ProbSevere time series tool

At the 2021 HWT, forecasters will be able to use a new feature of the ProbSevere AWIPS plug-in: a time series tool. Forecasters from previous HWTs have consistently given positive feedback on a web-based meteogram tool, and so we have implemented something similar in AWIPS. 

To use it, you simply double-click on a ProbSevere object, and a window opens up with the time series of ProbHail, ProbWind, ProbTor, and ProbSevere (prob. of any hazard) for the given storm. We hope this will help forecasters better monitor the trends in hazard probabilities.

Figure 1: A severe-hail-producing storm in northeastern North Carolina, and the associated history of its ProbSevere probabilities in a time series window (ProbSevere was equal to ProbHail for this storm).

ProbSevere v3 will also be demonstrated at this year's HWT. PSv3 is driven by a new statistical model (gradient-boosted decision trees) and incorporates new MRMS, ABI, GLM, and SPC mesoanalysis data. This storm was warned at 17:31 UTC, and produced 1-inch hail at 17:38 UTC. At 17:26 UTC, ProbHail v3 jumped to 25%, whereas v2 was only 4%. ProbHail v3 might have been able to highlight this strengthening storm to the forecaster, whereas version 2 did not. A predictor importance analysis of ProbHail v3 for this storm at 17:26 UTC revealed that the highest contributing predictors were:

1. MRMS reflectivity at -20C (52 dBZ)

2. Eff. bulk shear (40 kt)

3. MRMS composite reflectivity (66 dBZ)

4. MRMS MESH (0.55 in)

5. Wet-bulb 0C height (7180 ft)

We expect that ProbSevere v3 will be more accurate and better calibrated than ProbSevere v2, meaning the probabilities more closely match severe report occurrence.