Area Forecast Discussion
Issued by NWS Memphis, TN

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FXUS64 KMEG 281728 AAA
AFDMEG

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MEMPHIS TN
1228 PM CDT TUE JUL 28 2015

.UPDATE...
UPDATED FOR 18Z AVIATION DISCUSSION BELOW.

&&

.PREV DISCUSSION... /ISSUED 1102 AM CDT TUE JUL 28 2015/

DISCUSSION...

A 595DM UPPER RIDGE IS CENTERED JUST WEST OF THE MIDSOUTH.
VERY HOT AND HUMID CONDITIONS EXPECTED THIS AFTERNOON. TEMPS ARE
ALREADY INN THE LOWER 90S ACROSS THE AREA WITH DEWPOINTS IN THE
MID TO UPPER 70S...EVEN A FEW 80 DEGREE DEWPOINTS NOTED IN THE
DELTA. HEAT INDEX VALUES ARE ALREADY TOPPING 105 DEGREES ACROSS
EASTERN ARKANSAS. A FEW POP UP THUNDERSTORMS ARE POSSIBLE MAINLY
EAST OF THE MS RIVER WHERE THE RIDGING IS SLIGHTLY WEAKER.
FORECAST ON TRACK.

SJM

PREV DISCUSSION... /ISSUED 330 AM CDT TUE JUL 28 2015/

EXCESSIVE HEAT WILL CONTINUE THROUGH WEDNESDAY FOR THE ENTIRE
MIDSOUTH WITH HEAT INDICES FORECAST BETWEEN 105 AND 110 BOTH
TUESDAY AND WEDNESDAY. A COLD FRONT WILL MOVE THROUGH THE REGION
ON THURSDAY BRINGING AN END TO THE OPPRESSIVE HEAT AND HUMIDITY...

CURRENTLY...AN UPPER LEVEL RIDGE AXIS WAS BISECTING THE MIDSOUTH
AS A VERY STRONG SHORTWAVE TROUGH WAS MOVING THROUGH THE NORTHERN
PLAINS. A STRONG 996 MB SURFACE LOW WAS DEEPENING IN THE NRN
PLAINS/SRN CANADIAN PROVINCES WITH A SURFACE FRONTAL BOUNDARY
ANALYZED FROM NE CO/C NE/SE SD. SURFACE HIGH PRESSURE WAS ANCHORED
ACROSS MUCH OF THE SOUTHEAST US.

FOR TUESDAY...CONTINUED OPPRESSIVE HEAT IS FORECAST. GUIDANCE HAS
CONTINUED TO BE TOO WARM WITH OBSERVED HIGH TEMPERATURES 1-3
DEGREES LOWER THAN MOST GUIDANCE MEMBERS. THIS IS REFLECTED WELL
IN BIAS CORRECTED GUIDANCE SO A BLEND OF RAW AND BIAS CORRECTED
GUIDANCE WAS USED FOR BOTH TUESDAY AND WEDNESDAY. EVEN
STILL...FORECAST HIGHS WILL REACH THE MIDDLE AND UPPER 90S ON
TUESDAY WITH DEWPOINTS IN THE LOW AND MIDDLE 70S. HEAT INDICES
WILL HOVER BETWEEN 105 AND 110 DEGREES FOR FROM MIDDAY THROUGH
MUCH OF THE AFTERNOON. LOW TEMPERATURES TUESDAY NIGHT SHOULD BE A
CARBON COPY OF WHAT IS OCCURRING TONIGHT...MIDDLE TO UPPER
70S...NEAR 80 IN DOWNTOWN MEMPHIS.

WEDNESDAY AGAIN LOOKS HOT AND POTENTIALLY MORE HUMID THAN TUESDAY
AS A FRONTAL BOUNDARY ALLOWS MOISTURE TO POOL AHEAD OF IT. UNLIKE
THE PAST FEW DAYS...DEWPOINTS WILL HAVE TROUBLE MIXING OUT GIVEN A
DEEPER MOISTURE COLUMN ALOFT. FOR THIS REASON...THE HEAT ADVISORY
HAS BEEN EXTENDED THROUGH 8 PM ON WEDNESDAY WITH FORECAST HEAT
INDICES APPROACHING 110 ACROSS MUCH OF THE MIDSOUTH...THE EXCEPTION
BEING AREAS NEAR THE TENNESSEE RIVER IN WEST TENNESSEE WHERE
VALUES SHOULD BE ONLY SLIGHTLY LOWER. ISOLATED THUNDERSTORMS ARE
POSSIBLE WEDNESDAY AS WEAK FORCING ALOFT APPROACHES THE REGION
WITH STRONG SURFACE INSTABILITY PRESENT. WIDESPREAD COVERAGE IS
NOT EXPECTED AT THIS TIME.

