Storm Close to Amarillo Radar

The MRMS products were a big help in this case being able to look at multiple radars since my storm was right near the radar as depicted in the image below.

The Height of the 50dbz core went above 30,000ft agl, which was a trigger for issuing the warning. The 4 panel product below made the process easier in two ways. First the storm was near the radar and so having a 50 dbz echo core height product that took into account multiple radars was extremely helpful as the local office radar was unable to see the top of the storm. In addition, you could just look at the one screen and see the 50 and 60 dbz core height quickly without having to look through multiple slices of an adjacent offices radar to find the height of these cores.

The MESH and HSDA algorithms below both provided lead time for the quarter size hail that fell 11 miles north of Amarillo at 2236Z. The multi radar aspect of the MESH algorithm also made it easier to use than having to look at an adjacent radar to see the top of the storm. The HSDA is not multi radar and thus there were some limitations with this algorithm for the storm near Amarillo due to the close proximity of the storm to the radar.

Cloud Top Cooling (CTC) did a nice job of showing that convection was really trying to break out in Amarillo’s County Warning Area (CWA). There were numerous cloud top cooling signatures beginning at 20z. The first 50dbz echo reached the ground at 2146z. So it took awhile but eventually the storms overcame the cap and became severe (See image of CTC below).

Jeremy Wesely

Still Watching and Waiting in Amarillo…

Ok, well we’ve gotten some recent cloud-top cooling amounts from clouds in Randall County, TX.  Cloud top cooling rates as low as -17C/15 min were observed in Randall County as the outflow boundary moved across the area, as indicated in the image below.

Also, notice the rather distinct theta-e ridge that is still present and extending into Randall County per the LAPS data (image below). We’ll see if these products allow for an appropriate focus and help predict likeliest locations for eventual development.

For LUB’s CWA, Watch Out Garza and Eastern Lynn Counties (SW of Current Supercells)!

Watching for potential development SSW of current supercells over Floyd, Dickens, and King counties to the NE. CTC shows potential. Cirrus anvil across the NE CWA will likely inhibit any CTC effectiveness.

Unfortunately, GOES_CIMSS Nearcast (either E or W) data did not extend further enough east across the LUB CWA to be effective with this event. (see 2030 UTC CIMSS W projection below).

If the Garza area was to develop quickly, the OUN_WRF project indicates 0-1KM SRH to 200-260 m2/s2 which mean environment would be favorable for rapid rotation and potential tornadoes like earlier storms to the north.

We continue to monitor development closely.

Martello/Zimmerman

Tornadic Storm Fires Off Old MCS Outflow Near Floydada, TX

Strong convergence initiated northeast of Lubbock, TX near Floydada in Floyd County.  CTC product caught -16 to -17K/15 min around 18:15 UTC on this storm. Tornado warning was issued 19:21 UTC which resulted in 1 hr 6 min lead time if you had warned initially off the CTC signal.

Initialization in TX Panhandle

Texas panhandle is the area of main focus for the first part of this afternoon. Analyzing CI via the CTC product, as seen below, indicated development was expected to quickly form by 19z.

Image 1 – Cloud Top Cooling prior to CI around 18z.

Image 2 – Cloud Top Cooling at the time of CI over the central parts of Texas panhandle around 1815z.

Image 3 – Vis sat around 1815z, with CI. Vis at 1845z shows the explosion of the storm in the panhandle, with the Cloud Top Cooling product thus providing around a 30 mins lead time.

Image 4 – With the radar products unavailable at this time, using MESH and probability of severe hail to show the development of the storm to severe levels.  The CI on Cloud Top Cooling developed around an hour prior to the MRMS products reaching severe levels.

Daily Debrief: 5/20/13 and 5/21/13

With Monday being the "spin up" day and Tuesday a late shift where the Convective Initiation and Cloud-Top Cooling products were not utilized since convection was ongoing, only a few of the GOES-R products had utility in Tuesday's operations. We were hoping for better CI chances the next two days but now with GOES-13 out...the NearCast, CI, and CTC products will not be available until 23 May 2013 around 6Z at the earliest. Here are the highlights of the last two days...

