Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN

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FXUS64 KMRX 130908
AFDMRX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
408 AM EST SAT FEB 13 2016

.SHORT TERM...(TODAY AND TONIGHT)...COLD NORTHWEST FLOW WILL
CONTINUE INTO TODAY...BUT WILL GRADUALLY WEAKEN THIS AFTERNOON.
CLOUDS AND A FEW SNOW SHOWERS/FLURRIES WILL LINGER EARLY IN THE
PERIOD ESPECIALLY NORTH AND MOUNTAINS...AND WILL DIMINISH FROM
SOUTHWEST TO NORTHEAST DURING THE DAY.  HIGH/MID CLOUDS WILL
INCREASE OVERNIGHT AS MOISTURE BEGINS TO RETURN AGAIN WELL AHEAD OF
NEXT SYSTEM.  WIND CHILL ADVISORY STILL LOOKS GOOD AS IS...SO NO
CHANGES THERE AT THIS TIME.  MAV TEMPS GENERALLY LOOK
REASONABLE AND WILL STAY CLOSE.

.LONG TERM...(SUNDAY THROUGH FRIDAY)...MORE ACTIVE WEATHER IN STORE
DURING AT LEAST THE FIRST HALF OF THE EXTENDED PERIOD WITH SOME COLD
AIR IN PLACE ON SUNDAY AND AN ATMOSPHERE THAT WANTS TO GENERATE A
STRENGTHENING TROUGH PATTERN OVER THE CENTER OF THE NATION. AS WEAK
SHORT WAVE ENERGY SWINGS THROUGH THE LAKES/MIDWEST ON SUNDAY THE
RESPONSE WILL BE WINDS BECOMING SOUTHWESTERLY ALOFT. THIS WILL LEAD
TO PROBLEMS AS THE WARM AND MOISTENING FLOW RIDES ISENTROPICALLY
OVER THE LARGELY SUB-FREEZING AIRMASS ACROSS THE FORECAST AREA (THE
EXCEPTION BEING THE LOWER ELEVATIONS OF SOUTHEAST TENNESSEE). SO THE
LOW LEVELS WILL PROBABLY BE TOO COLD OVER MOST OF THE AREA WHEN THE
RISING...MILDER AIR BECOMES SATURATED AND FALLS TO THE SURFACE IN
THE FORM OF SNOW SUNDAY AFTERNOON THROUGH SUNDAY NIGHT. THROUGH THE
SUNDAY NIGHT INTO MONDAY MORNING PERIOD A SHORT WAVE SYSTEM WILL BE
DEEPENING OVER THE LOWER MISSISSIPPI VALLEY AND DRIVING EAST. THIS
IS THE OLD SCENARIO WHERE THE ATMOSPHERE WANTS TO WARM BECAUSE OF
THE STRENGTHENING SOUTHERLY FLOW AHEAD OF THE 85H AND SURFACE LOW
PRESSURE CENTERS WHICH APPEAR TO PASS DIRECTLY OVER THE FORECAST
AREA MONDAY NIGHT. THEREFORE IN THIS SCENARIO...SNOWFALL WOULD
ACCUMULATE LATE SUNDAY NIGHT THROUGH MONDAY MORNING OVER MUCH OF THE
FORECAST AREA WITH THE GREATEST IMPACT PERHAPS BEING ALONG THE I-40
CORRIDOR AND POINTS NORTH INTO SOUTHWEST VIRGINIA. OF COURSE STAYED
WITH THE BEST POSSIBILITY OF ACCUMULATING SNOW OVER THE CUMBERLAND
PLATEAU EAST NORTHEAST THROUGH NORTHEAST TENNESSEE AND SOUTHWEST
VIRGINIA WHERE SNOWFALL AMOUNTS COULD RANGE FROM TWO TO FOUR INCHES.
THE FORECAST GETS COMPLICATED WITH THE SNOW TO RAIN TRANSITION LATER
SUNDAY NIGHT INTO MONDAY WITH THE APPROACHING SURFACE LOW AS SNOW
MIXES WITH SLEET FOR A PERIOD BEFORE CHANGING ENTIRELY TO RAIN. THE
INITIAL SHORT WAVE MOVES AWAY TO THE EAST MONDAY NIGHT INTO TUESDAY
MORNING WHERE PRECIPITATION TYPE WILL BE DIFFICULT AGAIN AS SOME
COLDER AIR SPILLS INTO THE BACK SIDE OF THIS FEATURE CHANGING PRECIP
BACK INTO SNOW LEADING TO THE POSSIBILITY OF SOME LIGHT ACCUMULATION
ACROSS THE FORECAST AREA ONCE AGAIN. YET ANOTHER COMPACT LITTLE WAVE
IS DEPICTED BY THE MODELS TO RIP SOUTHEAST ACROSS THE SOUTHERN
APPALACHIANS TUESDAY AFTERNOON THROUGH TUESDAY NIGHT WITH
TEMPERATURE STRUCTURE KEEPING PRECIPITATION IN THE FORM OF LIGHT
RAIN DURING THE DAY WITH A LIKELY CHANGEOVER TO SNOW AT NIGHT AS
SOME CHILLY AIR BUILDS INTO THE BACK OF THIS UPPER TROUGH. KEPT SOME
LIGHT SNOW SHOWERS GOING WITH SMALL POPS ON WEDNESDAY...MAINLY IN
THE HIGHER TERRAIN AREAS ACROSS THE NORTHERN PART OF THE FORECAST
AREA AS NORTHWESTERLY WINDS GENERATE OROGRAPHIC SNOWFALL. FINALLY
WEDNESDAY NIGHT THROUGH FRIDAY DAYTIME PERIOD SHOULD BE DRY WITH A
MUCH WELCOMED WARMING TREND AS THE MORE ACTIVE STORM TRACK
THANKFULLY SHIFTS FARTHER NORTH ACROSS THE UPPER MIDWEST.


&&

.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN             34  21  40  35 /   0   0  20  60
KNOXVILLE MCGHEE TYSON AIRPORT, TN  30  18  34  31 /  10   0  30  70
OAK RIDGE, TN                       29  18  34  31 /   0   0  40  70
TRI CITIES AIRPORT, TN              25  13  30  26 /  10   0  30  70

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR BLOUNT SMOKY
     MOUNTAINS-COCKE SMOKY MOUNTAINS-JOHNSON-SEVIER SMOKY
     MOUNTAINS-SOUTHEAST CARTER-SOUTHEAST GREENE-SOUTHEAST
     MONROE-UNICOI.

VA...WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR RUSSELL-WASHINGTON-
     WISE.

&&

$$




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