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

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FXUS64 KMRX 291858
AFDMRX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
258 PM EDT FRI MAY 29 2015

.SHORT TERM (TONIGHT AND SATURDAY)...SOUTH TO SOUTHWEST FLOW
SURFACE TO ALOFT IS PULLING PLENTY OF MOISTURE INTO THE SOUTHERN
APPALACHIANS. AIR-MASS IS MARGINALLY UNSTABLE PRODUCING SCATTERED
CONVECTION OVER THE AREA THIS AFTERNOON. CONVECTION WILL DISSIPATE
SOON AFTER SUNSET DUE TO LOSS OF HEATING AND LACK OF SYNOPTIC
FORCING. MAIN CONCERN WITH STORMS WILL BE HEAVY RAIN...GUSTY WINDS
UP TO 40 MPH AND FREQUENT LIGHTNING.

DUE TO MID AND HIGH CLOUDS CLEARING OVERNIGHT AND SCATTERED RAIN
THIS AFTERNOON/EVENING...PATCHY DENSE FOG IS EXPECTED BY EARLY
SATURDAY MORNING.

FOR SATURDAY...MODEL SOUNDINGS SHOW A DRIER AIRMASS OVER THE REGION
WITH UPPER RIDGING A LITTLE STRONGER OVER THE SOUTHERN
APPALACHIANS. END RESULT WILL BE MUCH SMALLER COVERAGE OF
CONVECTION AND MAINLY CONFINED TO THE HIGHER TERRAIN.

.LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)...MODELS DIFFER
SLIGHTLY ON TIMING OF PRECIP SUNDAY AS A WEAK FRONT MAKES ITS WAY
IN TO THE AREA. STORMS THAT FORM WEST OF THE AREA SATURDAY NIGHT
ALONG AN AREA OF WEAK CONVERGENCE COULD CONTINUE TO MOVE EAST
THROUGH THE EARLY MORNING...AFFECTING THE PLATEAU COUNTIES.
OTHERWISE...SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
FORM EARLY AFTERNOON ACROSS MAINLY THE HIGHER ELEVATIONS...AND MOVE
IN TO THE VALLEY. STRONG TO POSSIBLY ISOLATED SEVERE ARE POSSIBLE
WITH THESE STORMS...ALTHOUGH AS MORE DETAILS APPEAR...CONFIDENCE
WILL INCREASE. WIND PROFILE FOR SUNDAY IS VERY WEAK...SO STORMS
THAT DO FORM WOULD MOVE SLOWLY...BUT BE VERY SHORTLIVED.
INSTABILITIES AVERAGE AROUND 2000 J/KG WITH SLIGHTLY HIGHER AMOUNTS
IN NORTHERN HALF OF CWA. ALSO IN NORTHERN HALF OF CWA...LARGE
AMOUNTS OF DRY AIR IN THE MID AND UPPER LEVELS WILL CAUSE CONCERN
AND THREAT OF STRONG DOWNBURST WINDS IN THESE STORMS. SOUTHERN HALF
OF CWA DOES NOT HAVE THE AMOUNT OF MID AND UPPER LEVEL DRY
AIR...BUT THREAT OF STRONG DOWNBURST WINDS WILL STILL BE PRESENT.
HAIL THREAT WILL BE MINIMAL WITH HIGH FREEZING LEVELS. BUT WITH THE
SLOW MOVING NATURE OF THE STORMS...LOCALIZED FLASH FLOODING COULD
BE AN ISSUE...ESPECIALLY IN ANY STORMS THAT MOVE OVER THE SAME
AREA. SUNDAY NIGHT THE CONVECTION IS EXPECTED TO WEAKEN
SLIGHTLY...WITH CONVECTION MAINLY LIMITED TO THE HIGHER ELEVATIONS
IN EAST TENNESSEE.

MONDAY...SHOWERS AND THUNDERSTORMS ARE EXPECTED TO AGAIN DEVELOP IN
THE EARLY AFTERNOON AS THE FRONT REMAINS OVER THE AREA. LARGE
AMOUNTS OF INSTABILITY...BUT VERY MOIST PROFILE...COULD AGAIN SEE
THREAT OF STRONG WINDS AND SMALL HAIL. MAIN THREAT HOWEVER WILL BE
LOCALIZED FLOODING WITH HEAVY RAINFALL AMOUNTS IN THE STORMS THAT DO
FORM. THIS IS ALL ASSUMING THE SOUTHERN FLOW CAN CONTINUE TO BRING
AMPLE MOISTURE IN TO THE AREA. MODEL RUNS THE PAST COUPLE OF WEEKS
HAVE BEEN CONSISTENTLY TOO WET...BUT RIGHT NOW WILL LEAVE IN
FLOODING THREAT. MONDAY NIGHT WILL AGAIN SEE STORMS THAT WEAKEN AND
MOVE OUT OF THE AREA...WITH A FEW SHOWERS POSSIBLE IN THE HIGHER
ELEVATIONS OF EAST TENNESSEE.

TUESDAY...THE WEAK FRONT FINALLY MOVES EAST OF THE AREA...AND WINDS
WILL SHIFT TO THE NORTHWEST BEHIND IT. CHANCES FOR SHOWERS AND
THUNDERSTORMS WILL REMAIN CLOSE TO THE MOUNTAINS OF EAST TENNESSEE.
BY WEDNESDAY...LOW PRESSURE TRIES TO DEVELOP OVER THE GULF STATES.
WITH FLOW AROUND THE LOW...MOSITURE WILL BE ADVECTED FROM THE SOUTH
TO SOUTHEAST IN TO THE AREA. DEPENDING ON THE POSITION OF THE
LOW...DEPENDS ON HOW MUCH MOISTURE WE GET IN TO THE AREA. WITH THE
LARGE DIFFERENCE BETWEEN MODEL RUNS LATELY...CONFIDENCE IS LOW ON
TIMING AND COVERAGE OF CONVECTION FORMING EACH AFTERNOON. WILL LEAVE
IN SLIGHT CHANCE FOR DIURNAL SHOWERS AND THUNDERSTORMS
FORMING...WITH PROMISE TO EDIT AS MODELS BECOME MORE CONSISTENT.
TEMPERATURES WILL REMAIN NEAR NORMAL AND VERY STATIC THROUGH THE
EXTENDED.

&&

.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN             66  86  66  81 /  20  20  20  50
KNOXVILLE MCGHEE TYSON AIRPORT, TN  64  86  65  80 /  20  10  20  50
OAK RIDGE, TN                       65  87  65  80 /  20  10  20  50
TRI CITIES AIRPORT, TN              62  85  62  78 /  20  20  20  60

&&

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

$$




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