NearCast

The GOES-R NearCast Thte-E trends and instability fields were good.

The NearCast instability products showed that instability was really increasing ahead of the southern Mississippi Valley line between 00-06Z last night...which suggested a prolonged event. The squall line kept going through the southeast and wind damage ended up occurring into central MS.


Convective Initiation

The Convective Initiation product picked up on intiiation potential in between the clusters...higher probabilities.

It appears that the CI product had limited false detections...low probabilities did not tend to develop into 35 dBZ echoes.

The CI product would be helpful when there are outdoor events going on that you are monitoring.

On Monday, the CI product gave a good indication of developing convection along the TX portion of the dryline after storms initiated in OK.


WRF Simulated Forecasts

The simulated IR forecasts showed good  accuracy in the two lines of convection...overall pretty good. 

I felt the IR forecasts were impressive...there was a single line of convection with good placement and it was remarkably similar to what was going on. This was using a 23-h fcst. 


Cloud-Top Cooling

Early on Monday, the Wichita Falls, TX storm had a strong CTC signal and that storm went on to produce baseballs.

It will be interesting to see how the CTC product will work for situational awareness for pulse severe situations.


PGLM

I used the PGLM moving trace tool for situational awareness on a few storms. Maybe during the heat of major outbreak it would take too much time to use...but this remains to be seen.

It does get difficult to assess more than one storm using the moving trace tool.

EWP2013 Mesoscale Discussion 21 May 2000 UTC

LAPS 2.5 Theta-E advection was strongest from central TX near more isolated/discrete severe storms from Burnet, Brady, to Hamilton Texas and northeast through Corsicana to Clarksville along the Red River Valley. GOES-R cloud top cooling (CTC) and Convective Initiation (CI) forecasts just an hour or so ago indicated the increase in the isolated severe cells over central TX well. However, GOES-R positioning was off, but not too far off regarding the tail end of the linear MCS across north and northeast TX.

CIMSS NearCast Layer GOES Theta-E and PWAT differences did show maximums right where the Brady and Burnet convection in central TX was occurring and handling maximum stripe just ahead of the linear MCS moving east across I-35 further across north and northeast TX.

OUN_LAPS SBCAPE appeared to be well in line with current SPC mesoanalyis real-time values and can be trusted for the next 1-2 hours. During the late afternoon and early evening hours, we expect the linear MCS to continue to progress east with potential for embedded meso-vorticies and weaker tornadoes along the leading edge, while larger discrete supercell storms both ahead across the east Texas Piney Woods and southwest into the eastern Texas Hill Country and central Texas to contain more intense modes. These storms will likely see better inflow of rich Theta-E air from the Gulf of Mexico leading to lower LCLs, and the potential for very large hail and longer track tornadoes, if the tail-end of the upper level forcing from long wave trough over the Plains can extend that far south.

CI/CTC AWIPS2 Loop

Tried to manually loop a 4 panel image of CI/CTC/Radar/Vis and with a 40 plus frame count it was too slow to be useful. It took over 20 seconds for all parameters to load. However, at a frame count of 12 it was much faster and of more use for following trends.

Wesely

Week 2 Debrief

While week 2 of the HWT Spring Experiment started out fairly quiet it certainly didn't end that way. Wednesday night's tornadoes in N. Texas ended up being the highlight of the demonstration so far and a lot of good feedback was collected from that event as well as the rest of the week. Check it out...

GOES-R CI
- 'On days where convection in more questionable it may be nice to have the ability to filter out the lower values to get rid of the confetti-like display, however on days where convective initiation is much more likely, those lower values provide some valuable information and help in keying in on particular growth.'
- 'Values of 57% or greater seemed to do fairly well on identifying initiation throughout the week.'

