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

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FXUS64 KMRX 251931
AFDMRX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
231 PM EST SUN JAN 25 2015

.SHORT TERM (TONIGHT AND TOMORROW)...THE LOW PRESSURE WILL
CONTINUE TO MOVE TOWARDS THE AREA THROUGH THE EVENING...PASSING
JUST TO THE NORTHERN CWA BORDER OVERNIGHT. WITH THE MOSTLY CLEAR
SKIES TODAY...TEMPS WERE BUMPED UP SEVERAL DEGREES...WHICH WILL
CAUSE A WARM START TO THIS SYSTEM MOVING IN. MID AND LOW LEVEL
MOISTURE WILL INCREASE THROUGH THE LATE AFTERNOON AND EVENING
ACROSS THE AREA...LOWERING CLOUDS AHEAD OF THE PRECIP. SCATTERED
RAIN SHOWERS ARE EXPECTED TO BEGIN ON THE PLATEAU AND MAKE THEIR
WAY EAST.

AS THE TEMPERATURES DROP BELOW FREEZING OVERNIGHT...THESE RAIN
SHOWERS ARE EXPECTED TO CHANGE TO SNOW SHOWERS. MODELS ARE IN
DECENTLY GOOD AGREEMENT THAT THE ATMOSPHERE WILL STAY FAIRLY MOIST
THROUGH THE MIDLEVELS UNTIL THE EARLY MORNING. HOWEVER...WITH THE
WARM TEMPERATURES TODAY...AND THE TIMING OF THE COLD AIR
ADVECTION...THE TEMPERATURES ARE NOT EXPECTED TO DROP BELOW FREEZING
UNTIL AFTER THE DRIER AIR MOVES IN. MODELS DIFFER ON TIMING OF THE
BELOW FREEZING TEMPERATURES...SO THERE IS STILL UNCERTAINTY WITH
EXACT SNOW AMOUNTS THROUGH MONDAY MID MORNING. WITH THE TREND THE
MODELS HAVE BEEN SHOWING...AND THE TEMPERATURE PROFILE THROUGH THE
NIGHT...HAVE SETTLED ON 1-3 INCHES IN THE MOUNTAINS...WITH UP TO 1
INCH IN SOUTHWEST VIRGINIA AND PLATEAU COUNTIES. OTHERWISE IN THE
VALLEY AND SOUTHWEST NORTH CAROLINA...TEMPERATURES LOOK TO BE TOO
WARM FOR MORE THAN FLURRIES OR A DUSTING TO DEVELOP. DUE TO THESE
AMOUNTS...WILL GO WITH AN SPS FOR THE NORTHERN PLATEAU AND SOUTHWEST
VIRGINIA COUNTIES...WITH AN ADVISORY FOR THE HIGHER ELEVATIONS IN
EAST TENNESSEE.

TOMORROW...TEMPERATURES WILL WARM TO ABOVE FREEZING IN ALL AREAS
EXCEPT THE HIGHEST ELEVATIONS. NORTHWEST FLOW WILL SET UP...WITH
JUST ENOUGH MOISTURE TO WARRANT MORE SNOWFALL ACCUMULATION IN THE
HIGHER ELEVATIONS. OTHERWISE...SKIES WILL REMAIN OVERCAST THROUGH
THE EXTENDED AND TEMPERATURES WILL BE A COUPLE OF DEGREES ABOVE
NORMAL OVERNIGHT...AND AFTER THE COLD AIR FILTERS IN...TEMPERATURES
WILL BE SEVERAL DEGREES BELOW NORMAL TOMORROW.


.LONG TERM (MONDAY NIGHT THROUGH SUNDAY)...PROBABLY A BRIEF BREAK
IN PRECIPITATION INTO MONDAY EVENING...BEFORE AN UPSTREAM SHORTWAVE
AND A SURGE OF MOISTURE SWEEP ACROSS MONDAY NIGHT AND TUESDAY. I
OPTED TO BACK OFF ON THE QPF AND LIGHT SNOW AMOUNTS...GIVEN THE
LIMITED MOISTURE AND LACK OF SIGNIFICANT INSTABILITY DURING THE
DAYTIME HOURS TUESDAY. NOT REALLY LOOKING LIKE EVEN ADDITIONAL
AMOUNTS SUFFICIENT FOR A WINTER WEATHER ADVISORY FOR FAVORED HIGH
TERRAIN LOCATIONS.

DRY FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT BEFORE A LOW PRESSURE
SYSTEM TRACKS EAST ACROSS THE MID MISSISSIPPI AND OHIO VALLEY
REGIONS THURSDAY. KEPT CONTINUITY WITH PREVIOUS GRIDS FOR JUST
CHANCE POPS FOR OUR REGION IN LINE WITH THE LIGHTER QPF NOTED FROM
12Z GFS MODEL. THE LOW POPS INTO EARLY FRIDAY ARE FOR THE BACKSIDE
OF THIS EXITING LOW PRESSURE SYSTEM.

FOR SATURDAY THROUGH SUNDAY NIGHT...GFS AND ECMWF MODELS DIFFER A
GREAT DEAL WITH ONLY THE ECMWF SHOWING ANY PRECIPITATION CHANCES.
DAY 4 THROUGH DAY 7 MODEL BLEND AND NEIGHBORING NWS OFFICES CARRY 20
TO 30 PERCENT POPS FOR BOTH SATURDAY NIGHT AND SUNDAY...WHICH I
BLENDED WITH. OF COURSE...GIVEN THE TIME OF YEAR (WINTER) OUR
PRECIPITATION TYPES WILL BE BOTH RAIN AND SNOW.



&&

.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN             37  42  31  46 /  70  20  10  10
KNOXVILLE MCGHEE TYSON AIRPORT, TN  35  42  26  40 /  80  60  10  20
OAK RIDGE, TN                       34  41  29  41 /  80  50  20  20
TRI CITIES AIRPORT, TN              34  40  24  35 /  80  60  30  30

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST MONDAY
     FOR BLOUNT SMOKY MOUNTAINS-COCKE SMOKY MOUNTAINS-JOHNSON-
     NORTHWEST CARTER-SEVIER SMOKY MOUNTAINS-SOUTHEAST CARTER-
     SOUTHEAST GREENE-SOUTHEAST MONROE-UNICOI.

VA...NONE.
&&

$$

JW/TG


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