Flash Flood Warning 94, NWS Memphis, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
1246 PM CDT THU MAY 20 2010

.DISCUSSION...

UPDATED FOR 18Z AVIATION DISCUSSION

&&

.PREV DISCUSSION... /ISSUED 1005 AM CDT THU MAY 20 2010/

DISCUSSION...
DEWPOINTS ARE ON THE RISE ACROSS THE SOUTHERN HALF OF THE MID
SOUTH AS A WARM FRONT LIFTS NORTH OF THE REGION. MUCAPE VALUES
WERE IN THE 500-1000 J/KG ACROSS NORTHERN MS AND SOUTHWEST TN WITH
VALUES GREATER THAN 2000 J/KG AS CLOSE AS CENTRAL MS. EXPECT THIS
WARM MOIST AIRMASS TO ADVECT INTO MUCH OF THE SERVICE AREA DURING
THE DAY AHEAD OF A STRONG H5 VORTICITY MAXIMA. A CONVECTIVE WATCH
BOX IS POSSIBLE BY MIDDAY WITH THIS SCENARIO IN MIND. THE 12Z NAM
SHOWS THIS VORTICITY MAXIMA MOVING THROUGH NORTHEAST AR AND FAR
WESTERN TN BETWEEN 12 PM AND 3 PM.

FLASH FLOODING REMAINS A CONCERN WITH SATELLITE ESTIMATES SHOWING
UP TO 1.5 INCH PER HOUR RAINFALL RATES ASSOCIATED WITH A LARGE
AREA OF SHOWERS AND THUNDERSTORMS ACROSS WESTERN AR AT 10 AM. A
FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH FRIDAY MORNING.

THE CURRENT FORECAST LOOKS GOOD. WILL NEED TO UPDATE IF A WATCH
BOX IS ISSUED.

OKULSKI

PREV DISCUSSION... /ISSUED 255 AM CDT THU MAY 20 2010/

CLOUDS ARE INCREASING ACROSS THE FORECAST AREA EARLY THIS MORNING
WITH TEMPERATURES MAINLY IN THE 60S. A LARGE AREA OF SHOWERS AND
THUNDERSTORMS IS MOVING SLOWLY NORTHEAST ACROSS NORTHERN AND
CENTRAL ARKANSAS.

WARM FRONT CURRENTLY EXTENDS FROM WEST CENTRAL ARKANSAS THROUGH
CENTRAL MISSISSIPPI AND INTO SOUTH ALABAMA. THIS FRONT WILL MOVE
NORTH INTO THE FORECAST AREA LATER TODAY. SOUTH OF THE WARM FRONT
THE ATMOSPHERE WILL BECOME QUITE UNSTABLE AND AS A COLD FRONT
APPROACHES FROM THE WEST. SHOWERS AND THUNDERSTORMS WILL BECOME
MORE NUMEROUS LATER TODAY AND TONIGHT. SOME OF THE THUNDERSTORMS
MAY BECOME SEVERE WITH LARGE HAIL AND DAMAGING WINDS BEING THE
MAIN THREAT WITH TORNADOES ALSO A POSSIBILITY. THERE ALSO REMAIN A
FLASH FLOOD THREAT MAINLY OVER NORTHERN SECTIONS OF THE FORECAST
AREA WHERE THE FLASH FLOOD WATCH IS IN EFFECT.

BY FRIDAY MORNING...THE COLD FRONT WILL BE MOVING THROUGH THE
FORECAST AREA WITH SCATTERED SHOWERS AND THUNDERSTORMS AHEAD OF
THE FRONT. THE COLD FRONT SHOULD BE EAST OF THE REGION BY FRIDAY
NIGHT ENDING THE THREAT OF RAIN FOR THE FORECAST AREA.

A LARGE UPPER LEVEL RIDGE BEGINS TO BUILD OVER THE CENTRAL U.S. BY
SATURDAY. THIS WILL BEGIN A PERIOD OF DRY WEATHER OVER THE REGION
WITH AFTERNOON TEMPERATURES APPROACHING 90 DEGREES. THIS PERIOD OF
DRY WEATHER AND VERY WARM TEMPERATURES WILL LAST THROUGHOUT THE
WEEKEND AND INTO MONDAY AND TUESDAY.

AN UPPER LEVEL LOW IS EXPECTED TO DEVELOP OVER THE SOUTHEAST
ATLANTIC COAST EARLY NEXT WEEK AND WILL GRADUALLY MOVE WEST TRYING
TO UNDERCUT THE UPPER LEVEL RIDGE. AS A RESULT...THERE MAY BE SOME
ISOLATED THUNDERSTORMS ACROSS THE FORECAST AREA ON WEDNESDAY.

ARS

.AVIATION...

