National Weather Service Weather Forecast Office

Area Forecast Discussion

234
FXUS64 KMRX 032027
AFDMRX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
327 PM EST SUN MAR 3 2013

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT)...AS UPPER TROUGH
ACROSS THE NORTHEAST MOVES EAST...THEN LOW-CLOUDS AND FLURRIES WILL
DISSIPATE THIS EVENING/TONIGHT ACROSS THE FORECAST AREA. FOR MONDAY...
RIDGING WILL DOMINATE BOTH SURFACE AND ALOFT...BUT PLENTY OF HIGH
AND MID-LEVEL CLOUDS WILL SPILL OVER THE RIDGE INCREASING CLOUDS
ONCE AGAIN. FOR MONDAY NIGHT...A STRONG UPPER TROUGH WILL MOVE
SOUTHEAST ACROSS THE PLAINS STATES WILL DEEPENING SURFACE LOW
HEADING SOUTHEAST TOWARD THE TENNESSEE VALLEY. INCREASING SOUTHERLY
WINDS WILL PRODUCE ISENTROPIC LIFT OVER THE TENNESSEE VALLEY. RAIN
WILL SPREAD INTO THE REGION WITH HIGHEST POPS OVER THE PLATEAU AND
SOUTHEAST TENNESSEE.

FOR TUESDAY...STRONG UPPER TROUGH WILL MOVE INTO THE MID-
MISSISSIPPI RIVER VALLEY WITH UPPER JET DIVING INTO THE NORTHERN
GULF COAST STATES. THE JET WILL PLACE THE FORECAST AREA UNDER THE
FAVORED RIGHT EXIT REGION OF THE JET. THE CIRCULATION AROUND THE
JET WILL ENHANCE THE FRONTO-GENETIC FORCING WITH THE INCOMING
FRONTAL BOUNDARY. ECMWF/GFS SHOW STRONG FRONTO-GENETIC FORCING OVER
THE AREA DURING THE AFTERNOON. SINCE THE UPPER TROUGH HAS DEEP COLD
AIR WITH 500MB TEMPERATURES BELOW -30 DEGREES CELCIUS...LAPSE RATES
WILL STEEPEN WITH CAPES ALONG AND AHEAD OF FROPA TO WARRANT A
CHANCE OF THUNDERSTORMS.

FOR TUESDAY NIGHT AND WEDNESDAY...STRONG COLD AIR ADVECTION ALOFT
ASSOCIATED WITH THE PASSAGE OF THE UPPER LOW OVER THE FORECAST AREA
WILL CONTINUE TO STEEPEN THE LAPSE RATES. CAPES OF 100-150 J/KG
WILL PRODUCE WIDESPREAD SHOWER ACTIVITY TUESDAY NIGHT DIMINISHING
SLOWLY WEDNESDAY. FORECAST SOUNDINGS SHOW PRECIPITATION WILL
QUICKLY CHANGED TO SNOW SHOWERS TUESDAY EVENING. ALONG WITH THE
INSTABILITY...INCREASING NORTHWEST BOUNDARLY LAYER FLOW WILL
PRODUCE GOOD OROGRAPHIC/NORTHWEST FLOW SNOWFALL INTO THE MOUNTAINS
FOR TUESDAY NIGHT...THEN DIMINISHING WEDENSDAY NIGHT.

HEAVY SNOW ACCUMULATIONS ARE POSSIBLE FOR THE FAR EASTERN TENNESSEE
MOUNTAINS AND HIGHER ELEVATIONS OF SOUTHWEST VIRGINIA...SUCH AS
HIGH KNOB. A WINTER STORM WATCH MAY BE NEEDED FOR THESE AREAS.
WIDESPREAD SNOW SHOWER ACTIVITY TUESDAY AND WEDNESDAY MAY ALSO
PRODUCE LIGHT SNOW ACCUMULATIONS FOR THE PLATEAU...SOUTHWEST NORTH
CAROLINA MOUNTAINS AND PARTS OF NORTHERN AND CENTRAL TENNESSEE
VALLEY.

FOLLOWED GFS MOS NUMBERS THROUGH TUESDAY...BUT UNDERCUT DUE TO THE
CLOUDS AND PRECIPITATION ON WEDNESDAY.

.LONG TERM (THURSDAY THROUGH SUNDAY)...A FAIRLY BENIGN PERIOD WITH
NICE SPRING WARMTH TO MAKE UP FOR ALL OF THE RECENT COLD. I WILL TRY
TO HEDGE A BIT HIGHER ON MAX TEMPS LATE NEXT WEEK THAN THE 00Z MEX
AND ENSEMBLE MEAN GUIDANCE GAVE...TIPPING THE HAT IN THE DIRECTION
TOWARD THE WARMEST ENSEMBLE MEMBERS. THE ECMWF IS MORE CONSISTENT
WITH ITS SOLUTION OF A SLOWER AND DEEPER ROCKIES TROUGH LATE IN THE
PERIOD THAT WILL HELP US WARM A LITTLE MORE THAN THE 00Z EXTENDED
GFS AND ENSEMBLE MOS WAS THINKING...AND THUS I WOULD EXPECT US TO
REMAIN DRIER A LITTLE LONGER THAN GFS WANTS TOO. NO PRECIP MENTIONED
THROUGH THE PERIOD.

LOOKING AHEAD...THE GFS RUNS ARE A LITTLE BOUNCY WITH THE DAY 8-9
FORECAST...WHILE THE ECMWF IS MORE CONSISTENT WITH A FAIRLY
SIGNIFICANT TROUGH SWEEPING THROUGH THE AREA MONDAY NIGHT OR TUESDAY
MORNING. GIVEN THE WARMTH AHEAD OF IT TO WORK WITH...THE BIRD`S EYE
VIEW MIGHT EXPECT A CONVECTIVE EVENT DURING THAT TROUGH PASSAGE.
PROBABLY A QUICK RESUMPTION OF SPRING TIME TEMPS THE NEXT DAY
FOLLOWING THE TROUGH PASSAGE.

&&

.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN             27  55  43  59  33 /   0  10  60  90  40
KNOXVILLE MCGHEE TYSON AIRPORT, TN  24  49  39  56  31 /   0  10  60 100  70
OAK RIDGE, TN                       24  49  39  56  31 /   0  10  70 100  60
TRI CITIES AIRPORT, TN              19  47  33  56  30 /   0  10  40 100  80

&&

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

&&

$$