Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN

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FXUS64 KMRX 301849
AFDMRX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
249 PM EDT SAT AUG 30 2014

.SHORT TERM...(TONIGHT THROUGH MONDAY)...GULF MOISTURE CONTINUES TO
STREAM NORTHWARD FROM THE WESTERN GULF OF MEXICO THIS AFTERNOON.
AIR MASS IS BECOMING SLIGHTLY TO MODERATELY UNSTABLE WITH SPOTTY
CONVECTION POPPING OVER SE TN...AND MORE SO TO OUR SW OVER NE AL.
I ADJUSTED THE SHORT TERM GRIDS FOR LATE AFTERNOON AND THIS EVENING
IN LINE WITH THE SIMILAR HRRR AND RAP MODELS...WHICH SUPPORTS
LIKELY POPS OVER WRN AREAS. THE SHORTWAVE TROUGH MOVES EAST ACROSS
THE WRN GREAT LAKES AND OHIO VALLEY REGION OVERNIGHT...WHICH SHOULD
KEEP HIGHER POPS IN ORDER AFTER MIDNIGHT ACROSS OUR NRN PLATEAU AND
EXTREME WRN SW VA COUNTIES.

FOR SUNDAY...STAYED WITH OUR LOW END OF LIKELY POPS...WHICH ARE
HIGHER THAN 12Z MOS GUIDANCE...SINCE THE SRN END OF THE UPPER
TROUGH WILL BE PASSING EAST ACROSS THE TN VALLEY AND SRN
APPALACHIANS DURING PEAK HEATING. LOWERED POPS FROM THE WEST
SUNDAY NIGHT WITH PASSAGE OF THE TROUGH AXIS. MONDAY ALSO SHAPING
UP DRIER THAN PREVIOUS GRIDS...SO CUT POPS BACK TO 20 TO 30
PERCENT...AND PUSHED MAX TEMPS BACK UP TO THE SIMILAR UPR 80S TO
LWR 90S FROM 12Z MOS. OTHERWISE...12Z NAM AND GFS MOS TEMPS WERE IN
GENERAL AGREEMENT AND CLOSELY FOLLOWED.


.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)...NOT MUCH FOCUS FOR
CONVECTION THROUGHOUT THE LONG TERM PERIOD OTHER THAN INTENSE SOLAR
HEATING AND OROGRAPHIC LIFT ON THE MAJOR TERRAIN FEATURES.
HOWEVER...THERE WILL BE SOME WEAK SHORT WAVE ENERGY MAKING ITS WAY
ACROSS THE NORTHEASTERN QUARTER OF THE NATION LATER TUESDAY INTO
WEDNESDAY AND THIS CONFIGURATION MAY COAX A WEAK COOL FRONT INTO THE
SOUTHERN APPALACHIAN REGION WEDNESDAY THROUGH FRIDAY. THIS BOUNDARY
MAY ALLOW FOR A SLIGHT INCREASE IN PROBABILITY OF PRECIPITATION
MAINLY ON WEDNESDAY IF IT CAN MAKE IT FAR ENOUGH SOUTH. OTHERWISE
GENERALLY KEPT POPS AROUND 20-25 PERCENT AS UPPER RIDGING HANGS
AROUND THE SOUTHEASTERN U.S. TRENDED MAX TEMPS A LITTLE CLOSER TO
SUGGESTED HIGHS FOR THE UPCOMING WEEK AS THE ANNUAL LATE SUMMER LAG
IN HEATING DUE TO LONG WAVE RE-RADIATION FINALLY CATCHES UP TO US.
STAYED PRETTY CLOSE TO MINS THROUGH THE PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN             71  87  71  93 /  60  60  40  20
KNOXVILLE MCGHEE TYSON AIRPORT, TN  69  86  70  91 /  50  60  30  20
OAK RIDGE, TN                       70  84  69  91 /  60  60  40  20
TRI CITIES AIRPORT, TN              66  87  65  87 /  50  60  40  20

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&

$$

TG



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