EWP Underway: UW-CTC and Echo Top Heights

The EWP @ HWT is underway.  While we're currently getting spun up getting data displayed, etc., the first conversation related to UW-CTC (cloud-top cooling rate) was not warning related, but aviation related with a representative from the Houston CWSU.  The representative was interested in the validation study performed by UW/CIMSS of the UW-CTC to future NEXRAD 18, 30, and 50 dBZ echo top heights, especially over their Gulf of Mexico responsibility region as well as the Houston TRACON (terminal radar approach).  Since the results of the echo top height were not included in the HWT training, we'll provide the echo top height analysis to the Houston CWSU.

Justin
UW/CIMSS

EWP underway

NWS forecasters and visiting scientists participating in the Monday afternoon overview briefing.

The Experimental Warning Program (EWP) portion of this year's Spring Experiment is now underway. This week we have 4 NWS forecasters visiting the HWT. During the first hour of the day from noon to 1pm the forecasters participated in a short overview briefing and then moved into the HWT to familiarize themselves with the data in AWIPS II. During this time, 2 of the forecasters who were unable to run through the Weather Event Simulator (WES) training case were able to do so. Currently the forecasters are focused over southern TX where a severe threat is currently ongoing. We may not issue any warning tonight as the forecasters are still getting comfortable working in AWIPS II.

NWS forecasters running through the 24 May 2011 WES training case prior to operations.

EFP CI and Severe desks

EFP CI (left) and severe (right) desks during the morning forecast period.

This year's Experimental Forecast Program (EFP) contains two main focus areas... convective initiation (CI) and severe. Both desks are using experimental high-resolution numerical models and ensembles of those numerical models (CAPS ensemble, SSEO, AFWA) to forecast the first occurrence of a 35 dBZ radar echo (CI) and the subsequent severe weather. They will be examining some of the simulated satellite imagery and unique GOES-R band differences during their forecast operations that we provide them from the NSSL-WRF 0Z 4km model, as well as from some of the members of the CAPS ensemble.

2012 Spring Experiment begins

Visiting scientists and forecasters participate in the Monday morning briefing during the Experimental Forecast Program

Today marks the beginning of the 2012 Spring Experiment. The experiment will run through June 15th this year and we have invited 24 NWS forecasters and 15 visiting scientists to participate in a wide range of activities all focused on the forecast and warning of convective initiation and severe weather. The Spring Experiment consists of 2 unique programs, the Experimental Forecast Program (EFP - which focuses on experimental numerical model guidance of convective initiation and severe weather) and the Experimental Warning Program (EWP - which focuses on the short-term warning of severe weather). The GOES-R component of this year's Spring Experiment will mainly be focused within the EWP. Products being demonstrated include the pseudo-Geostationary Lightning Mapper total lightning, convective initiation nowcasting, cloud-top cooling rates, simulated GOES-R ABI imagery and associated band differences, 0-6 hour GOES sounder-based 'Nearcast', and GOES sounder RGB airmass product. Constant forecaster interactions during real-time testing of GOES-R Proving Ground products will drive the feedback gathered from this year... which you will see posted in near-real-time on this blog. In addition, visiting scientist participants will be encouraged to blog about their experiences while they are interacting with the forecasters. Activities run from 8am to 10pm throughout most of the week, with a greater emphasis on severe weather warning as the day progresses.

14 April 2012 - Unique applications of NDVI and GOES dryness products

Bob Rabin from NSSL/UW-CIMSS provided me with a couple interesting images late last week in preparation for the upcoming events on Friday/Saturday. I thought I would share them here with you all to get a new perspective on a product that we used extensively within the Fire Weather Experiment last Fall to monitor vegetation and surface moisture. Bob Rabin gathers and generates NDVI composite imagery as well as GOES derived surface dryness values that we provide within SPC operations in support of their fire weather forecast desk. The products were mainly intended to monitor for dry vegetation and anomalously dry surface conditions that would be a potential hazard for fires. In these examples, Bob pointed out that the NDVI and GOES surface dryness products were both picking up on a very well defined dry / moist boundary across much of KS, OK and TX (see images below).

