As I mentioned in the previous pseudo-GLM post, there were several good lines of discussion during and after the event was run.
I had asked what the forecasters felt about the pseudo-GLM as a whole and how the WFOs use lightning now. One common response was that lightning is a "good to know" product, particularly for situational awareness. Lightning is good for outdoor events and monitoring lightning initiation. The pseudo-GLM improves the lead time on the first cloud-to-ground strike as most storms begin with intra-cloud lightning before the first cloud-to-ground strike. The pseudo-GLM also can assist in radar poor regions as well as gauge the intensity of the lightning activity.
Additionally, I was a little too concerned with influencing the forecasters' thought process during the event. As a result the lightning jump described in the previous post was not readily seen. During the post analysis, the discussion focused on the lightning jump and how it did help flag the southern cell a few minutes earlier than radar alone. The post-event analysis helped solidify the connection between the lightning jump and what was observed on radar.
I also asked about how the 8 km resolution worked for the forecasters. The main response is that everyone always prefers higher resolution. With that said, this resolution should be good enough to distinguish between the updraft and forward flank downdraft region of storms. It also can show the cores of individual storms.
Another comment by the forecasters was the interest in seeing total lightning during winter storms. They wish to determine if there is convective snow and they have found that the National Lightning Detection Network (that detects cloud-to-ground strikes) rarely indicates lightning. Knowing that a snow event is convective could lead to a doubling of the estimated snowfall amount.
One of the final topics I asked about was how to better include lightning data in public products. Currently, the WFOs do not issue "lightning warnings" like the 45th Weather Squadron does for Kennedy Space Center and Cape Canaveral Air Force Station. Also, the typical warning for severe thunderstorms or tornadoes starts with, "Doppler radar has indicated ..." We discussed how lightning wording could be added and I included some of my conversations with the Huntsville, AL and Melbourne, FL WFOs. There is the potential to state that, "A GLM lightning jump was detected ..." but this incurs problems with interpretation by the public. An excellent suggestion by the forecaster participants was to include the phrase, "... GLM lightning trends indicate a higher confidence that this storm is becoming severe or producing a tornado." This helps convey confidence in the forecast as well as adding additional lightning awareness.
Tomorrow I will update the blog with the discussions and comments from the real-time operations we performed over the Huntsville, Alabama domain today.
Wednesday, June 9, 2010
24 May 2008 Archived Lightning Case
With no lightning in any of our total lightning domains during operations Monday and Tuesday, the forecasters focused on the archived case from 24 May 2008 near Enid, Oklahoma. This case has served as a good introduction to the pseudo-GLM flash extent density product ahead of the real-time operations that have been taking place Wednesday afternoon. This event was interesting to go through, with a northern cell in Garfield County and a later, southern cell in Kingfisher County. The scenario starts with the northern cell already active. Both cells showed strong lightning jumps ahead of intensification.
For the northern cell, the jump preceded the formation of a strong rotation couplet. However, storm reports did not indicate an observed tornado or severe weather. I had remarked after the event that this was one of the stronger jumps I had seen without a severe weather report. Most of the forecasters warned on this storm due to the radar velocity signature, but the lightning jump helped add confidence. Potentially, severe weather occurred, but due to the location of the storm nothing was observed.
The southern cell demonstrated the utility of total lightning for both lightning safety and severe weather operations. As the southern cell began to develop, the pseudo-GLM indicated lightning activity 5 minutes before the first cloud-to-ground strike. Initially the pseudo-GLM was showing a flash density of 6 flashes at 1902 UTC. This gradually increased for the next 8 minutes and then demonstrated a rapid jump to 86 flashes by 1919 UTC. This occurred 8 minutes ahead of the first reported tornado just west of Lacey, Oklahoma at 1927 UTC. During the post analysis, this lead time was significant for the event as the radar velocity signature was weak at 1921 and was just showing signs of a couplet at 1926 UTC. The reflectivity was showing some signs of a hook at 1921.
