Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
020 FXUS64 KMRX 011833 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 233 PM EDT Thu Oct 1 2026 ...New DISCUSSION... .KEY MESSAGES... Updated at 232 PM EDT Thu Oct 1 2026 - Chances for showers and isolated storms will increase tomorrow and through the weekend with locally heavy rainfall possible. - Drier and cooler conditions will return next week. && .DISCUSSION... Issued at 232 PM EDT Thu Oct 1 2026 Currently, broad ridging is in place across the eastern U.S. with a 5,920m 500mb high along the Carolina Coast just west of Bermuda high pressure. A closed low is also ejecting just east of the Rockies with a surface low also having developed. For our local area, this pattern has continued the dry and warmer trend seen in the past several days to start the period. Heading into tonight, the closed low will lift to the north with the surface low weakening. Increasing frontogenesis is expected to the north and east following continued southerly flow from the Gulf and approaching Canadian high pressure. This will also lead to increasing moisture. During the day on Friday, a downstream upper jet will move to our north with the surface front approaching the Ohio River Valley. This will increase overall synoptic-scale lift with sufficient moisture leading to a return of rain chances, mainly north of Interstate 40. With poor lapse rates below 5 C/km and instability of 250 to 500 J/kg, at least isolated storms can be expected. By Saturday, another downstream jet will move closer to the region, along with the surface frontal boundary. By this time, significant moisture will be in the region with PWAT values approaching 1.8 inches, near max values for this time of year. Mid-level lapse rates are also expected to rise up to 5.5 C/km. By Sunday, the front will remain nearby but with stronger upper divergence aloft. Given these indications, higher area-wide rain can be expected with locally high amounts possible. Based on what the RRFS is showing, coverage looks to be higher on Sunday, in line with the upper jet strength. Isolated flooding remains possible, but this will depend on which places see repeated rainfall. By Monday, the high pressure to the north will be progressing into the Great Plains, pushing the frontal boundary to our south. Other than some lingering chances in the south early, drier and cooler conditions can be expected. This will be especially true by Tuesday night into Wednesday morning when the high is just to our north and east. Overall, daytime highs look close to normal in the 70s, but overnight lows could drop well into the 40s with the radiational cooling. && .AVIATION... (18Z TAFS) Issued at 106 PM EDT Thu Oct 1 2026 Main concern is potential of fog development at TRI. Any steam fog may move into the terminal early Friday morning. Confidence is too low to include. Otherwise, VFR conditions with surface and upper ridging keeping things quiet. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 67 91 70 87 / 0 30 20 60 Knoxville McGhee Tyson Airport, TN 65 89 68 83 / 0 20 40 70 Oak Ridge, TN 64 87 67 81 / 0 30 50 70 Tri Cities Airport, TN 59 85 64 77 / 0 10 50 80 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DISCUSSION...BW AVIATION...DH