Continental US NDVI composite from 9 April 2012. Green areas indicate regions with significant green vegetation cover, while yellow and brown regions indicate decreased green vegetation cover. Note the pronounced gradient in green vegetation along a line extending from western KS and OK into central TX.

Continental US GOES surface dryness composite from 11 April 2012. Green areas indicate regions with significant surface moisture mesurements, while yellow and red regions indicate dry surface measurements. Note the pronounced gradient in surface moisture along a line extending from western OK into central TX. It would be interesting to examine how these surface moisture boundaries interacted to potentially enhance convective initiation set up by circulations due to differential heating. In fact, one SPC forecaster noted this in a Mesoscale Discussion issued on the 14th prior to convective initiation along the TX/OK border. In addition, it would be interesting to examine the interaction these surface moisture boundaries have on the evolution of the dryline. It is exciting to see applications of satellite imagery used to detect these features not easily observable from other systems in such a constant and relatively highly spatial manner.

14 April 2012 - Simulated Band Difference

Part of the NSSL-WRF simulated satellite imagery that we get from CIRA includes a band difference unique to GOES-R that we began looking at during last year's Spring Experiment. One of the advantages of simulating satellite data from a model is that we have the opportunity to produce channels that we don't have currently, and we take full advantage of this by producing all 9 of the non-solar GOES-R IR bands. The 10.35 micron channel is a very clean window, and thus is very sensitive to surface temperature. The 12.3 micron channel however is sensitive to low- and mid-level water vapor. As moisture moves into a clear pixel area, the 12.3 micron brightness temperature will decrease, whereas the 10.35 micron temperature should stay the same. When this occurs, the 10.35-12.3 micron channel difference will become strongly positive and indicates areas of moisture convergence or pooling, which can lead to destabilization and subsequent convective initiation.
Unfortunately, because the imagery is generated by a numerical model, it is a) not an observation and b) only available on an hourly timescale. However, we can use the imagery generated from the model as a experimental tool to demonstrate some of the unique things we can do once we have the increased spectral resolution of the GOES-R Advanced Baseline Imager (ABI). In this example from the 14 April 2012 outbreak the 10.35-12.3 micron channel difference is useful in identifying the evolution of the dryline across western KS, OK and TX from 1900 UTC on the 14th to 0100 on the 15th (see images below). As moisture converges at the surface, the difference becomes more positive. These positive values show up as yellow, orange and red on the images below. The edge of the dryline is easy to detect and follow using this simple band difference within the NSSL-WRF. It will be very interesting to see observations of this band difference, and other imagery techniques such as RGBs, every 5 minutes over the continental US once we have the GOES-R ABI available to us.

14 April 2012 - Sounder Airmass RGB

Well, it's not quite the Spring Experiment yet, but we did have a significant severe weather event over the plains this past weekend that I figured would be a good opportunity to capture some of the GOES-R Proving Ground products that we receive at the Storm Prediction Center and Hazardous Weather Testbed. We will start with the GOES Sounder Airmass RGB that is provided to us by CIRA and NASA SPoRT. RGB simply stands for Red-Green-Blue, which is a composite image created by combining three separate channels or channel differences into one image. This technique helps us identify specific features in the atmosphere without the use of complex derived products. The airmass RGB is a combination of thermal infrared, water vapor and ozone channels that help us identify regions of warm and moist versus cold and dry airmasses, spin in the atmosphere and jet streaks. The airmass RGB has been used extensively over Europe using the Meteosat Second Generation satellite, which has similar spectral channels to what will be available on the GOES-R Advanced Baseline Imager (ABI). Current GOES imagers do not contain the spectral bands necessary to generate this product, but we are able to simulate the RGB using the GOES sounder, which does have some similar channels to the ABI. Unfortunately this data only arrives once hourly from the sounder, but when GOES-R is launched, we will be able to create this product every 5 minutes over the continental US.
Below is a time-series of the SPC's outlooks from day 7 up until the event on Saturday 14 April 2012 from the SPC Facebook page. You can see clearly that the SPC had a good handle on the threat a week in advance and that the threat area depicted on day 1 well outlined the events that occurred in NE, KS, OK and IA. Preliminary storm reports from the SPC website indicate 135 tornado reports (likely will end up being about 75 individual tornadoes following official surveys) occurred during this event, with what appears to be several long tracks across OK and KS.

