Autumn storms on the Plains

An energetic, negatively-tilted shortwave trough traversed the middle of the country last week, bringing several bouts of severe weather to the Great Plains. By visualizing the accumulation of the ProbSevere output (storm centroids ≥ 50% [pink boxes]), the NWS warnings (orange and red polygons), and storm reports (blue, green, and red circles), we see that the ProbSevere model handled the first event on October 4th quite well, at least qualitatively.

Figure 1: A toggle between the 12Z 10/4 ->12Z 10/5 accumulation of NWS warnings and reports, with overlaid ProbSevere centroids greater than or equal to 50%.

A very long-lived storm that approached the Norman, OK area produced numerous hail reports. It was first identified at 23:47 UTC, with a probability exceeding 60%, due to high effective bulk shear, MUCAPE, and strong satellite growth rates. The MESH was 0.24" and total flash rate was only 1 fl/min. After quick jumps in the MESH (to ~0.5") and the flash rate (to almost 20 fl/min), the probability exceeded 80%, and was promptly warned at 23:52 UTC. We can see a time series of the ProbSevere probability (thick red line) and constituent predictors in the time series below. Note that the satellite growth rates were both 'Strong', and expired a little after 02:00Z. We can also see when NWS warnings were valid and when severe weather was reported in the lower subplot.

Figure 2: Time series of ProbSevere and its predictors (top), and NWS severe weather warnings and severe weather reports (bottom). The axes on the right are associated with the time series on the top subplot, while the legend in the lower right is associated with the bottom subplot.

The stunning time lapse of this storm was captured by Jim Ladue (NOAA/NWS/WDTD) as it approached from the west. The range of this video is from about 23:52 UTC (when the storm was first warned) to nearly 01:00 UTC.




A second short-wave ejected through the Plains on October 6-7 (as Hurricane Matthew threatened the southeastern seaboard), bringing with it another bout of storms, and this time, numerous tornadoes. ProbSevere again handled most storms quite well, with few false alarms and a couple of missed wind reports.

Figure 3: A toggle between the 12Z 10/6->12Z 10/7 accumulation of NWS warnings and reports, with overlaid ProbSevere centroids greater than or equal to 50%.

We can see the evolution of the storms and associated warnings below, over Kansas, Oklahoma, and far northern Texas. The animation is from 18:30UTC to 00:00UTC every 10 minutes. The pre-frontal storms and those close to the triple-point (in north central KS) remain discrete longer than those which are forced by the cold front. The red, orange, and green polygons denote NWS tornado, severe thunderstorm, and flash flood warnings.

Figure 4: Animation of ProbSevere contours, NWS polygons, and MRMS MergedReflectivity from 20161006-18:30Z to 20161007-00:00Z .

September storms near the Great Salt Lake

A number storms formed in the early afternoon of September 22nd in response to forcing associated with the North American Monsoon over the Intermountain West region of the U.S. The image below shows the accumulations of NWS severe weather warnings, storm reports from SPC, and the centroids of ProbSevere objects attaining 50%+, at each time. Each accumulation is over the timeframe of 12Z on 9/22 to 12Z on 9/23. You can get a quick-look at how the model performed using these accumulations (the previous day accumulations are here). On this day, the NOAA/CIMSS ProbSevere model performed reasonably well, with high probabilities corresponding to numerous wind, hail and tornado reports. There were a couple of false alarms to the south east of the Great Salt Lake and a couple wind reports missed to its west and south.

Figure 1: Accumulations of ProbSevere objects, reports, and NWS warnings for 9/22/2016.

The storm that produced hail, wind, and the one the tornado reported initiated well to the southwest of Salt Lake City. The time series below of its probability and constituent predictors in ProbSevere demonstrates its evolution.

The probability of severe is the thick red line, with the scale on the left. The six predictors in ProbSevere have varying scales on the right. The NWP predictors of effective bulk shear and MUCAPE are the dashed black and brown lines, respectively. The MESH is solid orange, and the total lightning flash rate is solid green. The lifetime max normalized satellite growth rate and glaciate rate are depicted by the solid blue and dashed cyan lines, respectively. Both satellite growth rates use the blue scale on the right with nominal 'Weak', 'Mod.' (moderate), and 'Strong' designations.

