ProbSevere highlights storm heading toward Crowell, Texas

ProbSevere had a 65% probability at 23:08Z (Figure 1), and the NWS issued a warning 16 min later at 23:24Z (Figure 2). Like many of the warned storms in western Texas, we haven't received any reports yet. Several HWT forecasters have liked how ProbSevere highlights storms to watch, and how it helps consolidate much of the pertinent data they have to look at. They especially liked watching the trend in ProbSevere values.

Figure 1: ProbSevere, visible reflectance, and composite reflectivity at 23:08 UTC.

Figure 2: ProbSevere, visible reflectance, and composite reflectivity at 23:26 UTC, 2 min before a warning was issued.

-Cintineo

ProbSevere in Warning Decision Making

Here is an example where ProbSevere increased from 20% to 97% within 18 minutes (2218 to 2240 UTC) (click image to animate):

A three-body scatter signature (TBSS) developed at the end of this time frame, indicating the presence of hail aloft.

By 2248 UTC, MRMS indicated 65.5 dBZ at -20C:

This is another example where the rapidly increasing ProbSevere indicated an intensifying storm. A severe thunderstorm warning was issued for the storm.

Mahale

ProbSvr/Time Series for Warning Decision Making

With the severe thunderstorms that moved through the EWX CWA, we used ProbSvr and TimeSeries to help us decide if we were going to issue a new warning or expire/cancel a warning. Here are the examples from the two that we had going.

Here at 2308..the warning on the right was expiring at 2315z and the one on the left expires at 2330z. We needed to make a decision soon on the one on the right. It wasn’t too impressive in terms of reflectivity but we noted that the ProbSvr remained high and hadn’t faltered through the life of the storm. As well, the DTA (not shown) was continuing through the life of the storm as well.

At 2312..they are looking similar. At this point we decided to reissue a severe on the storm on the right. The ProbSvr holding strong every two minutes definitely helped us make this decision. Also to note the time series (shown at the bottom) is also steady on the one on the right.

At 2314z…we have issued a new severe on the one on the right and now the storm on the left is weakening per the ProbSvr. We were already considering letting the warning on that one expire so this helped our decision.

At 2322z…the storm on the right is still holding a strong ProbSvr Probability while the one on the left continues to diminish. We were still deciding if we wanted to issue a new one for the left for possibly a wind threat but at this point we decided to expire it.

And as you can see at 2335…the left storm has dissipated.

Here are the time series for both storms. The one on the left is the strom from the left above and you can see the quick drop off. The one on the right held steady and continued to help our decision to issue a new warning.

Also to note…this is a GIF from 13z-22z of the LAP CAPE data. We have been watching this each hour and the storms have been following the instability axis along the Texas border. We saw this earlier and were prepared for the storms to take that track.

Lauren/Ertel

Lightning Jump Detection Algorithm Suggestion

Image 1.  2238Z.  Sigma 1.

Image 2.  2239Z.  Sigma 2.

Image 3.  2240Z.  Sigma 3.

Image 4.  2241Z.  Sigma 5.

Image 5.  2242Z.  Sigma 0?

It’s nice having this information update every minute to capture trends.  However, since it updates every minute on AWIPS2 the color could change every minute over a short time (like above).  Forecasters can easily miss these fast changes given all of the data they need to look at.  It would be better for the data to update every minute, but leave the strongest Sigma in place longer.  (Maybe for 5 minutes using a separate product?)  This would allow forecasters to see the largest Sigma more easily.

So in the example above, Image 4 would show Sigma 5 for the area highlighted from 2241Z until 2246Z.  At 2247 the Sigma 5 color for the area highlighted would be replaced by the next strongest Sigma in that area (if any).

-Champion

T’Storm Development Ahead of Line

Thunderstorms have combined to form a line moving southeast across the southwestern SJT cwa. CI Prob was indicating further developing and convection ahead of line. The model showed a good bit of possible development ahead of this line.  The indication of convection has so far been overdone. This is similar to surface based warming that fuels PM convection. Though, a the line has extended north into this region and one new cell has formed in the area being watched closely. The first photo indicated CI Prob and the area forecasters should focus on.

Here you can see where a cell in the concerned area within SJT cwa developed and the line elongated northward.

UFFSU

NUCAPS Sample

In southwest TX.  Modified for the surface.  Severe thunderstorm with a TBSS moved through the area later.

Plus, another point to the north where nothing happened.

-Champion

More NWS warnings in SW TX

Two more warnings have been issued in SW TX, in addition to the southern storm, which has been around for a little while (Figure 1). ProbSevere for the storms (Figure 2) in the northern two warnings had lead-times of 6 and 18 min from the 70% threshold. One inch hail was recorded in the southernmost storm.

Figure 1: NWS warnings and 0.5 deg reflectivity from San Angelo, TX

Figure 2: ProbSevere, composite reflectivity, and visible reflectance.

-Cintineo

ENI vs ProbSvr for Developing Storm

In the line we are watching the southern storm started to strengthen more than the middle storm.  At 2044Z it started showing something like below with both storms in one PorbSvr bubble. It took until 2058z for it to slowly make the southern storm larger. After this scan, at 21z, it finally split the two storms.

However, at 2047 the ENI DTA had already lost the middle cell at focused on the southern storm. This image is at 2101 but just shows how long it took ProbSvr to separate them vs the ENI DTA.

Lauren

NUCAPS Sounding over Iced over Hudson Bay

Can you tell which of the two (unmodified) NUCAPS soundings below was taken over the ice-covered Hudson Bay?



A

B

If you guessed sounding A, you are correct! You can tell by the sharp temperature inversion just above the surface (below 850 mb). Sounding B, which does not have a surface inversion, is from a point a few km inland from the bay.

- Bill Line, SPC/HWT Satellite Liaison

CI with a developing line

We have been watching a line of storms that have continued redevelopment on the south side….

The south side keeps popping up new cells and actually the CI is picking up on that very well.. (the orange one towards the left).

I have been tracking this southern line and looking at radar and it is picking up on the new cell initiation.

This is at 2015Z.



Then here is the next image at 2030z.




And here is the line at 2044Z



Lauren