GOES-T launched successfully from Cape Canaveral, FL at 2138 UTC 01 March 2022. Given quiet weather elsewhere, 30-second mesoscale sectors from both GOES-East and GOES-West were collected imagery over the launch location, capturing fascinating details about the rocket hot spot and plume.
Starting with the GOES-East view of the launch, visible imagery captured the condensation trail (Fig 1), while SWIR imagery revealed the hot spot (Fig 2).
Figure 1: 01 March 2022 GOES-East VIS.Figure 2: 01 March 2022 GOES-East SWIR.
Combining VIS/NIR and SWIR gives us the Natural Fire Color RGB, which shows the hot spot along with the condensation trail (Fig 3).
Figure 3: 01 March 2022 GOES-East Natural Fire Color RGB.
Zooming out, an even longer vapor trail is visible in the 6.2 um water vapor imagery, along with the hot spot signature (Fig 4).
Figure 4: 01 March 2022 GOES-East UL WV.
Finally, combining the VIS, SWIR, and water vapor imagery, we are able to capture all features, including the hot spot (yellow), condensation trail (dark blue), and vapor trail (lighter green/mustard compared to background; Fig 5). This “Plume RGB” is recently available in AWIPS per the TOWR-S RPM v22 update, in the Local Menu Items menu.
Figure 5: 01 March 2022 GOES-East Plume RGB.
Similar bands/RGBs from GOES-West capture the launch from a much greater Viewing Zenith angle, providing a different perspective (Fig 6-9).
Figure 6: 01 March 2022 GOES-West VIS.Figure 7: 01 March 2022 GOES-West Natural Fire Color RGB.Figure 8: 01 March 2022 GOES-West UL WV.Figure 9: 01 March 2022 GOES-West Plume RGB.
An intense upper trough digging into the southwest US resulted in widespread strong winds and regions of blowing dust during the day on 15 Feb 2022. Per NWS Las Vegas, NV: “This mornings water vapor imagery (Fig 1) depicts a compact closed low dropping southward through central California with a swift southwesterly flow extending out ahead of it. Winds have been picking up through the night but will continue to increase through the remainder of the morning hours aided by a strengthening pressure gradient and daytime mixing.”
Figure 1: 15 Feb 2022 GOES-East 6.2 um Water Vapor Imagery.
In association with the south-moving cold front and possibly convectively enhanced, a wall of dense blowing dust, or haboob, surged south through Death Valley in CA near the NV border. See photo here. Again from NWS VEF: “Visible satellite imagery also depicted a well developed wall of dust progressing southward across Death Valley, possibly enhanced by some shower activity enhancing post frontal surface winds. Given the satellite presentation and susceptibility to dust storms in Death Valley, issued a Dust Storm Warning through 245 pm for the Furnace Creek and Death Valley junction region.”
NWS VEF leverages GOES visible, Geocolor, and Dust RGB imagery in their decision making during such blowing dust events. In events such as this one, satellite imagery is the primary method for deciding to issue a Dust Storm Warning. Corresponding GOES-West Geocolor imagery and referenced Dust Storm Warning polygon is shown in Fig 2. The wall of dust is obvious in the imagery surging south along the CA/NV border. Also notable in the imagery is the lack of data between 1900 and 2010 UTC. This was a planned GOES-17 outage. Note, GOES Geocolor imagery will be available to all NWS offices in the coming months.
Figure 2: 15 Feb 2022 GOES-West Geocolor Imagery.
GOES-16 also provides useful imagery over the region, and captured the haboob well (Fig 3). The SWD (Fig 4a) signal was quite strong, resulting in the obvious signature in Dust RGB imagery as well (Fig 4b).
Figure 3: 15 Feb 2022 GOES-East Geocolor Imagery.Figure 4a: 15 Feb 2022 GOES-East SWD-IR combo.Figure 4b: 15 Feb 2022 GOES-East Dust RGB Imagery. Enlarge
VIIRS Day Land Cloud RGB imagery provided a 375 m resolution view of the haboob as well, including 3 images during a ~100 minute period (Fig 5).
Figure 5: 15 Feb 2022 VIIRS Day Land Cloud RGB.
Considerable blowing dust developed elsewhere across the southwest US within the increasing southwesterly winds, resulting in multiple Dust Storm Warnings and Blowing Dust Advisories. An SWD-IR-L2 product combo, newly available with the recent AWIPS TOWR-S update, captures the many areas of lofted dust (dark gray) well, while also providing cloud brightness temperature information (Fig 6). Note, it is recommended to adjust the SWD colortable range to ~ -2 to 8 when using the SWD with B-W colortable to detect blowing dust.
Figure 6: 15 Feb 2022 GOES-East SWD-IR Imagery.