Figure 2: Time series of ProbSevere predictors and severe probability value for a long-lived storm affecting the Salt Lake City metro area.

We see that the normalized satellite growth rate from GOES-West was strong at 18:50Z, while the probability of severe jumped to 15%. The jump in MESH in a high shear environment also helped to jump the probability up to 50% at 19:12Z. Increasing MESH and flash rate helped the probability climb to over 90% by 19:50Z. The first severe thunderstorm warning was issued at 20:09Z. Golfball-sized hail was observed at the Antelope Island Marina at 21:37Z. The tornado in the city of Ogden was reported at 21:45Z, and left thousands without power.

Surprise Indiana tornadoes and total lightning in the ProbSevere model

A number of tornadoes spawned from storms in central and northern Indiana yesterday afternoon -- including strong ones -- in an area where tornadic activity was not expected. NOAA's Storm Prediction Center (SPC) forecasted a corridor of marginal to slight risk for general severe weather extending into Indiana, Ohio, and lower Michigan (Figure 1). However, the probability of a tornado within 25 miles of any given point was less than 2% in Indiana and Ohio (Figure 2).

Figure 1: SPC categorical outlook for August 24, 2016.

Figure 2: Tornado probability outlook for August 24, 2016.

Storms formed in the early afternoon in a juicy warm sector of an occluding system and put down multiple tornadoes, including an EF-3 tornado in Kokomo, Indiana, causing substantial damage to a shopping mall and leaving thousands without power.

Figure 3: SPC storm reports for August 25, 2016.

Though the NOAA/CIMSS ProbSevere model doesn't provide guidance to the type of severe weather, it could have given forecasters a heads up to some of the storms during this event. The animation below shows two storms developing in central Indiana (Figure 4). The first storm (near the Illinois border) had initially modest MESH (0.5-0.7"), but an excellent total lightning flash rate (50+ fl/min), before increasing to over 1" of MESH briefly. ProbSevere provided about 30 minutes of leadtime to the first severe thunderstorm warning from the 70% threshold. A tornado warning was issued at 18:37 UTC, and a damaging tornado reported at 18:55 UTC. One-inch hail was later reported in Indianapolis.

Further to the northeast, where MUCAPE was markedly less (~1600-1800 J/kg) but effective shear about the same (~45 kts), another storm formed west of the city of Kokomo, which produced the EF-3 tornado. This storm had low MESH (0.3-0.5"), but a rapid increase in flash rate (18->46->62 fl/min) in a well-sheared environment. This helped give the storm a probability of severe of 68% at 18:42 UTC, 8 minutes before a tornado warning was issued. The total lightning flash rate/effective shear predictor helped increase the probability of severe despite poor integrated radar reflectivity and satellite growth rates. A tornado emergency would later be issued for the community of Kokomo.

Figure 4: Two storms in central Indiana showcasing the utility of total lightning data in ProbSevere.

To show the effect of total lightning flash rate explicitly, ProbSevere was run with just radar, satellite and near-storm environment NWP data. As figure 5 shows, the probability of severe on the first storm only became elevated when the MESH neared or exceeded 1". In the Kokomo storm, the probability was 46% greater at the time of the initial tornado warning with lightning than without (70% vs 24%)! For both storms, the probability was generally 20-40% greater with the inclusion of total lightning data.

Figure 5: ProbSevere for the two storms in central Indiana, with total lightning data OMITTED from the probability computation.

The tornadic storm that traversed Kokomo traveled to the east side of Indiana, where it again re-intensified and became warned at 20:46 UTC. The probability of severe jumped up largely in response to an increasing flash rate. The storm would go on to produce numerous more tornado reports, beginning at 20:45 UTC.

