Flash Flood Warning 90, NWS Memphis, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
402 PM CST TUE NOV 23 2004

.DISCUSSION...

A POTENT UPPER LEVEL TROUGH OVER WEST TEXAS THIS AFTERNOON WILL
CONTINUE TO MOVE EAST NORTHEAST ACROSS THE MISSISSIPPI VALLEY
TONIGHT. A STRONG 130 KT UPPER LEVEL JET STREAK WILL CONTINUE TO
MOVE THROUGH THE BASE OF THE TROUGH AND EJECT NORTHEASTWARD TOWARDS
THE MID SOUTH LATER TONIGHT. AS THIS STRONG UPPER JET STREAK EJECTS
OUT OF THE BASE OF THE TROUGH...THE UPPER TROUGH WILL BECOME
NEGATIVELY TILTED...HELPING TO ENHANCE DIFFLUENCE ALOFT. THE REGION
WILL ALSO BECOME CO-LOCATED BENEATH THE LEFT EXIT REGION OF THIS JET
STREAK. THIS SHOULD ENHANCE LARGE SCALE ASCENT ACROSS THE AREA. THE
STRONG UPPER SYSTEM HAS ALSO INDUCED A SURFACE LOW OVER THE ARKLATEX
REGION THIS AFTERNOON. THIS SURFACE LOW WILL CONTINUE TO DEEPEN AS IT
MOVES NORTHEAST ACROSS ARKANSAS INTO SOUTHEAST MISSOURI LATER
TONIGHT. AS THIS LOW MOVES NORTHEAST IT WILL HELP TO DRAW A WARM
FRONT STRETCHED ACROSS NORTH-CENTRAL MISSISSIPPI THIS AFTERNOON
NORTHWARD ACROSS THE MID SOUTH. THIS FRONT MAY ACT TO FOCUS
CONVECTION LATER THIS EVENING ACROSS PORTIONS OF THE MID SOUTH.
WIND FIELDS THROUGHOUT THE ATMOSPHERE WILL CONTINUE TO STRENGTHEN
THIS EVENING AS WELL. THE NOSE OF A 65 KT. LOW LEVEL JET WILL ALSO
MOVE NORTH INTO THE AREA TONIGHT...HELPING TO SUPPORT CONVECTION.
SIGNIFICANT SHEAR WILL BE PRESENT TONIGHT TO ALLOW ANY
THUNDERSTORMS THAT DEVELOP TO BECOME SEVERE...WITH DAMAGING WINDS
AND ISOLATED TORNADOES THE MOST LIKELY MODE OF SEVERE CONVECTION.

ON WEDNESDAY...THE LOW PRESSURE SYSTEM WILL CONTINUE TO LIFT
NORTHEAST AND WILL HELP TO DRAG A COLD FRONT SOUTHEAST THROUGH THE
AREA BY LATER IN THE AFTERNOON AND EVENING. IN THE UPPER LEVELS...
THE STRONG JET STREAK FROM TUESDAY NIGHT WILL ROTATE THROUGH THE
AREA...HELPING TO DRY SLOT MOST OF THE REGION. THE AREA WILL REMAIN
ENTRENCHED IN THE WARM SECTOR THROUGH THE DAY...AND WITH
CONTINUED SIGNIFICANT WIND SHEAR IN PLACE...ANY STORMS THAT CAN FORM
ALONG THE FRONT WILL HAVE THE POTENTIAL TO PRODUCE DAMAGING WINDS AND
LARGE HAIL. CONVECTION SHOULD REMAIN MORE SCATTERED IN NATURE AS
COMPARED TO TONIGHT.

ONCE THE COLD FRONT MOVES THROUGH...MUCH COLDER AIR WILL SPILL INTO
THE REGION FROM THE NORTHWEST. SKIES WILL REMAIN CLOUDY WEDNESDAY
NIGHT...BUT WILL BEGIN TO CLEAR BY THURSDAY MORNING. THANKSGIVING
DAY WILL FEATURE PARTLY CLOUDY SKIES AND TEMPERATURES STRUGGLING TO
GET OUT OF THE 40S. THE FIRST FREEZE WILL BE POSSIBLE ACROSS THE
REGION THURSDAY NIGHT INTO FRIDAY MORNING.

