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

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000 FXUS64 KMRX 170521 AAA AFDMRX Area Forecast Discussion...UPDATED National Weather Service Morristown TN 121 AM EDT Sun Mar 17 2024 ...New AVIATION... .UPDATE... Issued at 1029 PM EDT Sat Mar 16 2024 No updates needed tonight. Temperatures have been a degree or two warmer than the forecast but still think overnight lows are in good shape. && .SHORT TERM... (This evening through Sunday) Issued at 318 PM EDT Sat Mar 16 2024 Key Messages: 1. Dry and pleasant for most tomorrow as moisture starved cold front crosses the region Sunday morning. Discussion: Clouds are finally breaking up this afternoon for remaining portions of the Tennessee foothills, and full brilliant March sunshine has led to a great day. Decent weather will hang on through tomorrow. Despite the cold front passing through overnight, the main cold air advection will hold on for one more day, with 850 mb temperatures not falling below 0C until after midnight Sunday night. Clouds will be on the increase overnight as a midlevel shortwave approaches the area. Daytime Sunday will therefore be decent, with mild and dry weather. Low chance for a sprinkle around daybreak south of Knoxville, but the drier atmosphere aloft might prevent that from reaching the ground. Otherwise maintained a low PoP across the counties bordering Georgia tomorrow afternoon, but CAMs are united on keeping precipitation south of us in Georgia. && .LONG TERM... (Sunday night through next Saturday) Issued at 318 PM EDT Sat Mar 16 2024 Key Messages: 1. Much colder temperatures will start the period with an area-wide hard freeze on Tuesday morning and very cold wind chills in the higher elevations. A warming trend will follow. 2. Very dry conditions are also expected Monday and Tuesday. 3. Rain chances will return Thursday into Friday with fairly light totals expected overall. Sunday Night through Wednesday At the start of the period, anomalous troughing will be building into the area from the north with a cold front having pushed to the south. During this time, high pressure originating in Canada will be expanding from the north with strong CAA taking place. By the day on Monday, 850mb temperatures will fall below the 10th percentile for this time of year, i.e. below -7 Celsius. Persistent northwesterly flow, the MSLP gradient, and very anomalous 850mb temperatures will make for breezy conditions and temperatures near or below January normals on Monday. As the high pressure arrives to our west, stronger subsidence will promote dry conditions during the day, followed by an area-wide hard freeze. The coverage of frost may be less widespread if winds continue, but even light winds will make for even colder wind chills in the higher elevations, possibly single digits in some areas. By Tuesday, the region will begin to see height rises and increasing southerly flow as troughing shifts further east and high pressure becomes centered further south. As the subsidence continues and temperatures increase, afternoon RH`s will likely drop lower than on Monday, possibly approaching 20 percent. For Wednesday, there are indications of increasing low-level moisture, which would likely limit dryness at the surface. However, recent southerly flow and continued height rises will still allow for many places to reach seasonal temperature norms in the 60s. Thursday through Saturday By Thursday, focus will turn towards a shortwave that will likely become cut off from the main flow over western Texas and Oklahoma before progressing towards the southeastern U.S. Based on the latest model guidance, this system is expected to reach the area towards Friday, which will also be the time of increasing rain chances. With the surface low pressure center expected to track south of our area, the better moisture and any instability are expected to remain well to our south. This will keep overall rain totals and impacts with this system very limited. Ultimately, this will provide widespread, overall light rain, which may continue into Saturday. && .AVIATION...
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(06Z TAFS) Issued at 119 AM EDT Sun Mar 17 2024 VFR conditions are forecast through this period. Clouds will increase through the morning but will remain at VFR levels, mainly around 10 kft today. Winds will increase in the mid/late morning hours, between 8-12 kt, and a few gusts near 20 kt are possible at TRI this afternoon.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 65 37 51 29 / 20 0 0 0 Knoxville McGhee Tyson Airport, TN 63 35 49 27 / 10 0 0 0 Oak Ridge, TN 64 34 49 25 / 10 0 0 0 Tri Cities Airport, TN 60 32 46 25 / 10 0 10 10
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...Wellington LONG TERM....BW AVIATION...DGS

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