RAMMB: GOES-R Proving Ground Blog

Category: Blowing Dust Detection (Split-window technique)

Blowing Dust associated with 10-11 April 2019 Central US Strong Cyclone

By Ed Szoke and Dan Bikos

A rapidly intensifying cyclone developed in southeast Colorado late on April 10 as a strong upper-level wave moved out of the Rockies, not quite the “bomb cyclone” of 13 March 2019 but a very intense storm that brought blizzard conditions and widespread snow from the Central Plains to the Upper Midwest. On the southern end of the storm, very strong winds across the Southwest US resulted in a large area of blowing dust from northern Mexico / southern New Mexico into west Texas. We can see the blowing dust quite clearly as shades of yellow on a loop of the experimental GOES-16 CIRA DEBRA (Dynamic Enhancement with Background Reduction Algorithm) Dust product:

click here or on the image for the animation

The intensity of the yellow color is related to the confidence of dust detection. This product is currently available in real-time on the CIRA SLIDER site and is also being developed for AWIPS display. The blowing dust caused significant travel problems in west Texas, as documented in this video taken near Midland, TX from April 10.

There are other ways to view dust currently on AWIPS, for example:

Notice that the GeoColor imagery shows the dust better than visible channel 2. The Dust RGB product (developed by EUMETSAT) is on AWIPS and depicts dust in magenta / pink with other features denoted by various colors. The CIRA DEBRA Dust product is designed to just highlight dust with clouds appearing as in visible imagery during the day and a simple gray scale for IR at night.

A mesoscale sector was in place centered over New Mexico and the western half of Texas on April 10. Loops of GeoColor, the DEBRA dust product and EUMETSAT dust product are shown below:

click here or on the image for the GeoColor animation

click here or on the image for the DEBRA dust animation

click here or on the image for the EUMETSAT dust animation

The dust plume advected towards the northeast on 11 April as the cyclone tracked in the same direction, depositing dust onto the new fallen snow as far north as Minnesota and Wisconsin, as shown in the hourly animation of the DEBRA dust product below:

click here or on the image for the animation

It becomes more difficult to see the dust as it goes further north due to extensive cloudiness. We speculate that we can still faintly see the dust because of some breaks in the clouds. The same DEBRA dust product from SNPP VIIRS shows this more northern dust even better due to improved resolution compared to GOES-16:

There were numerous social media postings from different NWS WFOs in the affected region, for example see this post from NWS LaCrosse, WI WFO.

More extensive coverage of the dust can be found in this article from the BBC

April 12, 2019
Dust event in the El Paso vicinity on 4 April 2017

The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. Users bear all responsibility for inspecting the data prior to use and for the manner in which the data are utilized.

During the afternoon of 4 April 2017, strong westerly winds and low relative humidity was observed in west Texas, southern New Mexico and northern Mexico as seen in the surface observations at 2100 UTC:

The winds were in response to a deepening low near the Texas Panhandle. Although none of the observations in the plot above show blowing dust, METAR sites such as ELP (El Paso, TX) included some periods of blowing dust in the late morning and afternoon hours. Here we explore how well the areas of blowing dust were seen in GOES-16 satellite imagery, using 3 different loops during the afternoon hours of 4 April.

The first loop (below) goes from 1827 to 2157 UTC and displays GOES-16 visible imagery (0.64 microns/Channel 2).

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=training/visit/loops/4apr17/vis&loop_speed_ms=80

Do you see any evidence of blowing dust in this loop?

Refer to the static image below which contains a yellow circle, refer to the visible loop above and look in the region of this yellow circle.

The blowing dust is extremely subtle in the static image and even in the animation, no other areas of dust are obvious in the loop.

Sometimes features such as blowing dust show quite well in the CIRA True Color product. True Color imagery approximates the response of normal human vision, providing a depiction of the satellite-observed scene. The natural color of the background often makes it easier to see certain features when compared to the standard 0.64 micron visible imagery. Since there is no green channel on GOES-16, CIRA creates a “synthetic” green band to make this product, more information is provided at:

http://rammb2.cira.colostate.edu/research/goes-r/proving_ground/cira_product_list/true_color_imagery.asp

The GOES-16 True Color product:

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=training/visit/loops/4apr17/true_color&loop_speed_ms=80

Does the True Color product improve our ability to see dust in this case?

If we return to the same region (yellow circle), this dust plume appears a little more obvious relative to the visible band only. North of this plume you may be able to discern additional plumes of dust, however they are still fairly subtle.

