Severe Thunderstorm Warning 342, NWS Morristown, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
140 PM EDT SUN AUG 17 2003

THE FOLLOWING ARE THE FORECAST DISCUSSIONS FROM THE PAST 24 HOURS...
WITH THE MOST RECENT FIRST.  THIS PROVIDES A HISTORY OF THE
DEVELOPMENT OF THE CURRENT FORECAST.

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EARLY AFTERNOON FORECAST DISCUSSION (UPDATE)
140 PM EDT SUN AUG 17 2003

SENT OUT QUICK UPDATE TO INCLUDE SEVERE THUNDERSTORM WATCH NUMBER
865.

LCM

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MID MORNING FORECAST DISCUSSION (UPDATE)
1000 AM EDT SUN AUG 17 2003

FORECAST APPEARS TO BE GENERALLY ON TRACK. WILL UPDATE TO REMOVE
FOG/MORNING WORDING. OTHERWISE...NO OTHER CHANGES ARE WARRANTED AT
THIS TIME.

LCM

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EARLY MORNING FORECAST DISCUSSION
330 AM EDT SUN AUG 17 2003

FRONT STILL EXPECTED TO MOVE THROUGH THE AREA LATER TODAY AND THIS
EVENING...PROVIDING THE FOCUS FOR THUNDERSTORMS.  AN UPPER LEVEL
VORT WILL PASS OVERHEAD AS WELL...ADDING TO THE CHANCE FOR
PRECIPITATION.  PER SWODY1...A FEW STORMS COULD BE SEVERE WITH HAIL
TO 1 INCH AND STRAIGHT-LINE WINDS BEING THE MAIN THREAT.  MODELS IN
DECENT AGREEMENT ON TIMING OF FRONT...SWINGING IT THROUGH FROM 16Z
TO AROUND 00Z...NORTH TO SOUTH ACROSS THE CWA.  BEST CHANCE FOR POPS
IN THE MORNING TO EARLY AFTERNOON IN THE NORTH...WITH BEST POPS IN
THE LATE AFTERNOON TO EARLY EVENING IN THE SOUTH.  CHANCE FOR SQUALL
LINE ON FRONT...BUT ALL MODEL INDICATIONS NOW ARE FOR SCATTERED
CONVECTION AND HAVE KEPT POPS IN THE CHANCE CATEGORY.  WOULD NOT BE
TERRIBLY SURPRISED TO SEE COVERAGE A LITTLE BETTER THAN PRESENT
FORECAST...BUT UNCERTAINTY LEVEL IS HIGH SO WENT WITH HIGH CHANCE
POPS.

STILL LOOKING FAIRLY DRY FOR MONDAY THROUGH WEDNESDAY...BUT KEPT
SOME SLIGHT CHANCE POPS IN THE SOUTH AND IN THE MTNS THROUGH MUCH OF
THE PERIOD DUE TO UPSLOPE IN THE MOUNTAINS AND PROXIMITY TO OLD
FRONT IN THE SOUTH.

CHA   92  71  92  68 /  40  40  20  20
TYS   88  69  88  65 /  40  20  10  10
TRI   84  63  85  60 /  50  20  10  10
OQT   88  68  88  65 /  40  20  10  10

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

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EVENING FORECAST DISCUSSION (UPDATED)
1000 PM EDT SAT AUG 16 2003

ISOLATED SHRA CONTINUE ACROSS FA LATE THIS EVENING. ATMOSPHERE
STABILIZING TO A CERTAIN DEGREE. HOWEVER...AIRMASS STILL QUITE MOIST
AND WITH S/WV FEATURE DROPPING S THRU CENTRAL APPALACHIANS MAY BE
ABLE TO SQUEEZE OUT A -SHRA OR POSSIBLY A TSRA TOWARD DAYBREAK
MAINLY ACROSS NRN PORTION OF FA. WILL NOT CHANGE SMALL/SLGT CHC POPS
FOR OVRNITE WITH THIS IN MIND. DO EXPECT SOME FOG FORMATION WITH
HIGH DEWPOINT AIRMASS AND EXPECT SOME OF THE FOG TO BECOME DENSE
ACROSS SW VA/NE TN AND PARTS OF CENTRAL EAST TENNESSEE WHERE SLOW
MOVING STORMS DUMPED RAINFALL AMOUNTS AROUND A HALF TO ONE INCH IN
SPOTS. THEREFORE...WILL UPDATE TO ADD PATCH DENSE FOG THESE ZONES.

