Dangerous heat, severe storm threat

Nicole Madden,

AM Weather Headlines:

  • Heat Advisory until 8pm

  • Blistering Heat Returns

  • Storms Explode This Afternoon

  • Severe Threat Possible

    • Damaging Wind Concern

  • More Typical Summertime Pattern Late Week

Discussion:

We’re back in the upper 90s to near 100 this afternoon, and with dewpoints holding in the 70s, the heat index will feel more like 105–108 across much of the region. A Heat Advisory is in effect until this evening, and after another night of lows only dipping into the mid 70s, the body hasn’t had much time to recover. This prolonged stretch of heat can be dangerous, especially for anyone without access to A/C.

The ridge that’s been sitting over us is finally starting to weaken, which means the cap that’s been keeping storms from forming, will start to break. This will set the stage for an upper level low to slide in over the southeast from the Bahamas adding lift and just enough instability aloft to spark scattered to widespread storms. Storms will likely backbuild from the northeast into the southwest due to the steering flow from this retrograding low, rather than the northwest to southeast which is what we usually expect. 

Storms will begin scattered and could merge into clusters or a line, but with high heat and moisture at the surface and dry air aloft, it’ll be just unstable enough for storms to collapse violently with downbursts a real concern. Storms will likely begin to fire up after 2-3pm and could linger past sunset. The biggest concern will be damaging straight line wind gusts, but isolated large hail and localized flooding from heavy downpours will also be possible. 

Late week will Thursday still be hot with highs in the low to mid-90s, but it won’t feel as extreme. We’ll keep a daily chance of afternoon storms, especially in the mountains and foothills, with heat index values still pushing into the triple digits. A Rex Block will likely block us into this pattern by the weekend, but by early next week, a weak cold front may help to increase storm coverage by Monday and Tuesday.