Flash Flood Warning 77, NWS Memphis, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
1244 PM CDT FRI MAY 14 2010

.DISCUSSION...

&&

.PREV DISCUSSION... /ISSUED 1035 AM CDT FRI MAY 14 2010/

UPDATE...SURFACE ANALYSIS THIS MORNING PLACES A COLD FRONT FROM
THE EASTERN GREAT LAKES BACK THROUGH THE MID SOUTH AND SOUTHERN
PLAINS. TEMPERATURES AS OF 10 AM CDT ARE PREDOMINANTLY IN THE
UPPER 70S TO AROUND 80. SEVERE THUNDERSTORM POTENTIAL IS THE
PREDOMINANT FORECAST CONCERN FOR THE REMAINDER OF TODAY.

12Z UPPER AIR SOUNDING FROM KLZK THIS MORNING INDICATES A VERY
UNSTABLE AIRMASS ACROSS THE LOWER MISSISSIPPI VALLEY THIS
MORNING. A MODIFIED SURFACE BASED PARCEL BASED ON THIS SOUNDING
PRODUCES SURFACE BASED CAPE VALUES APPROACHING 5000 J/KG...LI/S
AROUND -11...AND LOW WET BULB ZERO HEIGHTS AROUND 8000 FT. THIS
SUGGESTS A GOOD POTENTIAL FOR MICROBURSTS /DAMAGING WINDS/...LARGE
HAIL...AND HEAVY RAINFALL FOR ANY THUNDERSTORMS THAT BECOME
SEVERE. WILL MAKE SLIGHT ADJUSTMENTS TO TEMPERATURES BASED ON
LATEST SHORT TERM TRENDS...OTHERWISE FORECAST OVERALL IN VERY GOOD
SHAPE.

UPDATED GRIDS WILL BE AVAILABLE SHORTLY.

CJC

PREV DISCUSSION... /ISSUED 709 AM CDT FRI MAY 14 2010/

PREV DISCUSSION... /ISSUED 322 AM CDT FRI MAY 14 2010/

CURRENTLY...A 594DM UPPER LEVEL RIDGE IS CENTERED OVER THE
GEORGIA COAST THIS MORNING WITH A COLD FRONT STRETCHED FROM THE
SOUTHERN GREAT LAKES INTO SOUTHERN MISSOURI AND NORTHWEST
ARKANSAS. ATTM SHOWERS AND THUNDERSTORMS ARE LOCATED MAINLY ALONG
AND NORTH OF THE FRONT THOUGH SOME ELEVATED DEVELOPMENT IS
STARTING TO OCCUR ACROSS NORTHERN PARTS OF THE MID SOUTH ATTM WITH
HIGH CLOUDS ACROSS THE REMAINDER OF THE AREA. TEMPS ARE IN THE
LOWER TO MID 70S AT MOST PLACES WITH VERY HUMID CONDITIONS.
DEWPOINTS RANGE FROM THE MID 60S TO AROUND 70.

TODAY...THE COLD FRONT WILL MOVE SLOWLY SOUTH TO ROUGHLY
INTERSTATE 40 LATER THIS AFTERNOON. MEANWHILE THE MOIST AIRMASS
ACROSS THE MID SOUTH WILL BECOME VERY UNSTABLE AS TEMPS CLIMB INTO
THE 80S. LIFTED INDEX VALUES OF -8C AND SBCAPES OF GREATER THAN
3000 J/KG INDICATE PLENTY OF FUEL FOR SCATTERED THUNDERSTORM
DEVELOPMENT THIS AFTERNOON AS THE MID LEVEL CAP WEAKENS. POPS WILL
BE HIGHEST ACROSS THE NORTH HALF OF THE MID SOUTH. WIND SHEAR IS
NOT PARTICULARLY IMPRESSIVE THOUGH MID LEVEL WINDS OF 30-40 KTS
SHOULD PROVIDE MARGINAL SUPPORT FOR STORM ORGANIZATION. THERE IS
A SLIGHT RISK FOR SEVERE WEATHER ROUGHLY NORTH OF A BOONEVILLE MS
TO CLARKSDALE MS LINE. LARGE HAIL AND DAMAGING WINDS ARE THE MAIN
THREAT.

TONIGHT...SHOWER AND THUNDERSTORM ACTIVITY WILL PROBABLY BE ON
THE WANE DURING THE EVENING AS SURFACE HEATING ENDS. 00Z MODELS
POINT TO SOME REDEVELOPMENT OVERNIGHT AS AN UPPER LEVEL
DISTURBANCE MOVES OUT OF THE EAST TEXAS/WESTERN LOWER MISSISSIPPI
VALLEY REGION. IN RESPONSE A SOUTHERLY 850 MB LOW LEVEL JET
DEVELOPS ACROSS ARKANSAS WITH SHOWERS AND THUNDERSTORMS BREAKING
OUT ALONG AND NORTH OF THE STALLED SURFACE FRONT ACROSS THE AREA.
THE WRF IS THE MOST AGGRESSIVE WITH QPF OVER THE MID SOUTH WITH
THE GFS AND ECMWF CENTERED A LITTLE FURTHER WEST. WILL GO AHEAD
AND INCREASE POPS...MOST SUBSTANTIALLY ACROSS WESTERN SECTIONS OF
THE MID SOUTH. MILD AND HUMID AGAIN OVERNIGHT...LOWS IN THE 60S.