One can access hidden L2 product information from this new menu item by sampling the scene, in this case revealing a confirmation of dust (Aerosol Dust product), as well as the considerably dry airmass (TPW) in NW NM (Fig 7). The Dust RGB + L2 Readout option includes similar information.
Figure 7: 15 Feb 2022 GOES-East SWD-IR Imagery with L2 product readout.
NWS El Paso, TX notes their use of satellite imagery in tracking the lofted dust during this event (Fig 8): “Winds are increasing, especially across the Bootheel where a wind advisory remains in effect this afternoon and evening. Satellite imagery also shows several dust plumes moving NE out of Mexico with the thickest dust noted in Luna County. Deming is reporting 2 to 4 mile vis, while the Border Patrol station at Columbus reported 100 feet. A blowing dust advisory is in effect to account for this plume as well as some other plumes over Hidalgo County.”
Figure 8: 15 Feb 2022 GOES-East Geocolor Imagery over S NM.
NWS Phoenix, AZ was also busy tracking areas of blowing dust in satellite imagery throughout the day (Fig 9): “So far today, wind gusts upwards of 45-55 mph have been recorded across portions of southeast California with slightly stronger gusts recorded in southwest Imperial County. As a result, areas of blowing dust have been generated. The most notable dust plumes showing up on visible satellite imagery this afternoon have been originating near Anza Borrego and spreading eastward across Imperial County. Additional dust plumes have been noted across eastern Riverside County near Blythe. Visibility in these areas have dropped down to around a mile or even lower at times. Thus, A Blowing Dust Advisory is in effect for much of southeast California through this evening.
Figure 9: 15 Feb 2022 GOES-East Geocolor Imagery over S CA/SW AZ.
Bill Line, NESDIS and CIRA, Stanley Czyzyk, NWS/VEF
Previously warm temperatures across the region had caused an aging the snowpack to crust over, limiting its “blowability”. However during the day/evening of the 10th, another quick-moving shortwave brought an additional round of fresh snowfall to Red River Valley region in E ND and W MN. As discussed in a great NWS/FGF forecast discussion on the 10th:
“This is a classic arctic front blizzard set up. The main issue is that the warm temperatures ahead of the cold front will make the current snowpack nearly unblowable. With that said, water vapor imagery indicates an upper level wave (currently way upstream) that should lead to an area of very light falling snow behind the cold front, and combined with the strong winds would lead to a 3-5 hour period of blizzard conditions. Most guidance does indicate very light QPF. Typically, in these CAA regimes we tend to develop additional convective snow showers, which would prolong the blizzard type impacts. However, the development and intensity of these convective snow showers is uncertain. If the snow showers persist, blizzard conditions would last into Friday afternoon.”
As discussed in the above forecast, plummeting temperatures and strong winds behind the front indeed resulted in widespread blowing snow by the early morning hours of the 11th, lasting into the afternoon and aided by the development of HCRs, especially across the Red River Valley. GOES-East imagery was utilized by NWS/FGF forecasters during this event to narrow down the spatial extent of the Blizzard Warning, as discussed here and below. Corresponding GOES-East Imagery is shown over the region in Fig 1, along with the warning decision on the NWS WWA map (Fig 2).
“Along the glacial lake valley floor horizontal convective rolls can be seen on satellite and from KMVX radar indicating blizzard conditions with widespread white outs causing many east to west road closures in MN and portions of I29. With the help of the satellite imagery did narrow the blizzard warning and removed the tier of counties from Roseau to Mahnomen along with western Walsh and Cavalier in ND.”
Figure 1: 11 Feb 2022 GOES-East experimental Blowing Snow RGB. Last image highlights corridor of most intense blowing snow.
Figure 2: 11 Feb 2022 NWS Watch/Warning/Advisory map before and after trimming of Blizzard warning based on satellite imagery.
Afternoon VIIRS passes provide an alternative, high resolution view of the blowing snow and related HCRs (Fig 3+4).
Figure 3: 1818 and 1911 UTC 11 Feb 2022 VIIRS experimental Blowing Snow RGB.Figure 4: 1911 UTC 11 Feb 2022 VIIRS experimental Blowing Snow RGB zoomed in look around Grand Forks.
A full day (2/11) GOES-East animation captures the longer term evolution of the blowing snow and HCRs across the Red River Valley (Fig 5).
Figure 5: 11 February 2022 GOES-East experimental Blowing Snow RGB.
It has been an active Winter across the northern US plains as it relates to ground blizzards. NWS Grand Forks, ND (FGF) has been particularly impacted, including a couple of significant blowing snow events captured on this blog here and here. Recently, NWS/FGF investigated the use of the VIIRS Snowmelt RGB as a tool for helping to determine blowing snow potential, in addition to traditional techniques that involve environmental temperature, wind speed, and age of snowpack. The Snowmelt RGB, unique to VIIRS, is discussed in this blog post.
