Convection over the PIH CWA was fairly shallow today due to the limited instability. That being said, strong DCAPE developed, owing to pronounced Inverted-V profiles. The line of storms that developed was able to produce significant wind gusts, with multiple reports of 70 to 80 mph winds.
Satellite products were not particularly helpful in knowing what storms to issue warnings on due to the shallow nature of the convection. The loop below shows visible, IR, and water vapor imagery for the area of interest around the time we issued our first warning.
Figure 1 - Satellite imagery over the PIH forecast area around the time of warning issuance.
The thing that really stands out is that everything looks about the same. No single storm stands out as being particularly tall or possibly severe. The same is true when we look at the OCTANE Cloud Top Cooling product.
Figure 2 - Cloud Top Cooling around the time of warning issuance.
There was never a value of more than 3°C per 5 minutes over any of the developing convection, indicating the weak instability present. This doesn’t help much in figuring out what storms we need to focus on.
So we turned to radar. The KSFX radar showed an area of 50 knots inbounds associated with an area of higher reflectivity. This led to us issuing the first severe thunderstorm warning of the day.
Figure 3 - KSFX radar loop showing base velocity around the time of warning issuance.
After this, it became clear that almost any shower in the area was capable of producing severe wind gusts due to the favorable low-level thermodynamics and we began looking for similar looking signals in the satellite and radar products. We then issued several more severe thunderstorm warnings as the line progressed eastward.
-ei2018
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