SATURDAY...THE FRONT WILL CONTINUE TO MEANDER ACROSS THE
REGION...PERHAPS MOVING A LITTLE NORTH. THE SHOWERS AND
THUNDERSTORMS FROM FRIDAY NIGHT SHOULD PUSH NORTH OF THE AREA
EARLY SATURDAY WITH REDEVELOPMENT OCCURRING BY SATURDAY AFTERNOON
AS SURFACE HEATING...TEMPS 80-85 DEGREES...CREATES SUBSTANTIAL
AMOUNTS OF INSTABILITY ONCE AGAIN WITH SBCAPES GREATER THAN 2500
J/KG. WIND SHEAR WILL BE LIMITED WITH MID LEVEL WINDS OF ONLY
20-30 KTS. THERE IS A SLIGHT RISK OF SEVERE WEATHER NORTH OF A
BOONEVILLE TO CLARKSDALE LINE. LARGE HAIL AND DAMAGING WIND ARE
THE MAIN THREAT ONCE AGAIN.

SATURDAY NIGHT THROUGH MONDAY...A 500 MB TROF WILL BEGIN TO PUSH
INTO THE MISSISSIPPI VALLEY. A SURFACE LOW WILL DEVELOP AND MOVE
NORTH ACROSS MISSOURI LIFTING THE STALLED FRONT NORTH AS A WARM
FRONT. INCREASED LIFT ACROSS THE REGION WILL PRODUCE MORE
NUMEROUS SHOWERS AND THUNDERSTORMS SUNDAY THROUGH SUNDAY NIGHT. A
FEW STRONG TO SEVERE STORMS ARE POSSIBLE SUNDAY AFTERNOON AND
EVENING. LOCALLY HEAVY RAINFALL IS ALSO POSSIBLE AS PW VALUES HIT
1.75 INCHES. PRECIP CHANCES WILL START TO WIND DOWN ON MONDAY AS A
COLD FRONT PUSHES THROUGH AND HIGH PRESSURE STARTS TO BUILD IN.

TUESDAY THROUGH THURSDAY...SURFACE HIGH PRESSURE WITH COOLER
NORTHWEST FLOW ALOFT. EXPECT A GOOD DEAL OF SUNSHINE...SEASONABLE
TEMPS AND LOWER HUMIDITY LEVELS.

SJM

AVIATION...

18Z TAFS
TSRA TO CONTINUE TO DEVELOP ALONG THE I40 CORRIDOR ALL AFTERNOON.
DEVELOPMENT LINE TO MOVE SOUTH AS AFTERNOON PROGRESSES.  WINDS OUT
OF SW UNTIL FROPA...THEN NORTHERLY WIND ARE ON THE DOCKET. LITTLE OR
NO IMPROVEMENT IN CIGS THIS AFTERNOON. SOME BR IN MKL/TUP LATE TNGT.

WER

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  86  69  83  67 /  50  50  50  40
MKL  83  65  81  64 /  50  40  50  40
JBR  80  63  79  64 /  50  50  50  40
TUP  88  69  85  67 /  30  30  40  30

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MEMPHIS TN
405 AM CDT FRI MAY 14 2010

ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115-
MSZ001>017-020>024-TNZ001>004-019>021-048>055-088>092-151115-
ALCORN-BENTON MS-CALHOUN-CARROLL-CHESTER-CHICKASAW-CLAY-COAHOMA-
CRAIGHEAD-CRITTENDEN-CROCKETT-CROSS-DESOTO-DECATUR-DUNKLIN-DYER-
FAYETTE-GIBSON-GREENE-HARDEMAN-HARDIN-HAYWOOD-HENDERSON-HENRY-
ITAWAMBA-LAFAYETTE-LAKE-LAUDERDALE-LAWRENCE-LEE AR-LEE MS-MADISON-
MARSHALL-MCNAIRY-MISSISSIPPI-MONROE-OBION-PANOLA-PEMISCOT-
PHILLIPS-POINSETT-PONTOTOC-PRENTISS-QUITMAN-RANDOLPH-SHELBY-
ST. FRANCIS-TALLAHATCHIE-TATE-TIPPAH-TIPTON-TISHOMINGO-TUNICA-
UNION-WEAKLEY-YALOBUSHA-
405 AM CDT FRI MAY 14 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST ARKANSAS...
THE MISSOURI BOOTHEEL...NORTH MISSISSIPPI...AND WEST TENNESSEE.