18Z TAF CYCLE

ANOTHER ROUND OF SHRAS AND TSRAS IS STARTING TO DEVELOP ACROSS
AREAS EAST OF THE MISSISSIPPI RIVER ATTM WHERE MOISTURE AND
INSTABILITY ARE GREATEST. EXPECT MVFR/VFR CIGS WITH OCNL IFR
CONDS INVOF TSRAS AT KMEM...KMKL AND KTUP THROUGH ABOUT 21/01Z.
LARGE HAIL AND STRONG GUSTY WINDS ARE ALSO POSSIBLE INVOF TSRAS.
KEPT ONLY VCTS AT KJBR SINCE THIS AREA HAS BEEN STABILIZED BY THIS
MORNINGS CONVECTION OVER ARKANSAS. EXPECT SHRAS AND TSRAS TO
DIMINISH THIS EVENING...WITH VFR CONDS PROBABLY RETURNING. STILL
EXPECT STRATUS TO REDEVELOP AFT 21/09Z...LIFTING AROUND 21/16Z.
WINDS WILL GENERALLY BE SOUTHERLY AROUND 10 KTS GRADUALLY SHIFTING
TO SW FRIDAY MORNING.

SJM

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  82  69  86  69 /  80  80  30  10
MKL  78  67  81  61 /  70  80  50  10
JBR  78  65  84  62 /  80  80  30  10
TUP  83  68  85  67 /  60  80  50  10

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR CLAY-CRAIGHEAD-
     CRITTENDEN-CROSS-GREENE-LAWRENCE-MISSISSIPPI-POINSETT-
     RANDOLPH-ST. FRANCIS.

MO...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR DUNKLIN-PEMISCOT.

MS...NONE.
TN...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR CARROLL-CHESTER-
     CROCKETT-DECATUR-DYER-FAYETTE-GIBSON-HARDEMAN-HARDIN-
     HAYWOOD-HENDERSON-HENRY-LAKE-LAUDERDALE-MADISON-MCNAIRY-
     OBION-SHELBY-TIPTON-WEAKLEY.

&&

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MEMPHIS TN
1243 PM CDT THU MAY 20 2010

MSZ013-015-021-022-201815-
LAFAYETTE MS-PONTOTOC MS-YALOBUSHA MS-CALHOUN MS-
1243 PM CDT THU MAY 20 2010

...THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A SIGNIFICANT
WEATHER ADVISORY UNTIL 115 PM CDT FOR...

  NORTHERN CALHOUN COUNTY IN NORTHEAST MISSISSIPPI...
  EXTREME SOUTHWESTERN PONTOTOC COUNTY IN NORTHEAST MISSISSIPPI...
  SOUTHEASTERN LAFAYETTE COUNTY IN NORTHWEST MISSISSIPPI...
  NORTHEASTERN YALOBUSHA COUNTY IN NORTHWEST MISSISSIPPI...

A STRONG THUNDERSTORM PRODUCING PEA SIZE HAIL OR LARGER AND WINDS AT
LEAST 40 MPH WAS LOCATED 5 MILES SOUTHWEST OF BANNER AT 1243 PM
CDT...MOVING NORTHEAST AT 30 MPH.

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

PEOPLE IN CALHOUN...LAFAYETTE...PONTOTOC AND YALOBUSHA COUNTIES
SHOULD MONITOR THIS STORM CLOSELY.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MEMPHIS TN
112 PM CDT THU MAY 20 2010

MSZ015>017-201900-
LEE MS-ITAWAMBA MS-PONTOTOC MS-
112 PM CDT THU MAY 20 2010

...THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A SIGNIFICANT
WEATHER ADVISORY UNTIL 200 PM CDT FOR...

  NORTHWESTERN ITAWAMBA COUNTY IN NORTHEAST MISSISSIPPI...
  LEE COUNTY IN NORTHEAST MISSISSIPPI...
  EASTERN PONTOTOC COUNTY IN NORTHEAST MISSISSIPPI...

A STRONG THUNDERSTORM PRODUCING PEA SIZE HAIL OR LARGER AND WINDS AT
LEAST 40 MPH WAS LOCATED 5 MILES EAST OF TROY AT 112 PM CDT...MOVING
NORTHEAST AT 30 MPH.

PEOPLE IN ITAWAMBA...LEE AND PONTOTOC COUNTIES...INCLUDING LOCATIONS
NEAR TOMBIGBEE STATE PARK...TRACE STATE PARK...TUPELO AND VERONA...
SHOULD MONITOR THIS STORM CLOSELY.

.A SEVERE THUNDERSTORM WATCH ALSO REMAINS IN EFFECT FOR THE ADVISORY
AREA.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MEMPHIS TN
114 PM CDT THU MAY 20 2010

MSZ004-009-014-201900-
TIPPAH MS-PRENTISS MS-UNION MS-
114 PM CDT THU MAY 20 2010

...THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A SIGNIFICANT
WEATHER ADVISORY UNTIL 200 PM CDT FOR...

  NORTHWESTERN PRENTISS COUNTY IN NORTHEAST MISSISSIPPI...
  SOUTHEASTERN TIPPAH COUNTY IN NORTHEAST MISSISSIPPI...
  EASTERN UNION COUNTY IN NORTHEAST MISSISSIPPI...

A STRONG THUNDERSTORM PRODUCING PEA SIZE HAIL OR LARGER AND WINDS AT
LEAST 40 MPH WAS LOCATED OVER NEW HARMONY AT 114 PM CDT...MOVING
NORTHEAST AT 30 MPH.

PEOPLE IN PRENTISS...TIPPAH AND UNION COUNTIES SHOULD MONITOR THIS
STORM CLOSELY.

.A SEVERE THUNDERSTORM WATCH ALSO REMAINS IN EFFECT FOR THE ADVISORY
AREA.

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