Flash Flood Warning 122, NWS Memphis, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
1014 AM CDT MON AUG 18 2014

.DISCUSSION...

SKIES ARE PARTLY CLOUDY ACROSS MUCH OF THE FORECAST AREA THIS
MORNING WITH TEMPERATURES RANGING FROM THE MID 70S TO LOWER 80S. A
LARGE AREA OF SHOWERS AND THUNDERSTORMS WAS MOVING ACROSS
SOUTHWEST SECTIONS OF THE FORECAST AREA THIS MORNING WITH A FEW
THUNDERSTORMS ALSO MOVING OVER NORTHERN SECTIONS. THE ACTIVITY
OVER SOUTHWEST SECTIONS OF THE FORECAST AREA HAS BEEN DECREASING
IN INTENSITY OVER THE PAST HOUR OR SO. ADDITIONAL THUNDERSTORM
DEVELOPMENT IS POSSIBLE THIS AFTERNOON. CURRENT FORECAST LOOKS
GOOD AND NO UPDATES ARE NEEDED AT THIS TIME.

ARS

&&

.PREV DISCUSSION... /ISSUED 705 AM CDT MON AUG 18 2014/

DISCUSSION...

A CONVECTIVE OUTFLOW BOUNDARY REMAINS STRETCHED ACROSS NORTHEAST
ARKANSAS INTO NORTHWEST TENNESSEE EARLY THIS MORNING. LOW LEVEL
WEST SOUTHWEST FLOW OVER THE REGION OF ABOUT 30 KTS WILL CONTINUE
TO SUPPORT THE DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS
ALONG AND TO THE SOUTH OF THE OUTFLOW BOUNDARY THROUGH EARLY THIS
MORNING. CONSIDERING THE ORIENTATION OF THE LOW LEVEL FLOW INTO
THE WEST SIDE OF DEVELOPING THUNDERSTORM CLUSTERS...THIS SETUP
SHOULD YIELD THE POTENTIAL FOR BACKBUILDING CONVECTION...ALONG
WITH HEAVY RAINFALL AND ENHANCED LOCALIZED FLASH FLOOD POTENTIAL.
THE GREATER COVERAGE OF SHOWERS AND THUNDERSTORMS SHOULD OCCUR
LATER TODAY ACROSS THE SOUTHERN HALF OF THE MID SOUTH AS A MID
LEVEL SHORTWAVE DISTURBANCE MOVES EAST FROM THE ARKLATEX ACROSS
SOUTHERN PORTIONS OF THE REGION. THIS DISTURBANCE SHOULD COMBINE
WITH AN INCREASINGLY UNSTABLE ATMOSPHERE CHARACTERIZED BY MIXED
LAYER CAPE VALUES IN EXCESS OF 2000 J/KG AND AN UNCAPPED ATMOSPHERE
TO PRODUCE NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS EAST ARKANSAS
AND NORTH MISSISSIPPI. A FEW STRONG TO SEVERE STORMS WILL BE
POSSIBLE SOUTH OF INTERSTATE 40 WITH THE POTENTIAL FOR LOCALIZED
DAMAGING WIND GUSTS. IN ADDITION...THERE WILL BE THE POTENTIAL
FOR HEAVY RAINFALL AND LOCALIZED FLASH FLOODING AS THE AIRMASS
REMAINS VERY MOIST WITH PWATS IN EXCESS OF 2 INCHES. PLAN TO
MENTION THIS POTENTIAL IN THE LATEST HWO. SHOWERS AND THUNDERSTORMS
SHOULD SHIFT EAST OF THE AREA LATER TONIGHT.

ANOTHER MID LEVEL SHORTWAVE WILL EJECT FROM THE CENTRAL HIGH
PLAINS TONIGHT INTO THE MIDDLE MISSISSIPPI VALLEY ON TUESDAY IN
NORTHWEST FLOW ALOFT. THE ATMOSPHERE SHOULD BECOME MODERATELY TO
STRONGLY UNSTABLE ON TUESDAY DUE TO MOIST LOW LEVEL CONDITIONS AND
SURFACE HEATING. SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP
AND MOVE ACROSS NORTHERN PORTIONS OF THE MID SOUTH. CONSIDERING
THE AMOUNT OF INSTABILITY EXPECTED...A FEW OF THESE STORMS MAY
BECOME STRONG TO SEVERE WITH DAMAGING WINDS...LARGE HAIL...AND
HEAVY RAINFALL POSSIBLE. ANY STORMS SHOULD SHIFT SOUTHEAST OF THE
REGION BY TUESDAY NIGHT.