I feel the discussions from going through this event with four forecasters were the best results. I will follow-up with this in a subsequent post.
For the northern cell, the jump preceded the formation of a strong rotation couplet. However, storm reports did not indicate an observed tornado or severe weather. I had remarked after the event that this was one of the stronger jumps I had seen without a severe weather report. Most of the forecasters warned on this storm due to the radar velocity signature, but the lightning jump helped add confidence. Potentially, severe weather occurred, but due to the location of the storm nothing was observed.
The southern cell demonstrated the utility of total lightning for both lightning safety and severe weather operations. As the southern cell began to develop, the pseudo-GLM indicated lightning activity 5 minutes before the first cloud-to-ground strike. Initially the pseudo-GLM was showing a flash density of 6 flashes at 1902 UTC. This gradually increased for the next 8 minutes and then demonstrated a rapid jump to 86 flashes by 1919 UTC. This occurred 8 minutes ahead of the first reported tornado just west of Lacey, Oklahoma at 1927 UTC. During the post analysis, this lead time was significant for the event as the radar velocity signature was weak at 1921 and was just showing signs of a couplet at 1926 UTC. The reflectivity was showing some signs of a hook at 1921.
I feel the discussions from going through this event with four forecasters were the best results. I will follow-up with this in a subsequent post.
EWP daily briefing... 6/9/2010
Before the official briefing started, one of the forecasters mentioned to Lee Cronce and myself the idea of creating a filter for the CI product where cirrus is present so that the forecasters will know when the product will not be able to make any nowcasts, similar to how the radars have a certain color for areas where range folding is occurring. He mentioned that at some times they cannot understand why the product is not producing nowcasts in obvious situations of CI unless someone looks up the cloud type output for them. This was noted by Lee as a possibility for future input into the product's output.
24-hour thermal couplet detections and severe reports for 7 June 2010
During the briefing Lee presented some scan by scan output from the UWCI product over Wyoming during the 6/7 IOP. He mentioned that the first signal in the UWCI was seen at 2032 UTC, with more widespread signals occurring at 2045 UTC and beyond. The area of interest was actually located between two radars where coverage is fairly limited and the UWCI provided some information on the initiation about 15 minutes prior to detection on radar. He also showed the 24-hour thermal couplet detections and severe reports from the same event (see images above). There were a lot of detections associated with the severe reports, including one that was co-located with and prior to a report of a tornado near Scottsbluff, NE.
One of the forecasters mentioned the possibility of a GOES-R storm top divergence product. He mentioned how this would be very useful in determining storm characteristics in warning operations. I mentioned Bob Rabin's work with current GOES WV winds in producing real-time winds at various levels by tracking features in the WV imagery. From these winds he is able to calculate divergence, vorticity and wind speed contours. I showed them real-time examples from the website provided by Bob Rabin at http://cimss.ssec.wisc.edu/mesoscale_winds/. The forecasters seemed very interested in this and mentioned interest in demonstrating this in future experiments. I also made sure to point out that with GOES-R's great improvement on spatial and temporal resolution, these products will be much more accurate and will be able to capture smaller scale features. I also talked about GOES-R's increased capability for object tracking.
During the weather discussion I showed the forecasters the UW-CIMSS simulated satellite/observed satellite comparison page to see how well the NSSL-WRF was representing the day's weather. It seemed to be doing fairly well so I showed the simulated lightning threat product to see what the NSSL-WRF was showing for the possibility of lightning over the CONUS region. There seemed to be the possibility of some lightning occurring over the Nashville area later on this evening, so following the weather discussion for the day we decided to localize near Huntsville, AL for the possibility of real-time PGLM operations.
