June storms out west

Early to mid-June has supplied the western U.S. with several bouts of storms. On June 8th, storms developed in eastern Oregon and northern Idaho downstream from a 500mb trough with an embedded 60 kt jet, leading to an environment with excellent effective shear but only modest MUCAPE.

The first annotated storm in central Oregon only had weak satellite growth, but the ProbSevere value ramped up quickly an account of increasing MESH and the total lightning flash rate, in a very high shear environment. A brief tornado was reported at 20:22 UTC (probability > 90%) while golfball-sized hail was reported at 20:30 UTC.

Two other annotated storms in northern Idaho and far northeastern Oregon also had high probabilities. On both of these storms, the normalized satellite growth rate and glaciation rate were strong before the MESH became high, yielding 80%+ probabilities of severe. The flash rate also remained rather low until later in the lifecycle of the storms. The storm in Idaho had a report of 1" hail at 21:24 UTC, and later 2" hail at 21:45 UTC (a severe thunderstorm warning was issued at 21:12 UTC). The storm traveling from northeast Oregon to far southeast Washington report damaging 1.25" hail at 21:45 UTC (the hail dented vehicles).

Fig. 1: The OR-WA-ID tristate region, with ProbSevere contours, composite reflectivity, and NWS warnings.

On June 13th, a slow-moving storm brought hail to the Salt Lake City, Utah area in the early afternoon. Very strong satellite growth rates were observed at 17:45 UTC in an environment characterized by 1500 J/kg of MUCAPE and 25 kts of effective shear. A total flash rate of about 30 flashes/min and MESH close to 1" yielded a maximum probability of severe of 88% at 18:14 UTC. One-inch hail was reported at 18:20 UTC, and golfball-sized hail reported at 18:37 UTC.

Fig. 2: Storm near Salt Lake City, UT produces multiple large hail reports. ProbSevere contours are overlaid NWS warnings and composite reflectivity.

HWT 2016 GOES-R/JPSS Spring Experiment Complete!

The 4 week GOES-R/JPSS Spring Experiment in the HWT completed today, May 13.

Week 4 complete!

The fourth and final week of the HWT 2016 GOES-R/JPSS Spring Experiment is complete! After starting out very busy on Monday with severe weather, including tornadoes, in the Norman CWA, the week quieted down. However, we certainly still had enough severe convective weather across the CONUS Tues-Thurs to keep our participants plenty busy evaluating the satellite products.

Week 4 (9-13 May 2016) Summary and Feedback

The final week of the 2016 GOES-R/JPSS Spring Experiment concluded with our two pairs operating in the Nashville and Huntsville CWAs. Both were able to evaluate the PGLM product via the Huntsville LMA.

LAP
- Convection developed along the moisture and instability gradients in LAP.
- I liked seeing the model data where retrievals were unavailable. In addition to having a continuous field, it often allowed for quick comparisons of retrievals with nearby GFS.
- Our office does look at K-Index for flash flood situations.
- 30-min is a good temporal update frequency. Too frequent of updates would not be that useful, as such fields do not change so rapidly.
- Layer PW was my favorite LAP product as it was most unique, and added value to my analysis. It was particularly useful on days when we had strong low-level moisture advection, tracking the movement of moisture, and dry air aloft.

GOES-R CI
- When I had 1-min imagery, I did not need CI because I could identify areas of imminent CI in the imagery.
- In situations where you are expecting severe thunderstorm activity, you's look more at severe CI. Regular CI was not as useful for severe situations because you could see cb development in the 1-min data.
- When looking for general thunderstorms, I see CI being more helpful, including in the cool season. This would be valuable for DSS purposes.
- I found utility in having both CI products up. If severe CI was pinging on something in addition to regular CI, it helped to focus attention to particular areas of interest.
- It would be helpful to see probability trends for a particular cloud/area.
- We were fine with the display concept
- I like the current instantaneous visualization  over a smoothed probability field approach.

