FXUS64 KOHX 081755 AFDOHX Area Forecast Discussion National Weather Service Nashville TN 1155 AM CST Fri Dec 8 2023 ...New AVIATION... .UPDATE... Issued at 1108 AM CST Fri Dec 8 2023 Strong WAA is underway across Middle Tennessee this morning with gusty south winds up to 25 mph bringing in higher low level moisture and warmer temperatures. Current temps are already well into the 50s to around 60, and nudged up highs for this afternoon to the low to mid 60s for most of the area and upper 50s to around 60 on the Plateau. Already seeing a few blips on radar over our northwest counties, and latest CAMs indicate a few showers will develop late this afternoon and especially this evening into tonight areawide - and have adjusted pops based on this latest guidance. Will take a closer look at tomorrow's severe weather potential with the afternoon forecast package, but overall guidance is trending higher with CAPE/shear for our area which increases the threat somewhat. && .SHORT TERM... (Today through Saturday) Issued at 1224 AM CST Fri Dec 8 2023 Middle Tennessee finds itself under a strong southerly flow at the surface, so temperatures are enjoying a quick warm-up following yesterday morning's bottoming-out. Despite the dryness we experienced yesterday afternoon, the PWAT+ value from the 00Z sounding was an even 100 (meaning the observed Precipitable Water was exactly 100% of the daily mean value), and significant additional moisture advection is expected ahead of the next active weather system. Most locations west of the Cumberland Plateau will reach 60F or better this afternoon. It's going to be the last day like this for awhile, because showers will begin developing later tonight and certainly on Saturday as a strong cold front begins to impact the mid state. In addition to widespread showers, some storms are also possible given modest instability and the strength of the cold front. && .LONG TERM... (Saturday Night through next Friday) Issued at 1224 AM CST Fri Dec 8 2023 It appears that the most opportune period for convection is going to along or just ahead of the surface boundary, which will sweep across Middle Tennessee from late Saturday afternoon, through Saturday evening and into the overnight hours before colder air begins to infiltrate. Moisture transport ahead of the front looks to be significant, with 850 mb winds reaching 40-50 kts just ahead of the surface boundary. That the boundary will still be undergoing frontogenesis as it enters the mid state Saturday afternoon hints at the vigorousness of this system. For this reason, the SPC has placed most of Middle Tennessee west of I-65 under a slight risk of severe storms. Straight-line winds will be the primary threat. It is unclear whether CAPE values will be large enough to sustain updrafts needed for large-hail. And, although there will be plenty of speed shear in the pre-frontal environment, profiles are likely to remain largely unidirectional. Showers will continue into Sunday, with some light snow possibly mixing in during the afternoon. In fact, light accumulations (~0.2") are possible along the Cumberland Plateau Sunday evening before the precipitation entirely departs the mid state. Storm total QPF values from 06Z Saturday until 06Z Monday range from ~1.5" around Land-between-the- Lakes to ~2.5" along portions of the Cumberland Plateau. Looking ahead, temperatures next week will remain quite chilly. Readings Monday and Tuesday morning are expected to settle into the 20s, with freezing temperatures again Wednesday morning. Temperatures will warm somewhat by week's end, but no additional precipitation is expected through Friday. && .AVIATION... (18Z TAFS) Issued at 1150 AM CST Fri Dec 8 2023 An approaching low pressure system will bring increasingly gusty south winds throughout the TAF period. Cigs are expected to remain VFR until after 06z Saturday. They'll likely bounce between MVFR and VFR as isolated showers and storms develop through 18Z Saturday. Wind shear is expected to increase as low level jet winds increase after 10Z at CKV, BNA, and MQY. Additional storm coverage isn't expected at sites until after 18Z. && .PRELIMINARY POINT TEMPS/POPS... Nashville 65 55 67 44 / 0 40 90 100 Clarksville 63 56 66 39 / 10 50 90 90 Crossville 58 47 60 40 / 0 60 50 100 Columbia 64 55 66 40 / 0 40 90 100 Cookeville 61 51 63 41 / 0 60 80 100 Jamestown 59 47 62 41 / 0 50 60 100 Lawrenceburg 64 55 66 41 / 10 50 90 100 Murfreesboro 65 53 68 40 / 0 50 90 100 Waverly 63 55 65 37 / 10 50 90 90 && .OHX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.......Shamburger SHORT TERM...Rose LONG TERM....Rose AVIATION.....Whitehead