265 FXUS64 KMRX 160002 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 802 PM EDT Sat Oct 15 2022 ...New AVIATION... .UPDATE... Issued at 456 PM EDT Sat Oct 15 2022 Scattered showers and sprinkles moving across the northern Plateau into the western section of the Tennessee valley. Also, a good deal of mid-level cloud cover. Added slight chance of showers and sprinkles into these areas. Also, upped cloud cover across much of the area. && .SHORT TERM... (This evening through Sunday) Issued at 249 PM EDT Sat Oct 15 2022 Key Messages: 1. Low RH and gusty southwest winds this afternoon. Gusty winds subside this evening. 2. Precip chances increase tomorrow, with chances of showers and storms in the forecast. Discussion: The rest of this afternoon: low RH values and gusty southwest winds through late afternoon and early evening. Will headline this in the fire weather forecast. Otherwise, a few light showers are possible across the area but chances are very low due to the dry air that is still in place. Tonight, moisture continues to increase across the area from the west as high pressure is to our southeast and an upper trough is incoming from the northwest. The overnight hours will be mostly dry. POPs begin to ramp up tomorrow morning through tomorrow afternoon as the trough swings into the area with a cold front back across west TN. Highest POPs will be along and north of I-40 as this is where the best moisture will reside. Instability continues to be on the weaker side but a few hundred J/kg MLCAPE values are still possible so will continue with slight chance thunder in the forecast. Most areas will see one tenth of an inch or less of rainfall through the day tomorrow but some areas may pick up to one quarter of an inch. && .LONG TERM... (Sunday night through next Saturday) Issued at 249 PM EDT Sat Oct 15 2022 Key Messages: 1. Showers and thunderstorms will move across the area Sunday night, drying out by Monday morning. 2. Well below normal temperatures early/mid next week will bring first widespread frost and freeze conditions. Highs will be 15 degrees or more below normal for Tuesday and Wednesday. 3. Moderation of temperatures and dry RH values for Thursday into late week.. Discussion: By Sunday evening showers and possibly some thunderstorms should still be going on along the southward progressing cold front. Forecast soundings still show low end instability in the atmosphere, but also enough to warrant the mention of lighting in the forecast into the nighttime hours Sunday. Sunday night the focus for storm activity will likely be across northeast Tennessee and southwest Virginia closer to the stronger forcing on the south side of the system centered over Canada. By sunrise on Monday morning expect the front to be east of the Appalachian Mountains, leading to a dry forecast for the upcoming work week, and weekend. The main story will now turn to the very cold temperatures expected for most of the work week. Trough over Canada looks to strengthen and develop into a southern moving low, with the Ohio and Tennessee Valleys expected to be on the cold south/southwest side of the system. This will bring in the coldest Arctic air mass we've seen this season and temperatures are expected to be 15 or more degrees below normal through at least the middle of the work week. Coldest temperatures will be on Tuesday, Wednesday, and Thursday morning with widespread subfreezing temperatures, and places that don't freeze will likely still see frost form. 850 temps are forecasted to be multiple standard deviations below the normal for this time of year for most of the upcoming week. Can't completely rule out this bitterly cold atmosphere being capable of squeezing out a little bit of cold rain or light flurries... But any that does occur will likely stay in the air and not accumulate at the surface. Below is the low temperature records for the upcoming work week. Current forecast comes within a few degrees of these records at times. Daily Record Low Minimum Temperatures Date Chattanooga Knoxville Tri-Cities Oak Ridge 10-18 28(1943) 30(1943) 25(1943) 31(1976) 10-19 27(1948) 29(1948) 24(1948) 26(1948) 10-20 31(1948) 31(1992) 26(1972) 28(1981) 10-21 30(1972) 29(1987) 22(1952) 28(1989) The low will finally spin off to the northeast by the second half of the work week, and temperatures should return to a more moderate range heading into the weekend. High temperatures should return to the 70's or 60's by Saturday. However the dry pattern will continue with the next best chance of rain possibly coming from a front that could move thorugh during the middle of the next week. && .AVIATION... (00Z TAFS) Issued at 604 PM EDT Sat Oct 15 2022 An area of showers and clouds is slowly moving out of the TAF sites. Will have a period of VFR conditions through most of the night. Increasing coverage of clouds and showers for mainly Sunday afternoon. Besides near showers, VFR conditions with ceiling between 6-10 kft in the afternoon hours. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 56 79 56 68 / 10 20 50 10 Knoxville McGhee Tyson Airport, TN 57 76 54 66 / 10 50 60 0 Oak Ridge, TN 54 73 51 64 / 20 60 60 0 Tri Cities Airport, TN 53 71 51 62 / 10 60 70 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...DH LONG TERM....ABM AVIATION...DH