A cold front swept into New England on July 16, forcing severe “thunderstorms” in a low-CAPE environment. Thunderstorms is in quotations because many areas experiencing wind damage had no lightning. Most storms had lightning activity of 0 or 1 flash/minute. In fact, I only found 2 storms with more than... Read More
A mesoscale convective system (MCS) traversed the state of Alabama producing at least 200 damaging wind reports.Here is the SPC outlook discussion for this region. Interestingly, the western threat (in MO/AR) didn’t materialize nearly to the extent of the MCS in Alabama. The MCS was characterized by lots of CAPE... Read More
Numerous storms formed in the Pacific Northwest under dry microburst conditions, with relatively high CAPE for this region (500-1300 J/kg). One area of convection in southwest Idaho was moving northwestward. The ProbSevere v4 model tracked it very well with high probabilities before wind gust reports of 60-72 mph. It’s unclear... Read More
Moderate shear and moderate CAPE ahead of a shortwave trough produced numerous storm clusters in the Mid-Atlantic states. ProbSevere v4 captured the severe portions of these clusters fairly well (see below). There were some missed wind reports, but higher probabilities generally corresponded with NWS severe thunderstorm warnings quite well. In... Read More
LigthningCast v2 (LCv2) incorporates MRMS Reflectivity -10oC as a predictor alongside the GOES-R ABI predictors of LightningCast v1 (LCv1). Overall, we’ve found that LCv2 markedly outperforms LCv1. Below is an example in Oklahoma and Kansas where thick cirrus is obstructing the ABI’s view of developing convection underneath. LCv2 (on the... Read More
A number of convective clusters formed across a moist and moderately sheared airmass on May 23 and 24. Here are a few examples of ProbSevere v4 output. Please note that reports are valid for the 45 minutes after the image time. In Louisiana, PSv4 initially did an excellent job predicting... Read More
As noted in the SPC discussion, destabilization ahead of a shortwave in the Ohio Valley spawned prolific downburst-producing storms, in an environment characterized by 20-30 kt of shear and strong low-level lapse rates....Ohio Valley into the Mid-Atlantic and Southern New England... On the southern fringe of upper troughing over eastern... Read More
Two areas of focus came into view for severe weather this day. One in the Midwest, and one on the Great Plains. You can see both in the SPC’s outlook and verification graphic.In the Midwest, a mesoscale convective system from the previous night was traversing the middle of the country,... Read More
Hail, wind, and tornado hazards were plentiful over the weekend, with numerous opportunities to look at ProbSevere V4. We’ll take a quick look at a few areas.Eastern ColoradoA power supercell was moving east-southeast towards Kansas. There were no tornadoes reported, but numerous wind and hail reports. The ProbSevere probabilities of... Read More
May 13 brought a cold front to the Northeast U.S. and a potent shortwave to the Northwest U.S. It was a good day to test ProbSevere v4 for very different regimes. Here was the SPC’s 12Z synopsis discussion for both regions:... Portions of the Great Basin and the Central and... Read More
