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

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000 FXUS64 KMRX 160828 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 328 AM EST Mon Jan 16 2017 .SHORT TERM (Today and Tonight)...
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Another foggy start to the day. Patchy dense fog currently across the area with the worst of the fog in and around the Knoxville Metro area. Looking at cameras across the metro, it appears that the fog is patchy dense and a SPS is out until 10 am. Will continue to monitor conditions this morning to determine if a dense fog advisory is needed or not. Current radar imagery is showing little in the way of any precipitation as a shortwave ridge builds into the area from the west. Surface temperatures and dewpoints are generally in the 50s across the forecast area with a surface trough analyzed across the mountains and the stalled boundary just to the south. The ridge axis will pass to the east late this morning into this afternoon. Mid-level and upper level flow will become more southwesterly pushing the front, currently to the south, quickly northward. Models indicate a decrease in PW values this morning and early afternoon with values dropping in the 0.5-0.7 inch range. These values are still above normal for mid-January but below values observed over the last few days. Therefore, expect most of the day will be dry with only a small chance for an isolated shower. An upper level trough will race across the Central Plains into the Great Lakes late today into tonight. An associated cold front will approach the Mississippi River late in the short-term forecast period with rain chances increasing. High temperatures will once again be around 20 degrees above normal with strong warm air advection. Went on the higher side of guidance with highs being above forecast values for the last few days. The forecast calls for cloud cover most of the day, but if the sun does break out for an hour or so temperatures could get close to record highs. Overnight lows will be 20-25 degrees above normal with values generally in the 50s. Winds will be a bit stronger tonight as the front approaches and do not expect any dense fog again. .LONG TERM (Tuesday through Sunday)... The main system of concern for the extended will be a cold front moving in early in the period. Models continue to struggle with timing of this feature with the GFS the fastest...bringing it in on Tuesday into Tuesday night. The NAM is a bit slower with the main band of showers expect to move through Tuesday night. Will go with a bit of a compromise and spread likely pops from west to east across the area on Tuesday. Weak instabilty may develop over the region on Tuesday in advance of the front and could see a few rumbles of thunder...mainly over the western locations. Will mention a slight chance of thunderstorms for this. Also...a 40 to 50 KTs 850MB jet will accompany the front and should see breezy and gusty winds Tuesday afternoon...especially over higher terrain. The winds look like they should remain below advisory criteria. Will see likely pops through Tuesday night with the frontal passage. Scattered showers will linger into Wednesday. Model consistency quite poor though the rest of the extended and confidence low. Overall pattern shows two different areas of low pressure moving through for an active end of the extended period. The first low should move through around the Thursday/Friday time frame and the second during the weekend. Expect there will be a dry period in the time frame but timing of this unsure. Current model trend puts the best chance of briefly being between systems on will go with a mostly dry day with only low pops along higher elevations. Throughout the extended...temperatures are expected to remain above normal and all precip should be rain.
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Chattanooga Airport, TN 72 57 67 54 / 20 30 60 70 Knoxville McGhee Tyson Airport, TN 69 55 65 52 / 20 30 50 70 Oak Ridge, TN 69 56 65 52 / 20 40 60 70 Tri Cities Airport, TN 66 50 63 48 / 20 40 50 70
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