Severe Thunderstorm Warning 575, NWS Memphis, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
1242 PM CDT TUE JUN 21 2011

.UPDATE...
FOR 18Z AVIATION DISCUSSION

&&

.PREV DISCUSSION... /ISSUED 433 AM CDT TUE JUN 21 2011/

DISCUSSION...08Z SURFACE ANALYSIS PLACES A SURFACE LOW OVER NORTH
CENTRAL KANSAS...A WARM FRONT EXTENDING EAST OVER THE UPPER
MIDWEST AND OHIO VALLEY...AND A TRAILING COLD FRONT ACROSS CENTRAL
OKLAHOMA AND SOUTHWEST TEXAS. ACROSS THE MID SOUTH THIS
MORNING...TEMPERATURES HAVE BEEN VERY WARM AGAIN OVERNIGHT WITH
MOST LOCATIONS AVERAGING FROM THE UPPER 70S TO LOWER 80S AS A
NOCTURNAL 850 MB LOW LEVEL JET CONTINUES TO ADVECT WARM AND MOIST
AIR UP FROM THE GULF OF MEXICO. MOST OF THE CONVECTIVE ACTIVITY
OVERNIGHT HAS BEEN FOCUSED NEAR THE SURFACE LOW AND ATTENDANT COLD
FRONT. SEVERE WEATHER POTENTIAL AND CONVECTIVE CHANCES REMAIN THE
MAIN CHALLENGES IN THIS MORNING/S FORECAST PACKAGE.

SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)...A SURFACE LOW
CURRENTLY LOCATED ACROSS NORTH CENTRAL KANSAS WILL GRADUALLY MOVE
NORTHEAST INTO THE UPPER MIDWEST AND WEAKEN INTO WEDNESDAY.
MEANWHILE...A TRAILING COLD FRONT WILL SLOWLY MOVE FROM THE
SOUTHERN PLAINS TODAY AND INTO THE LOWER MISSISSIPPI VALLEY
TONIGHT AND WEDNESDAY. 00Z NAM CONVECTIVE ANALYSIS SEEMED SOMEWHAT
SUSPECT FOR THE FIRST 24 HOURS AND CONSEQUENTLY LEANED THIS
PORTION OF THE FORECAST TOWARDS THE 00Z GFS SOLUTION.

NONETHELESS...SHORT TERM MODELS INDICATE SHOWERS AND THUNDERSTORMS
WILL INCREASE IN COVERAGE ACROSS MID SOUTH TODAY. REGIONAL WSR-88D
RADAR TRENDS ALREADY SHOW SHOWERS AND THUNDERSTORMS INCREASING
ACROSS NORTHERN LOUISIANA AND SOUTHERN ARKANSAS. WENT WITH LIKELY
POPS THIS MORNING WEST OF THE MISSISSIPPI RIVER/CHANCE POPS
EAST...AND LIKELY ACROSS THE ENTIRE MID SOUTH FOR THIS AFTERNOON.

SHORT TERM MODELS INDICATE 20 TO 30 DM 500 MB HEIGHT FALLS WILL
BEGIN TO OVERSPREAD AREAS MAINLY WEST OF THE MISSISSIPPI RIVER
TODAY INTO TONIGHT. SURFACE BASED CAPE VALUES BETWEEN 3000-3500
J/KG...LI/S BETWEEN -8 TO -10...MODERATELY STEEP 700-500 MB LAYER
MID LEVEL LAPSE RATES BETWEEN 6.5 TO 7 C/KM....0-6 KM BULK SHEAR
VALUES AVERAGING BETWEEN 30 TO 35 KTS SUGGESTS A POTENTIAL WILL
EXIST FOR ORGANIZED SHOWERS AND THUNDERSTORMS WITH STRONG TO
SEVERE THUNDERSTORMS A DISTINCT POSSIBILITY...ESPECIALLY ALONG AND
WEST OF THE MISSISSIPPI RIVER TODAY INTO THIS EVENING. ANY
THUNDERSTORMS THAT BECOME SEVERE WILL HAVE THE POTENTIAL TO
PRODUCE LARGE HAIL AND DAMAGING WINDS. IN ADDITION...PRECIPITABLE
WATER VALUES OVER 2 INCHES AND K INDICIES APPROACHING 40 ALSO
SUGGEST THE POTENTIAL FOR THUNDERSTORMS TO PRODUCE LOCALIZED FLASH
FLOODING FROM HEAVY RAINFALL.

THE COLD FRONT WILL FINALLY BEGIN TO SLOWLY MOVE INTO THE MID
SOUTH AND GRADUALLY BECOME QUASI-STATIONARY BY WEDNESDAY NIGHT
INTO THURSDAY. SURFACE BASED CAPE VALUES BETWEEN 2000-3000
J/KG...LIS BETWEEN -6 TO -8...MODERATELY STEEP 700-500 MB MID
LEVEL LAPSE RATES BETWEEN 6.5 TO 7 C/KM...0-6 KM BULK SHEAR VALUES
BETWEEN 40-45 KTS SUGGESTS A CONTINUED POTENTIAL FOR ORGANIZED
SEVERE THUNDERSTORMS ACROSS THE MID SOUTH...ESPECIALLY ALONG AND
EAST OF THE MISSISSIPPI RIVER. LARGE HAIL AND DAMAGING WINDS WILL
AGAIN BE THE MAIN SEVERE WEATHER THREATS WITH A CONTINUED
POTENTIAL FOR FLASH FLOODING FROM HEAVY RAINFALL AS PRECIPITABLE
WATER VALUES REMAIN AT OR ABOVE 2 INCHES.

