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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS64 KMRX 032003
AFDMRX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
305 PM EST TUE DEC 3 2013

.SHORT TERM (TONIGHT AND WEDNESDAY)...
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ANOTHER MOSTLY CLOUDY DAY OVER
THE FORECAST AREA TODAY. PERSISTENT LOW LEVEL SOUTHEAST FLOW OVER
THE PLATEAU COUNTIES...SOUTHEAST TENNESSEE AND SOUTHWEST NORTH
CAROLINA AND SOUTHWEST FLOW ALOFT KEPT SKIES CLOUDY AND TEMPERATURES
ONLY IN THE LOWER TO MID 50S. FARTHER NORTH A BREAK IN THE CLOUDS
FROM LATE MORNING THROUGH EARLY AFTERNOON IN NORTHEAST SECTIONS
ALLOWED TEMPERATURES TO REACH TO THE UPPER 50S TO LOWER 60S. CLOUDS
WERE MOVING BACK INTO NORTHEAST SECTIONS AS WEAK SHORTWAVE IS MOVING
INTO THAT REGION LATE THIS AFTERNOON AND EARLY EVENING. LIFT IS WEAK
SO DO NOT EXPECT ANY RAIN. FOR TONIGHT AND EARLY WEDNESDAY WITH LOW
LEVEL SOUTHEAST FLOW AND ALREADY SATURATED ATMOSPHERE AND WEAK
SHORTWAVE ENERGY MOVING THROUGH BEST CHANCE OF RAIN OR DRIZZLE
ALTHOUGH SLIGHT WILL BE ACROSS SE TN AND SW NC. A WEAK WARM FRONT
WILL MOVE NORTH OVERNIGHT AND EARLY WEDNESDAY AS LOW PRESSURE
DEVELOPS OUT AHEAD OF DISTINCT ARCTIC FRONT OVER THE WESTERN STATES.
PATCHY FOG WILL FORM AS WELL ESPECIALLY SOUTH...AND LOCALLY DENSE.

THE HIGH PRESSURE RIDGE TO THE EAST WILL STRENGTHEN AND BRING WARMER
AIR NORTH WEDNESDAY. TEMPERATURES WILL CHANGE LITTLE OVERNIGHT IN
THE SOUTH NEAR WARM FRONT. LOWS NEAR 50 SOUTH AND MID TO UPPER 40S
ELSEWHERE. EXPECT SOME CLEARING AGAIN NORTHEAST HALF WEDNESDAY LIKE
TODAY BUT MOSTLY CLOUDY SOUTH. HIGHS SHOULD REACH THE MID 60S TO
NEAR 70 SOME 10 TO 15 DEGREES ABOVE NORMAL AND ABOVE TODAY AS A
STRONGER SOUTHWEST FLOW DEVELOPS BEHIND THE WARM FRONT AND AS
PRESSURE GRADIENT TIGHTENS AHEAD OF LOWER PRESSURE IN THE PLAINS
STATES.

.LONG TERM (WEDNESDAY NIGHT THROUGH TUESDAY)...MODELS ARE IN GOOD
AGREEMENT WITH THE SYNOPTIC-SCALE PATTERN THROUGHOUT THE EXTENDED
PERIOD...AND REVEAL A DEEP AND PERSISTENT SOUTHWESTERLY WIND FLOW
DEVELOPING OVER THE TN RIVER VALLEY BY THURSDAY AND LINGERING
THROUGH EARLY NEXT WEEK. IN FACT...IT APPEARS THIS SOUTHWESTERLY
FLOW WILL EMANATE FROM THE EASTERN PACIFIC OCEAN...RESULTING IN A
DEEPER MOISTURE FETCH WHICH COULD CREATE MORE RAIN THAN THE MODELS
CURRENTLY SUGGEST. THIS UPPER-LEVEL SOUTHWESTERLY FLOW WILL BECOME
PARALLEL TO A SLOW-MOVING ARCTIC COLD FRONT OVER THE TN RIVER
VALLEY...SO IT APPEARS THAT A PROLONGED RAINFALL EVENT WILL DEVELOP
FOR SEVERAL DAYS OVER THE FORECAST AREA FROM THURSDAY THROUGH MONDAY
NIGHT. RIGHT NOW...WIDESPREAD RAINFALL TOTALS OF TWO TO FIVE INCHES
APPEAR POSSIBLE BY MONDAY NIGHT...ESPECIALLY ALONG THE CUMBERLAND
PLATEAU AND SOUTHEAST TENNESSEE. WHILE IT APPEARS THAT FLASH
FLOODING FROM THUNDERSTORMS WILL NOT BE A PROBLEM...THE PROLONGED
NATURE OF THIS RAINFALL WILL LIKELY EVENTUALLY LEAD TO WIDESPREAD
FLOODING OF RIVERS AND STREAMS (AND OTHER LOW LYING AND FLOOD PRONE
AREAS).

ON THURSDAY...MODELS INDICATE SOME MARGINAL INSTABILITY DEVELOPING
OVER THE FORECAST AREA AHEAD OF THE APPROACHING COLD FRONT...WITH A
FAIRLY STRONG VEERING WIND PROFILE ALSO EXPECTED. THUS...IT APPEARS
THAT A FEW STRONG TO SEVERE STORMS WILL BE POSSIBLE ON THURSDAY
AFTERNOON AND EVENING...WITH DAMAGING WINDS AND LARGE HAIL BEING THE
MAIN THREATS.

MODELS STILL INDICATE A TEMPORARY BREAK FROM THE RAIN ON SATURDAY...
AS COLDER AIR TEMPORARILY MOVES INTO THE FORECAST AREA. ECMWF MODEL
STILL INDICATES THE POSSIBILITY OF SOME SUB-FREEZING LOW-LEVEL AIR
MOVING ONTO THE CUMBERLAND PLATEAU AFTER MIDNIGHT FRIDAY NIGHT...
WHICH COULD CREATE SOME SLEET OR FREEZING RAIN WITH ICING CONCERNS.
THE LATEST GFS MODEL RUN STILL KEEPS THE CUMBERLAND PLATEAU ABOVE
FREEZING EARLY SATURDAY MORNING...SO WILL JUST MENTION RAIN FOR
FRIDAY NIGHT AND SATURDAY MORNING...BUT WILL MENTION THE POSSIBILITY
OF SLEET OR FREEZING RAIN IN THE HAZARDOUS WEATHER OUTLOOK. AS FOR
TEMPS...WILL GENERALLY TREND CLOSE TO THE GFS GUIDANCE NUMBERS
THROUGH FRIDAY NIGHT...BUT WILL THEN TREND COOLER THEREAFTER...WHICH
IS IN BETTER AGREEMENT WITH THE ENSEMBLE MEANS.
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&&

.PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN   52  68  59  71  55 /  20  20  40  70  90
KNOXVILLE AIRPORT, TN     48  67  57  70  54 /  20  20  40  60  90
OAK RIDGE, TN             47  66  58  70  52 /  10  10  40  70  90
TRI CITIES AIRPORT, TN    41  65  53  68  53 /  10  10  40  60  90
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&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&

$$

TD/DMG