Certain products have been developed that are designed to highlight features such as dust plumes. One example is the band difference product between the 10.3 micron and 12.3 micron bands. The difference product would show a negative value in the presence of dust, which is shown as purple in the color table shown in the loop below:

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=training/visit/loops/4apr17/diff&loop_speed_ms=80

With this in mind, do you see any additional dust plumes in this product?

You should now be able to discern multiple east-west oriented dust plumes (purple color). Some of the plumes have a distinct source region associated with them. This product helps us to see dust plumes that was not obvious in the other imagery. Even in the GOES-16 era with 0.5 km visible band, dust may not be discernible without the help of a product designed to highlight dust. Examples of other dust products that are under development include one by CIRA known as the DEBRA dust product with real-time data available at:

http://rammb.cira.colostate.edu/ramsdis/online/msg-3.asp

April 5, 2017
10 November 2014 Colorado Dust Storm Matched to Aircraft Photo

By Steve Miller (CIRA)

This blog entry is in Powerpoint show format, click on the link below to view the Powerpoint show:

Powerpoint show file

November 19, 2014
More dust – this time amidst the clouds – 29 April 2014 case

A recent post took a look at the CIRA dust products for the widespread blowing dust event across the Southern Plains behind a strong cold front on 27 April. The associated upper-level trough moved into the middle of the nation and became a giant closed low that stalled for days. Figure 1 shows the position of the closed 500 mb low along with an analysis of sea level pressure and NOWRAD radar reflectivity for midweek (0000 UTC on 30 April). The giant upper-level low affected the weather across much of the nation; here we focus on the strong northerly winds on its backside across the plains of eastern Colorado and the Texas and Oklahoma Panhandles.

We will take a closer look at the 2000 UTC time, which is when the Suomi/NPP satellite passed over the area of interest. The surface plot near this time is shown in Figure 2.

Figure 2. Surface METAR plot at 1943 UTC on 29 April.

The very strong northerly winds, with gusts as high as 70 mph in eastern Colorado, produced intense areas of blowing dust that created very hazardous driving conditions, forcing a number of roads to close during the day (including for a time Interstate 70 in eastern Colorado). A picture taken in the late morning near the intersection of Highway 40 and 287, in eastern Colorado south of I-70, shows the near zero visibility (Figure 3).

Figure 3. Photo from eastern Colorado in the late morning showing the near zero visibility in blowing dust.

What was particularly interesting about this case, and challenging for forecasters, was the blowing dust being present amidst lots of clouds and even rain (and some snow) showers, as seen in the next two figures showing conditions near 2000 UTC.

Figure 4. NOWRAD radar reflectivity image at 2000 UTC on 29 April.

Figure 5. GOES visible satellite image at 1945 UTC.

Often blowing dust events occur without many clouds present, since the associated airmass is often quite dry (see for example the blog from 27 April). In this case it is certainly difficult to see dust plumes across the eastern Plains of Colorado amidst all the cloudiness, or farther to the south, given all the cloudiness. Did the CIRA dust products help in this regard? First we will focus on eastern Colorado, then shift farther to the south centering on the Texas Panhandle, all for the 2000 UTC Suomi/NPP pass. As noted in previous blogs, Polar orbiting satellites have higher spatial resolution but limited time resolution, but are useful to replicate products that will be available at both high spatial and time resolution in the GOES-R era. In Figure 6 a True Color visible image is shown, followed by the CIRA Pink Dust product in Figure 7.

Figure 6. Suomi/NPP True Color visible satellite image at 2000 UTC centered on Colorado.

Figure 7. CIRA Suomi/NPP Pink Dust satellite image at 2000 UTC centered on Colorado. Dust appears as pink colors.

The True Color visible image is striking, but the dust is difficult to see, whereas it is much more obvious in the CIRA Pink Dust product in Figure 7. The same is true for the blowing dust farther to the south at this time across the Texas Panhandle, with the dust not so easy to see in the visible True Color image in Figure 8 but very obvious with the CIRA Pink Dust product in Figure 9.

Figure 8. True Color visible image at 2000 UTC centered over the Texas Panhandle.

Figure 9. CIRA Pink Dust product at 2000 UTC centered over the Texas Panhandle.

CIRA also has a dust discrimination product using GOES, which allows for much better time resolution than from the Polar satellites, but considerably lower spatial resolution (10 km using a split window technique from GOES sounder data). This type of image for this case at 1945 UTC is shown in Figure 10.