CTC
- 'The CTC is useful but does have trouble in areas of cirrus.'
- 'Most of the storms that developed did have a high POD, but also had some FAR.'
- 'In operations we're looking for which storms have potential. This is where the CTC would definitely be useful.'
- 'For situational awareness the CTC is a big thing. It identifies which storms to watch.'
- 'It would have been a better experience on Wednesday night if we'd had Rapid Scan Operations for GOES-13.'

Nearcast
- 'The CAPE field was good to compare to other CAPE fields though it can be hard to wrap your head around exactly what you're looking at and how it was computed.'
- 'The color scheme was a bit confusing. With the theta-E difference I'm used to thinking that green, yellow, and red values, are values to key in on, but in this case it was the darker blues and pinks.'
- 'The GOES-E and GOES-W images were definitely different, they didn't match, so I wasn't sure which one I should look at. It would definitely be useful to have a seamless overlap.'
- 'CAPE is conventionally what we're used to looking at, but the theta-E difference was also very useful.'
- 'Yesterday I looked at the theta-E and PW values... there were no high PW values [in west KS] and so it made sense why the storms there weren't growing. This information was very beneficial to have.'
- 'Then on Wednesday the storms in OK and TX formed right on the low-level and mid-level maximums of theta-E, so it did very well.'

RGB Airmass
- 'Yesterday the RGB showed showed drier, cooler air behind the convection which is what you would expect, but as the day went on you could see the moisture return to the area... because of this I kept my eye on what was going on there.'
- 'On Wednesday the dryline structure in OK and TX was very visible and we keyed in on this area.'
- The RGB gives you more information about the airmass source, it's composition, etc. It's very helpful information to have for situational awareness.'
- 'I liked the RGB as an overview, especially when you first sit down to see where airmasses are setting up. Though once you get into the nitty gritty of warning operations I didn't use it as much.'

Simulated Imagery
- 'We'd use it as a comparison to the actual IR to see what was influencing the model later.'
- 'It doesn't seem to handle anvils very well, but this may be a good thing because you could see where the storms were developing without the anvil getting in the way.'
- 'It's fairly remarkable what this imagery can do, giving you a satellite image so many hours in advance.'
- 'It did very well this past Tuesday in holding off on convective initiation up in the Western GL.'

PGLM
- 'Add the number or percentage of sensors currently working... for testing purposes it's crucial that we have this information so that we can use the product accurately.'
- 'Perhaps the 30 flashes/min threshold should be colored different so that it stands out more.'
- 'I used this product to identify which storms were starting to intensify and what cells I should key in on.'

Well that's a wrap for the week 2 debrief... but don't forget, our 'Tales from the Testbed' webinar will be beginning within thirty minutes and will cover the use of all of our experimental products during the N. Texas tornado event on Wednesday night. It should be a very interesting discussion!

Slow Day in CI/CTC Land

Shown below is a classic example of CI/CTC spoilage by upper level cirrus clouds. Note the rather mature convective system over the GLD CWA. All of the SPoRT CI algorithm detections (upper left) are all in the cumulus field on the outer fringe. CTC detections, when they occur (upper right), are similarly absent from the main complex. This has been the case the entire shift. Perhaps without the cirrus, we would be able to see strength fluctuations in the convective line, but the constant presence of cirrus over the top does not allow the satellite to sense updrafts. While there have been improvements to CTC over the last year to two to deal with thin cirrus, even that work would not help here. Cirrus contamination is clearly the main drawback to these otherwise excellent and useful products.

051613 2230 UTC CI (top left), Visible Satellite with CTC (top right),  NLDN lightning (bottom left), and Reflectivity (bottom right)

CL

Struggling High-based Convection in SE CO using CI/CTC

A few high based storms have been struggling to develop across southeast Colorado due to abundant dry air and SBCAPE 500-1000 J/kg.

The first image was at 2045 UTC on May 16 where the GOESR UAH CI suggested some potential for convection with a few locations 61-78%, and the CIMSS CTC depicted a maximum of -18C/15 min. This appeared promising for deep convection.

