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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