CTC – Hot or cold

Forecaster comments from EWP blog...

Here’s a comparison of the UW-CTC product using the default AWIPS 2 color table (bottom right) vs. a warm to cold color table (upper right). In the upper right image the stronger cloud top cooling rates are displayed as a warmer color, similar to IR satellite color table enhancements that display the colder cloud top temperatures with warmer colors. This has the benefit of drawing the attention of forecasters who are conditions to associate warmer colors with more extreme values (ie, radar data).

GOES Simulated Satellite

Forecaster comments from EWP blog...

GOES 20z simulate satellite on 5/21 indicates deep moist convection breaking out over western OK and portions of northwest TX (above two images…20 hour forecast).  This is optimistic compared to 20z IR/WV (bottom two images).  However, convection over NM is verifying nicely.  Maybe simulated satellite handles orographically forced convection better?

West Texas CI

Forecaster comments from EWP blog...

Small area of cumulus developing over higher terrain in west Texas shows high strength of signal value on the UAH CI product at 1730z:

This area continued to develop into a mature CB, with the first cloud to ground lightning detected by NLDN at 1945z – a 2 hour lead time from the first CI signal to the initial cloud to ground lighting activity.

Simulated Satellite Imagery in EWP

Day 1 of the EWP this week is focusing on the AMA and LBB areas.  At the current time, no storms have yet formed in these regions, so the forecasters are looking at the various model solutions to determine which seem to be on track.  Simulated satellite imagery is an ideal tool for model evaluation because it shows where the model places clouds, boundaries, shortwaves, etc.  The image below shows the simulated imagery based on a 20-hour forecast from the NSSL WRF valid at 20Z today (top panels), along with the observed IR and WV imagery from GOES (bottom panels) also valid at 20Z.  Notice that the simulated IR image (top left) shows convective cloud formation in New Mexico that appears to match observations (bottom left) very well.  This gives forecasters confidence in the remaining NSSL-WRF forecast, including when storms will move into the Amarillo and Lubbock forecast areas.

UAH-CI provides 1 hour 20 minute lead time on 1 inch hail report

The UAH-CI product provided a strength of signal forecast of 75.0 at 1702 UTC on a cell developing in Lincoln County, New Mexico (see image below). At approximately 1820 UTC, the NWS received a report of 1" hail associated with this cell. This location in New Mexico is quite far from the GOES-East subsatellite point, yet the product still has very good utility at these distances. The University of Wisconsin CTR product followed up the UAH-CI forecast at 1745 UTC with a cooling rate of -24 to -25 C per 15 minutes.

Other cells have continued develop including the cell that featured a strength of signal over 90 in the image above!

CTC Captures Severe Convection in S. New Mexico

The UW-CTC product captured some severe convection in southern New Mexico, Lincoln County, and exhibited strong cooling rates well before the first report of severe hail.  Below is the screen capture from AWIPS-2 at 1745 UTC when the strongest CTC signal was evident valued at -25K/15min.

Following at 1820 UTC, the first report of severe hail at 1" was received by NWS.  Below is the screen capture of SPCs storm report page.

According to the reported time, UW-CTC provided a lead time of 45 minutes over this first hail report.

The week in the review

Working with the forecasters this week of Mother's day has been comprised of relative slow weather, at least as defined by people who live for the next severe weather event. Due to the relative calmness of the atmosphere, the visiting forecasters have had the opportunity to really dig into the tools presented to them in cases that most would consider marginal. As such, they each had time to interrogate each of the tools, both to test their individual strengths and weakness, as well as how the tools could be used together to give them a more complete picture of the near storm environment and the elements leading up to each interesting case.

