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

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000 FXUS64 KMRX 181906 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 306 PM EDT Sun Jun 18 2017 .SHORT TERM (Tonight through Monday night)...
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A line of storms moving east across Middle TN will present a marginal threat of damaging winds to the Cumberland Plateau in the next few hours. Some weakening of the line is expected to occur as it moves into the TN Valley, but the HRRR is likely too quick to dissipate it completely. As a cold front and upper trough move into the Ohio Valley region tonight, the SW low to midlevel flow increases and begins to advect deep moisture into the area. PW values increase to near 2 inches (over 90% of climatology) with deep, skinny CAPE profiles shown in NAM and GFS soundings. Near saturation through the column continues through Monday, for 12+ hours, and the slow-moving surface front will be moving into our NW sections in the afternoon. Flooding will be a concern with this pattern, particularly for SW VA and the northern Cumberland Plateau where locally heavy rain may occur today. The passage of the cold front and upper trough to our east occurs Monday evening, but the NAM hangs the front across the NC mountains and N GA through Monday night, so a chance PoP will be maintained overnight for that area. A Flash Flood Watch will be issued for the northern Cumberland Plateau counties and SW VA counties that border KY. QPF amounts in this area today through Monday will be in the 2-2.5 inch range. .LONG TERM (Tuesday through Sunday)... Much quieter start to the period with the cold front now to our east. However, the front washes out just to our east and models show a remnant boundary hanging in across the Carolinas through the day on Tuesday. Due to the proximity of the boundary to our area will have slight chance POPs across portions of the Southern Valley and chance POPs into Southwest North Carolina. Elsewhere, plenty of sunshine and dry conditions expected with highs in the low to mid 80s, with highs only in the mid to upper 70s across Southwest Virginia. Tuesday night lows will range from the upper 50s to lower 60s. Wednesday looks like another dry and nice day with highs in the mid 80s but at this time our focus turns to tropical moisture coming northward out of the gulf. Models haven`t been handling this feature too well but latest model runs show this system spreading moisture northward into our are Wednesday night and moreso on Thursday. Will reintroduce POPs areawide by Thursday afternoon with chance POPs across southern areas and slight chance elsewhere. Thursday night through Friday night is when models show this system moving through our area as an incoming longwave trough helps to pull it further northward. The upper-level longwave trough swinging through, behind the Thu/Fri system, will keep high-end chance POPs in the forecast for both Saturday and Sunday. Thursday through Sunday highs will generally be in the 80s with lows in the 60s. So overall, dry start to the period but increasing chances for showers and storms as the period progresses. If the tropical moisture takes a different track it will change our POPs quite a bit for late in the period, will continue watching.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 71 82 66 86 / 70 90 50 20 Knoxville McGhee Tyson Airport, TN 70 80 65 84 / 80 90 50 10 Oak Ridge, TN 71 80 63 85 / 80 90 40 10 Tri Cities Airport, TN 68 79 63 80 / 70 90 50 10
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&& .MRX WATCHES/WARNINGS/ADVISORIES...
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NC...None. TN...Flash Flood Watch from midnight EDT tonight through Monday afternoon for Anderson-Campbell-Claiborne-Hancock-Morgan- Scott TN-Union. VA...Flash Flood Watch from midnight EDT tonight through Monday afternoon for Lee-Wise.
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&& $$ DGS

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