Area Forecast Discussion
Issued by NWS Nashville, TN
Issued by NWS Nashville, TN
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619 FXUS64 KOHX 241443 AFDOHX Area Forecast Discussion National Weather Service Nashville TN 943 AM CDT Tue Sep 24 2024 ...New UPDATE... .UPDATE... Issued at 926 AM CDT Tue Sep 24 2024 At mid morning, scattered showers were occurring mostly in a band from Lafayette and Gallatin, southwest across Nashville Metro, with a few stragglers around Columbia and Lawrenceburg. There have been some local downpours and lightning strikes this morning, but nothing major so far. We continue to be under a marginal risk today (level 1 out of 5) for severe storms with gusty winds. Outside the noted shower areas, there were a lot of breaks in the clouds. These breaks will allow recovery and heating, so conditions will destabilize as we go into the afternoon. 1500-2000 J/kg ML cape still looks on target today. The biggest differences from previous days will be more forcing and much more shear. A couple of impulses will precede an approaching surface front. Also, shear will strengthen with 40KT deep layer shear and 500mb winds reaching 50KT. These factors will boost storm coverage and potential for embedded damaging wind gusts. Short range models seem to depict the general scenario well, although placement of main bands may be off somewhat. Generally, bands of showers and storms will fire up this afternoon with the main focus over our northwest counties just after lunchtime. Then the focus will shift to Nashville Metro southwest to Lawrenceburg area mainly 2 PM to 8 PM, then gradually shifting east of I-65 into the evening from 6 PM to midnight. && .SHORT TERM... (Today through Tonight) Issued at 109 AM CDT Tue Sep 24 2024 Water vapor imagery this morning shows an upper-level trough digging into the Great Plains while surface obs reveal a cold front to our west over Missouri & Arkansas. As this front pushes into the area today, storm coverage will increase across Middle TN. With SBCAPE of 1500 to 2000 J/kg and bulk shear increasing to 30 to 40 knots, a few of these storms may become strong to severe this afternoon. Main risk will be gusty to damaging winds. Hail looks to be unlikely as lapse rates will be poor at less than 6 C/km. Main time frame for severe thunderstorm potential is between 1pm and 8pm. Meanwhile, temperatures will start to cool thanks to increased cloud cover and the rain. A few showers may linger overnight, especially across the Plateau where the cold front looks to stall. && .LONG TERM... (Wednesday through next Tuesday) Issued at 109 AM CDT Tue Sep 24 2024 A more active week is still on tap. Starting Wednesday, another upper-level low dives southward into northern Arkansas and stalls in this area through the weekend. Meanwhile, eyes are also on the tropics as PTC9 is forecast to strengthen over the eastern Gulf this week, eventually becoming Hurricane Helene. It`s expected to make landfall on the Florida Panhandle Thursday, and then gradually weaken as it tracks northward into eastern TN Friday. Once the remnants of the tropical system move out the area, the low over AR will finally eject towards the northeast, clearing Middle TN by Monday or Tuesday. These two systems will bring rounds of rain to Middle TN through the remainder of this forecast period. Best chance for heaviest rainfall will be on Thursday & Friday thanks to the tropical moisture moving into the area, and with the track of future Helene to our east, it`ll be eastern Middle TN that will be favored for the highest rainfall amounts this time. The latest rainfall forecast is still showing a general 2 to 4 inches through this upcoming weekend with higher amounts possible across the Plateau. Minor flooding could be a concern by week`s end, but widespread flooding is currently not expected as the current drought status means that our rivers and creeks will have room for the welcome rain. But of course this forecast will continue to be refined as the future tropical system takes shape over the next few days so stay tuned. && .AVIATION... (12Z TAFS) Issued at 618 AM CDT Tue Sep 24 2024 A band of showers is marching across Middle Tennessee this morning, so we`ve got TEMPO -SHRA in for a couple of hours while the cells make their way through. We expect additional convection this afternoon, as the atmosphere is already showing some instability in place. As the surface boundary that is instigating this activity makes its way eastward overnight, look for additional showers and maybe some fog and low ceilings, especially after 06Z. && .PRELIMINARY POINT TEMPS/POPS... Nashville 86 67 79 65 / 70 50 50 50 Clarksville 82 62 78 61 / 70 40 30 40 Crossville 83 61 74 59 / 60 80 80 70 Columbia 86 64 78 61 / 80 60 60 50 Cookeville 83 63 75 62 / 80 70 70 70 Jamestown 82 62 74 61 / 80 70 70 70 Lawrenceburg 87 64 76 61 / 70 70 60 50 Murfreesboro 87 66 78 63 / 80 60 60 60 Waverly 82 62 77 60 / 80 40 30 40 && .OHX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.......13 SHORT TERM...Clements LONG TERM....Clements AVIATION.....Rose