Week 3 Debrief

Week 3 of the EWP side of HWT was very busy with many distractions due to the Moore tornado and people in and out of the HWT. However, everyone survived and there was good feedback on the GOES-R products despite the GOES-13 outage.


WRF Simulated Satellite Forecasts

It's good to see how the model is handling the environment with this product...e.g., is the fog and low stratus burning off in the model vs reality?

It looked like the real deal.

A loop that compared the simulated vs the observed would be good.

I had training problems with the WES simulation and the simulated IR. The procedures did not work...there was a work around apparently but I did not realize it.  


PGLM

The tracing tool is similar to warn gen in that I could step through pretty quick and develop a track.

I see this as a future product for decision support services when the biggest concern is lightning...there are alot of events where we need to know if lightning is going to happen. 

The tool is necessary but its just too time consuming in the warning process and im not sure how to make it better for warning...when lightning is my number one concern then I would use the tool more. 

I used the tool in combination with Cloud-Top Cooling...and there was good correlation there. 

I'm more of a fan of the cooler colors in the color table.

The flash extent density is excellent at showing the extent of the lightning in the anvil.


Convective Initiation

Although the product was not available for Wednesday and Thursday I saw enough where I would go online and look at the product.
This would be a good product for the mesoanalysis forecaster. 

It was also good for cell maintenance and for cell feeders into an MCS that we had on Tuesday.


NearCast

The thte difference is a good product...shows exactly what you want it to.


Cloud-Top Cooling

The product worked very well initially...but then struggled somewhat with convection to the north as there was an anvil cirrus shield overhead.

On Thursday we uses this product quite a bit in a situation when there was more of a cap...so sometimes u would see a signal and then no convection and then again...and then eventually convection would develop. Eventually the convection fired on the strongest of three signals and this shows the utility of the product diagnose when a cap was eroding. 

I would not use the product to just issue a warning...not enough confidence.

The CTC product is also useful close to the radar. The Lubbock convection was further from the radar...but the Amarillo storm was close to the radar...when we saw a strong signal there was a hour lead time on severe hail MESH. It's very useful close to the radar useful.

The initial convection was captured well and the product would be best used with other environmental data...know your environment.


Sounder RGB Airmass

I didn't have an opportunity to use the RGB airmass product...unfortunately the training material was limited on this product.

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

EWP Mesoscale Discussion May 23 2220 UTC

A complicated convective scenario continues to evolve over western Texas in an area of weak mid level flow where mesoscale features have been the primary driver for storm motion, storm type, and severe weather type.

Severe supercell storms with all severe weather threats continue to move south southeastward across King and Dickens Counties into Kent and Stonewall Counties.  These storms have a history of tornadoes, golfball sized hail, and 80 MPH winds.  This severe threat is expect to persist as these storms move slowly along a region of high theta-E air with dew points in the low to mid 60s.

Recent radar trends show strong mid level rotation continuing in King County…and there is no current reason to believe that this storm will weaken at any point soon.

Because storm mode is expected to be supercellular for at least the next couple of hours and possibly longer…significant severe threats of all modes should be expected in the path of this storm.  In addition to continuing to travel along this boundary of rich theta-E air…NEARCAST products indicate a region of substantial destabilization in the path of this storm.

To the north, in the AMA area, potential for convection continues to be monitored where considerable destabilization is forecast by GOES-Nearcast vertical theta-E difference product.  A strong outflow boundary has pushed to the north and west of the LBB area storms… which continues to complicate the convective scenario.  Originally…  deeper convection was noted on the Cloud Top Cooling product…and though the echo has struggled to develop…lightning and a severe MESH indicator are now noted within an echo in Potter County.  Convection may continue to increase along the outflow boundary in the next couple of hours…with hail and wind being the main threats.

To the south, in the Midland CWA, convection developed in areas of higher terrain and drifted slowly to the north-northeast.  The strongest storm at this time is moving into Andrews County.  These storms have been moving slowly to the north over an atmosphere characterized by dry air…and though the MESH product continues to indicate a threat of hail in the strongest storms…a threat of damaging wind will likely be the primary threat until the storms reach higher moisture.

- Sears/McCormick

SPORT Flash and Trace Tool Kent Co Texas

On a 4-panel with MRMS Sfc Z, Sfc Vil, and others.