THERE IS GOOD NEWS...HOWEVER. THE STRONG SHORTWAVE IN SOUTHERN
CANADA WILL FORCE A FRONTAL BOUNDARY THROUGH THE MIDSOUTH LATE
WEDNESDAY NIGHT/THURSDAY MORNING. THIS WILL MARK THE END OF THE
EXTENDED PERIOD OF HEAT AND HUMIDITY THAT HAS BEEN EXPERIENCED
OVER THE PAST FEW WEEKS. ISOLATED TO WIDELY SCATTERED
THUNDERSTORMS ARE POSSIBLE ALONG IT BUT UPPER LEVEL FORCING IS
WELL-REMOVED TO THE NORTH. THE MAIN STORY WITH THIS FRONTAL
PASSAGE WILL BE THE RELIEF FROM THE HEAT. MODELS HAVE DEPICTED A
SLIGHTLY FASTER FRONTAL PASSAGE WITH DEWPOINTS FALLING INTO THE
MID...THEN POTENTIALLY LOWER 60S. THIS WILL FEEL GLORIOUS AFTER
WHAT HAS BEEN EXPERIENCED ACROSS THE MIDSOUTH OVER THE PAST TWO
WEEKS.

IN THE LONG-TERM...A MOSTLY DRY FORECAST IS DEPICTED BY LONGER-
TERM GUIDANCE. STRONG RIDGING REDEVELOPS WITH THE STORM TRACK
CONTINUING TO BE WELL NORTH OF THE MIDSOUTH. A SLOW WARM UP IS
EXPECTED WITH HIGHS POTENTIALLY REACHING THE MIDDLE 90S AGAIN BY
EARLY NEXT WEEK.

TVT

&&

.AVIATION...
18Z TAFS

TSRA CHANCES WILL CONTINUE THIS AFTERNOON NEAR THE TN RIVER. NOT
LIKELY NEAR ENOUGH TO MKL TO WARRANT VCTS...BUT WILL CONTINUE TO
MONITOR TRENDS.

OTHER THAN PATCHY MVFR VSBY AT MKL...VFR WILL PREVAIL THROUGH THE
NEXT 24 HOURS. SHIFT TO NORTHWEST WINDS WILL OCCUR BY AROUND 15Z...
ASSOCIATED WITH A WEAK SURFACE COLD FRONTAL PASSAGE.

PWB

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...HEAT ADVISORY UNTIL 8 PM CDT WEDNESDAY FOR CLAY-CRAIGHEAD-
     CRITTENDEN-CROSS-GREENE-LAWRENCE-LEE AR-MISSISSIPPI-
     PHILLIPS-POINSETT-RANDOLPH-ST. FRANCIS.

MO...HEAT ADVISORY UNTIL 8 PM CDT WEDNESDAY FOR DUNKLIN-PEMISCOT.

MS...HEAT ADVISORY UNTIL 8 PM CDT WEDNESDAY FOR ALCORN-BENTON MS-
     CALHOUN-CHICKASAW-COAHOMA-DESOTO-ITAWAMBA-LAFAYETTE-LEE MS-
     MARSHALL-MONROE-PANOLA-PONTOTOC-PRENTISS-QUITMAN-
     TALLAHATCHIE-TATE-TIPPAH-TISHOMINGO-TUNICA-UNION-YALOBUSHA.

TN...HEAT ADVISORY UNTIL 8 PM CDT WEDNESDAY FOR BENTON TN-CARROLL-
     CHESTER-CROCKETT-DECATUR-DYER-FAYETTE-GIBSON-HARDEMAN-
     HARDIN-HAYWOOD-HENDERSON-HENRY-LAKE-LAUDERDALE-MADISON-
     MCNAIRY-OBION-SHELBY-TIPTON-WEAKLEY.

&&

$$



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