Flooding in Tennessee, February 21 to 23, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
1000 AM EST FRI FEB 21 2003

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 EST FRI FEB 21 2003

FORECAST FOR TODAY GENERALLY APPEARS TO BE ON TRACK. RADAR SHOWS
LIGHT PRECIP HAS OVERSPREAD VIRTUALLY THE ENTIRE FORECAST AREA...
WHICH JUSTIFIES THE CATEGORICAL POPS IN THE CURRENT FORECAST PACKAGE.
TEMPS LOOK REASONABLE. NO UPDATE WARRANTED AT THIS TIME.

LCM

********************************************************************
MORNING FORECAST DISCUSSION
415 AM EST FRI FEB 21 2003

BUSY SHIFT SO FAR TONIGHT AS WE AWAIT THE COMING OF THE NEXT
RAINMAKER...FLASH FLOOD WATCH WAS ISSUED FOR MOST OF THE WESTERN
PORTIONS OF THE CWA AS FLOODING GUIDANCE SHOULD BE MET IN THOSE
COUNTIES IF THE FORECASTED RAINFALL AMOUNTS FALL BY SAT AFTN.

SYSTEM IS PULLING OUT OF THE SOUTHERN PLAINS AND PLENTY OF RAINFALL
AHEAD OF THE LOW AS IT TAPS INTO THE GULF OF MEXICO. STRONG WAA WILL
ALLOW DEW POINTS TO CLIMB BY SAT AND ALLOW FOR THE POSSIBILITY OF
SOME STRONG THUNDERSTORMS ACROSS THE TENNESSEE VALLEY...DROPPING
EVEN MORE RAIN. QPF TOTALS FROM THE MODELS RANGE FROM 1 TO 4 INCHES
ACROSS THE TN VALLEY...DOWNSLOPING WINDS FROM THE SOUTHERLY FLOW MAY
HELP TO SOMEWHAT DISRUPT THE LARGER AMOUNTS OF RAINFALL ALONG THE
SOUTHERN APPALACHIANS IN TENNESSEE AND VIRGINIA.

SYSTEM WILL MOVE OUT SUNDAY WITH MUCH COLDER TEMPS AND SOME SNOW
FLAKES MIXED WITH THE RAIN SHOWERS. ANOTHER SHORT WAVE MOVES THROUGH
MONDAY REINFORCING THE COLDER AIR THROUGH MID WEEK.

MODELS SEEM TO HAVE A GOOD GRASP OF THE SHORT TERM WITH LITTLE
DIFFERENCES...THEY HAVE JUMPED THE LOW CENTER TRACK SOME FROM RUN TO
RUN...THIS WILL BE CRUCIAL FOR DETERMINATION OF THE HEAVIEST
RAINFALL AREAS AND POSSIBLE HEAVIER THUNDERSTORMS.

CHA   57  53  63  35 / 100 100  90  40
TYS   53  50  61  36 /  90 100  90  50
TRI   52  49  60  35 /  90 100  90  50
OQT   53  50  61  36 /  90 100  90  50

.MRX...
NC...NONE.
TN...FLASH FLOOD WATCH FOR THIS AFTERNOON THROUGH SATURDAY AFTERNOON
FOR ZONES TNZ012>014...TNZ035>037...TNZ067>069...TNZ081>084...
TNZ098>099.

VA...NONE.

BS
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EVENING FORECAST DISCUSSION (UPDATE)
925 PM EST THU FEB 20 2003

COVERAGE OF LIGHT RAIN HAS NOT BEEN VERY IMPRESSIVE...EXCEPT FOR SW
VA AND NE TN AREAS EARLY THIS EVENING...AND THAT RAIN HAS BEEN
DECREASING.  THERE ARE AREAS OF LOW CLOUDINESS AND PATCHY DRIZZLE
...BUT THREAT OF MEASURABLE RAIN FOR REST OF TONIGHT SEEMS TO HAVE
DIMINISHED.  THE LATEST RUC MODEL RUN DOES SPREAD SOME LIGHT RAIN
INTO THE PLATEAU AND SE TN BY 09-12Z...AND 18Z MESO-ETA IS SIMILAR.
MAY BE ABLE TO LOWER POPS BACK TO CHANCE IN A FEW MORE AREAS...BUT
LEAVE PLATEAU AND SE TN GROUPS AT LIKELY...BUT WORD AS MAINLY LATE.

WILL ATTEMPT TO GET ZFP UPDATED BEFORE 10 PM EST...THEN WILL FRESHEN
UP GRIDS AND WEB PRODUCTS AS WELL.  JURY STILL OUT ON THIS WEEKENDS
RAINS...BUT HOPEFULLY 12Z MODELS RUNS WILL VERIFY WITH THE HEAVIER
RAINS TO OUR WEST AND SOUTH.

