7/7 – Rob Knight’s “Summertime Pattern” Thursday Afternoon Forecast
High pressure will continue to shape the forecast into the weekend. As an upper level disturbance digs through the Great Lakes and Ohio River Valley, it will push a weak frontal boundary toward the area. But it will take until Saturday afternoon for it to get anywhere close to us.
With convective temperatures forecast to be in the lower 90s each day, anticipate isolated to scattered convection to develop by about midday each day, dissipating around. Wind fields remain very light and shear is limited across the area, so the main concern this afternoon and tomorrow will be isolated spots of very heavy rainfall. On Saturday, as the frontal boundary tries to work into the area, shear might be a little better across the northeast half of the area, but not remarkably so.
We’ll also have to keep an eye on heat index values the next few days. The max heat index values are creeping up toward the 108F criteria we generally use for advisories briefly each day, with potential for them to be exceeded in a few areas Friday and Saturday if thunderstorms are slow to develop. Day shift can reassess this for the afternoon forecast package. Sunday into next week, there will likely be daily round of showers and storms once the convective temperatures are reached. That’s around 90 degrees Sunday and Monday, but more likely to be in the 80s Tuesday and Wednesday. Similar to Saturday, there’ll be at least a small threat of gusty winds Sunday and Monday, but that threat diminishes beyond that point.