5/5 – The Chief’s “Marginal Severe Threat” Cinco De Mayo Morning Forecast
A very persistent pattern of weak upper level high pressure with passing disturbances will continue through the Lower Mississippi Valley. This pattern will be in place today through Sunday. This onshore flow regime will advect in a substantially more humid airmass into the area today and tomorrow, and this higher humidity will persist through the remainder of the weekend. Temperatures will remain above normal through the period with highs in the mid to upper 80s largely due to the weak subsidence associated with the ridging aloft. Subsidence will be more pronounced on Sunday as the ridge strengthens slightly, and any passing vorticity maxima shift more toward the I-20 corridor. Overall, the pattern is more reminiscent of early Summer rather than mid- Spring.
Convection will be entirely dependent on the timing of each upper level disturbance passing through the area. A front to the west will serve as the focusing mechanism for any convection that develops mainly from late morning into the afternoon hours as instability increases. There will be a low risk of an isolated severe storm forming today. Today will be the highest potential for severe storms as mid-level lapse rates become less supportive tomorrow. Any convection will quickly dissipate in the evening hours as temperatures cool into the 70s and instability wanes.
Tomorrow will see another disturbance pass directly over the forecast area. Increasing mid-level moisture combined with the weaker lapse rates will lead to a lower wind threat tomorrow. Once again, the convection will quickly come to end in the early evening hours as temperatures cool and instability wanes.
Sunday will see increasing high pressure and subsidence build over the area, and this will greatly limit the convective potential for the day. This increasing subsidence will be most felt along the coast, and have rain chances down to 20%.