The trace tool was used on upper-left panel and indicated how the flashes increased quickly with the severe storm over Dickens, Kent, and Stonewall counties in the southeastern portion of LUB’s CWA.

Admittingly, the latter 5 min occurred while I was creating the image, etc, so didn’t redo my centroid there, just the zig-zag bad data.

Martello

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: 5/22/13

Due to the GOES-13 outage and not operating in a LMA, GOES-R demonstration products had limited use yesterday. However, the WRF simulated satellite forecasts were utilized.

The WRF simulated satellite forecasts seemed to do pretty well with the placement of the larger synoptic-scale...but not as well with some of the isolated convection...especially across PA.

There was a storm that initiated in the simulated satellite forecasts along Lake Ontario early in the afternoon along the lake breeze and no others until later on past our shift across western NY...this seemed to verify well.


Note from the EWP coordinator:

Action will be in the TX Panhandle and W OK on Thursday for our last operations shift of EWP2013. A mid morning MCS over OK may leave an outflow boundary in the eastern PH. As the upper level ridge axis moves to the east, a more favorable deep layer shear profile will emerge, with a chance for supercells. Large hail will be the main threat, but tornadoes cannot be ruled out. Good opportunities for CI produvt and PGLM product evaluation also exist.

Possible CWAs:  Lubbock, Amarillo, Norman


One more note from me...the following products are unavailable today for the HWT forecasters to evaluate due to the GOES-13 outage: GOES-R Convective Initiation, NearCast, and Sounder RGB Airmass. Products available to the forecasters will be PGLM, WRF Simulated Satellite Forecasts, and Cloud-Top Cooling.

WRF Simulated Satellite at 23 UTC

The WRF simulated satellite image forecast for 23 UTC (top) compared well with the observed IR satellite (bottom) with respect to the mid-level boundary location across Indiana.  However, it did not handle the convection well that formed over PA.  Instead it showed more convection east of the higher terrain across MD and northern VA.

Simulated IR Imagery: 22Z

Simulated satellite imagery from last night's 00Z WRF runs showed strong convection near Lake Ontario in the early afternoon with clearing in western New York during the late afternoon hours.  Convection only sporadically tries to develops until well after 00Z in western New York.

GOES-R Product Update @ HWT - 22 May 2013

Most of the GOES-R products are not in play on the EWP side of HWT today due to the GOES-13 outage. The forecasters are working in Western NY in the Buffalo and Binghamton CWAs.

Therefore, there will be a limited number of blog posts today.

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.

HWT EWP Status for 22 May 2013: 12-8 pm Shift

Note from the EWP coordinator:

Slight Risk for portions of the upper Ohio Valley and the northeast, with the highest probabilities of severe centered over Ohio. The upper level trough continues slowly eastward, and at least one notable wave is progged to swing around the base. Low to moderate instability is expected as a surface cold front moves through the area. Expect convection to develop by early afternoon, and peak in severe potential during the late afternoon and early evening hours, after which it should tail off in severity. Expecting marginally severe hail (up to 1.5″) and possible wind damage up to 65 mph.

Likely CWAs: Wilmington OH, Cleveland, Detroit, Pittsburgh

The blog will be updated after 12pm CDT with GOES-R posts.

New York, New York

Note from the EWP coordinator:

The NE TX activity was mostly a “wind bag”, with very little hail or tornado threat any more. So we have opted to complete our shift up in the Empire State. Our new CWAs: Albany and Binghamton

Mesoscale Update - 00z WRF Simulated IR and Nearcast

I was very impressed with the accuracy of the WRF simulated IR (top left panel) given that the image valid at 23z is a 23hr forecast and was very close to verifying (second image below). See the two images below.

This NearCast shows a very unstable environment (bottom right image...valid at 0630Z) through the night, which should sustain the convective bow as it tracks across Louisiana. The instability and environment actually seems to improve based on this nearcast model. Will see if this verifies.

 Wesely

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

HWT EWP Status for 21 May 2013: 2-10 pm Shift

Note from the EWP coordinator:

Moderate Risk again for portions of SE OK, AR, NE TX, and NW LA. Convection will be ongoing in the late morning, and is expected to continue well into the late evening and overnight hours. With better convective initiation opportunities to occur later this week, and to allow for some time in the morning for damage survey activities in Moore, we are opting to capture the later portion of this event.

