3:00pm - Saturday 8/11/2018 - Chief Meteorologist Chris White
Good afternoon. Thunderstorms have developed again this evening with the heating of the day. These storms are producing rainfall rates over 1.5 inches per hour and isolated cores are producing rates near 2 inches per hour. This activity should continue to move ESE at 10mph, limiting flooding concerns to only isolated issues. That rainfall will continue to cause ponding of water on roadways though so travel with care. Remember turn around and don't drown.
Overall a surface stalled frontal boundary is stretched just to our East along roughly I-85. A trough is moving SE from the Great Lakes and an upper low will develop near Ohio on Sunday. Sunday afternoon a piece of energy will move toward our area. This will approach at about the same time thunderstorms erupt across the mountains. Due to this we will advertise higher rain chances on Sunday Afternoon. This convection will start across the mountains and spread East from there, across our western counties first, and then across our eastern counties. A few of these storms will be strong and possibly severe as well. Damaging straight line winds will be the severe threat from microbursts. There will be a risk of flash flooding too as these storms Sunday Afternoon cluster together. Although the threat will be low overall, areas that have seen high rainfall amounts this week will be more susceptible. The storms should become even more widespread and slightly stronger once they move East of our area. High temps Sunday will remain about where we are at this afternoon, mid and upper 80s's with heat indexes in the low and mid 90's.
On Monday another piece of energy will move into the area and this will lead to more scattered showers and thunderstorms. I think the best chance of seeing severe weather on Monday will be along and SE of I-85, out of our coverage area. High temps on Monday should top out in the upper 80's.
By Tuesday that stubborn stalled front will finally start to move out and the upper level low will start to move out of Ohio to the NE. This means better weather on Tuesday but still expect at least isolated thunderstorm coverage (20-30%). High temps on Tuesday will be around 90 degrees with heat indices nearing 100.
Great news for Wednesday if you are looking to take a day off this week. Dry weather is forecast and will take rain chances down to 5% in our area, just to allow for any shower that may move off the high elevations. Almost everyone will remain dry on Wednesday will be in the upper 80's to around 90 degrees with plentiful sun.
That will not last though. Thursday that brief ridge of high pressure that should keep us dry on Wednesday will move away and our next weather system approaches. Will advertise isolated to widely scattered showers and storms. Temps should still climb up to around 90 degrees.
Friday and Saturday things turn wet and stormy again across the area as a cold front moves in. There should be abundant moisture stream back into the area along the front. Friday really is taking on the look of a weather ready action day for strong storms and torrential rainfall. A lot will depend on timing of the front, how much sun we see early, and how Gulf of Mexico moisture plays into the equation. So as it normally is late in the forecast period, there are a lot of things to look at and changes to adapt with over the next few days. My concern is the heavy rainfall threat more than the severe storms. Our area has been doused with torrential rainfall and high rain totals the last two weeks. This is something that we will really need to pay attention too and High Impact Weather Briefings will be started on Monday Morning for our emergency management partners.