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

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000
FXUS64 KMRX 151912
AFDMRX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
312 PM EDT WED MAY 15 2013

.SHORT TERM...-- Changed Discussion --(TONIGHT THROUGH FRIDAY)...PATTERN CHANGING TO WARMER
MORE SUMMER LIKE ACROSS THE FORECAST AREA AS UPPER LEVEL SUBTROPICAL
RIDGE CONTINUES TONIGHT. AT MID AFTERNOON SKIES REMAIN SUNNY AND
TEMPERATURES ARE AT OR A LITTLE ABOVE NORMAL IN THE UPPER 70S TO MID
80S. SHORT RANGE ENSEMBLE MODELS DEVELOP WEAK UPPER-LEVEL LOW
PRESSURE AREA OVER THE SOUTHERN PLAINS TONIGHT AND MOVE IT EAST WITH
SHOWERS AND STORMS FORMING ACROSS WESTERN TENNESSEE BY MORNING. THE
FORECAST AREA WILL REMAIN DRY BUT CLOUDS WILL INCREASE FROM WEST TO
EAST LATE TONIGHT. THE MOIST SOUTHWEST FLOW AROUND THE WEAK LOW WILL
HELP INCREASE MOISTURE AND WITH MODERATE INSTABILITY THE CHANCE OF
SHOWERS AND THUNDERSTORMS WILL INCREASE THURSDAY NORTH AND ALL AREAS
FRIDAY AS THE UPPER LOW BECOMES ABROAD TROUGH WITH EVEN MORE
COVERAGE FRIDAY. THE BEST RAIN CHANCES WILL BE LATE AFTERNOON AND
EVENING AFTER PEAK HEATING.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)...WEAK UPPER LEVEL
TROUGH SLIDES INTO THE SOUTHERN APPALACHIAN REGION OVER THE WEEKEND
WHILE A WEAK SYNOPTIC BOUNDARY TRIES TO DROP SOUTH THROUGH THE OHIO
VALLEY INTO NORTHERN REACHES OF THE SOUTHERN APPALACHIANS. MID
SPRING SEASON HEATING IS UNDERWAY NOW SO CONVECTION WILL BE THE
MODE OF PRECIPITATION. WENT WITH A LITTLE HIGHER CHANCE POPS ON
SATURDAY AS BOUNDARY EDGES A LITTLE FARTHER SOUTH WITH UPPER TROUGH
OVER THE AREA. THE WEAKNESS IN THE UPPER LEVEL HEIGHT FIELD DOESN`T
SHIFT EAST OF THE APPALACHIANS UNTIL MONDAY SO MAINTAINED MEDIUM
CHANCE POP FOR CONVECTION ON SUNDAY. BY MONDAY THE FORECAST AREA IS
IN BETWEEN SYSTEMS WITH A NICE AMPLIFIED RIDGE IN PLACE AND
THEREFORE DOWNPLAYED PROBABILITY OF PRECIPITATION AT THIS TIME.
GRADUALLY TWEAKED POPS UP TUESDAY INTO WEDNESDAY AS GENERAL MODEL
AGREEMENT WAS NOTED WITH INCREASING MOISTURE AND INSTABILITY
TUESDAY AHEAD OF A PLAINS STORM SYSTEM. THE UPPER TROUGH BUILDS
INTO THE EASTERN HALF OF THE NATION BY WEDNESDAY WITH A SYNOPTIC
FRONTAL BOUNDARY FORCING AN AREA OF CONVECTION ACROSS THE REGION
PERHAPS LATER TUESDAY NIGHT INTO WEDNESDAY. STAYED AROUND THE
MIDDLE OF A MEX/ECM MOS BLEND FOR TEMPERATURES.-- End Changed Discussion --

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --CHATTANOOGA AIRPORT, TN 61 83 60 83 62 / 10 20 20 30 20
KNOXVILLE MCGHEE TYSON AIRPORT, TN 60 82 60 82 61 / 10 20 20 40 20
OAK RIDGE, TN 59 82 58 82 61 / 10 20 20 40 20
TRI CITIES AIRPORT, TN 52 80 53 81 57 / 10 20 20 40 20-- End Changed Discussion --

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

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