The next image was at 2115 UTC and continued to depict a few areas 20-62% for CI as well as -16C/15 min along with a few weak cells. At this point, there still remained hope for some deep convection.

The last image was at 2145 UTC respectively with lower CI and CTC values as well as a few non-severe/rather weak cells. So far, these cells have failed to intensify or become severe. Weak forcing aloft in conjunction with the lack of low level moisture may be the main culprits for the poor development of storms.

MESH and CTC in the GLD CWA

Setting up in the Goodland KS CWA today. A small cluster of storms is ongoing and certainly producing a lot of rainfall and lightning…note the 0.5 reflectivity on the upper left. To the upper right is CTC on top of the visible. No detections here…likely due to anvil cirrus hinderance. On the lower left, we have MESH from MRMS. Nothing at one inch or above here either. Reports from the area have consisted of small hail lately…0.75″ and less. This seems to reinforce the marginal nature of the storms depicted by MESH and other experimental products.

051613 2018 UTC Reflectivity (top left), CTC (top right), and MESH (bottom left)

CL

Daily Debrief: 5/15/13

Yesterday turned out to be the best day of the experiment thus far! Later in the evening we saw rapid convective initiation in Southern OK and Northern TX. Supercells formed just west of the Dallas-Fort Worth metroplex and produced very large hail as well as a series of strong tornadoes in the area. Check out the image below of the pair of supercells just west of DFW. Tornados from these cells caused a lot of damage in Cleburne and Granbury.

051513 0036 UTC Reflectivity (top left), Velocity (top right), CC (bottom left), and TDS (bottom right)

A lot of blog posts and feedback were collected from this event on the various experimental products. Here are some of the comments noted in this morning's debriefing:

PGLM
- 'I noticed a correlation between the MESH and the lightning data. Several minutes after there was a big jump in flashes, there was also a big jump in MESH values.'
- 'The OUN network kept losing sensors so it was hard to know what was a jump and what was data loss. It would be helpful to have the status information so we know that we've actually lost sensors and and when we've got a jump.'
- 'In my opinion forecasters won't like that you have [use the lightning moving trace tool] manually.'
- 'In real time I can see [the moving trace tool] being a little clunky to use, a little labor intensive, but for analysis of an event it would be awesome to see that trending information.'
- 'It would helpful to see the lightning data plotted with the hail/MESH information.'
- 'We didn't hardly get any lightning with the Oklahoma bow echo... perhaps this could be an indicator that it wasn't going to be as strong of an MCS.'
- 'I paid attention to the lightning cores and where it was increasing significantly. This seemed to be a good indication of a strong storm.'

GOES-R CI
- 'There were a couple of times where the CI gave us an 80/90% value that developed/initiated into a deep convective core.'
- 'Values were overall low yesterday in TX, but where it pinpointed the higher values it did a good job of indicating strong initiation.'
- 'I thought it did extremely well. We were looking at a decent sized cu field and it seemed to pinpoint on specific cu very well.'
- 'Yesterday there was enough of a difference in the CI values where you could pick out the more significant initiation, but on other days it seems to be far more confetti-like.'
- 'THe Montague storm had a CI value of 60%. An hour later it initiated. Thirty minutes later we had baseball sized hail. Fifteen minutes after that we had a strong tornado.'
- 'It seemed to do well with the clusters of strong updrafts, but had trouble in higher terrain. This may be an elevation/snow effect.'

CTC
- We had good CTC rates on a number of storms that ended up falling apart. It ended up that the storms had good initiation but were moving into an environment not conducive to further growth.'
- 'The CTC did a good job yesterday, but it's still very important to know your environment. We saw strong signals, but not all initiated because of other environmental factors not seen in the CTC.'
- 'The CTC gave consistent lead time of at least 20-30 minutes for severe storms on multiple occasions [in Texas].'

Our last day of operations this week doesn't look to be nearly as exciting as yesterday. We're currently in the Goodland, KS, and North Platte, NE CWA's where things have already began to initiate, and may move further south later in the evening. Stayed tuned for further updates as the day progresses...