The role of a convective initiation algorithm is to give indications of clouds that are exhibiting signs of growth associated with a developing storm. One that will produce a 35 dBZ radar echo, meaning at least rain, possibly more. The UAH CI product, or SATCAST is designed to give the user information, based on IR brightness temperature tests, of how a tracked cloud has grown/changed since the last satellite image. This signal will precede the radar echo, giving the forecaster knowledge of the environment of interest and, depending on the strength of the signal, and area to focus on. The blog has some great examples of the use of the UAH CI/UW CTC products used in collaboration to highlight areas of interest, to many to mention here, and real, the forecasters have done a fabulous job of describing the different cases presented during the week. Instead, I will focus on the ways the products were used and displayed. 

An obvious choice, placing the CI/CTC product on top of a visible satellite image. Regardless of the level of zoom, this setup allows for the familiar imagery to have a bit more utility. 

Utilizing the 4-panel display allows for the flexibility to view the data sets separately.

ALY - 16May12, 2010z

Some different set ups have included lightning data, radar data, and some of the newer products from the MRMS and Near-Cast suite of tools.

An example of the combination of tools made possible by the AWIPS-2 display, the Merged Reflectivity at the lowest altitude display from  the MRMS with the UAHCI and UW-CTC products overlaid allows one to follow the evolution of a cloud object by the satellite products through to the first radar echoes and beyond.

DVN - 15 May 12 2206z

In some cases, outflow boundaries from the storms would trigger additional satellite CI indications that also progress in time to initiation. The ability for the individual control of the color schemes of each of the products made the visualization of these three products simultaneously possible.

Finally, as day passed into night, overlaying the products over an IR image.

 

17 May 12, 2214z

Although the intent of having the product scientists on hand to answer the questions of the forecasters, in many ways, we spend more time learning from them.  Seeing how each forecaster uses the product, what their expectations are, and tapping into their vast knowledge of the storm environment from the operational perspective forces a different perspective.  One that should result in the fine tuning of the algorithms from something that is "geeky cool" to something that can be used everyday.

EWP end of week 2 debrief

Nearcast
- "Did a good job over FL… the gradient of the theta-e difference really lit up when a boundary hit it."
- "Highlighted well where you had a minima in instability over both ends of the CWA... had confidence that you would have the whole area light up."
- Archive case... "Saw a clearly defined dryline which helped us pick out where the convection was going to occur that day."
- "This CAPE product holds a lot of promise... I don't know about accuracy, but qualitatively it was highlighting the areas of interest."
- "Only having two layers is a drawback for now."
- "I would think that the more negative values would be unstable... That ended up being a source of great confusion for the first day because of what I looked at in the training... having that much variation hurt."
- "Warmer colors would intuitively seem to me as unstable."

SATCAST / UW Cloud-top Cooling
- "Several times the CI worked as it was supposed to, then you would get a strong CTC signal getting up towards -40 C/15 mins... I think it would be a really useful tool in a marine environment."
- "CI started to have a breakup of the signals, less random values popping up... you could see a transition of the signals."
- Archive case... "Saw some CTC hits late on in the event when we expected CI to be over... did see a rapid ramp up in the ongoing storms immediately after on radar."
- "The UAH CI strength of signal is a huge improvement... when I was using it with the CTC, I had to stop myself from comparing it to the signals in CTC because they didn't always match up."
- "Relating the stronger cooling rate to severe weather... I don't have a strong opinion one way or another... but the way it was presented to me I found myself really paying more attention to those stronger CTCs."
- "The CI products is something we are hoping to pull into the pilot project."

Simulated Satellite Imagery
- "Forecasters are just going to have to get used to looking at that... getting used to the display of the data... less blow off from your cloud tops that doesn't match actual satellite data... it's just going to take time to get used to what you're looking at, but it does have an amazing ability to show convection... I think it's a great tool."
- "Useful as a planning tool... trying to figure out where stuff is going to form, the location ended up being spot on."
- "I wonder a little bit would we have made the same decisions just looking at model QPF or other model fields... it was an accessible format being similar to satellite data... does that make it more believable?"
- "The training didn't do an effective job in explaining the difference between the water vapor imagery... only after I came here and talked to Chris did I understand that it was actually a different channel than what we currently have on GOES."
- "I did have some reservations that the color scales looking just like observed data."
- "I can see the channel difference being very useful in briefing non-mets about where the dry/moist air is and it's a quick way to pick out those areas."
- "It would be nice to get this stuff in GFE for sky cover."