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

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AFTERNOON FORECAST DISCUSSION
300 PM EDT SAT AUG 16 2003

TONIGHT AND TOMORROW...UPPER LEVEL VORT CONTINUES TO MOVE AWAY FROM
THE FORECAST AREA. HOWEVER...SCATTERED CONVECTION CONTINUES TO
DEVELOP IN ITS WAKE AS DAYTIME SURFACE HEATING APPROACHES MAXIMUM.
EXPECT THIS ACTIVITY WILL TEND TO WANE BY LATE AFTERNOON/EARLY
EVENING AS SUBSIDENCE INVERSION AND MID LEVEL WARMING SUCCEED THE
UPPER LEVEL DISTURBANCE. AM INCLINED TO KEEP FIRST PERIOD DRY...BUT
WILL BASE FINAL DECISION ON TRENDS AT TIME OF ZONE ISSUANCE. NEXT IN
A SERIES OF SHORT WAVES AND ITS ASSOCIATED SURFACE BOUNDARY WILL
APPROACH FROM THE NORTH IN THE SECOND PERIOD. THERE IS SOME
DISAGREEMENT ON THE AMOUNT OF MOISTURE AVAILABLE WITH THIS FEATURE.
TEND TO FAVOR THE CONSENSUS LESS MOISTURE AVAILABILITY AS PROJECTED
BY THE GFS...NGM AND SHORT RANGE ENSEMBLES. THUS WILL GO WITH ONLY
CHANCE POPS IN THE SECOND PERIOD RATHER THAN THE LIKELY POPS
SUGGESTED BY ETA. ALSO TENDED TO FAVOR GFS GUIDANCE TEMPS WITH ONLY
THE SCATTERED PRECIP COVERAGE EXPECTED.

LONGER TERM...WEAK BOUNDARY...HARD TO CALL IT A COLD FRONT...FORECAST
BY THE MODELS TO BE SOUTH OF THE AREA BY MONDAY MORNING.  MODELS ALSO
IN DECENT AGREEMENT IN SHOWING SIGNIFICANT DEEP LEVEL DRYING
MONDAY...BUT APPEARS SOME LOW LEVEL MOISTURE TO LINGER.  WILL
GO WITH CHANCE TO SLIGHT CHANCE POPS EARLY SUNDAY NIGHT...THEN SLIGHT
CHANCE MONDAY AFTERNOON.  FOR NOW WILL KEEP POPS CONFINED TO VA AND
MOUNTAINS TUESDAY AND WEDNESDAY...BUT CONFIDENCE NOT HIGH THAT IT
WILL STAY COMPLETELY DRY ELSEWHERE. GRADUAL MOISTENING OF ATMOSPHERE
EXPECTED FOR THE REMAINDER OF THE WEEK. WILL HAVE SLIGHT CHANCE ALL
ZONES BY THURSDAY...THEN CHANCE NEXT FRIDAY AND SATURDAY AS NEXT WEAK
FRONT MAY AFFECT THE AREA.  NO MAJOR ARGUMENTS WITH GUIDANCE TEMPS...
SO WILL STICK CLOSE.

PRELIMINARY NUMBERS FOLLOW:
CHA   71  91  70  91 /  20  30  30  20
TYS   70  86  69  88 /  30  30  20  10
TRI   67  83  64  85 /  30  30  20  10
OQT   70  85  68  89 /  30  30  20  10

NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-005-
006-008-181000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MORRISTOWN TN
600 AM EDT SUN AUG 17 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST TENNESSEE...SOUTHWEST
VIRGINIA AND EXTREME SOUTHWEST NORTH CAROLINA.

.DAY ONE (TODAY AND TONIGHT)...

A VERY MOIST AIRMASS REMAINS IS PLACE ACROSS THE REGION.
TEMPERATURES WILL WARM INTO THE MID 80S TO THE LOWER 90S. THE
ATMOSPHERE WILL BECOME INCREASINGLY UNSTABLE BY THIS AFTERNOON.
AN UPPER LEVEL TROUGH WILL PUSH A COLD FRONT INTO THE AREA FROM THE
NORTH THIS AFTERNOON. THESE FEATURES WILL AID IN THE DEVELOPMENT OF
STORMS.

SHOWERS AND STORMS WILL BE SCATTERED ACROSS THE AREA BOTH TODAY AND
TONIGHT.  SOME ISOLATED SEVERE WEATHER IS POSSIBLE...IN THE FORM OF
DAMAGING STRAIGHT-LINE WINDS AND TO A LESS EXTEND...LARGE HAIL.

THE MAIN THREAT FROM THESE STORMS WILL BE FLOODING.  STORMS WILL BE
SLOW-MOVING...AND WITH SUCH A HUMID ATMOSPHERE...HEAVY RAIN IS
LIKELY.

.DAYS TWO THROUGH SEVEN (SUNDAY THROUGH FRIDAY)...

MONDAY THROUGH SATURDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS
TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.

STAY TUNED TO NOAA WEATHER RADIO OR VISIT OUR WEBSITE AT
WWW.SRH.NOAA.GOV/MRX.

SON