1. A “cap” in the atmosphere – exactly like a lid on a shaken soda bottle – could keep strong to severe storms from ever forming in parts of our area today and tomorrow. The strong cap mainly applies to parts of the Austin metro and our eastern counties, where cloud cover has kept the surface from heating up much today.
From Meteorologist David Yeomans early Thursday afternoon: “The NWS is sending up a special weather balloon any moment, and also analyzing aircraft soundings, to see if this (cap) is starting to show signs of breaking.”
As of Thursday evening, the cap is still in place, and likely to hold. That means a mainly dry evening for us, but any storms that do develop have the potential to become severe quickly, with large hail and damaging winds.
2. That said, we are still in a Marginal (1 out of 5 on the severe weather possibilities scale) to a Slight (2 out of 5) risk of developing damaging winds and large hail over the next 48-72 hours. Best windows of opportunity will be late Thursday evening into Friday morning, again Friday afternoon and then Saturday afternoon. Most activity will be isolated, but still could have a high impact. It’s import to keep your eyes to the sky the next few days.
3. We are not in the highest risk area. Unfortunately, our friends and neighbors in Kansas and Oklahoma are under a High Risk (5 out of 5) of severe weather development tonight. A “major severe weather outbreak” is possible, according to the Storm Prediction Center. So far in 2017, 34 people have died from tornadoes. Fewer than 20 were killed in all of 2016.
4. We need the rain. So far in May, Camp Mabry, Austin’s official reporting site, is 2.01″ behind monthly expectations. We have received just over a third of an inch of rain, and by the end of the month we normally expect to see about four and a half inches. We have the potential to make up those totals in just the next 3-4 days, if these systems continue on their current track.
5. Threats are divided. The risk for strong to severe storms stops after Saturday, and our threat transitions into a heavy rain one, with a slow-moving cold front that could stall in our area, creating storms in the same spots for multiple hours. Up to 4-5 inches of rain are possible by the end of this weekend, mainly over the Hill Country. Austin could see 2-3 inches of rain. It would take 3-4 inches falling in one hour anywhere in Central Texas to trigger a Flash Flood Warning, which is possible, though not very likely.
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