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

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000 FXUS64 KMRX 141702 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 102 PM EDT Thu Mar 14 2024 ...New AVIATION... .SHORT TERM... (Today and tonight) Issued at 242 AM EDT Thu Mar 14 2024 Key Messages: 1. Low afternoon relative humidity for much of southwest Virginia and northeast Tennessee today. 2. Unseasonably warm today with highs some 15 to 20 degrees above normal. 2. A line of showers and embedded thunderstorms will move across the area Friday morning. Strong storms are possible across the Plateau and southeast Tennessee. Some of these storms may be strong producing high winds causing down trees and power lines. 3. Localized heavy rainfall possible across the Plateau and southeast Tennessee. Isolated flooding problems possible. Discussion: For today, upper ridging and increasing warm southerly flow into the Tennessee valley and southern Appalachians will produce mostly sunny sky and unseasonably warm conditions. Highs today will be just below record highs but some 15 to 20 degrees above normal. Definitely will feel more summer-like this afternoon. Here are the record highs for today... Date Chattanooga Knoxville Tri-Cities Oak Ridge 03-14 83(2012) 85(1990) 82(1990) 84(1990) For southwest Virginia and northeast Tennessee, another day of low afternoon relative humidity is expected. For tonight, conditions will remain mostly clear until midnight then a strong upper jet across the Ohio into the Tennessee valleys will produce broad divergence aloft. The right entrance region will enhance the front-genetic forcing with an approaching front. Also, in response to the upper jet dynamics, an increasing low- level jet toward Friday morning with 850mb southwest winds of 35-40 knots. The low-level jet will produce isentropic lift toward daybreak. For friday, the strong frontal-genetic forcing along with elevated CAPE of 250-750 J/Kg will produce a solid line of showers and embedded thunderstorms area-wide. The strongest of the storms will move across the Plateau and southeast Tennessee between 6 and 10 am. This line may produce localized high winds causing isolated down trees and power lines. NAEFS shows high PWs around the 95th percentile with 850mb moisture transport around 1 standard deviation above normal. End result will be localized heavy rainfall mainly across the Plateau and southeast Tennessee. Due to the relatively fast speed of the showers/storms, only isolated flooding is possible. Winds Friday, will be breezy area-wide by afternoon with windy conditions across the higher terrain. && .LONG TERM... (Friday through Wednesday) Issued at 242 AM EDT Thu Mar 14 2024 Key Messages: 1. Showers/storms gradually taper off Friday night, with conditions mostly dry through the remainder of the extended forecast period. 2. Hard Freeze growing increasingly likely for much of the area Tuesday morning. This would be accompanied by wind chills in the the teens for portions of SW Virginia, the Cumberland Plateau, NE Tennessee Valley, and the E TN mountains. Discussion: By Friday night the main frontal forcing and impactful weather will have shifted southeast of the area, though some lingering light showers and perhaps an isolated rumble of thunder will be possible overnight. Saturday continues to trend dry. Shortwave energy then sharpens upper level troughing into Sunday, sending a reinforcing cold front through the region. This quick moving front looks moisture starved and slight chance PoPs have been limited to higher elevations of the East Tennessee mountains. Perhaps portions of NE TN see some drizzle, but the main impacts will be increased clouds and much cooler air filtering in post-fropa. By Monday night, low temperatures are expected to be below freezing area wide. Light northwesterly winds will result in windchill values in the teens for portions of NE TN, SW VA, and the Cumberland Plateau. Wind chills in higher elevations of the East Tennessee mountains may fall into the single digits. The cold blast will be short-lived however. Height rises will lead to a gradual warming trend through the remainder of the work week. Conditions will also remain mostly dry through this time. GEFS and ECMWF ensemble mean suggest a vort lobe rounding the base of the trough Monday night could bring light snow flurries to higher elevations of SW VA and the E TN mountains but probability of snowfall GTE 1 inch is less than 20% at this time. NBM has left mentionable PoPs out of the forecast and see no reason to deviate from this at this time. && .AVIATION...
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(18Z TAFS) Issued at 1259 PM EDT Thu Mar 14 2024 Mostly clear skies with occasional wind gusts expected the rest of the daytime hours today. Late tonight and into tomorrow morning a line of showers and thunderstorms will quickly blast through the region. Have put in PROB30 during the most likely time period of heaviest showers/storms, but will hold off on the details until later TAF issuances. Expect lower ceilings to remain in place tomorrow after the initial round of storms.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 60 70 53 70 / 50 80 60 0 Knoxville McGhee Tyson Airport, TN 60 68 50 66 / 50 70 30 0 Oak Ridge, TN 59 68 50 67 / 60 70 30 0 Tri Cities Airport, TN 53 66 48 64 / 40 80 50 0
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM... LONG TERM....KRS AVIATION...

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