132  
FXUS64 KMRX 130748  
AFDMRX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MORRISTOWN TN  
348 AM EDT TUE APR 13 2021  
   
SHORT TERM...(TODAY AND TONIGHT)
 
 
NOT A WHOLE LOT TO TALK ABOUT IN THE SHORT TERM. BIGGEST QUESTION  
IS WHETHER ANY AREAS ACTUALLY SEE PRECIP REACH THE GROUND. RIDGE  
IS TO OUR SOUTH AND UPPER TROUGH TO OUR NORTH. THIS RESULTS IN  
ZONAL FLOW ACROSS THE AREA WITH SOME MID-LEVEL VORTICITY SET TO  
MOVE ACROSS THE AREA TODAY. LATEST GUIDANCE CONTINUES TO SUGGEST  
THERE IS A SLIGHT CHANCE FOR A FEW SHOWERS, MAINLY ALONG AND NORTH  
OF I-40. ANY PRECIP REACHING THE GROUND WILL BE LIGHT WITH ONLY A  
FEW HUNDREDTHS OF AN INCH OF LIQUID POSSIBLE. MOST AREAS WILL  
STAY DRY.  
 
OTHERWISE, INCREASING CLOUDS ARE EXPECTED THROUGH THE DAY BUT  
TEMPERATURES WILL REMAIN ABOVE NORMAL FOR THE SOUTHERN AND  
CENTRAL TN VALLEY AND NEAR NORMAL ACROSS NORTHEAST TN AND  
SOUTHWEST VA. SOUTHERLY FLOW WILL KEEP TEMPS MILD OVERNIGHT WITH  
LOWS RANGING FROM THE UPPER 40S TO LOW 50S. PARTIAL CLEARING AND  
DRY CONDITIONS EXPECTED OVERNIGHT.  
 
SR  
   
LONG TERM...(WEDNESDAY THROUGH MONDAY)
 
 
WEDNESDAY WILL BEGIN WITH QUASI-ZONAL FLOW ALOFT, WITH CUTOFF LOWS  
TO OUR NORTH OVER THE WESTERN GREAT LAKES REGION AND ALSO OUT WEST  
OVER NEVADA. THIS TRANSITIONS TO NORTHWESTERLY FLOW ALOFT BY LATE  
WEDNESDAY AS THE GREAT LAKES UPPER LOW DROPS SOUTHEAST TOWARDS  
PENNSYLVANIA, HELPING TO PUSH A WEAK COLD FRONT THROUGH THE FORECAST  
AREA DURING THE DAY WED. HAVE LOW-END CHANCE POPS GOING ACROSS THE  
AREA BY DAYBREAK BUT AM A LITTLE UNCERTAIN THERE GIVEN THE SPREAD IN  
QPF IN NUMERICAL GUIDANCE. NEVERTHELESS, A +70KT JET STREAK WILL  
MOVE OVERHEAD BY MIDDAY WHICH SHOULD LEAD TO WIDESPREAD SHOWERS  
ACROSS THE CWA BY THE AFTERNOON HOURS AND HAVE POPS RAMPING UP  
ACCORDINGLY. DO HAVE SOME THUNDER IN THE FORECAST AS WELL BUT MODEL  
SOUNDINGS SHOW VERY MEAGER INSTABILITY SO SUSPECT IT WILL BE FAIRLY  
HARD TO COME BY AND MOSTLY OVER THE MOUNTAINS.  
 
THE COLD FRONT AND ANY ASSOCIATED PRECIP IS LIKELY EAST OF THE AREA  
BY DAYBREAK THURSDAY OR SO. LOW AND UPPER LEVEL FLOW TRANSITIONS TO  
AN ALMOST WINTER-LIKE NORTHWESTERLY PATTERN, WITH H85 TEMPS DROPPING  
BELOW FREEZING IN THE NORTH AND THE LOW SINGLE DIGITS EVEN IN THE  
SOUTH. WILL LIKELY HANG ON TO AT LEAST SOME SCATTERED CLOUDS THROUGH  
MUCH OF THE DAY THURSDAY IN THIS NORTHWEST FLOW PATTERN. THIS COOLER  
PATTERN WILL CONTINUE THROUGH LATE THIS WEEK. TEMPERATURES SHOULD BE  
NEAR NORMAL ON WEDNESDAY, BUT WILL DROP SEVERAL DEGREES BELOW NORMAL  
THROUGH THE END OF THE WEEK.  
 
CLOUDS AND PRECIPITATION CHANCES MAKE A RETURN OVER THE WEEKEND AS  
THE UPPER LOWS BREAK DOWN, AND A SHORTWAVE MOVES OVER THE AREA  
COMING OUT OF THE PLAINS. CONFIDENCE IN HOW THIS PLAYS OUT IS RATHER  
LOW AT THE MOMENT. THE GFS HAS A DEEPER SHORTWAVE/CLOSED LOW  
SHIFTING EAST ACROSS MISSOURI WITH WIDESPREAD RAIN OVER THE TN  
VALLEY, WHILE THE ECMWF IS ESSENTIALLY DRY WITH A WEAKER, OPEN WAVE  
TO OUR NORTHWEST. FOR NOW, HAVE SOME SLIGHT CHANCE POPS IN TO  
ACCOUNT FOR AT LEAST SOME LOW-END RAIN CHANCES.  
 
CD  
 

 
   
AVIATION
 
 
06Z TAF DISCUSSION.  
 
VFR CONDITIONS EXPECTED AT ALL SITES THROUGH THE PERIOD ALONG WITH  
MUCH LIGHTER WINDS COMPARED TO YESTERDAY. CLOUDS WILL SLOWLY  
INCREASE OVERNIGHT AND THROUGH THIS AFTERNOON AS A WEAK DISTURBANCE  
MOVES THROUGH WITH CIGS IN THE 8 TO 9K FT RANGE AT TYS AND TRI.  
 
SR  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
CHATTANOOGA AIRPORT, TN 81 54 73 49 66 / 10 10 70 10 10  
KNOXVILLE MCGHEE TYSON AIRPORT, TN 75 53 71 47 63 / 10 10 70 30 10  
OAK RIDGE, TN 74 53 70 45 63 / 20 10 70 30 0  
TRI CITIES AIRPORT, TN 68 50 70 45 59 / 20 10 60 40 0  
 

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

 
 

 
 
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