CTC and CI Provide Lead Time on Texas Storms

Currently monitoring storms in Clay/Montague counties and potential CI further to the S/SW. Broad field of Cu was seen further south but it was hard to distinguish which of those Cu fields would finally grow into a thunderstorm.

051513 2145 UTC CTC (top right), CI (bottom left), and reflectivity (bottom right) 

Please have a look at Palo Pinto county, where the CTC product had a 80-90% signal strength of showing initiation potential (the lower orange dot). At the same time in the reflectivity fields only a few weak signals were seen.

051513 2215 UTC CTC (top right), CI (bottom left), and reflectivity (bottom right)

About 30 min later, the CTC instantaneous product showed a modest signal of -15K/15 min over the NE part of that county with reflectivity appraoching 40 dBz at the same time and place.

051513 2230 UTC CTC (top right), CI (bottom left), and reflectivity (bottom right)

Finally at 2230 Z reflectivity revealed a small core with 60 dBz. The first lightning strike occurred at 2237Z. Those products gave the forecaster a good indication which area would finally see the highest probabilities for thunderstorm development and there was abundant lead time left before that storm finally took off. 

Helge

Using CTC to issue 2116 UTC Comanche Country SVR

Based upon CTC rates around -20 to -25 C and initiation within a LAPS-analyzed region of approx. 2500 J/kg of CAPE, we warned on a cell that was developing around the Brown/Comanche/Mills intersection, expecting that strong cooling rates within an axis of (model-represented) good instability would at least result in a hail threat. However, the cell quickly weakened as it moved into the FWD CWA. Based upon recent sounding from MPEX in Seymour, TX, current atmospheric column across central TX may be too dry, resulting in growing updrafts entraining too much dry air and dissipating from negative buoyancy.

CTC Rate (SW portion of CWA) at 2045 UTC

LAPS analyzed instability and reflectivity at 2115 UTC

Daily Debrief: 5/15/13

After a quiet start yesterday forecasters did get some weather to work with later in the evening, mostly out in Texas but were also watching some clusters of storms up the western Great Lakes. Check out the feedback below:

- 'The CI product was more in its element yesterday because [we were watching] a nice, defined band of cumuls and it was easier to see the trend in the signals.'
- 'The CI product was much more accurate in Western Texas then it had been previously in the NW US.'
- 'The CI did well showing the trend on the line in Western TX.'
- 'The CTC did well in storms with strong updrafts, but got fooled by cirrus blow off on several occasions.'
- 'There were several instances where there were no CTC detections at all but you could see the storms developing beneath the cirrus shield.'
- 'Despite being about an hour off, the simulated IR did very in showing where the severe storms were in NE Iowa.'
- '[The Simulated Imagery] was really good. It showed the cluster in Iowa and also downplayed what we though would happen further north.'
- 'The RGB was a really neat tool and showed the various airmass boundaries in SW Texas.'

Today we'll doing a 1-9pm shift and are already seeing some convection right over our heads here in Norman. Focus areas today will be the DFW CWA where there is a slight risk and also, with the chance (finally) for some lightning activity, the OUN CWA.

CTC Struggles in Areas of Broad Ice Clouds

The CTC algorithm missed a developing storm that went on to become a robust storm and prompted an experimental severe thunderstorm warning. The storm in question is highlighted below within the red hatching at 2114Z when visually it was very apparent the storm was rapidly intensifying.

The algorithm “missed” this developing storm mainly due to the algorithm defining the cloud type in the vicinity of the developing storm as thick ice and cirrus at 2032Z and 2045Z. This storm was likely within the thick ice and cirrus definition…and therefore was included in the ice cloud exclusion zone and not given a CTC rate.

This example merely illustrates that not all developing storms will be captured by the algorithm even if visually it looks to be clearly intensifying. This is especially the case in a situation where multiple storms are in one area.