This storm and another to it's north moved into Ohio, still producing tornadoes. However, the ProbSevere model only had low probabilities at this point for both storms, as the flash rates dropped into the single digits and MESH was largely below 0.33". So the flash rate did not contribute much with these two storms later on (see Figure 6). It is still uncertain what aspect of the environment in far northeastern Indiana modified the morphology of these storms.

Figure 6: Two storms in northeastern IN / northwestern OH that had poor ProbSevere values but produced tornadoes. These storms show that total lightning doesn't help every storm.

This event in Indiana and Ohio is interesting for a number reasons, including the unexpected number and severity of tornadoes, as well as the seemingly different morphologies of storms in reasonably close proximity. These examples highlight where total lightning flash rate improves ProbSevere probabilities, despite a meager reflectivity signature, as well as where total lightning doesn't contribute. I hope this case also shows the utility of an 'ingredients-based' approach to forecasting using observations (and near-storm environment data), where one data source may give insight to future storm severity when another is not, or when multiple observation sources may corroborate each other to enhance forecaster confidence and leadtime. This case also underscores NOAA/CIMSS's efforts to provide hazard specific guidance in future improvements to ProbSevere.

EDIT: This blog post by Jeff Frame gives a good post-mortem of the event. It appears the MCV in Illinois/Indiana played a key role, and that the environment itself was actually reasonably favorable for tornadoes, but that NWP guidance struggled depicting it as well as depicting the morphology of the storms.

2015 North American monsoonal storms

The NOAA/CIMSS ProbSevere model was reprocessed with total lightning data for several days in the fall of 2015 upon request from the National Weather Service. This post recaps a few of the interesting storms from these days.

October 18, 2015

A cluster of storms affected the Phoenix, AZ metro in the afternoon/evening of October 18, with one storm intensifying and producing severe weather in downtown Glendale. This storm only had weak satellite growth, but the good total lightning flash rate (up to 40 flashes/min) and strong MRMS MESH (1.08") generated a ProbSevere value of 51% at 22:48Z, despite rather weak effective bulk shear. The first wind report was at 22:50Z. So there wasn't much lead-time at all for this storm from the 50% threshold, but the ramp up in probabilities could have signaled to the forecaster that this was a storm to watch (3%-->11%-->17%-->38%-->41%-->51%), as well as how much higher the ProbSevere value was than neighboring storms. The storm produced multiple large hail (up to 1.25") and severe wind reports.

Figure 1: ProbSevere, MRMS composite reflectivity, and NWS warnings for storms near Phoenix, AZ.

Further southeast, northwest of Tucson, a very small storm produced big hail (1" diameter) at 21:04Z. A maximum MESH of 0.89", moderate satellite growth rate, and very low lightning (0-1 fl/min) combined for a max probability of only 21%, at the time of the first report. The very low lightning combined with modest effective bulk shear (~25 kts) certainly helped to keep the probability of severe low. This example shows that more training with western U.S. storms is necessary for the ProbSevere model, especially as far as total lightning is concerned.

Figure 2: ProbSevere and MRMS composite reflectivity for a small storm near Tucson. This storm had nearly zero observed lightning flashes (IC or CG). 

Strong storms also erupted in southeast California this day, with strong satellite growth rates, good total lightning flash rates, and strong MESH values, all combining to produce probabilities in excess of 90%. Only one storm was warned despite the high MESH values (as high as 1.45"), but no reports were recorded from these storms in the Mojave Desert region of California. The MESH might possibly have been biased due to rather sparse radar coverage in this region.

Figure 2: ProbSevere, MRMS composite reflectivity, and NWS warnings for storms in the Mojave Desert.

October 6, 2015

Numerous storms developed in southern Arizona in the early afternoon of October 6th. One storm stood out southwest of Phoenix, with a good flash rate (32 flashes/min), and good MESH (0.92"), but no satellite growth rates. The ProbSevere value ramped up from 17% to 66% in 10 min (from 18:58Z to 19:08Z). The probability then hovered in the 40-50% range before a tornado was reported at 19:34Z. Though ProbSevere doesn't have any predictors explicitly for tornadogenesis, this case demonstrates that it can highlight a strongly developing storm to the forecaster, which signals the need for him/her to further investigate it.