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

TG

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AFTERNOON FORECAST DISCUSSION
305 PM EST THU FEB 20 2003

MAIN ISSUES THIS FORECAST CYCLE REVOLVE AROUND POPS THROUGH THE
SHORT TERM AND SIGNIFICANCE OF LATE FRIDAY/EARLY SATURDAY EVENT.

SURFACE ANALYSIS SUGGESTS BOUNDARY HAS SLID DOWN TO OUR SOUTHERN
FORECAST AREA AT THIS TIME. WAVES ALONG THIS SURFACE BOUNDARY
CONTINUE TO GENERATE INTERMITTENT AREAS OF LIGHT PRECIP. THIS
BOUNDARY IS PROJECTED TO PULL BACK TO THE NORTH AS AN UPPER LEVEL
TROUGH APPROACHES FROM THE WEST ON FRIDAY. THIS WILL GENERALLY PUT
OUR FORECAST AREA IN THE WARM SECTOR BY FRIDAY AFTERNOON.

MODELS CONTINUE TO TREND TOWARD A FARTHER WEST SOLUTION OF THE
FRIDAY/SATURDAY SYSTEM...KEEPING THE SOUTHERN APPALACHIANS IN THE
WARM SECTOR THROUGH MUCH OF THIS EVENT. COLD FRONT WILL MOVE THROUGH
THE AREA BY MID-DAY SATURDAY. GIVEN THE RELATIVELY WARM TEMPS
EXPECTED IN THIS WARM SECTOR...WOULD EXPECT SOME THUNDER ASSOCIATED
WITH THE COLD FRONTAL PASSAGE. IT APPEARS INSTABILITY WILL BE
MARGINAL BUT DYNAMICS WILL BE RELATIVELY STRONG AT THE TIME OF THE
FRONTAL PASSAGE. MODELS ARE NOT IN COMPLETE AGREEMENT ON RAINFALL
AMOUNTS AT THIS TIME...WITH ETA PROJECTING QPFS GENERALLY LESS THAN
AN INCH...THE GFS UP TO TWO INCHES...AND THE CANADIAN ABOUT 25 MM
(ROUGHLY ONE INCH). WILL NEED TO CONTINUE TO MONITOR THIS EVENT
CLOSELY.

MAV TEMPS AGAIN LOOK MOST REASONABLE THIS RUN FOR THE MOST PART...
WILL GENERALLY STAY CLOSE.

CHA   47  56  52  62 /  70  80 100  80
TYS   46  54  50  62 /  60  80 100  80
TRI   43  52  47  61 /  50  80 100  80
OQT   45  54  50  62 /  60  80 100  80

LCM

NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-005-
006-008-212200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MORRISTOWN TN
417 AM EST FRI FEB 21 2003

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

.DAY ONE (TODAY)...
A DEVELOPING LOW PRESSURE SYSTEM WILL MOVE NORTHEAST FROM THE
NORTHWEST GULF OF MEXICO TO THE MID TENNESSEE VALLEY BY EARLY
SATURDAY. A FLOOD WATCH IS IN EFFECT FOR PORTIONS OF EAST TENNESSEE
NEAR AND ACROSS THE CUMBERLAND PLATEAU. RAINFALL AMOUNTS TODAY ARE
EXPECTED TO BE RELATIVELY LIGHT. TONIGHT AS A WARM FRONT MOVES NORTH
THROUGH THE AREA IN ADVANCE OF THE APPROACHING LOW PRESSURE SYSTEM
...MODERATE RAINFALL WILL BECOME WIDESPREAD. IN ADDITION...STRONG
SHOWERS...CAPABLE OF PRODUCING HEAVY DOWNPOURS WILL BE EMBEDDED IN
THE RAIN AREA. THUNDERSTORMS DEVELOPMENT IS ALSO LIKELY THROUGH
THE OVERNIGHT. SOME OF THESE STORMS MAY BECOME SEVERE WITH THE MAIN
THREAT BEING WIND GUSTS IN EXCESS OF 60 MPH. SOUTHERLY WINDS WILL
ALSO BE ON THE INCREASE LATER TONIGHT AND A WIND ADVISORY IS LIKELY
ACROSS HIGHER ELEVATIONS.

HAZARDOUS WEATHER IS POSSIBLE AT THIS TIME.

.DAYS TWO THROUGH SEVEN...
FLOODING IS LIKELY TO CONTINUE THROUGH SATURDAY. A SLIGHT TO MODERATE
SEVERE THUNDERSTORM RISK WILL CONTINUE MAINLY EARLY SATURDAY. AN
ISOLATED TORNADO IS POSSIBLE MAINLY ACROSS SOUTHEAST TENNESSEE.

HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL BE LIKELY OVERNIGHT AND EARLY SATURDAY.

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