FIgure 10. CIRA dust discrimination product from the GOES sounder data, for 1945 UTC on 29 April. Dust appears as yellow, or red for thicker dust.

With the lower resolution it is not so easy to see the dust amidst the clouds in Figure 10, but the technique does a nice job of showing the dust farther to the south.

You can find more information on this (and other CIRA GOES-R Proving Ground products) product at http://rammb.cira.colostate.edu/research/goes-r/proving_ground/cira_product_list/ The products are available for display in AWIPS I or II; contact CIRA if interested in receiving them.

May 2, 2014
April 27 – Severe weather followed by blowing dust across the Plains

The extensive outbreak of severe weather on Sunday 27 April (see SPC plot of reports below in Figure 1) made headlines with many destructive tornadoes. A strong cold front associated with an intense low lifting out of the Rockies led to the large outbreak (Figure 2 shows the low at 1200 UTC Monday morning 28 April). Meanwhile very strong winds behind the front produced a large area of blowing dust across the Southern Plains. In this blog entry we will take a look at this dust area through some satellite products designed to highlight blowing dust.

Figure 1. Plot of severe weather reports from the Storm Prediction Center for 27 April.

Figure 2. Surface mslp analysis with fronts at 1200 UTC on Monday 28 April.

First a comparison is made between how the dust storm looked on Sunday afternoon on GOES visible imagery currently on AWIPS and imagery from about the same time from the Suomi/NPP (Polar orbiting) satellite with the VIIRS instrumentation. The products from the Suomi/NPP satellite represent the type of imagery that will be available at high spatial and temporal resolution when the GOES-R satellite is launched. For now the spatial resolution is high (1 km) but the temporal resolution is low, with 2 times that can be shown using VIIRS for this case, one at 1859 UTC and the other at 2038 UTC. Similar looking imagery is also available from the MODIS Aqua and Terra Polar orbiting satellites, but is not shown here as the image swaths are at about the same time.

Images for the first time are shown in Figures 3-5. Figure 3 shows how the dust appears in AWIPS for a GOES visible image at 1852 UTC, overlaid with METAR observations from 1900 UTC. Gusty (30 mph or greater gusts) southwest winds prevail across much of Kansas and Oklahoma, with even strong winds farther west across the High Plains, lifting plumes of dust. Visible imagery from VIIRS with a true color background at 1857 UTC is shown in Figure 4. So much dust is lifted that it looks like we can easily see the plumes in the AWIPS image, and somewhat better in the true color image. It is not always so easy to see where the dust plumes are, however, so CIRA has developed a product that highlights the dust in a pink color (a similar version uses yellow for the dust), and this image is shown also for 1857 UTC in Figure 5. You can find more information on this (and other CIRA GOES-R Proving Ground products) product at http://rammb.cira.colostate.edu/research/goes-r/proving_ground/cira_product_list/ The dust plumes are easily seen in this image, which represents a product that will be available in the GOES-R era. Notice how the southernmost plume of dust in the Texas Panhandle is easily seen, whereas it is not so obvious in the GOES visible image shown in Figure 3.

Figure 3. GOES visible image at 1852 UTC on 27 April from AWIPS overlaid with 1900 UTC observations.

Figure 4. Suomi/NPP True Color image at 1857 UTC on 27 April.

Figure 5. CIRA Suomi/NPP Pink dust image at 1857 UTC.

The same images are shown for the second available time (2038 UTC). Strong southwest winds continue to prevail across the Southern Plains, with areas of dust discernible in the visible image (Figure 6) across west-central KS and OK and the TX Panhandle. The Suomi/NPP images are shown for two areas in Figures 7-10. For the northern area most of the dust shown in the Pink dust image can also be seen in the two visible images. Figures 9 and 10 show the area farther to the south, and here the CIRA dust product in Figure 10 highlights dust plumes farther to the south that are not so obvious in the AWIPS visible imagery or even the true color image, showing the potential value of such a product.

Figure 6. GOES visible image from AWIPS at 2038 UTC on 27 April with 2000 UTC observations

Figure 7. Suomi/NPP True Color image at 2038 UTC.

Figure 8. CIRA Suomi/NPP Pink Dust image at 2038 UTC over the same area.

Figure 9. Suomi/NPP True Color image at 2038 UTC but zoomed in on the Texas Panhandle.

Figure 10. CIRA Suomi/NPP Pink Dust image at 2038 UTC also over the Texas Panhandle.