Figure 3: ProbSevere and MRMS composite reflectivity for a storm southwest of Phoenix, which produced a tornado. 

Further southeast in Tucson, a storm exhibited moderate glaciation and normalized satellite growth rates, modest lightning (< 20 fl/min), and modest MESH (lifetime max was 0.58"). The shear and MUCAPE were adequate (~35 kts and 1000 J/kg, respectively). The ProbSevere predictors all pointed to a garden variety thunderstorm (max probability was 24%), yet this warned storm went on to produce two 1" hail reports and a wind report in Tucson. The MESH may have been underestimated due to the storm being near the radar, and thus possibly partially in the "cone of silence". The next closest radar is in Phoenix, with it's lowest tilt being over 8,000 feet at the storm's location (possibly higher, depending on atmospheric conditions). It's also possible the storm may have been shallow, as well, with MESH not being as representative. The SPC mesoanalysis archive shows that the melting level was relatively low (~2500 m), which in the future might help correct the MESH in shallow storms.

Figure 4: A storm near Tucson, AZ, which produced severe hail and wind.

Finally, later in the afternoon, a storm quickly intensified (went from 10% at 21:50Z to 70% at 21:58Z), heading toward Casa Grande, AZ, and was promptly warned. The increasing MESH and total lightning caused the rapid increase in probability. The storm began producing golfball and silver dollar sized hail at 22:10Z.

Figure 5: A strong storm picked up by ProbSevere heading toward Casa Grande, AZ.

September 14, 2015

A couple of storms developed near the Phoenix, AZ metro area on the evening of Sept. 14th, with one storm producing multiple wind reports (e.g., trees and power poles down) in downtown Phoenix. The MUCAPE and effective bulk shear parameters for the wind-producing storm were good (~2200 J/kg and 30-35 kts, respectively). At 01:00Z, a moderate normalized satellite growth rate and MESH at 1.01" combined to generate a probability of 47% (the max in its lifetime). The flash rate was 7 flashes/min. About 10 min later, the storm diminished markedly, as the MESH went below 0.1" and flash rate below 5 fl/min. The ProbSevere values were in the single digits when the storm first began producing severe wind reports. So unless the radar operator was paying close attention to the probabilities nearly an hour prior, ProbSevere may not have helped much in this case. That being said, development is underway to incorporate other NWP and radar fields to better predict wet-microbursts. For instance, the low-level lapse rates were very good in this region (as shown by the SPC mesoanalysis archive), which helps in momentum transport. The ProbSevere developers will be investigating many fields, including low-level lapse rates to better predict severe wet-microbursts. The low ground-based total lightning also didn't help. It's not certain whether this is a detection efficiency or a meteorological cause, but it underscores the need for more training for western U.S. storms.

Figure 6: ProbSevere and MRMS composite reflectivity for a storm affecting the Phoenix metro.

These cases show that ProbSevere can help highlight storms for forecasters to watch and further interrogate, and that forecasters must also continue to bear in mind data problems (e.g., sparse radar coverage, possible low lightning detection efficiency), as well as environmental factors not captured in the ProbSevere model (e.g., shallow storms). We hope the ProbSevere model will constitute another piece of useful guidance to the forecaster and compliment the warning process.

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

Broadcast media perspectives of new products

This week I was lucky enough to experiment with tools and products that will help forecasters make faster and more accurate decisions regarding severe weather.  As someone who works on the TV side of things, I have a different view of how useful these products could be to me and my colleagues.  While the forecasters main goal is to issue timely warnings to save lives and property, my goal is to quickly and clearly communicate warnings and threats to the public, via tv, social media. etc... .
While ALL the products are valuable, there are several which I would think would be most beneficial to me if I had them available to me to share with viewers

1 minute VIS. Satellite- Total eye candy...after all I work in a visual world. The stunning displays would give our viewers something to look at, and I could point out certain features that concerned me (rapid development etc...).

