Severe Thunderstorm Warning 171, NWS Morristown, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
320 PM EDT MON JUL 22 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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AFTERNOON FORECAST DISCUSSION
320 PM EDT MON JUL 22 2002

AREA RADARS SHOWING SCATTERED ECHOES IN THE EASTERN FORECAST AREA...
AND THE VALLEY LOCATIONS TO THE EAST ARE HEATING UP APPRECIABLY.
CAPES IN THE TENNESSEE VALLEY ARE IN THE MODERATE RANGE...AND
EXPECT SCATTERED COVERAGE OF SHOWERS AND THUNDERSTORMS TO MOVE
NORTHWEST...INTO VALLEY LOCALS. THESE STORMS ARE EXPECTED TO WEAKEN
AND DISSIPATE DURING THE LATE EVENING HOURS...SO WILL WORD POP WITH
AN EVENING SCATTERED POP.

A COLD FRONT WILL CONTINUE TO APPROACH THE FORECAST AREA ON
TUESDAY...WITH BETTER UPPER AIR TROUGHING. PERHAPS MORE THAN
SCATTERED PRECIPITATION COVERAGE LOOKS TO INVADE THE NORTHWEST
FORECAST AREA...SO WILL GO WITH LIKELY AFTERNOON POP/S HERE.
ELSEWHERE...THE SCATTERED AFTERNOON POP SCENARIO CONTINUES (THOUGH UP
TO 50 PERCENT). MOS HIGH TEMPERATURES CLOSE AND REASONABLE...MAINLY
LOWER 90S CENTRAL/SOUTHERN TENNESSEE VALLEY LOCALS.

FOR TUESDAY NIGHT...HIGHER MOISTURE VALUES AND PROXIMITY OF FRONT
IS ENOUGH FOR A MOSTLY CLOUDY SKY...AND SCATTERED POP/S DURING THE
PERIOD. A 50 PERCENT CHANCE WILL BE ADVERTISED ON WEDNESDAY...WITH
MOSTLY CLOUDY SKIES AND SLIGHTLY COOLER TEMPERATURES.

ON THURSDAY...THE FRONTAL BOUNDARY MAY HANG UP IN THE FORECAST AREA.
HOWEVER...THE LONG-TERM MODELS SUGGEST THAT DRIER AIR WILL WORK IN
FROM THE NORTHWEST...WITH SURFACE HIGH PRESSURE TO THE WEST. SO...
WILL PLAY THIS SCENARIO FOR NOW...AND GO WITH PARTLY CLOUDY AND A 30
POP.

DM
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MIDDAY FORECAST DISCUSSION (UPDATE)
1040 AM EDT MON JUL 22 2002

PARTLY CLOUDY SKIES WILL DEVELOP ACROSS THE FORECAST AREA TODAY...AS
THE 24-HR MOISTURE PROFILE HAS CHANGED LITTLE. HOWEVER...L/L MOISTURE
SHOULD INCREASE A LITTLE EARLY THIS AFTERNOON...AND DESTABILIZATION
IS EXPECTED TO DRIVE SCATTERED SHOWERS AND THUNDERSTORMS IN THE
WESTERN FORECAST AREA (CUMBERLAND PLATEAU AND HIGHER ELEVATIONS
ADJACENT TO THE SEQUATCHIE VALLEY).

THEREAFTER...SCATTERED MOUNTAIN T-STORMS WILL BE ADVERTISED...AND
SOME OF THE STORMS IN THE PLATEAU MAY GET INTO THE TENNESSEE VALLEY
LATE.

NO FORECAST UPDATE PLANNED.

DM
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MORNING FORECAST DISCUSSION
300 AM EDT MON JUL 22 2002

TRANSITION TO INCREASINGLY UNSETTLED WEATHER IN STORE FOR THE NEXT
FEW DAYS. EAST TO WEST ORIENTED UPPER RIDGE CURRENTLY STRETCHING
FROM THE MIDDLE ATLANTIC STATES TO THE CENTRAL PLAINS WILL BE ERODED
ON ITS NORTHERN AND EASTERN PERIPHERY BY A NORTHERN STREAM SHORT
WAVE. AN ASSOCIATED COLD FRONT IS PROJECTED TO APPROACH THE SOUTHERN
APPALACHIANS BY TUESDAY AFTERNOON. THIS WILL INCREASE CHANCES OF
PRECIP AS MOISTURE PROFILE BECOMES MORE CONDUCIVE FOR CONVECTION.
HAVE CONTINUED CURRENT POP TRENDS FOR THE THIRD AND FOURTH
PERIODS.

QUESTION THEN BECOMES WHETHER OR NOT FRONT WILL PUSH THROUGH THE
AREA. MODELS PROJECT FRONT WILL MOVE SOUTH OF THE REGION. BASED ON
RECENT TRENDS THE FRONT STALLING ACROSS OR NEAR THE SOUTHERN
APPALACHIANS IS PROBABLY THE MOST LIKELY SCENARIO. THEREFORE WILL
CONTINUE WITH LOW POP FOR WEDNESDAY. TEMPS SHOULD REMAIN ABOVE
CLIMATOLOGY BEFORE DROPPING BACK TO NEAR CLIMATOLOGY ON WEDNESDAY.

REGARDING TEMPS...MOS GUIDANCE GENERALLY CLOSE AND APPEARS REASONABLE
BASED ON PERSISTENCE. TENDED TO FAVOR A BLEND WHERE SIGNIFICANT
DIFFERENCES OCCURRED.

PRELIMINARY CCF FOLLOWS:
CHA   94  72  93  72 /  30  20  40  50
TYS   91  71  90  71 /  30  20  40  50
TRI   90  67  88  68 /  30  20  40  50
OQT   91  71  90  72 /  30  20  40  50

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

LCM

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EVENING FORECAST DISCUSSION (UPDATE)
910 PM EDT SUN JUL 21 2002

RADAR SHOWING ISOLATED SHOWERS AND THUNDERSTORMS HAVE MOVED SOUTH OF
OUR AREA.  WILL UPDATE ZONES TO TAKE PRECIPITATION CHANCES OUT FOR
THE REST OF TONIGHT.  SHOULD HAVE MORE PATCHY FOG DEVELOPING LATER
TONIGHT...WHICH IS WELL COVERED BY THE CURRENT FORECAST.
TEMPERATURES LOOK GOOD.

GH