Likely CWAs: Shreveport, Fort Worth, Little Rock, Tulsa, and Norman

The blog will be updated after 2pm CDT with appropriate GOES-R posts.

Welcome to HWT Week 3

Welcome to week 3 of the HWT. The forecasters are busy trying to get spun up on using all the demonstration products in a short amount of time since storms have exploded over OK earlier this afternoon. Once this takes place, the blog will explode as well. :-)

Forecasters are here from Wakefield, VA, Fort Worth, TX, Huntsville, AL, Upton, NY, and the Norman, OK forecasters will join us tomorrow hopefully. Most of the Norman folks were out completing storm surveys this morning from yesterday's tornadoes...which very may well occur again tomorrow. GOES-R support this week at HWT includes myself (Chad), Jim Gurka, and Lori Schultz.

There have been problems with data ingest earlier...but now things are slowly coming back online.

Since I started this post...a devastating tornado tracked 8 miles north of the National Weather Center. Its a chilling reminder that one of the GOES-R goals is to assist in increasing lead time for tornado and severe thunderstorm warnings.

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

20Z Nearcast Analysis of CAPE Trends Through the Afternoon

The 20Z Nearcast model shows slow but steady weakening of instability fields through the afternoon. Ribbon of 800-1000 J/KG along the CO/KS border between 20-22Z with a theta-e diff of 8-11K decreases through the late afternoon and evening to roughly 600-900 J/KG. There is a similar trend in theta-e difference with 6-9K theta-e difference in this region through the early evening…along with about 30kts of 0-6 km shear. Further east into central Kansas…CAPE and theta-e difference significantly drop off…so from this forecast one can expect any storms that develop within the convergence zone along the KS/CO border to move east and have some marginal strength and organization before dissipating as they approach central Kansas.

051613 2000Z Nearcasting CAPE

Sad Storms so far in SE CO/NW KS - No juice in the Nearcast

051613 22:31 Nearcast Precipitable Water Difference and Reflectivity

This image depicts CIMSS-NRE 700-300 mb precipitable water values overlaid with 0.5 Reflectivity from KDDC. These struggling high based storms are over an area with precipitable water values only 0.05 to 0.11 inch between 300 and 700 mb. It seems very unlikely these storms will do anything, unless they can quickly move east in the next few hours where much higher precipitable water values exist. 

Scotten

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.

Close... but No Cigar... Held Off SVR Based on GOES-R CI/MRMS

051613 2138 UTC MRMS fields

Held off issuing a severe thunderstorm warning for a developing storm over northern Nebraska due to MESH staying around 0.75 inch and maximum reflectivity of only 55 dBZ at the -20C level.

051613 2045 UTC GOES-R CI

In addition, the GOESR UAH Convection Initiation Products depicted a few pixels of 10-40% in the hour prior to this storm developing, perhaps suggesting that the environment may not be conductive for explosive storm development.

Flash Extent Density and Updraft Strength

Playing a bit with the SPoRT flash initiation density product and the evolution of an updraft. Although it’s not a serious storm, it represents the ongoing pulsating activity very well which could eventually gain strength when entering a more unstable air mass to the east. Below you can find the ‘Flash initiation density product’ at 2035Z and 2040Z, showing a marginal increase in lightning activity. Reflectivity at the same time showed a core with 35-40 dBz and only a few isolated lightning strikes occurred.

051613 2035 UTC PGLM Flash Extent Density

051613 2040 UTC PGLM Flash Extent Density

051613 2055 UTC Reflectivty

At 2055Z, the storm finally strengthened in reflectivity fields (the core peaked at near 60 dBz) . Although that was just a temporal strengthening trend of that storm it is great to see the lead time you get with that lightning product before the updraft eventually strengthens. 

Helge

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

RGB Airmass Use Over NE and KS

051613 1901 UTC RGB Airmass

The GOES Sounder Air Mass image is very useful in highlighting the different features of interest for today. First of all the compact disturbance which is about to leave NE Colorado to the east/northeast is well visualized by mid-level drying in the image. Weak forcing ahead of that feature already caused some initiation over N/NE Nebraska with another round of storms evolving over extreme NE Colorado. Of interest is a southward extending and weakening vorticity lobe which is about to enter Kansas from the west right now. Also, the dryline is well recognized by that product, showing warm/moist air ahead of the dryline advecting to the north (green-ish colour). This correlates well with mid-level moisture, seen in latest RAP output. A gradual transition from ‘green to blue’ occurs when moving westward (e.g. towards the TX Panhandle). This corresponds well with some residual low-level moisture f.ex. in the lowest 850 hPa, which gradually mixes out. We will monitor both the dryline and the eastward moving but weakening PVA lobe for some kind of interaction during the following hours and eventually for sporadic CI. 