Lightning Jump- Another one of my favorite visual tools.  I would use a modified version of this, and obviously the language wouldn't be "sigma".  I could however imagine a version of this where the categories were small-moderate-large-extreme...or negative.  It would be easy to communicate quickly that if we see these jumps, that means the potential is there for severe storm development, or at least these storms warrant close watching.  Once storms reach severe levels I'm not sure I would continue to use that tool.  I believe I would switch at that point to PGLM.

PGLM- I would use this tool to track severe storms and show the lightning.  We currently show lightning flash counts, and the viewers love it, but I would prefer the visual display presented as it is in PGLM.

PROB Severe- Initially I was ALL FOR IT.  I loved the outline display.  After tracking storms in the Southeast today where the product under-performed due to a different atmospheric environment, an environment that is much closer to my home one, I changed my mind.  If this product could be fine tuned specifically for region or season, then I would LOVE to show viewers a severe probability parameter storm cell by storm cell.

CI & CI Severe- Still unsure of the value this would have to viewers.  If there were no storms present, but storms expected I could see this being something that could help show storm potential, but I would want to have higher confidence in the product.  I would probably also only want to show probs of 80 or higher on air. 

Even though I wouldn't necessarily use the assessment products on air (LAP, NU CAPS) I am glad that NWS forecasters will have these available because I see their value as well.  

-StormFront

ProbSevere HUN Highest of day with Rotating Cell

ProbSevere achieved its highest percentage with a storm over northern Alabama that was rotating at 73%. Satellite growth rates were really strong with this storm and whether coincidence or not the ProbSevere did the best with what was easily the most dangerous storm of the day. Compared to other probsevere ratings today...it was the highest by over 20%. Below is a screen capture of the highlighted cell. Note that the actual rotation of concern was outside of the probsevere highlighted area just to the east. Included is a .gif of the progression of ProbSevere in this situation. -Jason Bourne

2030-2250 UTC GOES-14 SRSOR MEGA-LOOP

The 1-min loop over the past few hours provides the user with the aesthetic and meteorological beauty of the GOES-14 SRSOR-1-min imagery.

For example, a short-wave can be seen over IA, with plenty of post frontal stratocumulus and cumulus over the upper Midwest, western Great Lakes Region, and IL.

Upper level cirrus, and anvil blow-off from the convection over KY, TN, and OH continues to move into the central Great Lakes Region ahead of the cold front.

Finally, the overshooting tops and cumulonimbus evolution of the strong to severe thunderstorms can be beautifully seen over the TN Valley, Midwest, and the OH Valley.

May the Force be with You!

-Yodamaster777

NUCAPS Cross-Section Shows Cold Front

We learned today that we are able to look cross sections of NUCAPS data. With a cold front moving through the midwest toward the Ohio Valley today, we took a look at the 19Z NUCAPS data from the Suomi-NPP satellite pass. Below is a cross section of equivalent potential temperature (Theta E) running from northern Florida up through central Kansas.

In this image, Florida is to the right and Kansas is to the left. Based on METAR observations, the cold front was oriented over central Missouri and Arkansas at 19Z. The cold front appears to be approximately 600 km from western-most point of the cross-section.  Lower theta-E values can been at the lower levels west of this point, with the isotherms sloping upward from east to west on the cool side of the frontal boundary. This is a cool way to visualize the location and structure of a frontal boundary! -JP

Very High Lightning Flash Density Animation

Here is an animation of some very high lightning flash rates with a warned storm in Northern Alabama. These flash rates were the highest of the day. After re-evaluating the color curves presented for a flash rate this high, I determined I preferred the upper right color curve. This stood out the most to me and also did not mimic the color scale from other products like the default does. This storm also had a lightning jump of 6 sigma (top right in figure 2) which was one of the highest we saw of the day. Using the PGLM and the Lightning Jump products in tandem was a great confidence booster for warnings. As far as the PGLM was concerned I like that it is not tied to the individual cell as it can give an idea of how far away from the storm that lightning can travel. I could see this being a useful visual presentation for an Emergency Manager trying to decide to evacuate a stadium full of people or not. -Jason Bourne

NUCAPS Pop-Up SKEW-T

One of the beautiful things about NUCAPS in AWIPS is the ability to view pop-up Skew-T's.  One can move the cursor over the points from the Met-Op satellite. These pop-up Skew-T can give a quick-look of thermodynamic profile across the green dots.  Some of the yellow dots may look good too.  Overall, Pop-Up Skew-T's they rule!!!

