Severe Thunderstorm Warning 221, NWS Morristown, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
1000 AM EDT MON AUG 19 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 (UPDATE)
1000 AM EDT MON AUG 19 2002

FOG HAS DISSIPATED...WILL UPDATE ZONES TO REMOVE IT.  MCS SHOULD
REMAIN TO OUR NORTH...BUT PROBABLY SEE THICKER HIGH CLOUDS IN OUR
NORTHERN ZONES.  WILL GO WITH A MOSTLY CLOUDY SKY IN THE NORTH.
ALSO EXPECTING A FEW OUTFLOWS TO MOVE INTO OUR AREA BY THIS
AFTERNOON.  WITH THE GOOD INSTABILITY...WILL BUMP UP POPS TO 40
PERCENT IN ALL AREAS.  WILL ALSO LOWER WINDS A BIT IN THE VALLEY
WITH A FAIRLY WEAK GRADIENT.  TEMPERATURES LOOK GOOD.

GH

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MORNING FORECAST DISCUSSION
330 AM EDT MON AUG 19 2002

WEAK SURFACE FRONT STILL LINGERING TO THE WEST OF THE FORECAST AREA
ACROSS MIDDLE TENNESSEE WILL SLOWLY DRIFT ACROSS THE AREA OVER THE
NEXT 36 HOURS.

SOME BIG DIFFERENCES IN THE ETA AND THE GFS/AVN MODELS ON TUESDAY.
ETA HAS THE AREA COMPLETELY DRIED OUT BY TUESDAY WHILE AVN HANGS ON
TO GOOD MOISTURE.  HAVE LEANED TOWARDS THE AVN AND PUT SLIGHT CHANCE
SHOWERS IN THE TERRAIN AREAS OF THE FORECAST AREA.

TEMPERATURES WILL BEGIN TO CLIMB TODAY THROUGH WEDNESDAY UNDER
SOMEWHAT CLEAR SKIES...EVEN WITH THE WETTER AVN MODEL.

CHA   90  69  92  69 /  30  30   0  10
TYS   88  70  90  67 /  30  30   0  10
TRI   87  66  87  63 /  30  30   0  10
OQT   88  70  90  67 /  30  30   0  10

.MRX...
NC...NONE.
TN...NONE.
VA...NONE.
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EVENING FORECAST DISCUSSION
855 PM EDT SUN AUG 18 2002

LINE OF SHOWERS AND THUNDERSTORMS THAT MOVED SOUTHEAST FROM KENTUCKY
AND MIDDLE TN EARLIER THIS AFTERNOON INTO SW VIRGINIA AND NORTHEAST
TN THIS EVENING SENT AN OUTFLOW BOUNDARY THROUGH THE MORRISTOWN AREA
THE PAST HOUR. WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE
BEGINNING TO DECREASE ACROSS NORTHEAST TENNESSEE. STRONG
THUNDERSTORMS CONTINUE WEST AND NORTHWEST OF CHATTANOOGA. RUC SHOWS
SHORTWAVE MOVING ACROSS WEST AND MIDDLE TN WITH WEAKER VORTICITY
LOBE EXTENDING ACROSS NORTHEAST TN. THIS SHORTWAVE MOVES SOUTHEAST
INTO NORTH AL OVERNIGHT TONIGHT. CURRENT FORECAST HAS A CHANCE
THUNDER. PLANNING TO KEEP SLIGHT CHANCE NORTHERN AREAS AND 30
PERCENT SOUTHERN SECTIONS A FEW MORE HOURS. MAY HAVE TO UPDATE AGAIN
TO TAKE RAIN CHANCE OUT FOR THE REMAINDER OF THE NIGHT.

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

TD
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AFTERNOON FORECAST DISCUSSION
300 PM EDT SUN AUG 18 2002

THUNDERSTORMS/SHOWERS POPPING OVER MIDDLE TN TO CUMBERLAND PLATEAU.
CONSOLIDATING INTO A SOLID LINE AT LEADING EDGE. TODAYS POPS GOOD.
THESE WILL MOVE THROUGH THE ENTIRE CWA FROM WEST TO EAST AND DROP
MUCH NEEDED RAIN ON MOST PLACES. EXACT TOTALS UP IN THE AIR.

WE STILL SIT AHEAD OF THE WEAKENING FRONT TO THE NORTHWEST. MODELS
WEAKEN FRONT STILL FURTHER UNTIL ITS A SHADOW OF ITS FORMER SELF
BY ITS ARRIVAL MONDAY NIGHT. IT WILL SWEEP THROUGH THE REGION
KEEPING A CHANCE FOR CONVECTION THROUGH MONDAY NIGHT. HAVE REMOVED
ALL MENTION OF PRECIP FOR TUESDAY THROUGH THURSDAY DUE TO DEEP
DRYING AND BUILDING OF RIDGE (REMOVAL OF UPPER SUPPORT). NOT TO
SAY THAT AN ISOLATED SHOWER WONT FIRE SOMEWHERE IN THE SUNSHINE, SO
LEFT 10 POP IN REVISED DIGITAL FORECAST.

TEMPS AND WINDS LOOK BUT DID TWEAK WIND DIRECTIONS A BIT TO ACCOUNT
FOR SLIGHT WIND SHIFT WHEN FRONT MEANDERS ACROSS REGION. DONT
BELIEVE FOG WILL WARRANT PLACEMENT IN FORECAST.

LATER ON IN EXTENDED...ANOTHER FRONT COMES ON FRIDAY-SATURDAY.
MODELS DEPICT IT MORE STRONGLY THAN THIS ONE. HOWEVER...IT MIGHT
BECOME WEAKER AS THE WEEK PROGRESSES. STILL...PUT SLIGHT CHANCE
IN FRIDAY AND CHANCE ON SATURDAY. BACK TO PARTLY CLOUDY SUNDAY,
WHICH WAS A LITTLE DIFFICULT TO DECIDE, BUT SO FAR OUT AND WITH THE
MOISTURE AND DYNAMICS A LITTLE SO-SO WENT WITH CONSERVATIVE WORDING.

FOLLOWING FORECAST ARE PRELIMINARY:

CHA   71  91  69  90 /  30  30  30  10
TYS   69  89  67  89 /  30  30  30  10
TRI   66  86  64  87 /  30  30  30  10
OQT   69  88  67  88 /  30  30  30  10

BB

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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.

BB

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