Heat Advisory 13, NWS Memphis, TN

Clay County, AR, Craighead County, AR, Crittenden County, AR, Cross County, AR, Greene County, AR, Lawrence County, AR, Lee County, AR, Mississippi County, AR, Phillips County, AR, Poinsett County, AR, Randolph County, AR, St. Francis County, AR, Dunklin County, MO, Pemiscot County, MO, Benton County, MS, Calhoun County, MS, Chickasaw County, MS, Coahoma County, MS, DeSoto County, MS, Itawamba County, MS, Lafayette County, MS, Lee County, MS, Marshall County, MS, Monroe County, MS, Panola County, MS, Pontotoc County, MS, Quitman County, MS, Tallahatchie County, MS, Tate County, MS, Tippah County, MS, Tunica County, MS, Union County, MS, Yalobusha County, MS, Crockett County, TN, Dyer County, TN, Fayette County, TN, Hardeman County, TN, Haywood County, TN, Lake County, TN, Lauderdale County, TN, Shelby County, TN, Tipton County, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
437 AM CDT WED SEP 5 2012

.DISCUSSION...

AN UPPER LEVEL RIDGE OF HIGH PRESSURE REMAINS STRETCHED ACROSS THE
MID SOUTH THIS MORNING. THIS RIDGE WILL BEGIN TO BREAK DOWN ACROSS
NORTHERN PORTIONS OF THE FORECAST AREA LATER THIS AFTERNOON AS A
MID LEVEL SHORTWAVE NOTED ON EARLY MORNING WATER VAPOR IMAGERY
ACROSS EASTERN KANSAS AND OKLAHOMA APPROACHES THE REGION. THIS
SHORTWAVE WILL LIKELY MOVE ACROSS THE NORTHERN PORTIONS OF THE
AREA AND TRIGGER SCATTERED SHOWERS AND THUNDERSTORMS. DEEP LAYER
SHEAR IS FORECAST TO INCREASE TO AROUND 30 KTS OVER NORTHERN
SECTIONS AND WILL COMBINE WITH STRONG INSTABILITY WITH SBCAPE
VALUES GREATER THAN 3000 J/KG...LI/S BETWEEN -6C AND -10C...AND
MID LEVEL LAPSE RATES AROUND 6.5C/KM. THESE PARAMETERS COMBINED
WITH THE APPROACHING SHORTWAVE COULD POSE SOME THREAT FOR AT LEAST
LOOSELY ORGANIZED SEVERE STORMS ACROSS OUR NORTHERN COUNTIES.
PLAN TO ADD MENTION OF POSSIBLE SEVERE STORMS IN OUR NORTH THIS
AFTERNOON AND EARLY EVENING.

THE OTHER BIG STORY TODAY WILL BE THE BUILDING HEAT AND HUMIDITY
EXPECTED PRIOR TO STORM DEVELOPMENT. LATEST THOUGHTS ARE THAT
TEMPERATURES WILL LIKELY RISE INTO THE MID AND UPPER 90S COMBINED
WITH DEWPOINTS IN THE LOW TO MID 70S. THIS COMBINATION OF HEAT AND
HUMIDITY RESULTS IN HEAT INDEX VALUES IN EXCESS OF 105 DEGREES
ACROSS THE WESTERN TWO-THIRDS OF THE MID SOUTH. A HEAT ADVISORY
WILL BE ISSUED FOR THESE LOCATIONS. HEAT INDICES WILL LIKELY BE
KNOCKED DOWNWARD IN NORTHERN AREAS LATE THIS AFTERNOON IN
LOCATIONS IMPACTED BY CONVECTION.

THE SHORTWAVE WILL MOVE EAST LATER THIS EVENING WITH AN EXPECTED
DOWNWARD TREND IN CONVECTIVE COVERAGE AND INTENSITY. PLAN TO HOLD
ONTO SLIGHT CHANCE POPS OVERNIGHT TO ACCOUNT FOR ANY LINGERING
CONVECTION ALONG DEVELOPED OUTFLOW BOUNDARIES. WARM TEMPERATURES
AND HUMID CONDITIONS WILL PERSIST.

ADDITIONAL ISOLATED TO POTENTIALLY SCATTERED SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE THURSDAY AND THURSDAY NIGHT ALONG
ANY RESIDUAL OUTFLOW BOUNDARIES OR IN ADVANCE OF SUBTLE SHORTWAVES
MOVING ACROSS THE AREA IN WEAK NORTHWEST FLOW ALOFT.

