Issued: 2pm on Wednesday, August 19th 2020
Technical Forecast Discussion
Short Term (Wednesday 8-19-2020 through Saturday 8-22-2020)
Large scale subtropical troughing is expected to continue over the next 48 hours. This is being greatly influenced by a VORT max located in the central gulf, and Mississippi valley states, along with a strong closed upper low and its associated PVA forcing a positively tilted northern branch of a trough. While the northern branch will be driven eastward by PVA downstream, and NVA upstream, The southern branch looks to remain stationary–being more affected by tilting than propagation forcing. NVA over the majority of Ohio will slightly raise heights going into the next 12-24 hours. Increasing differential thickness advection will work to slightly tilt the southern trough more neutrally over the next 24-48 hours. Expect temperatures across the state to remain moderate as this southern trough remains stationary–however, highs will not be quite as cool as they have been over the past several days. Expect highs in the latter part of the week to reach the middle 80s (with a few upper 80s scattered throughout the area). A VORT axis (coming off the southern trough) will advect into the area Thursday night into Friday morning. A vertical PGF will drive sfc confluence along this feature, promoting the genesis of a weak quasi-stationary warm front. This front will move north into the area early Friday morning, and will set itself up along the I-70 corridor by noon Friday. Behind this front, sufficient WAA will provide a source of negative omega, and produce mainly light showers (with a possible rumble of thunder or two). These showers and thundershowers should be ongoing into Friday night to Saturday evening as the southern VORT max is advected further northward during this time. Highs should be in the lower and middle 80s with a few upper 70s because of this precipitation.
Long Term (Sunday 8-23-2020 through Tuesday 8-25-2020)
Inconsistencies exist in the long term with respect to the depth of the upper low. This is due to disagreement on the extent of increasing differential thickness advection with this upper low and associated trough. Should this upper low become closed, a tight height gradient would drive an upper jet streak, causing cyclogenesis at the left exit of this feature Saturday night into Sunday over the southeastern states. This would keep precip chances high until at least Monday across the forecast area. However, after this feature propagates eastward, strong NVA will eventually build a ridge into the area. This will occur Monday night into Tuesday. This will cause temperatures to reach back into the upper 80s and lower 90s toward the middle of next week. Due to the lack of vorticity advection, and therefore lack of negative omega, skies should remain mainly clear to partly cloudy after Sunday’s rain through the middle of next week.