366 FXUS64 KMRX 181534 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 1034 AM EST Sat Nov 18 2023 ...New UPDATE... .UPDATE... Issued at 1030 AM EST Sat Nov 18 2023 Recent satellite imagery shows post frontal partly to mostly cloud skies this morning. These clouds will slowly scatter out by the afternoon hours. North winds behind the front and CAA will keep temperatures cool today with high temperatures near seasonal values. The forecast is on track with minor updates to hourly temperatures and dewpoints. && .SHORT TERM... (Today and tonight) Issued at 251 AM EST Sat Nov 18 2023 Key Message: Light rain is coming to an end this morning leading into cooler weather today. Discussion: Currently the front is still progressing through eastern Kentucky early this morning with temperatures cooling down and winds turning more northwesterly once the front passes through. Expect this to slowly move into the eastern Tennessee Valley and then eventually east of the Appalachians through the rest of the morning hours today. A few more spotty showers can be expected along the actual front, but amounts will be very light, likely less than 0.05 inches for anyone that does see rain in northeast TN and southwest VA. Any lingering rain will come to an end by the late morning hours, and around this time we'll start to see clouds eroding as drier air funnels in from the northwest. The sunny skies wont be enough to offset the colder air from the northwest and daytime highs today will likely top out about 10-15 degrees colder than what we experienced on Friday... But will still be a few degrees above normal for this time of year. Clear skies will also lead to a much colder night tonight with lows dropping down into the 30s across most of the eastern Tennessee Valley, and near freezing in northeast Tennessee and southwest Virginia. && .LONG TERM... (Sunday through Friday) Issued at 251 AM EST Sat Nov 18 2023 Key Messages: 1. Dry Sunday and much of Monday with above normal temperatures. 2. Favorable pattern for strong south to southeast winds in the foothills and east Tennessee mountains Monday night into Tuesday. 3. Significant rainfall looks likely Monday night through Tuesday night. 4. Dry for Thanksgiving Day and Friday with temperatures just a bit below normal. Discussion: We start the period under the influence of an upper ridge and surface high pressure. Sunday will be dry with temperatures a little above normal, and with low afternoon RH values bottoming out from the mid 20s to the mid 30s across much of the area. The upper ridge and surface high pressure will shift to our east by Monday. Models are still struggling with the details of the complex system that evolves to our west, with the GFS often showing less phasing of the southern stream and northern stream energy, while the Euro has been more on board with the two systems getting in phase and a more vigorous surface low developing. While there is still considerable spread, there is also quite a bit of support among the ensemble members for the stronger solution, and confidence is nudging upward for the possibilty of a significant mountain wave event mainly Monday night into Tuesday as a surface low likely tracks by to our west and northwest and 850 mb flow likely approaches or exceeds 50kt across the mountains from the S and/or SE. Given the ongoing serious drought and the most likely scenario of the rain holding off for at least the first part of the potential high winds, there remains a threat of a period of increased fire danger mainly along and just to the west of the E TN mountains. The wind threat and fire danger threat will continue to be highlighted in the HWO. The good news is models also continue to show our first significant rainfall in quite some time occurring with this system, and current QPF shows amounts between 0.75 and 1.5 inches across most of our area by the end of Tuesday night. Cooler and drier are expected to be moving in on Wednesday behind a cold front. The operational GFS looks to be a bit of an outlier in keeping more energy hanging back and showing a wetter solution for Wednesday, and for now will just keep some low PoPs for a few lingering showers. Thanksgiving Day and Friday look to be dry with temperatures just a bit below seasonal normals as surface high pressure builds in. && .AVIATION... (12Z TAFS) Issued at 619 AM EST Sat Nov 18 2023 MVFR conditions at KTRI will continue for the first few hours of this TAF cycle. Expect a general lifting and clearing of the cloud deck during the morning with prevailing VFR conditions and light winds for much of the day. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 67 42 66 47 / 0 0 0 10 Knoxville McGhee Tyson Airport, TN 63 37 63 43 / 0 0 0 0 Oak Ridge, TN 62 37 63 42 / 0 0 0 0 Tri Cities Airport, TN 58 31 61 37 / 0 0 0 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...Diegan AVIATION...