Also, the cross-section is shown in the main-image, as the Pop-Up Skew-T is in the upper left.

-Yodamaster777

pGLM Color Table Discussion (continued)

One cell in the northern portion of Huntsville's forecast area produced a tremendous amount of lightning  in the last 2 mins.

At 2200 UTC, the pGLM Total lightning rate increased significantly for near full usage of the color tables.  After further review, the upper right looks like the best one transitioning from cool to warm colors, and then back to cool.

The cell at 2216 UTC started to produce over 120+ flashes per 2 minutes with a transition to white colors in all the color tables.  I like the lower left less now, and like the right two panels more.

At 2218 UTC, my final thoughts are the upper right "takes the cake", as my favorite color table for the HWT GOES-R testbed.

-Yodamaster777

PGLM compare and contrast

We were finally lucky enough to use the PGLM lightning tool today.  I found it visually pleasing and useful.  I like that fact that once you figure out the scale, it immediately conveys the severity of the lightning.  For example.

I learned that anything over dark blue (in the default frame) is OVER 30 flashes.
That's all I need to know.  I can tell by looking at this storm that there is a LOT of lightning.  If I want to get the exact amount I can scroll over, but I don't need to.  It's like a visual threshold for me.  I prefer the non-pixelated version, and as far as color tables...I prefer the default. I initially chose the top right corner because it was more intuitive with red bring stronger, but the blues in the default give a very clear demarcation of major vs. minor lightning.
-StormFront

Random Michigan storm

A storm in lower Michigan stood out from a line of weak to moderate convection, thanks to increasing severe probability from the NOAA/CIMSS ProbSevere model. The storm, which was outside of the SPC marginal severe outlook, had steadily increasing MRMS MESH and flash rate before the warning was issued, at 21:42Z. ProbSevere was ≥ 50% fourteen minutes prior to the warning and ≥ 80% 4 minutes prior to the warning. Every other identified storm in Michigan had a probability of 5% or less. So far, no reports have been received.

Fig. 1: ProbSevere contours, MRMS composite reflectivity, and 5-min NLDN CG flashes in AWIPS2. Notice how this storm clearly stands out from all of its neighbors in the state

Fig. 2: KDTX base reflectivity and severe thunderstorm warning.

CI Shows Additional Convective Threat With Trailing Cold Front

The main band of showers and thunderstorms has mostly cleared the Nashville CWA at this point. However, the CI algorithm has been highlighting convective potential along the pre-frontal trough and then along the trailing cold front later this afternoon and this evening. The CI values have been fairly modest, and the severe CI are low, so we are not expecting the additional showers moving in over the next few hours to be all that strong.

MRMS mosaic 0.5 deg. radar is now showing some better developed echoes associated with the pre-frontal trough draped from western TN down through northern MS and south AR. There are also some weak echoes showing up from south IL down through the MO panhandle associated with the cold front. -JP

pGLM Color Tables Thoughts

The activity has been kind of quiet over OHX forecast area.  However, here are some thoughts on the pGLM color tables.

Preference is for the color table in the upper right or lower left. They work the opposite from each other going from warmer to cooler colors in the lower left panel, and cooler to warmer colors in the upper right.  I do not like the color table in the upper left panel, since it is an AWIPS default color scheme for other convective parameters such as CAPE, stability indices, etc.  The lower right is decent but goes from gray-scale to cooler colors, and then to the warm or HOT colors.  It might take some time to make this jump.

-Yodamaster777