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

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000 FXUS64 KMRX 211924 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 324 PM EDT Wed Jun 21 2017 .SHORT TERM...(Tonight and Tomorrow)...Both moisture and cloud cover will continue to increase across our area overnight thanks to Tropical Storm Cindy. Increasing clouds and southerly flow will keep overnight lows mild, around 3 to 5 degrees above normal. With tropical moisture advecting northward, PWs increase overnight and through the day tomorrow to around 2 inches by tomorrow afternoon. This is near max values for this time of year. Increasing LLJ and PWs will lead to an increase in shower and storm activity through the day tomorrow. The NAM and GFS both show the first rain band of significance moving into the Southern Valley later tomorrow morning and then spreading northward into the Central and Northern Valley through the afternoon. With this initial band of rain we can expect anywhere from 0.25 to 0.5 inches of rainfall across the aforementioned areas. Lighter rainfall expected across NETN and SWVA with around 0.25 inches expected. A few embedded storms are possible but not expecting anything strong. Expect plenty of clouds tomorrow along with below normal highs. Highs will be around 80 degrees for most areas, which is anywhere from 5 to 8 degrees below normal. .LONG TERM...(Thursday night through Wednesday)...A brief lull in the heavier rainfall is anticipated Thursday night into early Friday. Tropical moisture will continue to surge into the area Friday as the remnants of TS Cindy push into west Tennessee and get absorbed into a slow moving cold front. For east Tennessee, southwest Virginia, and far western North Carolina, the period of heaviest rain appears to be Friday afternoon into early Saturday as the system crosses directly overhead. There should also be enough instability (CAPE values in the 500-1500 J/kg range, depending on the model) Friday afternoon to help trigger some thunderstorms along and ahead of the frontal boundary, with the main threat being isolated damaging wind gusts. With PWATs in the 1.5 to 2.5" range (near climatological maxes for this time of year), storms will be efficient and rainfall amounts through Saturday afternoon will range from 2-4" across the area with locally higher amounts possible. There are still some model differences with regards to the exact track of TS Cindy and frontal passage timing. These small differences will impact the exact axis of heaviest rain, but at this point it appears to be across the Cumberland Plateau. Rain chances will slowly taper off during the second half of the weekend as the front progresses eastward, with just a slight chance for some lingering showers and thunderstorms through Monday. Following this through mid next week, our area will be in a mainly dry, slightly cooler northwest flow pattern. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 70 80 72 84 / 40 80 70 70 Knoxville McGhee Tyson Airport, TN 69 79 70 83 / 20 80 60 70 Oak Ridge, TN 70 80 71 81 / 20 80 70 80 Tri Cities Airport, TN 65 79 67 80 / 10 70 60 60 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ SR/EMH is the U.S. government's official web portal to all federal, state and local government web resources and services.