESBURG   74  91  74  87 /  34  81  62  69
NATCHEZ       72  90  73  85 /  36  68  56  66
GREENVILLE    74  91  73  88 /  51  57  33  50
GREENWOOD     73  91  71  89 /  55  61  36  51

&&

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

COHEN/03/22

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
230 PM CDT MON JUN 28 2010

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
291930-
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-
230 PM CDT MON JUN 28 2010

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

.DAY ONE...TONIGHT AND TUESDAY

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH THIS
EVENING. A FEW OF THE STORMS COULD BE STRONG TO SEVERE AND PRODUCE
WIND GUSTS BETWEEN 50 AND 60 MPH...WITH THE MOST LIKELY TIME FOR
STRONG TO SEVERE STORMS OCCURRING UNTIL 8 PM THIS EVENING. THE
THUNDERSTORMS WILL ALSO BE CAPABLE OF PRODUCING VERY HEAVY RAINFALL.

FOR TUESDAY...NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED
DURING THE AFTERNOON AND EVENING HOURS. A FEW OF THE STORMS COULD BE
STRONG AND PRODUCE WIND GUSTS TO 50 MPH...WITH THE MOST LIKELY TIME
FOR STRONG STORMS OCCURRING BETWEEN 2 PM AND 8 PM. THE THUNDERSTORMS
ON TUESDAY WILL BE CAPABLE OF PRODUCING VERY HEAVY RAINFALL...AND
LOCALIZED FLASH FLOODING COULD BECOME A CONCERN WHERE STORMS MOVE
OVER THE SAME LOCATIONS.

.DAYS TWO THROUGH SEVEN...TUESDAY NIGHT THROUGH SUNDAY

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 SUNDAY.

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

COHEN

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
226 PM CDT MON JUN 28 2010

ARZ074-075-282005-
ASHLEY AR-CHICOT AR-
226 PM CDT MON JUN 28 2010

A LINE OF STRONG THUNDERSTORMS CAPABLE OF PRODUCING 40 TO 50 MPH
WINDS WAS LOCATED FROM SNYDER TO 3 MILES NORTHEAST OF LAKE VILLAGE
AT 225 PM CDT...MOVING NORTHEAST AT 5 MPH.

IN ADDITION VERY HEAVY RAIN ALONG WITH CONTINUOUS CLOUD TO GROUND
LIGHTNING ARE ALSO POSSIBLE WITH THESE STORMS. HEAVY RAIN MAY CAUSE
PONDING OF WATER ON ROADWAYS AND IN OTHER LOW LYING AREAS.

PEOPLE IN CENTRAL CHICOT AND NORTHEASTERN ASHLEY COUNTIES SHOULD
MONITOR THESE STORMS CLOSELY.

7

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
241 PM CDT MON JUN 28 2010

MSZ051-052-057-058-282030-
CLARKE MS-JASPER MS-NEWTON MS-LAUDERDALE MS-
241 PM CDT MON JUN 28 2010

A CLUSTER OF STRONG THUNDERSTORMS CAPABLE OF PRODUCING PEA TO DIME
SIZE HAIL AND 40 TO 50 MPH WINDS WILL CONTINUE OVER CLARKE...JASPER
AND LAUDERDALE COUNTIES THROUGH 330 PM CDT. THE STORMS WERE NEARLY
STATIONARY.

IN ADDITION...VERY HEAVY RAIN ALONG WITH CONTINUOUS CLOUD TO GROUND
LIGHTNING ARE ALSO POSSIBLE WITH THIS STORM. PERIODS OF HEAVY RAIN
WILL CAUSE PONDING OF WATER ON ROADWAYS AND IN OTHER LOW LYING
AREAS. RAINFALL RATES WERE HEAVIEST FROM MEEHAN TO MIDDLETON.

PEOPLE IN LAUDERDALE...SOUTHEASTERN NEWTON...JASPER AND CLARKE
COUNTIES SHOULD MONITOR THIS STORM CLOSELY.

7

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
318 PM CDT MON JUN 28 2010

MSZ046-282050-
KEMPER MS-
318 PM CDT MON JUN 28 2010

A STRONG THUNDERSTORM CAPABLE OF PRODUCING PEA TO DIME SIZE HAIL AND
40 TO 50 MPH WINDS WAS LOCATED 6 MILES NORTHWEST OF ELECTRIC MILLS AT
318 PM CDT...MOVING NORTHWEST AT 5 MPH.

IN ADDITION...VERY HEAVY RAIN ALONG WITH CONTINUOUS CLOUD TO GROUND
LIGHTNING ARE ALSO POSSIBLE WITH THIS STORM. PERIODS OF HEAVY MAY
CAUSE PONDING OF WATER ON ROADWAYS AND IN OTHER LOW LYING AREAS.

THIS STORM IS INTENSIFYING AND COULD BECOME SEVERE RAPIDLY.

PEOPLE IN NORTHEASTERN KEMPER COUNTY SHOULD MONITOR THIS STORM
CLOSELY.

7

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
411 PM CDT MON JUN 28 2010

MSZ031-039-282140-
LOWNDES MS-NOXUBEE MS-
411 PM CDT MON JUN 28 2010

A STRONG THUNDERSTORM CAPABLE OF PRODUCING PEA TO DIME SIZE HAIL AND
40 TO 50 MPH WINDS WAS LOCATED 4 MILES SOUTHEAST OF BROOKSVILLE AT
411 PM CDT...MOVING NORTHEAST AT 5 MPH.

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 NORTHEASTERN NOXUBEE AND SOUTH CENTRAL LOWNDES COUNTIES
SHOULD MONITOR THIS STORM CLOSELY.

GARRETT

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
412 PM CDT MON JUN 28 2010

MSZ018-019-025-282140-
BOLIVAR MS-SUNFLOWER MS-LEFLORE MS-
412 PM CDT MON JUN 28 2010

A STRONG THUNDERSTORM CAPABLE OF PRODUCING PEA TO DIME SIZE HAIL AND
40 TO 50 MPH WINDS WAS LOCATED 3 MILES WEST OF RULEVILLE AT 412 PM
CDT...MOVING EAST AT 15 MPH.

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 NORTHWESTERN LEFLORE...CENTRAL SUNFLOWER AND SOUTHERN
BOLIVAR COUNTIES SHOULD MONITOR THIS STORM CLOSELY.

GARRETT

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
521 PM CDT MON JUN 28 2010

MSZ025>028-282250-
GRENADA MS-LEFLORE MS-CARROLL MS-MONTGOMERY MS-
521 PM CDT MON JUN 28 2010

A STRONG THUNDERSTORM CAPABLE OF PRODUCING PEA TO DIME SIZE HAIL AND
40 TO 50 MPH WINDS WAS LOCATED 3 MILES NORTHEAST OF DUCK HILL AT 521
PM CDT...MOVING EAST AT 15 MPH.

VERY HEAVY RAIN IS ALSO POSSIBLE WITH THIS STORM.

PEOPLE IN NORTHERN MONTGOMERY...NORTHWESTERN CARROLL...NORTHERN
LEFLORE AND GRENADA COUNTIES SHOULD MONITOR THIS STORM CLOSELY.

GARRETT