If we take a look at the sounder airmass RGB product at 12 UTC on 14 April 2012 (top image below), we can see a strong center of circulation over CA/AZ/UT/NV with indications of a significantly lowered tropopause, associated jet streaks and high PV (red hues) within the circulation and extending along the Pacific coast up into Canada. This can be confirmed by overlaying the tropopause pressure from the RUC analysis (middle image below) or the the 500 mb heights and vorticity (bottom image below).

If we move forward to 15 UTC (image below), just prior to initiation in KS, we can begin to see evidence of a moisture boundary (blue-to-green hue gradient) setting up along a line extending from NW KS near the KS/NE border down into the OK panhandle and down into west TX. Initiation in southern KS and down through the OK panhandle into TX would occur along a dryline located in this area, which is likely what the airmass RGB is picking up at this time.

Moving forward to 02 (top image below), 03 (middle image below) and 04 UTC (bottom image below) on 15 April 2012, the moisture gradient feature really begins to tighten up and better define itself as the dryline continued to evolve and the Pacific cold front approached, initiating a line of storms extending into central TX.

GOES R Proving Ground MVFR/IFR Assessment

There was an excellent area of mixed MVFR/IFR clouds across eastern OH, western PA and all of WV that was used to assesses the performance of the GOES R MVFR/IFR satellite product. The GOES R product did an excellent job with the depiction of the area covered by the clouds, but some perceived weakness in the accuracy of showing the appropriate percentage of MVFR and IFR. The series of images below show how the cloud area did not change over about 1 1/2 hours (see 4 vis images), yet the MVFR satellite analysis showed the percentages increasing with time. The obs at this time showed the deck was solid mvfr with a few sites sitting in ifr conditions. This was pretty stable. We were speculating whether this had to do with the increasing visible reflectance with increasing sun angle, or some other underlying element within the algorithm.

















A suggestion would be to reassess the enhancement curve applied to the MVFR/IFR products. Due to the sharp color shift at a specific percentage, it causes your attention to focus (probably too much) on specific areas that aren't significantly different. For example, the "yellow" 74% is not statistically different from the "red" 76%. Yet, the product suggests this is a big jump. We discussed using a curve with more of a gradient, in this case a grey scale from the vis enhancement. This introduced a more natural looking product. It is understood that colors are a very personal thing and this is open to lots of opinions! :)





Steve Davis NWS Milwaukee/Sullivan
Justin Sieglaff CIMSS

Notes from 9/27/11 CIMSS/NWS Testbed Session

We discussed many different ideas and made notes about improvements that each of us can make to help in forecast operations.

One question to ask yourself when working on the short term shift is, "Will there be some clearing in the clouds tonight?" A stationary upper low pressure system has been sitting over southern Lake Michigan and northern Illinois for the past 4 days at least. Timing the clearing skies vs. the cloudy skies has been a big challenge, to say the least. It makes a big difference when forecasting minimum temperatures. There are some products provided by the CIMSS group that are available in AWIPS that can help us with our sky cover forecast for tonight.

The first image is actual, current infrared (IR) satellite imagery of the midwest at 1930Z Tue Sep 27 (230 pm). The second image is the GOES-R ABI simulated IR imagery Band 11 (8.5 um) for 0400Z Wed Sep 28 (11 pm Tue Sep 27). The simulated imagery shows clearing in the lower/mid levels over central WI tonight. This actually verifies with several other model output, including NAM and GFS sky cover grids available in the Gridded Forecast Editor. We can infer that this Band 11 imagery is showing clearing in the low levels because we also looked at Bands 8, 9 and 10 which show more of the water vapor-type imagery, and there were no high clouds depicted in that area either.