THE NEXT COLD FRONT WILL APPROACH ON FRIDAY NIGHT INTO SATURDAY...
BRINGING THE NEXT CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS THE
AREA. DRY WEATHER WILL COME BACK FOR SUNDAY...WITH ANOTHER STORM
SYSTEM BRINGING RENEWED CHANCES FOR SHOWERS ON MONDAY AND MONDAY
NIGHT.

&&

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

JLH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MEMPHIS TN
1143 AM CST TUE NOV 23 2004

ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115-MSZ001>017-
020>024-TNZ001>004-019>021-048>055-088>092-241200-
ALCORN-BENTON-CALHOUN-CARROLL-CHESTER-CHICKASAW-CLAY-COAHOMA-
CRAIGHEAD-CRITTENDEN-CROCKETT-CROSS-DECATUR-DESOTO-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-
1143 AM CST TUE NOV 23 2004

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

.DAY ONE...

A POTENT LOW PRESSURE SYSTEM OVER TEXAS WILL MOVE NORTHEAST THIS
AFTERNOON AND EVENING. THIS WILL ALLOW A WARM FRONT TO PUSH NORTH
ACROSS THE MIDSOUTH...BRINGING WARM AND VERY HUMID AIR INTO THE AREA.
AS THE LOW APPROACHES THE MIDSOUTH...WIDESPREAD SHOWERS AND
THUNDERSTORMS WILL DEVELOP...WITH THE POSSIBILITY OF SOME OF THE
STORMS BECOMING SEVERE.

THERE IS A MODERATE RISK OF SEVERE WEATHER OVER SOUTHWESTERN
PORTIONS OF THE MIDSOUTH...ROUGHLY FROM LEE COUNTY ARKANSAS TO
CALHOUN COUNTY MISSISSIPPI.

THERE IS A SLIGHT RISK OF SEVERE WEATHER ACROSS THE REST OF THE
MIDSOUTH.

THE FIRST THREAT OF SEVERE WEATHER WILL BE THE POSSIBLE DEVELOPMENT
OF SUPERCELL THUNDERSTORMS...PRIMARILY OVER THE MODERATE RISK AREA...
BEGINNING LATE THIS AFTERNOON AND PERSISTING INTO THIS EVENING. THESE
SUPERCELLS WILL BE CAPABLE OF PRODUCING TORNADOES AND LARGE HAIL.

THE SECOND THREAT WILL OCCUR AFTER MIDNIGHT...AS A SQUALL LINE IS
EXPECTED TO MOVE ACROSS THE MIDSOUTH. THE LINE OF THUNDERSTORMS IS
EXPECTED TO ENTER EASTERN ARKANSAS AROUND MIDNIGHT...PUSHING THROUGH
THE MEMPHIS METROPOLITAN AREA AROUND 2 AM...AND EXITING THE MIDSOUTH
AROUND 6 AM. THE MAIN THREATS FROM THESE STORMS WILL BE DAMAGING
STRAIGHT LINE WINDS...LARGE HAIL...AND ISOLATED TORNADOES.

HEAVY RAIN IS POSSIBLE IN THUNDERSTORMS WITH LOCALIZED FLASH
FLOODING POSSIBLE.

.DAYS TWO THROUGH SEVEN...

A COLD FRONT WILL MOVE INTO THE MIDSOUTH WEDNESDAY AFTERNOON AND
EVENING. SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG THE
FRONT DURING THIS TIME PERIOD. SOME OF THESE STORMS COULD BECOME
SEVERE. THERE IS A SLIGHT RISK FOR SEVERE WEATHER ACROSS THE ENTIRE
REGION. DAMAGING WINDS AND LARGE HAIL WILL BE THE MAIN THREATS FROM
THESE STORMS...WITH ISOLATED TORNADOES POSSIBLE.

NO HAZARDOUS WEATHER IS EXPECTED FOR THURSDAY THROUGH MONDAY AT
THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL LIKELY BE NEEDED THIS AFTERNOON AND
TONIGHT...AND MAY BE NEEDED AGAIN ON WEDNESDAY.

JFB