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

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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS64 KMRX 171527 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 1127 AM EDT Sun Mar 17 2024 ...New UPDATE... .UPDATE...
-- Changed Discussion --
Issued at 1121 AM EDT Sun Mar 17 2024 Temperatures for most locations were a little warmer than forecast this morning, so blended in some MOS guidance to bring hourly temperatures and the max temperature for the day up slightly. Current visible satellite shows a mix of sun and clouds across the region, with some locations cloudier and some sunnier. Dewpoints have been a couple degrees higher than forecast as well, indicating the front has been slower to cross than thought. Otherwise today is still on track for dry and pleasant weather.
-- End Changed Discussion --
&& .SHORT TERM...
-- Changed Discussion --
(Today and tonight) Issued at 239 AM EDT Sun Mar 17 2024 Key Messages: 1. Dry today as moisture-starved cold front and upper disturbance cross the region this morning. 2. Much colder and drier air build into the area tonight. Discussion: A weak southern stream shortwave trough will spread mid to high level clouds across the area through today. Radar is showing precip in southern West and Middle TN, but obs show light rain staying south of the TN/MS border. As this spreads east, the precip falling from midlevel clouds will encounter dry low level air with the chance of measurable precip at the ground being low. Meanwhile, a cold front located across KY this morning will push SE through our area during the late morning and early afternoon. The main impact with this front will be an increase in winds to 10-15 mph and dry air advection. Dewpoints will be falling through the afternoon behind the front. Tonight, there will still be quite a bit of cloud cover in the evening, eventually clearing out after midnight as drier midlevel air builds in. Some wind and mixing will prevent temperatures from plummeting, but northern sections may see sub- freezing lows tonight.
-- End Changed Discussion --
&& .LONG TERM... (Monday through Saturday) Issued at 239 AM EDT Sun Mar 17 2024 Key Messages: 1. Much colder temperatures Monday through Tuesday with area-wide hard freeze Tuesday morning and very cold wind chills in the higher elevations. A warming trend follows Wednesday. 2. Very dry conditions are also expected Monday and Tuesday. 3. Rain chances return late Thursday into Friday with only light precipitation totals expected. Monday through Wednesday At the beginning of the week, upper low over the northeast Canadian coast with deep trough to the southwest extending all the way to the mid Mississippi Valley Monday morning. A much colder airmass will begin to move in Sunday night with this colder and drier airmass taking over the forecast area. Winds will increase from the NW during the day Monday and the cold air advection will continue all day and overnight Monday night. The strong NW flow and the packed surface pressure gradient will cause gusty winds as high as 30 mph in the valleys and up to about 40 mph in the higher elevations for a few hours late Monday and Monday evening. Possibly borderline wind advisory criteria in the higher mountains. Highs Monday will be 10 to 15 degrees below normal, 40s to lower 50s. Also minimum relative humidity levels will be as low as 30 percent Monday afternoon. Lows Monday night/Tuesday morning will be much below freezing, a hard freeze across the region. Actual frost formation may be limited by the strong northwest winds. No freeze warning will be issued based on climatology but the limited growing vegetation...early flowers and blooming trees may be affected. Wind chills in the higher elevations will stay below 20 degrees much of the day and then drop to 0 to 10 Monday night and Tuesday morning. Even lower elevations will drop to 10 to 20 degree wind chills overnight Monday night. Tuesday a warming trend begins as heights rise and an increasing southerly flow develops as the pronounced eastern trough shifts east northeast. Temperatures will still be below normal, in the 50s but winds shift to the southwest. High pressure becomes centered farther south. Subsidence continues and afternoon RH`s will likely drop about 5 percent lower than Monday, approaching 20 to 25 percent. Wednesday more warming but also increasing low-level moisture, which will allow relative humid values to be around 10 percent higher. Temperatures will warm to near normal 60s with height rises and more southerly flow. Thursday through Saturday Wednesday night and Thursday southerly flow continues with more moisture increasing and a weak shortwave approaches from a cut off low over Texas and western Oklahoma. A weak front that is moisture starved moves through Wednesday night and Thursday but no precipitation. The GFS model shows the cutoff low approaching the Mississippi Valley late Thursday and Thursday night with the upper flow switching to the southwest and brings a chance of light showers to the eastern Tennessee Valley Thursday night and especially Friday. More significant precipitation will track eastward along the Gulf coast. The latest model guidance is drier with the ECMWF versus the GFS with this system. It keeps most of the precipitation along the Gulf Coast Thursday night and Friday. With the surface low pressure center expected to track south of the area, the better moisture and instability are expected to be well to the south. So confidence in any significant rainfall is low. Rainfall amounts look to be very light and impacts with the system limited. Saturday high pressure rebuilds over the region. && .AVIATION... (12Z TAFS) Issued at 714 AM EDT Sun Mar 17 2024 High and midlevel clouds will be over the area through most of this period. A cold front will cross the area today, shifting winds to a more westerly direction and bringing some 10-15 kt winds with gusts up to 20 kt at times at TRI this afternoon. Expect diminishing winds this evening, and decreasing clouds later tonight. && .PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Chattanooga Airport, TN 68 38 52 29 / 10 0 0 0 Knoxville McGhee Tyson Airport, TN 65 34 49 27 / 0 0 0 0 Oak Ridge, TN 66 34 50 26 / 0 0 0 0 Tri Cities Airport, TN 62 31 47 26 / 0 0 10 10
-- End Changed Discussion --
&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...Wellington LONG TERM....TD AVIATION...DGS

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