RJM

Simulated Imagery and CI/CTC in Northern Mesoscale Discussion

Two areas seem to be possible for convection near and west of the Great Lakes. The first is across northern Iowa as an outflow boundary and sfc trough are providing strong sfc convergence in an area of higher sfc dew points in the 50s. Limited instability and shear in this area would limit organization of storms. Main threat here would be dry/wet microbursts as hail/rain cores descend into deep dry layer below cloud base. Stronger shear is present in the second area of concern, ahead of northern stream shortwave trough in northeast Minnesota and Upper Peninsula of Michigan. CTC rates of -15C/15 min noted along a sfc front/convergence zone just north of the Canadian border at 1945 UTC and this area extends south into northern Minnesota.

The CIRA Simulated IR satellite shows storms initiating in both of these areas by 01 UTC. (see image). This was the general area stroms did form although the simulation was about an hour or two slower than reality (see IR satellite image from 2345 UTC).

Top image is the CIRA/NSSL WRF simulation 10.4um IR for 01Z Wed MAY 14th, showing some convective initiation across the Upper Peninsula of Michigan and some bigger storms across northern Iowa and eastern Nebraska. Bottom image is the actual 2345 UTC IR satellite image.

As of 20 UTC, the GOES-R CI Sfc convective initiation shows the highest percentages (around 77%) in southern MN and western WI. By 21 UTC the highest percentages (up to 90%) were across Nebraska. CTC cooling rates were 5-15C/15minutes in these stronger updrafts, which were small and isolated, stretching from CO to WI. The line of higher convective initiation decreased as the storms initiated, then were followed by individual storm cloud-cooling tops identified by the CTC. See following images.

GOES-R CI at 2015 UTC

10km Radar Coded Message at 2119 UTC showing the line of showers and thunderstorms.

CIMSS Cloud top cooling – Instantaneous image at 2130 UTC. Max values around -15C/15 minutes, that spiked up to -40C/15 min by 22Z UTC from NE Iowa to SE Minnesota. Severe microburst winds hit Mason City, Iowa around 2150 UTC. The storm showed a CTC cooling rate of -25C/15 min at 2132 UTC. The algorithm gave a value of -70C/15 min for one storm, which was probably a misinterpretation caused by anvil blowoff from a previous updraft.

Ostuno

Consistent CTC Allows for 90 minutes of Lead Time

051413 1915 UTC Cloud Top Cooling

051413 1945 UTC Cloud Top Cooling

051413 2002 UTC Cloud Top Cooling

051413 2015 UTC Cloud Top Cooling

051413 2115 UTC Cloud Top Cooling and warning polygon

The sequence of images depicts a consistent area of cloud top cooling (at least -10C/15 minutes) that occurred about 90 minutes prior to the issuance of SVRs with large hail
likely with MESH values above 1 inch. If a consistent CI signature occurs, this may significantly increase lead time for severe thunderstorms.

14May2013 Mesoscale Discussion: W Great Lakes

Monitoring the potential for convective development across W Minnesota / SE South Dakota, and across central Nebraska.

Shortwave trough currently progressing east across S Saskatchewan into E Ontario providing support for some initial development across the Canadian provinces, as seen in IR / VIS / CTC data. Large-scale lift aloft, in association with eastward progressing frontal boundary is supporting a line of agitated cumulus extending south into NW Minnesota. Nearcast difference CAPE product indicates an axis of weak-to-moderate instability (500-1000 J/kg) in front of this boundary extending south into NE and IA. WRF simulated IR fails to develop much of any activity across N Minnesota, keeping all activity developing after dark across the UP of Michigan. Farther south and west, it shows better development across Iowa and Nebraska around 00Z. However, considering best large-scale forcing exists closer to the Canadian border, and model fields were generally overestimating surface dew points farther south (forecast >60 versus AOB lower 50s being observed), thought is that best potential may exist closer to the international border over the next few hours.

If storms can develop, dry low levels and steep lapse rates support a high wind threat from higher based storms. Better wind fields farther north (0-6 km shear >50 kts) and slightly cooler temps also support an enhanced threat for marginal severe hail closer to the Canadian border.

Picca