Just noting current frame and prob severe has been confirming what we have seen on radar some short bowing line segments and we agree the threat seems to be wind…but from what we have been seeing on velocity products they have not been meeting severe criteria. Although we did just receive a report of some trees down in Worcester Co…maybe our first warning.

Quick trigger on second storm, as pattern seemed to allow for quick development.  ProbSevere was high on the initial cell here too.  Was little in the way of lightning as well.  DVIL collapsed soon after warning issued though.

Despite rapid initial cloud growth, it took a little time for the cell in Custer Co. to mature. Before any type of warning was being considered, a 90% ProbSevere showed up before lowering to ~30%. While working on another monitor, the ProbSevere jumped back to ~90% which grabbed our attention and ended up leading to a warning being issued. We issued an SPS about 7 minutes prior.

Working in this environment of cells vs lines, it’s easy to see ProbSevere is much more accurate.

Initial NUCAPS (below) had a low SBCAPE, based on dry conditions.  Temperature looked good on original sounding, but when I moistened the environment up (image above), got to the 4500-5000 CAPE SPS meso was showing earlier.  Large spread of dewpoints over the area, likely b/c of topography?  Perhaps the RUC smoothes over those dewpoint changes and that’s the reason SPC meso had the large CAPE.

Here is a possible way to display the ENI total lightning data and points to select a time series in the panel to the left and then the resulting time series to the panel to the right, so both are visible. Here my selected point 13 and total lightning plot is what generated the times series for point 13. MrSnow

Close to issuing a warning here, but want to see it grow more.  Decided to go with an SPS for 40 mph and dime-sized hail.  Should it continue to grow a warning will be issued.

Used All Tilts data to decide that hail likely was getting large enough to make it to the surface.

First probsevere came in with a 71% probability for severe.  Show a very quick growth rate, expected from high low and mid level lapse rates.

Watching the CI values along a line of weak showers, the 1945Z image popped up an 83%. The corresponding radar image out of FGF showed nothing more than a weak thunderstorm in the area with only one lightning strike detected (not displayed)

Fast forward to 2000Z, the higher CI values (71%) have moved westward along the line. This makes sense as the line of weak showers/thunderstorms continue to build west. There has been no further development of cell that had the earlier flag of 83%.

Fast forward even further to the 2015Z images. The CI output disappears and the corresponding radar image shows no further development.

-Shasta

The GOES SRSO imagery from 1848-2015 UTC shows the influence of the cool onshore flow with marine stratus holding on the southeast coast of New England from Groton, CT (KGON) to Providence, RI (KPVD) to Marshfield, MA.  Just to the north of that region the smooth texture of the marine stratus changes to rolls/streets showing us where it might be possible to convection to develop. MrSnow/inthecards

Moving to a high CAPE and DCAPE environment.  SPC Meso analysis has 5000/1700 for each.  Near cast model shows the region is fairly unstable.  Area under clear skies now.  12Z sounding had 12 kft freezing level as well as 8500 wbz.  PW of 0.67 is dry.  Have some cu over western Pennington that is blowing up now.  Seems region is unstable.  CI had a high value just before that cell went up.

The yellow area above did not blow up, but the next image below did go quickly…see following image as well.