... Daily showers and thunderstorms will steadily become more numerous as the week progresses. High temperatures of a couple degrees above normal through Wednesday will become near to below normal by the end of the week with the deeper moisture and considerable cloud cover.
NEAR TERM /THROUGH TONIGHT/... As of 1045 AM EDT Wednesday: Good insolation this morning is permitting temperatures and instability to get off to a quick start. Have adjusted maxes up a degree in most areas for the afternoon hours. SBCAPE analysis reveals plenty of 2000+ J/kg areas already this morning. Some modest dewpoint mixing is possible from the west, but weak low-level convergence and near 70 dewpoints will provide for early afternoon triggering in the Piedmont, with differential mountain heating supplying similar timing along the ridges. Thunderstorm coverage should peak in the high scattered to numerous PoP range mid to late afternoon. Expect gusty winds with any 55+ dBZ cores reaching near 28 kft, but modest sfc to mid-level theta e lapses and DCAPE should limit the severe scope quite a bit. Any storms will be slow-movers with a localized hydro threat with any training.
Otherwise, mid to upper heights will recover modestly over the fcst area today as heights fall to our west over the Mississippi River Valley ahead of a weak cutoff low. East of this system, scattered evening convection could linger into the overnight as weak low-lvl convergence persists across the CWFA. Mins will run slightly above climo once again.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 320 am Wednesday: The main driver of the weather across our area...indeed across much of the Southeast during the late week will be a upper vorticity center over the western Ohio Valley and associated frontal zone extending from the lower Miss Valley into the Mid-Atlantic. As the vorticity center drifts slowly east through the period, forcing and moisture will increase across much of the region, with precipitable water values likely reaching...if not exceeding 2" across much of our area during the Thu/Fri time frame. Although the better forcing will still be west of the area through much of Thursday, ingredients should support high coverage of mainly diurnal showers and storms. The main threat Thu into Thu night...as it will be for much of at least the next 5 days...will revolve around the potential for locally excessive rainfall. On Thu, this threat will be largely driven by the high number of showers/storms, anticipated warm rain processes/efficient rainfall producers, and slow cell movement, as forecast soundings depict average LCL-EL mean wind of < 5 kts. However, as time goes on, a more organized excessive rainfall threat could emerge Thu night through Fri night, when guidance is in generally good agreement in lifting a surface wave west of the Appalachians, which would tend to focus low level forcing and relatively strong SE upslope flow into southwest NC. While most guidance sources reflect this "big picture" scenario, differences in the intensity and atmospheric response to the key features is significant among the various solutions, so an organized hydro threat is by no means a slam dunk, but the signal is there. Otherwise, high pops...generally 60-80% are carried through the period. Although the highest pops are tied to the afternoon/evening peak of the diurnal heating cycle, convection will be possible, if not likely well beyond this window. Max temps will be near to slightly below climo and min temps above climo through the period. LONG TERM /SATURDAY THROUGH TUESDAY/... As of 340 am Wednesday: Very unsettled weather will persist into at least the early part of the medium range, as the upper vorticity center of the short term period, which is forecast to be more or less evolved into a bonafide trough by the start of the medium range, will still be to our west, supporting continued tropical moisture and respectable forcing over the forecast area. This will support continued high pops...generally 70-80% on Saturday, with a continued excessive rainfall threat, which is likely to increase with each day as antecedent conditions steadily deteriorate. However, as the weekend progresses, the GFS and ECMWF are somewhat converging toward a consensus in progressing the trough across the region and shoving the moisture plume east by Monday. Thus, the forecast will feature a gradual downward trend in pops for Sun-Tue, also with a trend toward more of a typical diurnal convective cycle. However, the details of this trend toward less active weather remain very much up in the air. Temps will begin the period below normal, but gradually trend back toward climo with time.