Area Forecast Discussion
Issued by NWS Nashville, TN
Issued by NWS Nashville, TN
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788 FXUS64 KOHX 250105 AFDOHX Area Forecast Discussion National Weather Service Nashville TN 805 PM CDT Tue Sep 24 2024 ...New UPDATE... .UPDATE... Issued at 750 PM CDT Tue Sep 24 2024 Scattered showers and storms are continuing to push across Middle Tennessee with the last line extending from Perry County northeastward to Robertson County. The trend of that line has been downward over the last 30 minutes. IR satellite have shown a general warming of cloud top over the last hour. The 00z OHX sounding shows MUCAPE values still above 1000 J/kg but mlCAPE around 500 J/kg which indicates that the low levels have been fairly worked over. Some gusty winds may be possible with the strongest cells over the next hour or two but I`m not expecting anything severe. Shower and storm coverage will decrease as we approach midnight. Some additional showers should begin to lift into the area from the south late tonight into tomorrow as upper level energy pivots around the upper low. The forecast is on track and no major changes were made. && .SHORT TERM... (Rest of today through Wednesday) Issued at 1114 AM CDT Tue Sep 24 2024 After parts of the area had morning showers and a few storms, much of Middle Tennessee was experiencing a midday break. We do expect showers and storms will build up again through the afternoon and we continue to be under a marginal to slight risk (level 1 to 2 out of 5) for severe storms with gusty winds. Variably cloudy skies will allow for periods of sunshine and heating into the 80s this 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. The tornado risk is very low, but not zero. Short range models seem to depict the general scenario well, although exact timing and placement of main bands may be off. Generally, bands of showers and storms will fire up this afternoon with the main focus over our northwest counties starting 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. The front moving in today will stall out tonight and Wednesday as an upper level low pressure system cuts off just to our west. This will keep showers and a few storms scattered across the area tonight through Wednesday. The extra clouds and scattered rain will limit Wednesday`s temps to the 70s for most areas. As shower activity lessens in the nighttime hours, some partial clearing and patchy fog will form. && .LONG TERM... (Wednesday Night through next Tuesday) Issued at 1114 AM CDT Tue Sep 24 2024 Confidence continues to increase for soaking rainfall late this week as the remnants of tropical system Helene impact the region. The center of Helene is expected to move onshore Thursday evening along the Florida Gulf Coast as a major hurricane. By that time, heavy rain and gusty winds will have spread well north of the center as the tropical moisture begins to interact with the cutoff upper level low just to our west. The best time for widespread and possibly heavy rainfall will be Thursday afternoon through Friday morning. Although the heaviest rain with Helene is expected to our east, Middle Tennessee is still in line for 2 to 3 inches of rain Thursday afternoon into Friday morning based on the latest WPC QPF. The higher end amounts are expected over the Plateau. Additional showers outside that time period could push the late week event totals toward 4 or 5 inches. However, if the track is farther east or the main swath of rain moves through quickly, event totals could be lower. Model statistics give us at least 80 percent chance for more than 1 inch late this week, so we should be excited for some drought relief. After the main swatch moves through by Friday afternoon, we will have on and off scattered showers through the rest of the weekend. && .AVIATION... (00Z TAFS) Issued at 624 PM CDT Tue Sep 24 2024 Showers and a thunderstorm could impact BNA/MQY/CSV/SRB through the evening hours before rain chances decrease. Models show MVFR, possibly IFR stratus developing behind a weak front that will move through the terminals overnight. Showers will lift from the south and should impact SRB/CSV near dawn and continue off and on through the rest of the forecast period. The shower activity will likely reach BNA/MQY during the afternoon. CKV will remain dry for the taf period. Winds overnight and through the day on Wednesday are expected to be 5 kts or less. && .PRELIMINARY POINT TEMPS/POPS... Nashville 67 80 64 78 / 60 50 40 90 Clarksville 62 79 59 78 / 30 30 30 80 Crossville 61 72 57 70 / 80 80 70 100 Columbia 65 79 59 75 / 60 40 40 90 Cookeville 64 73 60 72 / 70 60 60 100 Jamestown 62 73 59 71 / 80 70 70 100 Lawrenceburg 65 78 59 74 / 60 50 50 90 Murfreesboro 65 79 61 76 / 60 50 50 100 Waverly 62 78 58 77 / 30 30 30 80 && .OHX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.......Reagan SHORT TERM...13 LONG TERM....13 AVIATION.....Reagan