MESH high ProbHail Moderate

At 2120z SFX radar depcited a potentially severe thunderstorm located SW of Pocatello.  At this time, nearly 50 dBZ returns were observed in excess of 35kft.  The -20C level was approximately 17kft.  The MESH readout in ProbSevere showed 1.59″.  However, ProbHail was only 55%.  This appears to be a case where the ProbHail algorithm was reducing the probability based on the environment despite several aspects that support issuing in warning for severe hail.  A warning was issued for this storm at 2101z.

2120z SFX 0.5 radar.
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EWX ProbHail Case

Had an interesting opportunity to watch a quickly intensifying cell relatively close to the radar.  While ProbHail did a decent job monitoring the trend in this cell, its (2 to 4 minute) latency in an environment conducive of rapidly intensifying cell could possibly lead to a reduction in Lead Time. By monitoring the cell via All-Tilts BR/BV/CC/ZDR and GOES-East Satellite Imagery via Mesosector, I was able to get roughly 5 additional minutes of lead time on my warning (ProbHail was less than 45% by warning issuance). A good reminder as to how the ProbSevere suite is best utilized as an additional tool, and not necessarily the deciding factor in warning ops, especially in freshly forming cells.

Quick update: The earlier warning did verify with quarter-sized hail. I did find some utility with the ProbHail when it came to making the decision to re-issue the warning or not, especially as the storm began to near the “cone of silence.” Accessing the time series  which continued to show >95% ProbHail and a quick glance at a neighboring radar, I had enough forecasting confidence to continue the warning downstream.

—————————————————————————————————- Mountain Bone

SVR issued more because of previous reports

Had separate reports of 51 and 58 mph from earlier storms in the area.  ProbSevere wasn’t very high in those cells, and neither was the lightning FED.  Given a high DCAPE environment, decided to pull the trigger a little earlier on some of the stronger cells going up.

Charley

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All Sky LAP CAPE Too High?

Just prior to 20z the All Sky LAP CAPE shows 1000-1200 J/kg of CAPE across eastern ID.  However, most of this is in a cloudy or GFS layer depiction.  Looking at the GOES 16 derived CAPE, it only shows a narrow region a calculated data in eastern, ID that is about half (500-600 J/kg) of what is shown by the All Sky LAP.

All Sky LAP CAPE.
GOES 16 CAPE.
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Convective Threat for Eastern, ID

The day convection RGB depicts stronger updrafts moving from northern UT to southern ID as of about 2030z.  This area is under a severe thunderstorm watch with no warnings in effect at this time.

Day Convection RGB loop.
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