24-hour thermal couplet detections and severe reports for 7 June 2010
During the briefing Lee presented some scan by scan output from the UWCI product over Wyoming during the 6/7 IOP. He mentioned that the first signal in the UWCI was seen at 2032 UTC, with more widespread signals occurring at 2045 UTC and beyond. The area of interest was actually located between two radars where coverage is fairly limited and the UWCI provided some information on the initiation about 15 minutes prior to detection on radar. He also showed the 24-hour thermal couplet detections and severe reports from the same event (see images above). There were a lot of detections associated with the severe reports, including one that was co-located with and prior to a report of a tornado near Scottsbluff, NE.
One of the forecasters mentioned the possibility of a GOES-R storm top divergence product. He mentioned how this would be very useful in determining storm characteristics in warning operations. I mentioned Bob Rabin's work with current GOES WV winds in producing real-time winds at various levels by tracking features in the WV imagery. From these winds he is able to calculate divergence, vorticity and wind speed contours. I showed them real-time examples from the website provided by Bob Rabin at http://cimss.ssec.wisc.edu/mesoscale_winds/. The forecasters seemed very interested in this and mentioned interest in demonstrating this in future experiments. I also made sure to point out that with GOES-R's great improvement on spatial and temporal resolution, these products will be much more accurate and will be able to capture smaller scale features. I also talked about GOES-R's increased capability for object tracking.
During the weather discussion I showed the forecasters the UW-CIMSS simulated satellite/observed satellite comparison page to see how well the NSSL-WRF was representing the day's weather. It seemed to be doing fairly well so I showed the simulated lightning threat product to see what the NSSL-WRF was showing for the possibility of lightning over the CONUS region. There seemed to be the possibility of some lightning occurring over the Nashville area later on this evening, so following the weather discussion for the day we decided to localize near Huntsville, AL for the possibility of real-time PGLM operations.
Tuesday, June 8, 2010
Thermal Couplet detection prior to spotter funnel report
An interesting thermal couplet case not within the assigned WFO emulations. At 2202 UTC a thermal couplet was detected right near the border of northeastern KS/northwestern MO within the EAX CWA. At that time, no LSRs indicated any severe reports other than flooding. Approximately 15 minutes later a report came in of a funnel cloud via a spotter network. As an additional note, there is currently no severe thunderstorm warning for the storm with the detected thermal couplet. Perhaps this would be a good case of increasing forecaster confidence for warning with the associated thermal couplet detection?
Now 2239 UTC, and the cell that produced the thermal couplet is now tornado warned
TX Panhandle CI in the HWT-EWP 6-8-10
Today in the NOAA HWT EWP in Norman we have been watching a line of cu over the TX Panhandle. At 1932 UTC we first noticed the CI "pre-cloud growth" and the "likely" indications. It was interesting to note however that the "likely" was associated with cloud-top cooling rates in the -4 to -7 range, but the "pre-cloud growth" was associated with greater values of cloud-top cooling rates of around -9. Eventually the area of -9 became the first convective initiation spot, and those values increased to -14 before we saw the first 35 db echo. The first 35 db echo showed up at 1955 UTC, which was 23 minutes later. At 2025 UTC a 1" hail report was logged with that same storm.
One other point to note was that we were monitoring the products on the web site (http://cimss.ssec.wisc.edu/snaap/convinit/quicklooks2.php) and estimated that the CI indications were approximately 3 minutes faster than the LDM feed into AWIPS.
One other point to note was that we were monitoring the products on the web site (http://cimss.ssec.wisc.edu/snaap/convinit/quicklooks2.php) and estimated that the CI indications were approximately 3 minutes faster than the LDM feed into AWIPS.
Identified Overshooting Top
The above overshooting top was identified at 2032 UTC outside the current IOP area of Wichita and Topeka, Kansas, with the associated severe thunderstorm warning issued at 2038 UTC by the Shreveport WFO. However, unsure what the forecasters were thinking when issuing the warning, and whether the OT product would have been helpful in their decision.
