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

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000 FXUS64 KMRX 230914 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 410 AM EST FRI JAN 23 2015 .SHORT TERM (TODAY THROUGH SATURDAY)...
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LOW PRESSURE SYSTEM WILL TRACK OUT OF THE GULF NORTHEAST INTO THE CAROLINAS AND THEN OFF THE COAST SATURDAY. AN INVERTED SURFACE TROUGH WILL EXTEND INTO OUR AREA TODAY INTO TONIGHT...AND COLDER AIR WILL PUSH IN LATER TONIGHT INTO SATURDAY AS UPPER TROUGH MOVES ACROSS AND THEN EAST OF THE AREA. PRECIPITATION WILL CONTINUE TO OVERSPREAD THE AREA TODAY. WILL CARRY 100 POPS ALL AREAS. FREEZING LEVELS WILL BE QUITE HIGH FOR THE MOST PART. THERE MAY BE SOME SNOW AND/OR SLEET ON THE FRONT END MAINLY HIGHER ELEVATIONS AND NORTH...BUT THIS IS EXPECTED TO BE FAIRLY BRIEF SO NOT MUCH IN THE WAY OF ACCUMULATION. WILL CONTINUE TO MENTION SOME MINOR ACCUMULATION IN SPS. COLDER AIR WILL BEGIN TO PUSH IN AGAIN LATER TONIGHT AND SATURDAY...WHICH SHOULD CAUSE THE RAIN TO MIX WITH AND/OR CHANGE TO SNOW BEFORE ENDING...ESPECIALLY HIGHER TERRAIN AND NORTH. APPEARS THERE MAY BE AN INCH OR TWO OF SNOW POSSIBLE OVER SOME OF THE HIGHER ELEVATIONS...AND WILL CONTINUE THE SPS TALKING ABOUT THIS AS WELL. PRECIP SHOULD END SATURDAY MORNING FOLLOWED BY SOME CLEARING. JUST SOME MINOR ADJUSTMENTS TO MAV TEMPS. .LONG TERM (SATURDAY NIGHT THROUGH THURSDAY)...MODELS HAVE SOME RELATIVELY MINOR TIMING ISSUES WITH INDIVIDUAL SHORT WAVE FEATURES DURING THE PERIOD BUT STAY ON COURSE WITH THE ARRIVAL OF A CLIPPER SYSTEM SUNDAY AFTERNOON WITH DEPARTURE DURING THE DAY ON MONDAY. STILL TOO EARLY TO REALLY NAIL THIS SYSTEM DOWN IN TERMS OF THE DETAILS AS CRITICAL ASPECTS SUCH AS SYSTEM TRACK AND STRENGTH AS WELL AS TEMPERATURE AND MOISTURE PROFILES MAY CHANGE DURING THE NEXT 24-48 HOURS. HOWEVER...THROUGH THIS MODEL CYCLE IT STILL APPEARS THAT...TYPICALLY THE BEST CHANCE OF SNOW WILL BE IN THE HIGHER TERRAIN SUNDAY NIGHT INTO MID DAY MONDAY WHERE SNOWFALL ACCUMULATION COULD REACH 2-4 INCHES. AT THIS TIME IT LOOKS LIKE THE LOW LEVEL AIRMASS ACROSS MUCH OF THE GREAT VALLEY MAY NOT CHILL SUFFICIENTLY FOR A CHANGE OVER FROM RAIN TO SNOW DURING THIS PERIOD. HOWEVER THE POLAR JET MAY REMAIN ACTIVE FROM MONDAY AFTERNOON INTO EARLY TUESDAY MORNING AND POSSIBLY WELL INTO THE AFTERNOON HOURS ON TUESDAY. THIS ENERGETIC JET MAY ALLOW FOR YET ANOTHER WEAKER SHORT WAVE TO BUILD ACROSS THE SOUTHERN APPALACHIANS MONDAY NIGHT INTO TUESDAY AND DURING THIS TIME FRAME TEMPERATURE STRUCTURE IN THE LOW LEVEL ATMOSPHERE SHOULD BE COLD ENOUGH FOR SNOWFALL EVEN IN THE VALLEY. HOWEVER...MODEL SNOWFALL DEPICTS ONLY A LIGHT ACCUMULATION OCCURRING FROM AROUND KNOXVILLE/MORRISTOWN (ONLY A DUSTING) NORTHEAST TO THE TRI-CITIES VICINITY WHERE AMOUNTS MAY BE CLOSER TO ONE INCH...POSSIBLY A LITTLE MORE IN THE VALLEYS OF SOUTHWEST VIRGINIA. ONCE AGAIN...THE HIGHER TERRAIN SHOULD PICK UP HIGHER TOTALS IN THIS MONDAY NIGHT INTO TUESDAY NIGHT PERIOD WHERE A HEALTHY UPSLOPE COMPONENT TO THE LOW LEVEL FLOW WILL ENHANCE LIFT OVER THE TERRAIN. THE NORTHWEST FLOW SNOWFALL SHOULD FINALLY SHUT DOWN AROUND TUESDAY NIGHT INTO WEDNESDAY AS HEIGHTS SLOWLY BUILD IN THE WAKE OF THE EASTWARD MOVING LONG WAVE TROUGH. RIDGING KEEPS THE FORECAST AREA DRY THROUGH EARLY THURSDAY. HAD TO INTRODUCE SLIGHT AND LOW CHANCE POPS FOR SOME LIGHT RAIN THURSDAY AFTERNOON INTO THURSDAY NIGHT FOR THE ARRIVAL OF ANOTHER WAVE.
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&& .PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN 44 35 46 33 / 100 70 20 0 KNOXVILLE MCGHEE TYSON AIRPORT, TN 42 34 45 32 / 100 90 40 10 OAK RIDGE, TN 42 35 44 33 / 100 90 30 10 TRI CITIES AIRPORT, TN 42 35 42 28 / 100 90 70 10
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$

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