Flash Flood Warning 167, NWS Memphis, TN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MEMPHIS TN
956 AM CST MON NOV 21 2011

.UPDATE...
COOLER AND MORE STABLE AIR HAS SPREAD INTO THE AREAS NORTH AND
WEST OF MEMPHIS AT MIDMORNING...BEHIND A COMPLEX OF SHOWERS AND
THUNDERSTORMS. THESE NORTHERN AREAS WILL LIKELY SEE OCCASIONAL LIGHT
SHOWERS DURING THE AFTERNOON...BUT THUNDER POTENTIAL IS LIMITED.
FORECAST UPDATE HAS BEEN SENT. ADDITIONAL DOWNWARD ADJUSTMENTS TO
AFTERNOON TEMPS MAY NEEDED IN A FORTHCOMING UPDATE.

HEAVY RAIN STILL POSSIBLE LATE TONIGHT... AS WARM SECTOR RECOVERS
IN ADVANCE OF A POTENT MIDLEVEL SHORTWAVE ARRIVING LATE TONIGHT.
NO SIGNIFICANT SECOND PERIOD CHANGES AT THIS TIME.

PWB

&&

.PREV DISCUSSION... /ISSUED 603 AM CST MON NOV 21 2011/

UPDATE...UPDATED TO EXPAND THE FLASH FLOOD WATCH TO THE SOUTH
BASED ON RADAR TRENDS.

PREV DISCUSSION... /ISSUED 533 AM CST MON NOV 21 2011/

WIDESPREAD SHOWERS AND THUNDERSTORMS ARE ONGOING ACROSS MUCH OF
THE MIDSOUTH EARLY THIS MORNING WITH THE MAIN FOCUS OF THE
ACTIVITY SHIFTING GRADUALLY TO THE SOUTHEAST. RAINFALL TOTALS HAVE
EXCEEDED ONE INCH ACROSS A FAIRLY LARGE PORTION OF THE MIDSOUTH
TONIGHT...MAINLY ALONG AND NORTHWEST OF THE INTERSTATE 40
CORRIDOR. TEMPERATURES ARE GENERALLY STEADY...IN THE LOW TO MIDDLE
60S...ALTHOUGH A FEW LOW TO MIDDLE 50S HAVE FILTERED INTO
NORTHEAST ARKANSAS AND THE MISSOURI BOOTHEEL ON THE NORTH SIDE OF
A STATIONARY FRONT. THE FRONT IS NOW LOCATED FROM WEST CENTRAL
KENTUCKY....TO NEAR WALNUT RIDGE ARKANSAS...TO NEAR RUSSELLVILLE
ARKANSAS. IS SHOULD REMAIN IN THE SAME GENERAL LOCATION OVER THE
NEXT 24 TO 36 HOURS.

MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED
TODAY...TONIGHT AND TOMORROW. A STRONG SHORTWAVE WILL EJECT OUT
OF THE PLAINS TUESDAY CAUSING THE COLD FRONT TO SURGE TO THE
EAST...RESULTING IN ONE LAST CHANCE OF STRONGER TO SEVERE
THUNDERSTORMS BEFORE PRECIPITATION COMES TO AN END. TODAY AND
TONIGHT...A FEW STRONG STORMS ARE POSSIBLE...BUT THE MAIN CONCERN
IS THE POTENTIAL FOR FLOODING. A GREATER CHANCE OF STRONG TO SEVERE
STORMS WILL BEGIN EARLY TUESDAY AS BETTER DYNAMICS ALOFT MOVE IN
COINCIDING WITH DAYTIME HEATING.

NOW THROUGH TOMORROW NIGHT...ATMOSPHERIC MOISTURE CONTENT WILL
REMAIN VERY HIGH...FEATURING PRECIPITABLE WATER VALUES WELL ABOVE
NORMAL FOR THIS TIME OF YEAR...OR REALLY FOR ANY TIME OF YEAR.
VALUES WILL RANGE FROM 1.6 AND 1.75 ACROSS MOST OF THE
MIDSOUTH...WITH THE HIGHEST READINGS ALONG THE NORTHWEST OF THE
INTERSTATE 40 CORRIDOR. STORMS WILL TEND TO TRAIN ALONG A COLD
FRONT ACROSS THIS REGION FOR AT LEAST THE NEXT 24 HOURS.  A FLASH
FLOOD WATCH IS IN EFFECT THROUGH TOMORROW. RAINFALL TOTALS COULD
EXCEED FIVE INCHES WHERE THE MOST INTENSE TRAINING OCCURS. ALTHOUGH
LAPSE RATES ARE RELATIVELY WEAK...HIGH DEWPOINTS WILL HELP KEEP
CONDITIONS MARGINALLY UNSTABLE. CAPES WILL LIKELY RUN BETWEEN 200
AND 500 J/KG WITH LI'S GENERALLY AROUND -2C. LOW LEVEL STORM
RELATIVE HELICITY WILL BE FAIRLY UNIMPRESSIVE...ONLY AROUND
100-150 M/S2 THROUGH THE DAY TODAY AND MOST OF THE NIGHT TONIGHT.
ON TUESDAY...AS A STRONG SHORTWAVE APPROACHES FROM THE WEST...THE
EXISTING MARGINALLY UNSTABLE CONDITIONS ALREADY IN PLACE WILL
BECOME ENHANCED. 0-3 KM HELICITY WILL INCREASE TO 300-500 M/S2
RESULTING IN THE POSSIBILITY OF SEVERE THUNDERSTORMS. BOWING
SEGMENTS ALONG OR JUST AHEAD OF THE COLD FRONT WILL LIKELY POSE THE
MAIN THREATS WHICH WILL INCLUDE SOME HAIL...BUT MORE LIKELY
DAMAGING WIND AND POSSIBLY SHORT LIVED TORNADOES. THE GREATEST
CHANCE FOR SEVERE STORMS WILL BE ACROSS NORTHERN MISSISSIPPI
MIDDAY TUESDAY JUST BEFORE THE FRONT MOVES INTO ALABAMA.

