893
FXUS64 KMRX 192006
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
306 PM EST TUE NOV 19 2019
SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
A 115 KNOT JET WILL MOVE ACROSS THE TENNESSEE VALLEY THIS EVENING
THROUGH EARLY WEDNESDAY MORNING. THIS JET WILL INCREASE THE
DYNAMIC FORCING ACROSS THE AREA BETWEEN 00-06Z WITH A LOW-LEVEL
JET BECOMING MORE SOUTHWESTERLY. THIS SOUTHWEST LOW-LEVEL JET WILL
INCREASE THE ISENTROPIC LIFT OVER THE AREA AND BRIEFLY TIGHTENING
THE FRONTO-GENETIC FORCING. MAIN LIMITING FACTOR FOR PRECIPITATION
IS LIMITED MOISTURE ABOVE 600MB WITH PWS GENERALLY 0.50 INCH OR
LESS.
THERE MAY BE A BRIEF PERIOD OF WINTRY PRECIPITATION OVER THE
HIGHEST ELEVATIONS OF THE SMOKY MOUNTAINS WITH A DUSTING OF
ICE/SNOW POSSIBLE ABOVE 5KFT.
EXPECT SCATTERED SHOWERS DEVELOPING THIS EVENING WITH THE
PRECIPITATION MAINLY FROM INTERSTATE 40 NORTWARD. THE GREATEST
COVERAGE WILL BE ACROSS SOUTHWEST VIRGINIA AND NORTHEAST
TENNESSEE. AS SYSTEM MOVES EAST, MAIN FORCING WILL BE OROGRAPHIC
LIFT INTO THE NORTHWEST FACING SLOPES THROUGH MID-MORNING
WEDNESDAY.
CLOUD COVER WILL BE SLOW TO ERODE OVER THE NORTHERN HALF/THIRD OF
THE AREA WEDNESDAY GIVEN THE STRONG INVERSION ABOVE THE LOW-LEVEL
MOIST LAYER.
LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
MODELS COMING INTO
BETTER AGREEMENT WITH THE THURSDAY NIGHT THROUGH SATURDAY NIGHT
SYSTEM, SO FORECAST CONFIDENCE HAS RISEN A BIT FROM THIS TIME
YESTERDAY, ALTHOUGH MODEL RUN TO RUN CONSISTENCY IS STILL A PROBLEM.
WE START WITH A DRY PERIOD AS THE MID/UPPER LEVEL RIDGE WILL BE OVER
THE REGION, BUT THIS RIDGE WILL GRADUALLY SHIFT EAST AND A COMPLEX
SYSTEM WILL AFFECT THE AREA STARTING THURSDAY NIGHT. MODELS HAVE
BACKED OFF OF THE PHASING OF THE NORTHERN AND SOUTHERN STREAM
SYSTEMS, WITH A STRONG WAVE MOVING THROUGH THE GREAT LAKES REGION
AND A WEAKER UPPER LOW EJECTING OUT OF THE THE ROCKY MOUNTAINS AND
ACROSS THE SOUTHERN/CENTRAL PLAINS. THIS SOUTHERN STREAM SYSTEM IS
THEN FINALLY PICKED UP BY ANOTHER WEAKER NORTHERN STREAM WAVE AND
EJECTS EAST BY SUNDAY. A COLD FRONT WILL PUSH INTO OUR AREA, AND A
SURFACE WAVE WILL LIKELY FORM ON THE FRONT AND MOVE ACROSS THE
REGION. EXACT DETAILS OF TIMING/PLACEMENT OF THESE FEATURES STILL
SOMEWHAT UNCERTAIN GIVEN POOR RUN TO RUN CONSISTENCY OF THE MODELS,
BUT WE SHOULD SEE RAIN AT TIMES AS EARLY AS THURSDAY NIGHT AND
CONTINUING INTO SATURDAY. SOME SHOWERS MAY LINGER INTO SATURDAY
NIGHT, AND A FEW SPOTS MAY SEE A SNOW SHOWER BEFORE THE PRECIP ENDS
ESPECIALLY OVER THE HIGHER TERRAIN.
SUNDAY AND MONDAY ARE EXPECTED TO BE DRY AS MID/UPPER LEVEL RIDGING
BUILDS OVER THE AREA ONCE AGAIN, BUT RAIN MAY RETURN AS EARLY AS
TUESDAY AS THE NEXT SYSTEM APPROACHES.
AVIATION
VFR CONDITIONS EXPECTED AT KCHA BUT MVFR CIGS EXPECTED AT KTYS AND
KTRI IN THE LATE EVENING PERSISTING THRU THE NIGHT. IFR CONDITIONS
NOT EXPECTED AT KTRI BUT COULD OCCUR IF RAIN BECOMES HEAVY ENOUGH
THIS EVENING. CURRENTLY HAVE TEMPO FOR 6SM -RA BR BKN012 AT KTRI
FROM 23Z-03Z. SFC WINDS SHOULD SHIFT TOWARDS THE NW LATE TONIGHT
AND WED MORNING.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 40 61 40 67 49 / 0 0 0 10 20
KNOXVILLE MCGHEE TYSON AIRPORT, TN 41 57 38 64 48 / 20 0 0 0 30
OAK RIDGE, TN 41 58 38 64 49 / 20 0 0 10 30
TRI CITIES AIRPORT, TN 39 52 34 64 44 / 50 10 0 0 30
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
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