Paralax correction good/bad

Raw visible satellite data over VA showing cu towers with lightning flashes.

 

Note the parallax corrected puts the tower right where the lightning flashes are!

 Here's an example from NC. Again with OT and lightning. Shadow is displaced well north of the lightning cluster.

Parallax correction win!  Note the shadow right around the flash cluster!

That was the good.  Now for the bad.  Chunky display, particularly with anvil next to clear skies.

 

Here's the raw vis:

 

BAJ

How Much For That Doggy In D2D?

The pink poodle shaped lightning jump illustrates the weaknesses in having storm interrogations not able to separate cells in a multi-cluster environment if using the wrong Lightning Jump scale.

Forecaster: Manbearpig

ProbSevere Reduced Situational Awareness

A pair of severe storms were approaching our CWA from the north. Just before these storms entered the CWA, the ProbSevere began to fall, dropping to 60% and 48% respectively. At this same time, traditional radar signatures remained elevated and a warning issuance was appropriate.
Due to the rapid increase of convective activity across the CWA at this time, I was relying on ProbSevere to highlight storms of interest while I was interrogating or warning on other storms. Because of the drop in ProbSevere, on the storms mentioned in the previous paragraph, I did not further interrogate those storms until they were right on the border. As soon as I saw the traditional radar signatures, a severe warning was issued.
In this situation, ProbSevere actually reduced my situational awareness and the lead time on the warning on these storms. That said, I was working sort of a "worst case" scenario, because several storms were reaching severe criteria at the same time I was was issuing warnings on my own (partner was writing a blog post). I all likelihood, multiple people would have been working this event and I would have had a more manageable workload, so I wouldn't have missed this storm. However, I feel like these "worst case" scenarios are exactly when ProbSevere can help, by identifying which storms require further interrogation.

 -Toki Wartooth

2 Severe Storms Issued in the Raleigh Area

The loop here shows rapid trending of ProbSVR values, and each storm showing sigma jumps of at least 3.0.  In subsequent scans, the northern storm approaching Raliegh had ProbSVR values jump from 54 to 67 to 94 percent, and a solid hail core aloft to justify severe potential. The second storm made a similar jump in ProbSVR as 48 to 56 to 60 to 82. The rapid jumps in ProbSVR coinciding with the Lightning jump anomallies occurring with each cell showind the ProbSVR parameters in the middle of these jumps (60 to 70 pecent) gives this forecaster a chance to build upon speed of analysis and increase lead time. In addition, the northern storm was moving near the cone of silence and could have had lost data that may have delayed a warning in real time.

Forecaster: Manbearpig

GOES-R CI targets convective initiation in Texas Panhandle

GOES-R CI (top left) probabilities increased to over 50% in the Lubbock CWA at 1900 UTC. At 1930 UTC, probs over 75 were sampled, and at 1945 UTC, increased to over 80. Convective initiation was apparent in visible imagery beginning at 2000 UTC.

Severe CI probabilities over 70 were sampled at 1945 UTC.

Storms associated with this development produced 1 inch hail at 2124 UTC.

CI Review for 28 April

CI worked well in RNK today, April 28. The highest CI (orange and red) developed into the severe weather.

 

However, nothing registered in Severe CI.  This is interesting since ProbSevere increased to high ranges first from cloud growth rates. Why did Severe CI not register with this?

 

BAJ

Lightning Jump and ProbSevere Give Some Leadtime On Likely Severe Weather In RAH

A storm in the northwestern portion of the RAH CWA began to display borderline severe radar signatures around 2015z. At time time, there had been no lightning jumps and ProbSevere had yest to exceed 50% on this storm. Given the ample instability available to this storm, I decided to pull the trigger on the warning despite the lack of support from the lightning jump algorithm (LJA) and ProbSevere.
At 2023z, there was a 2-sigma lightning jump followed by a 5-sigma jump at 2025z. By 2033z, ProbSevere finally jumped above 50% to 65%, eventually making it to 99% by 2041z.
As of this writing, no severe reports had been reported on this storm. However, at 2037z, a significant three body scatter spike (TBSS) was apparent, so I am confident that this storm produced severe hail shortly after this time. Assuming this storm did not produce severe hail before the TBSS appeared, the LJA provided a roughly 15 min lead time on the severe hail, and ProbSevere provided about 5 minutes lead time (using 60% as a warning trigger). Forecaster lead time on this event was around 20 minutes.

-Toki Wartooth

Experimentation with ProbSVR Color Schemes

When it comes to viewing algorithm and derived products, this forecaster prefers more dramatic jump points to new colors over a slowly changing color scale.  In most cases a ProbSVR jump value going of 20 percent would be enough to get the forecaster's attention for further inspection, but the association of colors to specific range of number would be easier to monitor, especially for a shift-coordinator that would prefer a more simplistic view of things.  The color scale shown in the lower left attempts to reflect radar reflectivity, but could be modified to be more compatible with color overlays used for the Lightning Jump overlays.

Forecaster: Manbearpig

Vis Satellite shows boundary for possible TOR

Cold Air Damming is retreating across the VA piedmont. A look at the 1445Z scan shows the back edge of the low stratus over the central part of this image. At that time there was strong heating south and stable clouds north. Around 18Z, cu developed along this line. the cell that then moved over this area and produced a mesocyclone and possible tornado. There would have been a boundary.

BAJ

NUCAPS Analysis May Slightly Overestimate CAPE in Clear Skies

As the Visible loop above indicates mostly sunny skies an 18Z NUCAPS sounding arrived for diagnosis over South Central NC. Surface obs near Richmond County Airport near Rockingham, NC suggested a temperature and dewpoint of 77 and 62 degrees respectively, which lined up well with the surface report of 80 and 64 degrees respectively.  As the Rockingham report increased to 85/65 by 1930z, the NUCAPS plot was modified to include the surface obs, leading to a CAPE estimate over 3600 J/kg as shown in the modified sounding above. Given that the unmodified sounding from 18z illustrated only 1708 J/kg, the continued mixing of mostly sunny skies and southwest winds should mean the boundary layer moisture profile should be drier. It would be nice to have a model-based tool that could automatically factor in low level mixing influences to save time in an operational environment.  Still the midday CAPE assessment with temperatures climbing should suggest realistic CAPE values in Southern North Carolina to be in the neighborhood of 2500 J/kg. Interestingly enough, the 20z SPC Mesoanalysis surface based CAPE revealed a CAPE contour of 2500 J/kg within 80 miles of Rockingham (to the west), and values just over 2000 J/kg on top of this same area.

Forecaster: Manbearpig