.DAY ONE...TODAY AND TONIGHT

THERE IS A SLIGHT RISK FOR SEVERE WEATHER NORTH OF A BOONEVILLE
MISSISSIPPI TO CLARKSDALE MISSISSIPPI LINE THIS AFTERNOON AND THIS
EVENING. A COLD FRONT WILL PUSH SOUTH INTO THE AREA TODAY AND
INTERACT WITH A MOIST AND INCREASINGLY UNSTABLE AIRMASS. SEVERE
THUNDERSTORMS WILL BE POSSIBLE WITH DAMAGING WINDS AND LARGE HAIL
AS THE MAIN THREAT. LOCALLY HEAVY RAINFALL IS ALSO POSSIBLE. THE
BEST TIME FOR SEVERE THUNDERSTORM DEVELOPMENT WILL BE BETWEEN
NOON AND 9 PM THOUGH SOME THREAT WILL CONTINUE OVERNIGHT.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

SCATTERED TO NUMEROUS THUNDERSTORMS WILL BE POSSIBLE SATURDAY
THROUGH MONDAY. SOME OF THESE STORMS COULD BECOME SEVERE AS A
SERIES OF UPPER LEVEL DISTURBANCES INTERACTS WITH A WARM...MOIST
AND UNSTABLE AIRMASS ACROSS THE MID SOUTH. DAMAGING WINDS AND
LARGE HAIL WILL BE THE MAIN THREATS WITH ANY STORMS THAT BECOME
SEVERE.

ONE TO TWO INCHES OF RAINFALL IS POSSIBLE THROUGH MONDAY WHICH COULD
RESULT IN SOME LOCALIZED FLOODING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED AT TIMES FROM THIS AFTERNOON
THROUGH THIS WEEKEND.

SJM

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MEMPHIS TN
1138 AM CDT FRI MAY 14 2010

TNZ021-054-055-141700-
DECATUR TN-CARROLL TN-HENDERSON TN-
1138 AM CDT FRI MAY 14 2010

...THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A SIGNIFICANT
WEATHER ADVISORY UNTIL NOON CDT FOR...

  NORTHERN DECATUR COUNTY IN TENNESSEE...
  SOUTHEASTERN CARROLL COUNTY IN NORTHWEST TENNESSEE...
  NORTHEASTERN HENDERSON COUNTY IN SOUTHWEST TENNESSEE...

A STRONG THUNDERSTORM PRODUCING PEA SIZE HAIL OR LARGER AND WINDS AT
LEAST 40 MPH WAS LOCATED OVER WILDERSVILLE AT 1139 AM CDT...MOVING
EAST AT 20 MPH.

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

PEOPLE IN CARROLL...DECATUR AND HENDERSON COUNTIES...INCLUDING
LOCATIONS NEAR NATCHEZ TRACE STATE FOREST AND NATCHEZ TRACE STATE
PARK...SHOULD MONITOR THIS STORM CLOSELY.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MEMPHIS TN
1144 AM CDT FRI MAY 14 2010

ARZ035-048-141715-
CROSS AR-ST. FRANCIS AR-
1144 AM CDT FRI MAY 14 2010

...THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A SIGNIFICANT
WEATHER ADVISORY UNTIL 1215 PM CDT FOR...

  SOUTHWESTERN CROSS COUNTY IN EASTERN ARKANSAS...
  NORTHWESTERN ST. FRANCIS COUNTY IN EASTERN ARKANSAS...

A STRONG THUNDERSTORM PRODUCING PEA SIZE HAIL OR LARGER AND WINDS AT
LEAST 40 MPH WAS LOCATED 7 MILES SOUTH OF FAIR OAKS AT 1145 AM CDT...
MOVING NORTHEAST AT 25 MPH.

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

PEOPLE IN CROSS AND ST. FRANCIS COUNTIES SHOULD MONITOR THIS STORM
CLOSELY.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MEMPHIS TN
1223 PM CDT FRI MAY 14 2010

ARZ028-TNZ048-141800-
MISSISSIPPI AR-LAUDERDALE TN-
1223 PM CDT FRI MAY 14 2010

...THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A SIGNIFICANT
WEATHER ADVISORY UNTIL 100 PM CDT FOR...

  CENTRAL MISSISSIPPI COUNTY IN EASTERN ARKANSAS...
  WESTERN LAUDERDALE COUNTY IN SOUTHWEST TENNESSEE...

A STRONG THUNDERSTORM PRODUCING PEA SIZE HAIL OR LARGER AND WINDS AT
LEAST 40 MPH WAS LOCATED 3 MILES SOUTHEAST OF OSCEOLA AT 1223 PM
CDT...MOVING NORTHEAST AT 20 MPH.

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

PEOPLE IN LAUDERDALE AND MISSISSIPPI COUNTIES...INCLUDING LOCATIONS
NEAR FORT PILLOW STATE PARK...LUXORA AND OSCEOLA...SHOULD MONITOR
THIS STORM CLOSELY. THIS SIGNIFICANT WEATHER ALERT ALSO INCLUDES OPEN
LAKE...SUNK LAKE AND THE CHUTE.

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