UPPER LEVEL RIDGING WILL BUILD INTO THE MID SOUTH WEDNESDAY WHICH
SHOULD SUPPRESS CONVECTIVE POTENTIAL AND LEAD TO HOTTER AND HUMID
WEATHER CONDITIONS. THE UPPER RIDGE WILL STRENGTHEN OVER THE
REGION THROUGH THE END OF THE WEEK AND INTO NEXT WEEKEND WITH DRY
WEATHER ALONG WITH HOT AND HUMID CONDITIONS. IN FACT...BEGINNING
WEDNESDAY AND CONTINUING INTO NEXT WEEKEND THE COMBINATION OF HOT
TEMPERATURES AND HIGH HUMIDITY MAY LEAD TO HEAT INDEX VALUES
TOPPING 105 DEGREES IN MANY LOCATIONS. HEAT ADVISORIES WILL LIKELY
BE NEEDED FOR MUCH OF THE EXTENDED FORECAST PERIOD. RELIEF FROM
THE LATE SUMMER HEAT MAY NOT ARRIVE UNTIL SOMETIME NEXT WEEK.

JLH

&&

.AVIATION...

12Z TAF CYCLE

AN UPPER LEVEL DISTURBANCE WILL BE MOVING THROUGH THE MID-SOUTH
THROUGH MONDAY. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS
CAN BE EXPECTED. BETTER TSRA COVERAGE WILL EXIST FOR OUR
SOUTHERNMOST SITES THROUGHOUT THE DAY. LOW CLOUDS THIS MORNING MAY
CAUSE FOR SOME MVFR CONDITIONS AT KMEM BUT SHOULD MIX OUT QUICKLY
WHEN THE SUN RISES. FOG SHOULD LIFT AT KMKL BY 14Z. ANOTHER UPPER
LEVEL DISTURBANCE WILL SWING THROUGH NORTHERN PORTIONS OF THE
REGION TONIGHT CAUSING INCREASED MOISTURE FOR KMKL...SO ANOTHER
ROUND OF FOG MAY FORM. WINDS WILL BE FROM THE SOUTH THROUGHOUT THE
TAF CYCLE MAINLY BETWEEN 5-10 KTS.

JPM3

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MEMPHIS TN
415 AM CDT MON AUG 18 2014

ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115-
MSZ001>017-020>024-TNZ001>004-019>022-048>055-088>092-191115-
ALCORN-BENTON MS-BENTON TN-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-
415 AM CDT MON AUG 18 2014

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

.DAY ONE...TODAY AND TONIGHT

A FEW STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE ACROSS THE
MID SOUTH TODAY. THE HIGHEST POTENTIAL FOR STRONG TO SEVERE
STORMS WILL BE ACROSS SOUTHERN PORTIONS OF THE MID SOUTH. THE
PRIMARY THREATS WILL BE LOCALIZED DAMAGING WINDS ALONG WITH HEAVY
RAINFALL AND FLASH FLOODING.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

SCATTERED STRONG TO SEVERE THUNDERSTORMS WILL AGAIN BE POSSIBLE
ACROSS NORTHERN PORTIONS OF THE MID SOUTH ON TUESDAY. THE PRIMARY
THREATS WILL BE DAMAGING WINDS...LARGE HAIL...AND HEAVY RAINFALL.

HOT AND HUMID CONDITIONS WILL DEVELOP ACROSS THE MID SOUTH BY MID
WEEK AND PERSIST THROUGH NEXT WEEKEND. THE COMBINATION OF HOT
TEMPERATURES AND HIGH HUMIDITY WILL LIKELY RESULT IN HEAT INDEX
VALUES IN EXCESS OF 105 DEGREES ACROSS MANY AREAS OF THE MID
SOUTH. HEAT ADVISORIES MAY BE NEEDED DURING THIS TIME PERIOD.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED ACROSS THE SOUTHERN HALF OF THE
MID SOUTH TODAY AND ACROSS NORTHERN AREAS ON TUESDAY.

JLH