There are many satellite-derived products from CIMSS that are available in AWIPS, including cloudy type, MVFR/IFR probability, fog depth and a cloud mask. The cloud mask is shown below, valid at 1445Z (945 am) Tue, Sep 27, and is compared to the actual IR satellite 11-3.9 um difference field at 1431Z. The cloud mask is most useful in operations at night where it may be unclear if we're seeing clouds or snow on IR imagery, or where the actual edge of the clouds are. The ABI channels are combined, or made into a consensus, to develop the cloud mask product.

These derived products and simulated ABI products spawned numerous ideas for future products that may be produced by CIMSS. First, it would be great to see the simulated ABI products from its run time all the way out to 36 hours (or the length of the run). Right now, we only see the 12-36 hour forecast products. It would also be useful if the fog product could be simulated into the future (using the ABI simulated bands). This could help with seeing where fog over the lake (if it is picked up by the model) may advect during the day and if it will spread inland. It also could help to forecast fog development 6-12 hours in advance if we're in a situation with high pressure and great diurnal cooling, or another fog-conducive environment.

The cloud type product (see below) has the ability to detect cirrus that is overlaid on top of low clouds. It works best if there is a semi-thin cirrus shield with much warmer clouds below it. This situation is famous for producing "sneaky" snow events with the seeder-feeder process.

There is a new product available online now (not yet in AWIPS) that is ABI simulated visible satellite imagery (see below). The link is http://cimss.ssec.wisc.edu/goes_r/proving-ground/nssl_abi/nssl_abi_rt.html . We compared this simulation to visible satellite imagery (see below) at 20Z (3 pm) this afternoon and it verified quite well.

Submitted by Marcia Cronce, NWS

Andrew Heidinger, NOAA at CIMSS/SSEC

Wayne Feltz, CIMSS/SSEC

Notes From 9/6/11 Training Session

This image is from the simulated water vapor ABI imagery, band 8, forecast at 1800z on 9/6/11. This simulated water vapor image shows quite a bit of high clouds/moisture across the high plains and western Texas. This band usually shows moisture in the upper levels of the atmosphere, thus the cirrus clouds. It also shows a fair amount of dry air wrapping into the circulation of the remnants of Lee over the Ohio River Valley. Compare this to the image below:

This is a simulated water vapor ABI image, band 10, forecast at 1800z on 9/6/11. This simulated water vapor image shows moisture in the low to mid levels of the atmosphere. Thus, it shows a lot of dry air in the southern high plains and western Texas. It also shows this dry air wrapping around the circulation with the remnants of Lee over the Ohio River Valley. From these images, it can be concluded that just some high clouds were moving into the southern high plains and western Texas, with the dry conditions in the lower to mid levels continuing. One could also say that the dry air wrapping into the remnants of Lee may reduce the clouds and precipitation associated with it.

Example 2:

In this GOES-R probability of MVFR ceilings product, from 1115z on Tuesday, September 6, 2011, several areas of higher probabilities were noted. These areas included parts of northwest Wisconsin, southeast Wisconsin, north central Illinois and far northeast Minnesota. There was also a large area of higher probabilities over Minnesota back into the northern Plains. Let's compare with an operational GOES East image below:

This visible GOES East image was taken at 1125z on 9/6/11, 10 minutes later than the MVFR probability image earlier. The MVFR probability product did identify the clouds that were present across the area. This product showed probabilities of MVFR ceilings of generally 50 to 80 percent. However, the observations showed all of the ceilings were VFR (generally 3500 to 5000 feet above ground level). These values are on the lower end of the VFR ceiling spectrum, so even though the ceilings were not MVFR, they were close. This would give the forecaster more confidence that lower end VFR ceilings were occurring.

J. J. Wood
Meteorologist
National Weather Service
Milwaukee/Sullivan, WI