EWP daily briefing... The 2345 UTC hour-long satellite gap
At the beginning of the briefing we discussed the previous day's event. Unfortunately due to a few problems we were not able to draw any conclusions from the UWCI or OTTC products from yesterday's event. First, we were not able to display any satellite imagery, so overlaying the UWCI and OTTC products was not possible. Lee Cronce did suggest that we overlay the products on radar towards the middle of the IOP last night, but at this point the second problem came into play... cirrus. During the later half of the IOP the entire region was covered with thin/thick cirrus and thus made the UWCI products inoperable. The OTTC product were still working, but at this point we encountered the hour long void of satellite data from 2345 UTC to 0045 UTC. This hour long void has been causing a lot of trouble during our evening IOPs in the EWP. I have also been hearing complaints from SPC operations as this is a very important time-frame for severe weather and the forecasters don't understand why this time period was selected. Once this occurs we essentially have to shut down the GOES-R aspect of the IOP because the forecasters become disillusioned by the extremely poor temporal resolution of any satellite data during this time period. By the time the satellite data returns, there is no continuity in the products in the forecasters minds and they therefore stick to the radar products they have been comfortable looking at over the past hour. The silver lining from yesterday is that we did see our first thermal couplet detection in real-time last night and it did occur at the time of the issuance of a tornado warning by one of the forecaster groups. In this case it did not provide any lead time, but it did provide confidence in their warning decision.
During the weather briefing I showed the forecasters the NSSL-WRF simulated satellite imagery and lightning threat to help determine the location for tonight's IOP. The forecasters were very interested in the model output and asked to see it every day during the weather briefings. For tomorrow I will also show them the verification page that UW-CIMSS has created for the simulated satellite imagery. We decided to spend the first half of the IOP by splitting the forecasters up into two groups... one participating in a WES case for the PGLM, while the other monitors the location of interest for this evening's IOP for convective initiation. We have decided to localize over Kansas City, MO for the real-time IOP. Updates to follow.
During the weather briefing I showed the forecasters the NSSL-WRF simulated satellite imagery and lightning threat to help determine the location for tonight's IOP. The forecasters were very interested in the model output and asked to see it every day during the weather briefings. For tomorrow I will also show them the verification page that UW-CIMSS has created for the simulated satellite imagery. We decided to spend the first half of the IOP by splitting the forecasters up into two groups... one participating in a WES case for the PGLM, while the other monitors the location of interest for this evening's IOP for convective initiation. We have decided to localize over Kansas City, MO for the real-time IOP. Updates to follow.
Monday, June 7, 2010
Alternatives to satellite underlayment
As an alternative to overlaying the CI product on satellite imagery, I suggested that the forecasters overlay it on radar imagery for lead time purposes. The caveat in this is that the radar data was down for a while, too. They were able to get the mosaics back up and running, but the composite imagery could not be referenced.
As a side note, the Goodland, KS WFO emulation was transferred over to the North Platte, NE WFO.
As a side note, the Goodland, KS WFO emulation was transferred over to the North Platte, NE WFO.
EWP technical difficulties
As is the nature of experiments, things do not work all of the time. Today following the training we went into a real-time IOP with the groups localized over Cheyenne, WY and Goodland, KS. Unfortunately the feed for the satellite imagery into the AWIPS systems went down and cannot be fixed until the morning, so it makes it hard to evaluate the Proving Ground products today. Fortunately this is just a familiarization day so we didn't totally lose out on a day with the forecasters.
EWP back in action
Today the EWP starts up again after a (refreshing) week off. Lee Cronce and Sarah Monette from UW-CIMSS are here to provide support for the UWCI and OTTC products, and Geoffrey Stano from NASA SPoRT is here to provide support for the PGLM product. Training is taking place for the first half of the day, but we plan to do a short familiarization IOP during the evening with some severe weather expected to occur near the CO/WY/NE border. We will be posting regularly throughout the week on forecaster interactions and some discussion on product performance.
Subscribe to:
Posts (Atom)