PGLM
- "Signals were very weak over the MLB area, didn't really have much impact on decision making for this event."
- "I would like some more training on what we should be looking at in regards to jumps and relating that to what we were seeing on the ground."
- "I think it will be huge when we have it everywhere from a satellite perspective."
- "From a severe weather perspective, it was hard to tell what it was showing me."

Overall / Training
- "What deserves my increased attention is such a challenge to determine when you have to triage data in a warning environment... having some sort of quantifiable way to determine what deserves my attention would be nice to have."
- When under pressure and at first glance of new products... forecasters mentioned that they immediately went to 'warn on red' for the colors in the products... which wasn't the case for some of the 3DVAR and Nearcast products.  Forecasters mentioned it took them some time to remember 'no wait, we need a value of X' and go back and re-evaluate the product's output.
- "An 'all-tilts' display method for 3D gridded data in AWIPS II would be extremely useful."
- "Anything we've seen this week we would like to pull into the pilot project."
- "It was an excellent idea to have the training day before we arrived in the HWT."
- "If we had the training available a little earlier, it would have helped."
- "The training material was a good amount for an 8-hour shift... although the amount in the WES was a little problematic to load."
- "A quick reference guide for the training would have been helpful."
- "We needed that amount of training, but by the end of the day doing it all at once I was left exhausted."

CI & CTC May Provide Lead Time on JAX-area Storm

Forecaster comments from EWP blog...

Another severe thunderstorm warning was recently issued (2148 UTC) for a portion of southeastern Georgia (Appling and Jeff Davis Counties), west of Vidalia.  It’s worth noting that both the UAH CI and the UW CTC products flagged this storm quite some time ago.

The first indication on this cell occurred with a 59 strength-of-signal indication from the UAH CI product.

UAH CI and Visible Satellite valid 2012-05-17 1945 UTC

The SOS increased to 68 on the next satellite scan, then 71 on the subsequent scan (2015 UTC).  The UW CTC flagged the storm for the first time at 2045 UTC with CTC rates of -13 to -14 C/15min, and that decreased to -16 C/15 min on the next image.

 UW CTC and Visible Satellite valid 2012-05-17 2045 UTC

The visible imagery becomes quite impressive with overshooting tops by 2130 UTC.  The SVR was issued at 2148 UTC, based mostly on distant radars.  The 3DVAR analysis domain was just recently expanded to include this area, and MRMS POSH and MEHS were not particularly impressive.

Visible Satellite valid 2012-05-17 2145 UTC

CIMSS Nearcasting: Predicts the convective development pattern in Central Florida

On Thursday morning, May 17, the CIMSS GOES Sounder Nearcasting model indicated that unstable Ɵ_e lapse rates would persist over Central Florida throughout the morning and into the afternoon.  Lapse rates would remain relatively weak, but unstable, with the nearcasting CAPE indicating values of 750 to 1000 joules per kilogram.  At 1400 UTC the CIMSS nearcast products indicated that a minimum of weak instability would persist into the afternoon across Central Florida, along a line extending SSW to ENE, with stronger gradients N and S of the line.   Coverage was good at this time because the region was relatively cloud free.

At 1900 UTC HWT forecasters detected a developing convective cell north of Lake Okeechobee and a weaker line of convection south of Gainsville.  Convection in Central Florida remained suppressed. Forecasters noticed that the development matched the nearcasted dƟ_e gradients quite well.

Shown below is a 5 1/2-hour nearcast of dƟ_e  and CAPE valid 1930 UTC, May 17, 2012.  Also shown is the verifying GOES visible and radar images.  Nearcasted CAPE values were strongest along the southern gradient which is where the strongest convection formed.  The areas east of Tampa remained devoid of strong convection.