Severe Thunderstorm Warning 217, NWS Morristown, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
940 AM EDT SUN AUG 18 2002

THE FOLLOWING ARE ALL THE FORECAST DISCUSSIONS FROM THE PAST 24
HOURS...WITH THE MOST RECENT ON TOP. THIS PROVIDES A HISTORY OF THE
DEVELOPMENT OF THE CURRENT FORECAST.
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LATE MORNING FORECAST DISCUSSION
940 AM EDT SUN AUG 18 2002

WILL UPDATE ZONES TO REMOVE MORNING FOG WORDING.  WILL LEAVE POPS AS
IS WITH CONVECTION ALREADY TAKING PLACE IN SE TN AND SOLAR HEATING
ON TRACK TO FIRE THINGS UP.

.MRX...
NC...NONE.
TN...NONE.
VA...NONE.

BB

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MORNING FORECAST DISCUSSION
330 AM EDT SUN AUG 18 2002

FRONT ACROSS THE OHIO VALLEY REMAINS NEARLY STATIONARY WITH GOOD
SOUTHWEST FLOW CONTINUING AT ALL LEVELS OVER THE NEXT FEW DAYS.  THE
FRONT WILL SLOWLY SAG SOUTH AND BE NEAR THE FORECAST AREA LATE
MONDAY OR EARLY TUESDAY.  SCATTERED SHOWERS WILL CONTINUE INTO
TUESDAY.

MODELS VERY CLOSE AS IS GUIDANCE NUMBERS.  ONLY MINOR DEVIATION FROM
A BLEND FORECAST OF NGM...AVN FORECAST NUMBERS.

CHA   90  70  91  71 /  50  30  30  20
TYS   88  69  90  70 /  50  30  30  20
TRI   87  66  88  67 /  50  30  30  20
OQT   88  69  90  70 /  50  30  30  20

.MRX...
NC...NONE.
TN...NONE.
VA...NONE.

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EVENING FORECAST DISCUSSION
900 PM EDT SAT AUG 17 2002

SHOWERS AND ISOLATED THUNDERSTORMS HAVE MOVED EAST AND NORTHEAST OUT
OF THE FORECAST AREA THIS EVENING AS THE SUN HAS SET. BEST
INSTABILITY AHEAD OF COLD FRONT APPROACHING THE OHIO VALLEY LIES TO
THE NORTHWEST AND WEST OVER KENTUCKY AND WEST TENNESSEE. WEAK
VORTICITY LOBE WILL MOVE NORTHEAST OUT OF MS AND NORTH AL INTO
MIDDLE TN OVERNIGHT AND EARLY SUNDAY. WITH REDEVELOPMENT POSSIBLE
SOUTHWEST AND WEST OF THE FORECAST AREA RELUCTANT TO TAKE OUT SLIGHT
CHANCE FOR FEAR SHOWERS AND A POSSIBLE THUNDERSTORM WILL MOVE IN
LATER. UPDATE TO DECREASE WINDS.

TD
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AFTERNOON FORECAST DISCUSSION
300 PM EDT SAT AUG 17 2002

LINES OF CONVECTION MOVING NORTHEAST ACROSS FA ATTM. LARGEST AREA OF
SHOWERS OVER CUMBERLAND PLATEAU APPEARS TO BE BREAKING UP AS IT
MOVES EAST...BUT THIS MAY BE DUE TO NARROWING BEAM WIDTH OF MRX
RADAR AS THE SHOWERS MOVE CLOSER. STILL...LIKELY POPS FOR TODAY
APPEAR JUSTIFIED ALL AREAS.

ON WV IMAGERY THUNDERSTORMS OVER NORTH GEORGIA ARE THE ONLY THINGS
THAT APPEAR WITH ENHANCED TOPS IN THE REGION...SO BELIEVE THAT MOST
OF THE STORMS WILL NOT REACH SEVERE LIMITS. ALSO LACK OF GOOD UPPER
SUPPORT WILL LIMIT MOST OF THEM TO BRIEF HEAVY RAIN SHOWERS. WILL
TAKE THAT. WORSENING DROUGHT WILL BE HELD AT BAY FOR THE TIME BEING.

WV ALSO SHOWS ANTICYCLONIC UPPER OUTFLOW ASSOCIATED WITH MCS OVER
CENTRAL PLAINS.  THIS SYSTEM IS DISSIPATING BUT IS STILL SPURRING
THUNDERSTORMS OVER SE MO SO MUCH POTENCY LEFT.

RIDGE OVER SE US FLAT WITH MAINLY ZONAL FLOW OVER TOP. FORECAST
AREA SITS BETWEEN CENTER OF RIDGE TO SOUTH AND STRONGEST HT GRADIENT
OVER OHIO VALLEY. SERIES OF SHORTWAVES WILL MOVE EAST CLIPPING
AREA. KEPT PARTLY TO MOSTLY CLOUDY THROUGH THURSDAY AS A RESULT WITH
SOME KIND OF CHANCE EACH PERIOD. FRIDAY BETWEEN SHORT WAVES WITH
SATURDAY SEEING TROF MOVING OVER DEVELOPING WESTERN OMEGA BLOCK AND
DIGGING TOWARD TENNESSEE. I REALIZE THIS IS WELL OUT IN THE
FORECAST PACKAGE...BUT IF MRF VERIFIES THE BLOCK COULD AFFECT OUR
WEATHER FOR A WHILE WITH POTENTIAL FOR SERIES OF DEEPENING TROFS
OVER THE EAST AND THE POOR WEST BEING HOT AND DRY.

ADJUSTED HIGH TEMPS UP A DEGREE OR TWO OVER THE BLEND NUMBERS
WITH LOWS DOWN A DEGREE OR TWO.

CHA   70  88  70  89 /  20  50  30  30
TYS   68  87  69  88 /  20  50  30  30
TRI   66  84  64  87 /  20  50  30  30
OQT   68  87  69  88 /  20  50  30  30

BB