ProbSevere
- It would be nice to see a meteogram with a history of ProbSevere probs.
- Everyone is fine with the display and color-scale.
- Similar to VIL of the day, might be helpful to determine "ProbSevere Prob" of the day.
- I think it really well with discrete cells, but later would merge nearby cells.
- I would say this was my favorite product outside of the 10min imagery.
- I thought it performed great this week.
- We would all use this in operations.
- I've worked 5 or 6 severe events in the last month, and I've ProbSevere up for all of them. Usually I have storm relative velocity all tilts, regular velocity in the middle, and the third screen has different fields, including composite reflectivity with ProbSevere. I've also even started putting it on all-tilts. The display does not distract me. In my office, the threshold to warn depends on the day, but I've found with most of our events, especially with severe wind, we can get severe with a threshold of ~60%. Definitely not using it as a yes/no.

SRSOR
- All forecasters loved using it this week!
- 5-min is certainly bettern than 15. But when you are tracking low-end severe situations, subtle boundaries can make all the difference between something going up or not. We get better than 5-min radar data, but 1-min satellite data can fill gaps that we still have. 5-min will be useufl, but 1-min is optimal.
- I think it is certainly time to make the jump to 1-min satellite imagery. There is so much that can be seen, even outside of convection. Forecasters need to use satellite data more in day to day operations.  Generally, I think forecasters don't think satellite imagery is as useful as it is, and they have a hard time understanding exactly how much they will see in the 1-min imagery.
- It was helpful to view long loops of the 1-min imagery on the regional scale to get a big picture idea of how the system was evolving.
- It was really helpful for analyzing frontal structure and all the different boundaries.
- Satellite imagery is truly the only visual representation you have of a storm that you can't get with any other product.
- I found it useful to match 1-min lightning data with 1-min satellite data.

SRSOR Winds
- I liked the winds a lot. You could see the vertical structure of a front, and how winds changed with height from the surface. Seeing rapid change over a short vertical distance was intriguing. AMV's could be a big help with our TAFs.
- I felt that the low-level winds were more useful than the upper-level winds. They indicated areas of low-level convergence, moisture transport, veering of winds from the surface, potential for tornadoes.

Lightning Jump
- I liked it more as the week went on. I usually used it in tandem with ProbSevere and PGLM Flash Extent Density. I could see all of these being in a 4-panel and helping with situational awareness for severe operations. Especially on Thursday, I noticed the storms with the biggest LJ's were the ones that strengthened considerably thereafter.
- I'll be interested to use this during cool season events, as I am always looking for more information in these situations.
- I like the way it is now, though I can see others preferring a contoured look.
- I like a 4-panel layout with ProbSevere, lightning jump, Severe CI, Lightning, composite reflectivity, and satellite imagery.
- Forecasters are/will always change to their preferred color tables.
- There will always be a spot for a product like Lightning Jump in my display.

GLM Total Lightning
- The lightning data will be very helpful for DSS - events, fairs, etc. It will be very helpful to have this information updating every 1 minute.
- Especially for cool season events, we are always looking for more data. Lightning from satellite will be helpful.
- I can see this being helpful in EM's decisions to evacuate stadiums.
- This will be big for us during fire weather season in the NW US.
- In the future, with lightning in field offices, there must be very good training on all of this. There is/will be a lot of different lightning data. Generally, forecasters do not know the differences in lightning verbage.
- I will likely overlay it on radar or satellite.
- LMA-1 was the favorite among the group

NUCAPS
- The plan view and cross-section components were my favorite aspect of NUCAPS this week
- The lure is that it is an observation. I think it should remain observationally driven, even though we know there could be a source of error. If so, we know the source of the error. If you add in model data, you don't always know the source of the error.
- Pop-up skew-T will be good to use before and during an event with NUCAPS.
- Modification is not an issue for me. In our office we modify RAP soundings all the time. It takes some time, but it works. 
- NUCAPS has a lot of potential, but a lot of bust potential for captivating an office.
- I can't get anyone to look at it in my office in Portland.
- The lack of detail is a killer. That's why I think plan view and cross section displays are more valuable.
- People will use it if they see the value, and it is made clear that this is an observation.

General
- Participants felt that the start of week orientation/familiarization was great.
- It was the perfect amount of products to evaluate.
- It would be nice to have a DRT WES case for slow days.
- I suggest having a group briefing after the groups complete their mesoscale analysis but before CI.
- The broadcaster commented that this was a great experience, and it was wonderful to be able to work directly with NWS forecasters.
- Some of the training material should be put on the CLC so we can go back and look at it in the future.