 Helge

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...

Flash Density Trace for Tornadic Storm near Leon, OK

A tornado was reported at 0022Z near the town of Leon in OK. The associated flash extent density trace from the parent storm is below. Focus on the time frame between 00Z and 0031Z. Notice a consistent trend upward in flash extent rate…with a peak value of 48 at 0021Z. Unfortunately…the trace was not created soon enough to capture the flash rate as the storm was intensifying prior to 00Z but the upward trend in flash rate correlated well with the pre-tornadic organization phase.

Here is a look at the storm near Leon at the time of the tornado report. Rotation tracks peaked at 11 s-1, MESH was maximized at 0.47″ and the vertically integrated ice peaked at 16 kg/m-2.

PGLM and Warnings in OUN

Loaded the one minute SPoRT Flash Extent Density product and used the editable Moving Trace tool. The moving trace circle had to be expanded for each frame; forecasters won’t like this because it doesn’t have a “apply to all” feature for this. It is also not intuitively obvious to forecasters that have been using other tools such as the warngen pathcast tool and distance/speed tool in AWIPS. The trace tool makes a graph showing “Flash Extent Density”, which showed trends in lightning for the selected storm.

1914 UTC Flash Extent Density. This product could be useful for NWS event support to describe specific lightning threats to outdoor activities. It could also be useful to identify strengthening updrafts that could produce large hail. One storm that showed a quick spike in Flash Extent Density above 50 Lma at 1912 UTC went on to drop 1 inch hail at 1926 UTC, for a 14 minute lead time. See Becca’s blog entry on this storm.

There were several bad one-minute data samples caused by loss of input data into the Oklahoma LMA. Two of them are illustrated below.

One minute Flash Extent Density showing the sharp drop that was apparently the result of a temporary loss of input data into the Oklahoma LMA. This occurred again at 1948 UTC see the trace graph below.

- Ostuno

PGLM and Rotation Tracks Associated with Weak Bow Echo

Rapidly developing convection showed a rapid increase in flash extent rates in the low teens to the mid 30s with a few pixels spiking in the 40s. This activity rapidly morphed into a bow echo that raced across south central Oklahoma. The SRM velocity gradient along the front end of the bow was very tight…and the rotation tracks product showed an interesting progression of bow-like rotation signatures from north to south. There were gaps between each line (seen in the graphic below) unlike a single storm track which is fairly continuous.

At the north end of the bow…the values of the rotation tracks were strongest which is to be expected in the region of the northern bookend vortex. The flash extent rate was relatively weak with the bow…along with weak sfc velocities estimated to be around 20 kts from mesonet observations. So although the reflectivity structure looked as if it could be an intense bow echo with moderate midlevel convergence…and rotation tracks were depicting embedded circulations within the line…no reports of severe wind or damage were reported or observed.

The highest values for sfc rotation tracks around 23s-1 were in the vicinity of the bow where smaller cells were merging with the main line near the northern bookend vortex. The best velocity couplet depicted on SRM went between Byng and Francis around 2349Z and was just southeast of the highest values for the sfc rotation tracks.

RJM

Nearcasting and High Based Thunderstorms

As mentioned a bit earlier in a post, the NRE product showed enhanced chances for convection all the way to the Lubbock area. Especially the theta-e difference product placed the tongue of mid-level unstable air just where high based thunderstorms finally evolved. Surface dewpoints in the mid 30s and temperatures in the low 90s point to elevated and high based thunderstorms with a distinct downburst/ heatburst? risk. The product helped a lot to focus on the anticipated area of initiation. LAPS also did a great job in developing the elevated thunderstorm activity both in space and time.

051513 2300 UTC Vertical Theta-E Difference (top left), Sustained Convection Index (top right), CAPE (bottom left),  and Visible Imagery (top right)

Helge