LONG TERM...(THURSDAY THROUGH MONDAY)...00Z GFS/ECMWF LONG TERM
MODELS INDICATE AN ACTIVE PATTERN WILL PERSIST ACROSS THE LOWER
MISSISSIPPI VALLEY THURSDAY INTO EARLY NEXT WEEK AS A QUASI-
STATIONARY BOUNDARY REMAINS IN PLACE ACROSS THE REGION AND
NORTHWEST UPPER LEVEL FLOW ALOFT RE-ESTABLISHES ITSELF ACROSS THE
MIDDLE AND LOWER MISSISSIPPI VALLEYS. AS A RESULT...WENT PRIMARILY
WITH SCATTERED SHOWERS AND THUNDERSTORMS THROUGH MOST OF THE LONG
TERM FORECAST BASED ON MODEL TRENDS. TIMING OF INDIVIDUAL
SHORTWAVES/MESOSCALE CONVECTIVE SYSTEMS /MCS/ WILL REMAIN A
CHALLENGE. NONETHELESS...STRONG TO SEVERE THUNDERSTORMS ALONG WITH
HEAVY RAINFALL WILL REMAIN POSSIBLE EACH DAY.

CJC

&&

.AVIATION...
18Z TAFS

TS HAVE DEVELOPED ACROSS THE MEG FORECAST AREA THIS MORNING...MAIN
AREA OF TS IS NOW EAST OF MEM...RAIN RPTD NOW AT MKL WITH
EMBEDDED TS INDICATED ON RADAR AND TUP WILL LIKELY BE SOON TO FOLLOW
WITH TS DEVELOPING TO THE WEST. BROUGHT A TEMPO GROUP FOR TS INTO
JBR AT 20Z WITH A NEW AREA OF TS LIKELY TO DEVELOP OVER AR. THIS
AREA MAY AFFECT MEM TERMINAL BTN 22-00Z...BUT IT IS QUESTIONABLE
WHETHER IT WILL THE ATMOSPHERE WILL BE ABLE TO DESTABALIZE AGAIN
THIS AFTERNOON AFT CURRENT RAIN ENDS.

DURING THE OVERNIGHT HOURS LEFT VCSH IN TIL 06Z AT ALL BUT
JBR...FOR JBR LEFT IT IN FOR THE OVERNIGHT HOURS WITH THE BOUNDARY
TO THE WEST OF JBR. AS FRONT WASHES OUT ON WED OVER AREA WINDS
SHIFT MORE SW TOMORROW MORNING...ALONG WITH A CHC OF MVFR CIGS AT
ALL LOCATIONS. AS FRONT STALLS/BECOMES STATIONARY THERE WILL BE A
CHC OF TS DEVELOPING AGAIN WED AFTERNOON DURING MAX
HEATING...ADDED VCSH AND CB BY 16/17Z AT ALL LOCATIONS.

NGU

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  74  89  72  89 /  70  60  30  30
MKL  71  87  67  88 /  70  60  30  30
JBR  71  88  67  89 /  70  50  20  30
TUP  72  88  70  90 /  70  70  30  30

&&

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

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MEMPHIS TN
735 AM CDT TUE JUN 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>092-221145-
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-
735 AM CDT TUE JUN 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

THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS ACROSS THE ENTIRE
MID SOUTH. ANY THUNDERSTORMS THAT BECOME SEVERE WILL HAVE THE
POTENTIAL TO PRODUCE LARGE HAIL AND DAMAGING WINDS. LOCALIZED FLASH
FLOODING FROM HEAVY RAINFALL IS ALSO POSSIBLE.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

A COLD FRONT WILL STALL OUT ACROSS THE LOWER MISSISSIPPI VALLEY
THURSDAY AND REMAIN IN PLACE THROUGH EARLY NEXT WEEK. A SERIES OF
UPPER LEVEL DISTURBANCES MOVING ALONG THE SURFACE BOUNDARY WILL
HAVE THE POTENTIAL TO PRODUCE STRONG TO SEVERE THUNDERSTORMS ALONG
WITH LOCALIZED FLASH FLOODING FROM HEAVY RAINFALL EACH DAY.

.SPOTTER INFORMATION STATEMENT...

STORM SPOTTER ACTIVATION MAY BE REQUIRED TODAY AND WEDNESDAY AND
OCCASIONALLY THROUGH EARLY NEXT WEEK.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEMPHIS TN
904 AM CDT TUE JUN 21 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1148 AM     TSTM WND DMG     1 N YUMA                35.86N 88.33W
06/18/2011                   CARROLL            TN   NWS EMPLOYEE

            COUPLE LARGE TREES DOWN NEAR HOAN CREEK BETWEEN YUMA AND
            CLARKSBURG.

&&

BORGHOFF