SRSOR Sandwich

Below is a SRSOR 1-min-updating animation of visible imagery with transparent IR imagery overlaid. This imagery depicts the line of convection moving into the Southeast, through our area of operation today (Huntsville and Nashville). This image combination allows forecasters to view rapidly changing storm-top features with the detail of the higher-res visible imagery and ability to see/sample temperature from the IR imagery.

Using Pop-up Skew-T with NUCAPS

Pop-up skew-T is a feature in AWIPS that allows forecasters to quickly visualize temperature and moisture profiles on a skew-T diagram from model-derived or observed sources. The user has the ability to move their mouse over a field and see the profile change in space. This is of particular use for NUCAPS, allowing a forecaster to get a quick look at the profile before clicking it and interrogating it further. See instructions and images below to use pop-up skew-T in AWIPS-II with NUCAPS.

1) Load NUCAPS Sounding availability (so you know where the swath is).

2) Load pop-up skew-T (top of "Volume" menu)

3) Turn on Sampling

3) Right click and hold anywhere in the screen, hover mouse over "Sample Cloud heights/radar skew T" at top of menu, Select NUCAPS. (see image 1). A Skew T box will appear somewhere on you screen.

4) Move mouse into NUCAPS swath to see temp/mois profile change in space (see image 2).

Pop-up skew-T for AWIPS

The Pop-up skew-T feature in AWIPS works for NUCAPS. This feature allows forecasters to quickly view soundings from NUCAPS before interrogating them further in NSHARP.

Mobile, AL had a special 18z radiosande launch today (shown below). The profile reveals a moist layer below 700 mb, with a dry layer centered around 400 mb. SBCAPE in the sounding is about 2100 j/kg, while TPW is 1.5 inches.

A modified NUCAPS sounding was sampled over the same location. The sounding depicts a similar moist low-layer, with a dry layer around 400 mb. CAPE is about 2200 j/kg, and TPW is 1.36 in, both similar to that from the observed radiosande.

Final Thoughts 5/12/16 HUN

Final thoughts on the day. Today was a huge success for the PGLM. Looking at flash densities for storms in the Huntsville area was highly beneficial. I liked that the output was not tied to the cells and also I preferred the smoothing on the product. As I was not really interrogating it like I would radar data, smoothing was preferred and I could see easily exporting this to an emergency manager or social media post.

Atmospheric vectors did a great job of showing the structure of the pre-frontal trough in the vertical.

1 minute data was vital in tracking the speed of the prefrontal trough, outflow boundaries and the front itself as the afternoon evolved. As always, tracking overshooting tops was beneficial to the warning process and also to monitor storms as they were decaying as well.

NUCAPS did well with the soundings and was also impressed by the theta-e cross section presented across the frontal boundary. While some observational data still needed to be modified, I could see this data being highly useful in the office. 

ProbSevere was understandably lower today in this environment but qualitatively the worst cells  had the highest probsevere ratings. As a forecaster, this was still a useful product to have today.

CI didn't have a chance to present itself today as convection had already initiated before the session began. - Jason Bourne

Final Convection thoughts with the pGLM

At 2310 UTC, a broken line of convection continues from south of Nashville, TN into northern AL, and northern MS.  The ENTLN shows the 5-min total LTG with the individual cells in the broken line.  The pGLM shows the various color tables for the Flash LTG density at 2310 UTC. From a pure visualization perspective you can see the benefits of the pGLM in a procedure to assist a forecaster with convection forecasting, whether it is for general convection or severe.  This blogger still thinks the upper right color table is the best to show the flash extent density from the pGLM.

-Yodamaster777

1 Min Vis Satellite: Normal image vs. parallax-corrected image

In addition to the 1 minute visible satellite imagery, we also had access to a parallax-corrected version of the product this week. It was interesting to compare the two images.

Below are 2 images centered over northern Alabama. There are several overshooting tops apparent on developing cells. Comparing the locations of the centers of the overshooting tops, I found that the the regular and the parallax-corrected images differed by around 8-10 miles. This could make a significant difference if a forecaster was using an overshooting top to try to center a warning track.

Note: I also discovered today that overlaying lightning flash density from the pGLM network on top of the satellite imagery was a nice display. In this case, you can see that the higher flash densities better correspond to the overshooting tops on the parallax-corrected image. - JP

Normal visible imagery

Parallax-corrected visible imagery