Dust discrimination imagery can also be created from the current GOES satellites through the GOES sounder, with a split window technique that uses the 10.7 um (more-transparent longwave) and 12.0 um (less-transparent longwave) infrared window bands. The resolution is much lower (10 km) than for images from the Polar satellites (and from what will be available in the GOES-R era), but there is the advantage of hourly time resolution, which means one can loop the imagery. Further description of the imagery and how it is made can be found on the link to the CIRA products page given earlier. An example of this GOES-based dust imagery produced by CIRA for this case is shown in Figure 11 for 1846 UTC and in Figure 12 at 2046 UTC on 27 April. Dust appears as yellow or red (red for thicker dust).

Figure 11. CIRA GOES-based dust product at 1846 UTC on 27 April.

Figure 12. CIRA GOES-based dust product at 2046 UTC on 27 April.

The imagery shown in this example is available now for display in AWIPS I or II; contact CIRA if interested.

May 1, 2014
More blowing dust with strong cold front on 11 March 2014

A strong cold front moved south across the High Plains on Tuesday afternoon and evening, bringing an episode of blowing dust with it. Here we look at what happened and how it appeared with some GOES-R Proving Ground products that highlight blowing dust. The sequence of surface maps displayed below in Figure 1 show the southward plunge across the plains east of the Front Range, with very strong northerly winds pushing the cold air rapidly southward. It appears that the strongest northerly winds (20 to 30 knots sustained with gusts over 40 knots) occur behind the initial frontal surge.

Figure 1. Sequence of surface plots showing the push of cold air southward on 11 March.

One of the problems that operational meteorologists have when it comes to blowing dust is that it can be hard to see in conventional visible satellite imagery. We demonstrate this with the GOES visible image below taken from AWIPS.

Figure 2. Visible satellite image at 1745 UTC with METAR observations.

A number of stations report visibility restrictions due to haze (in southeastern Colorado) or haze and blowing dust (for example, KGCK in southwestern Kansas). But it is difficult to see this dust in the image. The CIRA MODIS dust products use the 11 and 12 micrometer thermal IR bands form the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments which fly on the polar-orbiting NASA Terra and Aqua satellites to highlight dust in either yellow or pink. Because the satellites are Polar orbiters we only get one pass each during the daytime over the area of interest. An example of each product is shown below for the pass closest to the time of the image shown in Figure 2.

Figure 3. CIRA yellow dust product for 1805 UTC, with METARs.

Figure 4. Pink dust product for 1805 UTC on 11 March.

Both dust products clearly highlight the most intense areas of blowing dust, which are found in southeastern Colorado at 1805 UTC. A similar comparison is made below for the time of the next pass at 1945 UTC, in Figures 5-7 below (note that for this time we have a visible image at the same time).

Figure 5. GOES visible image from AWIPS at 1945 UTC with 2000 UTC METARs.

Figure 6. CIRA yellow dust product for 1945 UTC with 2000 UTC METARs.

Figure 7. CIRA pink dust product for 1945 UTC.

Blowing dust can be a significant hazard to all modes of travel, and in an earlier blog we documented traffic accidents that occurred during a dust storm earlier this winter in eastern Colorado. The National Weather Service (NWS) Weather Forecast Offices (WFOs) at Boulder and Pueblo issued Dust Advisories for this event (shown below in Figures 8 and 9) and included discussion of the dust in their “Weather Stories” (Figures 10 and 11).

Figure 8. Boulder WFO forecast graphic page for Tuesday afternoon showing the location of the Dust Advisory.

Figure 9. Pueblo WFO forecast graphic page for Tuesday afternoon showing the location of the Dust Advisory.

Figure 10. Boulder WFO “Weather Story” graphic page for Tuesday afternoon.

Figure 11. Pueblo WFO forecast graphic page for Tuesday afternoon.

The strong winds and dust moved south into the Texas Panhandle during the late afternoon and evening hours of Tuesday (after 0000 UTC on 12 March). An extraordinary photo taken from a low flying aircraft was posted on the WFO Amarillo Facebook Page and is shown below.

Figure 12. Great view of the arc of dust (with some small clouds) moving south near Amarillo, Texas, as taken from a low-flying aircraft. Courtesy of WFO Amarillo.

The dust then moved further south into the Lubbock (LBB) WFO forecast area. WFO LBB made an excellent post on this event (see http://www.srh.noaa.gov/lub/?n=events-2014-20140311-wind) and images below are taken from this summary. The first one is a view of the dust at sunset (about 8 PM Local Time) approaching Lubbock (Figure 13). Their graphic summary of the event follows in Figure 14, then in Figure 15 is a summary of wind gusts in the WFO LBB forecast area.