RAIN AND THUNDERSTORMS WILL COME TO AN END TUESDAY NIGHT...AND A
SLIGHTLY COOLER...BUT MUCH DRIER AIRMASS WILL FILTER IN ACROSS THE
MIDSOUTH. THURSDAY WILL BE THE COOLEST DAY...DRY AND MILD WITH
LOWS AROUND 40 AND HIGHS IN THE MIDDLE 60S.

GUIDANCE IS VERY INCONSISTENT AND DIVERSE WITH THE NEXT SYSTEM. 24
HOURS AGO IT LOOKED LIKE WE WOULD SEE A HIGHLY AMPLIFIED TROUGH
SWING OUT OF THE PLAINS FRIDAY AFTERNOON...BRINGING A ROUND OF
SHOWERS AND THUNDERSTORMS TO THE MIDSOUTH FRIDAY NIGHT INTO
SATURDAY. NOW IT DOESN'T LOOK QUITE AS CERTAIN AS THE ECMWF AND
AROUND ONE THIRD OF THE GFS ENSEMBLE MEMBERS FEATURE A LESS
PROGRESSIVE...CUTOFF LOW. THE ECMWF IS THE LEAST
PROGRESSIVE...CUTTING THE LOW OFF OVER NORTH CENTRAL MEXICO...AND
RESULTING IN A DRY FORECAST ACROSS THE MIDSOUTH. CONFIDENCE IS
VERY LOW IN THE FORECAST FRIDAY AFTERNOON AND BEYOND...BUT TOOK A
CONSISTENCY APPROACH HOLDING ON TO SHOWERS AND THUNDERSTORMS
FRIDAY NIGHT THROUGH SATURDAY NIGHT WITH COOLER CONDITIONS
FOLLOWING.

30/SIRMON

&&

.AVIATION...
12Z TAF CYCLE

CEILINGS WILL BE MAINLY MVFR OR LOWER THROUGH MOST OF THE FORECAST
PERIOD ALTHOUGH SOME BRIEF PERIODS OF VFR CONDITIONS ARE POSSIBLE.
SHOWERS AND THUNDERSTORMS COVER MUCH OF THE NORTHERN HALF OF THE
FORECAST AREA AND WILL CONTINUE TO MOVE ACROSS THE REGION THROUGH
MUCH OF THE DAY AND EVENING HOURS. WINDS WILL VARY IN DIRECTIONS
DEPENDING ON THE LOCATION OF THE COLD FRONT WHICH WILL REMAIN
NEARLY STATIONARY OVER THE REGION. WINDS SPEEDS WILL MAINLY RUN AT
5 TO 10 KNOTS FOR MOST OF THE FORECAST PERIOD.

ARS

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  75  63  73  49 /  90  60 100  20
MKL  71  60  74  47 /  90  70 100  30
JBR  64  58  69  45 /  90 100 100  10
TUP  76  63  77  51 /  70  30  70  50

&&

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

MO...FLASH FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR DUNKLIN-PEMISCOT.

MS...FLASH FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR DESOTO-TUNICA.

TN...FLASH FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR CARROLL-CHESTER-
     CROCKETT-DECATUR-DYER-FAYETTE-GIBSON-HARDEMAN-HARDIN-
     HAYWOOD-HENDERSON-HENRY-LAKE-LAUDERDALE-MADISON-MCNAIRY-
     OBION-SHELBY-TIPTON-WEAKLEY.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MEMPHIS TN
601 AM CST MON NOV 21 2011

ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115-
MSZ001>017-020>024-TNZ001>004-019>021-048>055-088>092-221400-
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-
601 AM CST MON NOV 21 2011

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

.DAY ONE...TODAY AND TONIGHT

A FLASH FLOOD WATCH IS IN EFFECT THROUGH LATE TONIGHT GENERALLY
NORTH OF A LINE FROM WALNUT GROVE TENNESSEE TO ELANE ARKANSAS. PLEASE
CONSULT THE FLASH FLOOD WATCH FOR ADDITIONAL INFORMATION.

A FEW STRONG STORMS ARE POSSIBLE TODAY AND ACROSS ALL OF THE
MIDSOUTH. HAIL AND GUSTY WINDS WILL BE THE MAIN THREATS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A FLASH FLOOD WATCH WILL REMAIN IN EFFECT THROUGH TUESDAY AFTERNOON
NORTH OF I-40. PLEASE CONSULT THE FLASH FLOOD WATCH FOR ADDITIONAL
INFORMATION.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE ENTIRE
MIDSOUTH TUESDAY. THE GREATEST RISK FOR SEVERE WEATHER IS EAST OF
THE MISSISSIPPI RIVER FROM LATE MORNING THROUGH AFTERNOON.
DAMAGING WIND IS THE MAIN THREAT...WITH A SMALLER AND MORE
CONDITIONAL CHANCE FOR TORNADOES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED IN SUPPORT OF SEVERE WEATHER TUESDAY.

30/SIRMON