Issued: 3pm on Sunday, August 2nd 2020
Technical Forecast Discussion
Short Term (Sunday 8-2-2020 through Tuesday 8-3-2020)
A deep shortwave trough is currently set up over the forecast area. A closed upper low at 700 mb and its associated VORT max is sitting just to our northwest over SE Michigan and NW Ohio. This feature will be advected off to the east and undergo phasing with a stronger closed low further northeast over the eastern Hudson Bay. However, due to the highly amplified nature of this trough (and ridge off to the west), Retrograding of the low will occur (because of its primary source of VORT coming from planetary VORT). This will leave a relatively comfortable pattern over the forecast region for the next 36 hours or so. Continued increasing differential PVA, and WAA will bring about stratiform, and perhaps a few areas of convective precip chances across northern, and southwestern Ohio Monday. Decreasing differential WAA over Quebec will allow the broadly closed upper low to begin to start filling in as it retrogrades back south and westward by early Tuesday morning. This largely positively tilted trough will begin to take on a neutral tilt due to decreasing differential CAA upstream, and strongly increasing differential WAA downstream of the feature. This will also cause deepening of the closed upper low, which will be located over lower Michigan at this point. While this is occurring, the remnants of hurricane Isaias will be travelling up the east coast, and should reach the Chesapeake Bay region by 2 PM Tuesday. A jet streak associated with the aforementioned trough will cause weak cyclogenesis in the right entrance. This will quickly undergo phasing with Isaias’s remnant cyclone. Questions remain on whether or not phasing will occur too quickly to bring about frontogenesis across eastern Ohio Tuesday afternoon. Because guidance is still showing a moderate VORT max over eastern Ohio Tuesday afternoon, I do believe a brief, weak, and shortly lived cold front will be able to form across much of eastern Ohio. Given sufficient MLCAPE values, convection will be able to initiate mainly east of I-77 (further north), and OH-13 (further south). With dry mid-levels, an isolated damaging wind threat can’t be ruled out with thee storms, likely forming into a disorganized mess. Predictability is quite low at this time, so monitor the latest forecasts.
Long Term (Wednesday 8-5-2020 through Saturday 8-8-2020)
Strong PVA, pointing northeastward will advect the trough out of the forecast area by Tuesday night/Wednesday morning. A brief period of NVA will cause slight height rises over the state before the next disturbance comes through. This should make for a somewhat calm day on Wednesday, with mainly partly cloudy skies and highs likely in the upper 70s and lower 80s. Wednesday is the day to be out in about across SE Ohio. However, weak PVA that will come off the mountains will bring about another period of slight height falls Thursday. However, with a lack of a strong height gradient due to weak baroclinicity aloft, a strong jet max is not expected to form, hindering any positive forcing for cyclogenesis or strong upward motion. However, a very isolated shower can’t be ruled out Thursday into Friday due to weakly negative omega brought about by weakly increasing differential PVA and weak WAA at 500 mb. After this disturbance passes by Friday evening, NVA will raise heights across the area throughout the day Saturday. This will bring back the middle and upper 80s to the area, with mainly dry conditions and sunny skies.