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

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
972
FXUS64 KMRX 041912
AFDMRX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
312 PM EDT WED MAY 4 2016

.SHORT TERM /TONIGHT AND THURSDAY/...
A SHARP COLD FRONT IS QUICKLY MOVING THROUGH SOUTHERN KENTUCKY AND
NORTHERN MIDDLE TENNESSEE...AND TRACKING TOWARD THE PLATEAU...
EASTERN TENNESSEE VALLEY AND THE SOUTHERN APPALACHIANS.
ALONG/AHEAD OF THE FRONT...A LINE OF SHOWERS AND EMBEDDED
THUNDERSTORMS CONTINUES TO PROGRESS TOWARD THE AREA AS
WELL...MAKING INTO THE PLATEAU BETWEEN 19-20Z...AND SPREADING
ACROSS THE MRX CWA BETWEEN 21-03Z. GIVEN THE VERY STEEP LAPSE RATES
IN PLACE /7 TO 7.5 DEG C PER KM/...AND THE COLD AIR ALOFT...SOME
SMALL HAIL IS LIKELY TO ACCOMPANY THIS ACTIVITY...ALONG WITH SOME
BREEZY TO GUSTY GRADIENT WNW WINDS.

AFTER SUNSET...COLD AIR ADVECTION WILL TAKE PLACE IN WAKE OF THE
INITIAL FRONTAL PASSAGE AS THE UPPER-PARENT LOW ROTATES SOUTH INTO
THE SOUTHERN APPALACHIANS. THE HEIGHT OF THE MELTING LEVEL WILL
DROP TO AROUND 4000-4500 FEET OVERNIGHT...TRANSITIONING ANY
LINGERING SHOWERS ALONG THE SMOKY MOUNTAINS TO SNOW LATER TONIGHT.
IT IS NOT OUT OF THE REALM OF POSSIBILITY FOR SOME 1 TO 2 INCH
SNOWFALL TO OCCUR AT THE VERY TOP OF THE MOUNTAINS /ABOVE 5000
FEET/...SO HAVE A SPECIAL WEATHER STATEMENT TO ACCOUNT FOR THIS
VERY LOCALIZED TERRAIN DRIVEN SNOWFALL.

A BREAK IN THE PRECIPITATION SHOULD OCCUR LATE TONIGHT INTO
THURSDAY MORNING. THEN...ANOTHER ROUND OF LIGHT SHOWERS AND DENSE
CLOUD COVER WILL MOVE IN...THANKS TO ANOTHER SHORTWAVE LOBE OF COLD
AIR...ROTATING INTO THE REGION. THIS ACTIVITY WILL BE FAIRLY
LIGHT...BUT THE PRECIPITATION...COLD AIR ADVECTION AND THE CLOUD
COVER WILL KEEP HIGHS 15 TO 25 DEGREES BELOW NORMAL IN THE 55 TO 60
DEGREE RANGE.

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
EASTERN U.S. UPPER LOW SHIFTS VERY SLOWLY EAST FROM THE SOUTHERN
APPALACHIANS TO THE MIDDLE ATLANTIC COAST AT THE START OF THE
EXTENDED PERIOD TO A POSITION OVER THE MIDDLE ATLANTIC COAST BY
SATURDAY MORNING. STILL A FAIR AMOUNT OF MOISTURE AND SOME SHORT
WAVE LIFT IN A SLIGHTLY UNSTABLE ENVIRONMENT THROUGH THIS EARLY
PART OF THE FORECAST FOR A FEW MORE SHOWERS AND SOME
THUNDERSTORMS...MAINLY ACROSS SOUTHWEST VIRGINIA AND NORTHEAST
TENNESSEE. THE CHANCE FOR A SHOWER OR THUNDERSTORM GRADUALLY
INCREASES FROM NORTHERN SECTIONS INCLUDING SOUTHWEST VIRGINIA AND
NORTHEAST TENNESSEE THROUGH CENTRAL EAST TENNESSEE SATURDAY INTO
SUNDAY AS A SHORT WAVE DRIVES SOUTHEAST FROM THE GREAT LAKES ACROSS
THE NORTHEASTERN STATES. A COOL FRONTAL BOUNDARY WILL SLIP FARTHER
SOUTH INTO THE FORECAST AREA SATURDAY NIGHT INTO SUNDAY REQUIRING
THE ADJUSTMENT TO MEDIUM CHANCE POPS. THIS BOUNDARY PRESSES BACK TO
THE NORTH OF THE FORECAST AREA SUNDAY NIGHT INTO MONDAY AS ANOTHER
UPPER TROUGH AMPLIFIES OVER THE MIDDLE OF THE NATION. THERE SHOULD
BE A RELATIVE MIN IN PROBABILITY OF PRECIP SUNDAY NIGHT INTO MONDAY
NIGHT. HOWEVER...THE AMPLIFIED TROUGH MOVES THROUGH THE MISSISSIPPI
VALLEY TUESDAY INTO WEDNESDAY DRIVING ANOTHER SURFACE FRONTAL
SYSTEM THROUGH THE MID SOUTH. THE CHANCE FOR CONVECTION WILL RAMP
UP AHEAD OF THIS BOUNDARY WITH THE HIGHEST POPS ON WEDNESDAY AS THE
SYSTEM COLD FRONT MOVES INTO THE FORECAST AREA.


&&

.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN             46  62  49  72 /  50  20  10   0
KNOXVILLE MCGHEE TYSON AIRPORT, TN  44  57  47  68 /  80  50  30  20
OAK RIDGE, TN                       44  58  47  69 /  80  50  30  10
TRI CITIES AIRPORT, TN              42  55  45  61 /  90  70  60  30

&&

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

$$

AMP/TH



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.