Figure 13. View of the approaching dust from Lubbock, Texas near 8pm on Tuesday, 11 March.

Figure 14. Description of the dust event from WFO LBB.

Figure 15. Collection of wind gust reports (mph) from WFO LBB.

The METAR observations from LBB nicely show a period of blowing dust that continued for several hours, as shown below in the last figure.

Figure 16. METAR observations for KLBB from 1053 UTC on 11 March (bottom) to 1153 UTC on 12 March (top).

March 13, 2014
A look at the 16 Jan 2014 dust storm in eastern Colorado using VIIRS imagery

Strong winds coupled with dry soil led to widespread blowing dust across the eastern plains of Colorado and areas east on Thursday 16 January 2014. A short video clip shows the blowing dust obscuring visibilities in Logan County in far northeastern Colorado (see www.youtube.com/watch?v=uxMdMTzlRFI ). The lowered visibilities in the blowing dust resulted in a multi-car accident that closed Interstate 70 near Burlington Colorado (close to the Kansas border) for several hours from 11:30 AM MST to 4:25 PM (1830 to 2325 UTC). A story of the dust storm and the accidents that closed Interstate 70, courtesy of Denver 7 News, can be found here http://www.thedenverchannel.com/news/local-news/dust-storm-closes-eb-i-70-us-24-to-kansas-line-us-34-closed-as-poor-visibilty-causes-accidents.

Below is a surface plot from early afternoon on the 16th showing sustained wind speeds of 30 to 40 knots with gusts as high as 55 knots.

Surface plot at 2043 UTC on 16 January.

In this blog entry we will take a look at how the dust appeared in standard GOES visible imagery and compare this to different imagery from the SUOMI NPP VIIRS instrument Polar satellite. Some of the images we will show demonstrate the capabilities that will be available when GOES-R is launched.

We start with a look at “standard” GOES visible imagery during the event, shown for two times below. In the visible images the plains of eastern Colorado and surrounding areas have a collection of clouds at different levels in addition to some areas of old snow cover as well as the blowing dust. From this imagery alone it is difficult to distinguish between these.

Shown below is similar type of visible satellite imagery but using VIIRS with a natural color background and of course higher spatial resolution (~0.5 km vs 1.o km from the current GOES). Right away we can see that the improved contrast and resolution allows one to see dust plumes in the first image below from 1848 UTC, but things are not so apparent in the second image from 2029 UTC.

VIIRS True Color visible satellite image at 1848 UTC on 16 January.

VIIRS True Color visible image at 2029 UTC on 16 January.

Using different bands from VIIRS a specialized type of imagery can be created which isolates the dust, making it stand out far more clearly. CIRA creates two types of dust discrimination imagery, one with the dust highlighted in yellow and the other where the dust has a pinkish color, as shown below. The purpose of these products is to clearly isolate dust from other surrounding clouds and general background.

Pink dust product using NPP VIIRS imagery at 1848 UTC on 16 January

Pink dust product using NPP VIIRS imagery at 2029 UTC on 16 January

The above imagery is especially useful for the 2029 UTC time, when the earlier visible satellite image showed a more complex mix of dust and clouds. Similar imagery is also made using MODIS Polar orbiting satellites. Shown below are the pink and yellow dust products using the MODIS Aqua satellite imagery at 2020 UTC.

Pink dust product using Aqua MODIS imagery at 2020 UTC on 16 January.

Yellow dust product using Aqua MODIS imagery at 2020 UTC on 16 January

We noted earlier that there was also snow in the background in some spots across the Plains, as well of course in the mountains. The next set of imagery shows the CIRA snow/cloud (discriminates snow from clouds) and snow/cloud layer (further discrimination of the type of clouds, pinkish for generally higher ice clouds and yellow for generally lower water clouds).

Snow/cloud discriminator product using NPP VIIRS imagery at 1848 UTC on 16 January

Snow/cloud layer discriminator product using NPP VIIRS imagery at 1848 UTC on 16 January

Snow/cloud discriminator product using NPP VIIRS imagery at 2029 UTC on 16 January

The snow/cloud layer discriminator product uses the 1.38 micron “cirrus” band to isolate higher level ice clouds (an added step from the binary snow/cloud discriminator product). An example of the cirrus imagery by itself is shown below for the 2020 UTC time.

Cirrus product using Aqua MODIS imagery at 2020 UTC on 16 January

January 22, 2014