GREATER CHANCES FOR SHOWERS AND THUNDERSTORMS WILL OCCUR ACROSS
THE MID SOUTH FROM FRIDAY INTO SATURDAY AS A POTENT MID LEVEL
SHORTWAVE AND ASSOCIATED STRONG COLD FRONT MOVE ACROSS THE AREA.
STRENGTHENING DEEP LAYER SHEAR AND AMPLE INSTABILITY WILL LIKELY
SUPPORT THE POTENTIAL FOR SEVERE WEATHER. STORMS SHOULD FORM ALONG
AND AHEAD OF THE FRONT...WITH THE POTENTIAL FOR A SQUALL LINE WITH
EMBEDDED SEVERE STORMS AND POTENTIAL FOR DAMAGING WINDS AND LARGE
HAIL. THE SEVERE THREAT SHOULD SHIFT TO SOUTHEAST SECTIONS OF THE
MID SOUTH ON SATURDAY BEFORE THE FRONT SWEEPS SOUTHEAST THROUGH
THE AREA.

CANADIAN HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT WITH A
RETURN TO DRY WEATHER...MUCH COOLER TEMPERATURES...AND LOWER
HUMIDITY. VERY PLEASANT FALL LIKE CONDITIONS WILL PERSIST OVER THE
MID SOUTH FOR THE END OF NEXT WEEKEND AND INTO THE FIRST PART OF
NEXT WEEK.

JLH

&&

.AVIATION...

06Z TAF CYCLE

VFR CONDITIONS SHOULD CONTINUE FOR THE MAJORITY OF THE NEXT 24
HOURS. WINDS ACROSS THE REGION SHOULD BE CALM UNTIL SOUTH WINDS
PICK UP IN THE LATE MORNING HOURS. SURFACE DEW POINT DEPRESSIONS
ARE ALREADY MINIMAL ACROSS PORTIONS OF THE MID-SOUTH. THEREFORE
IFR TO LIFR VISIBILITIES ARE EXPECTED DUE TO FOG AT KMKL AND KTUP.
HAVE REINTRODUCED FOG AT KMEM...BUT ONLY 5 SM SINCE THE MEMPHIS
METRO AREA WILL STAY WARMER. SHOWER AND THUNDERSTORM CHANCES SEEM
MEAGER ACROSS THE REGION FOR TOMORROW SO NO VCSH OR VCTS WILL BE
ADDED TO THE TAFS AT THIS TIME.

RRH

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  98  78  96  77 /  10  20  20  20
MKL  95  73  94  72 /  20  20  20  20
JBR  97  74  95  73 /  30  20  20  20
TUP  95  75  95  74 /  10  20  20  20

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...HEAT ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS EVENING
     FOR CLAY-CRAIGHEAD-CRITTENDEN-CROSS-GREENE-LAWRENCE-LEE AR-
     MISSISSIPPI-PHILLIPS-POINSETT-RANDOLPH-ST. FRANCIS.

MO...HEAT ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS EVENING
     FOR DUNKLIN-PEMISCOT.

MS...HEAT ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS EVENING
     FOR BENTON MS-CALHOUN-CHICKASAW-COAHOMA-DESOTO-ITAWAMBA-
     LAFAYETTE-LEE MS-MARSHALL-MONROE-PANOLA-PONTOTOC-QUITMAN-
     TALLAHATCHIE-TATE-TIPPAH-TUNICA-UNION-YALOBUSHA.

TN...HEAT ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS EVENING
     FOR CROCKETT-DYER-FAYETTE-HARDEMAN-HAYWOOD-LAKE-LAUDERDALE-
     SHELBY-TIPTON.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MEMPHIS TN
947 PM CDT TUE SEP 4 2012

ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115-
MSZ001>017-020>024-TNZ001>004-019>021-048>055-088>092-052030-
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-
947 PM CDT TUE SEP 4 2012

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

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

HOT AND HUMID CONDITIONS WILL PREVAIL WEDNESDAY AND THURSDAY. HEAT
ADVISORIES ARE LIKELY.

AN ISOLATED STRONG THUNDERSTORM OR TWO WILL BE POSSIBLE THURSDAY AND
FRIDAY. FRIDAY WILL SEE INCREASED CHANCES OF THUNDERSTORMS...A FEW
OF WHICH COULD REACH SEVERE LIMITS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED ON FRIDAY.

PWB