By end of January, a nearly uniform appearing snowpack was present across E ND/W MN, per the consistent and relatively light shade of blue across the scene in the VIIRS Snowmelt RGB (Fig 1).
Figure 1: 29 Jan 2022 VIIRS Snowmelt RGB.
Liquid wintry precipitation (freezing drizzle/rain) fell across portions of the snowpack 30-31 Jan. The result on the snowpack was a “crusting” of the outer layer, and enlargement of the average grain size. This region of crusted snowpack is visualized in VIIRS Snowpack RGB imagery on 01 Feb as a swath of relatively dark blue over eastern North Dakota (Fig 2). A crusted snowpack will be less susceptible to blowing snow, even with gusty winds and cold temperatures.
Figure 2: 01 Feb 2022 VIIRS Snowmelt RGB. With outline
Also on 01 Feb, strong northwesterly winds (>35 knots widespread) developed across the area in the presence of cold temperatures (single digits). An experimental ABI blowing snow RGB is shown in Fig 3 to characterize the extent of blowing snow with this event. An outline of the crusted snow, based on the Snowmelt RGB, is included on the imagery. Cloud cover is present much of the day over far northeast ND. While plumes of blowing snow (relatively light pink to mustard) are present across the scene over the snowpack (red), including over the crusted region, they appear to originate west (and east) of the crust. Plumes of blowing snow behave similar to plumes of blowing dust, capable of traveling far from their source regions.
Figure 3: 01 Feb 2022 GOES-East experimental Blowing Snow RGB.
A higher resolution VIIRS version of the experimental blowing snow RGB also supports the claim from ABI of a lack of blowing snow originating from the crusted region (Fig 4).
Figure 4: 01 Feb 2022 VIIRS experimental Blowing Snow RGB.
Environmental conditions did not support blowing snow on 02 Feb, but appeared possible (but quite marginal) on the 3rd. Therefore, a NWS/FGF forecaster mentioned the following in their Forecast discussion when considering the potential for blowing snow: “Uncertainty lies in snowpack susceptibility in being blown around. Latest VIIRS Snowmelt RGB reveals a ripened or crusted over snowpack in much of central ND extending into the Devils Lake basin and northeast North Dakota west of the Red River Valley. This may be evidence of limited “blowability” by the snowpack in these locations, and could limit the amount of blowing snow impacts and/or coverage.”
Blowing snow was not observed across the region on the 3rd (Fig 5). While temperatures were still quite cold (around zero degrees Fahrenheit), winds generally remained less than 30 knots, likely influencing a lack of blowing snow, in addition to the crusted snowpack.
The following day (Feb 4), the Snowmelt RGB depicted a similar pattern of crusted snowpack (Fig 6). Gusty northwesterly winds and very cold temperatures within the Red River Valley resulted in blowing snow originating just east of the crusted snowpack, as was shown in both ABI (Fig 7) and VIIRS (Fig 8).
Figure 6: 04 Feb 2022 VIIRS Snowmelt RGB.Figure 7: 04 Feb 2022 GOES-East experimental Blowing Snow RGB. EnlargeFigure 8: 04 Feb 2022 VIIRS experimental Blowing Snow RGB.
Zooming into the northern US Red River Valley, the region of apparent blowing snow originates just outside of the eastern edge of apparent crusted snowpack (Fig 9).
Thereafter, a series of light snow events crossed the area, followed by a period of warming above freezing. By the 10th, the snowpack across the region appeared to have a uniform and comparatively crusty (darker blue) appearance (Fig 10). Another quick-moving shortwave brought snow, wind, and cold temps to the region on 11 Feb, resulting in another round of intense blowing snow (see post here).
Figure 10: 10 Feb 2022 VIIRS Snowmelt RGB.
Important to note is that the VIIRS Snowmelt RGB is not available to forecasters in AWIPS. Forecasters view the imagery on CIRA SLIDER, which does not have an ideal projection of VIIRS imagery for CONUS users, and does not include an option for political boundary overlays outside of State Boundaries, making geolocation of features difficult. Ideally, forecasters would have this information in AWIPS to allow for more efficient and accurate analysis, and for viewing in concert with other datasets. In the meantime, an online “CONUS-friendly” projection and display of VIIRS products such as this one, with political boundary overlays, would be appreciated by users.
Bill Line (NESDIS and CIRA) and Carl Jones (NWS/FGF)
A quick-moving Northeast US shortwave and associated cold front brought a brief period of snowfall to higher elevation areas of W MD/E WV/S PA during the early morning overnight hours of 25 Jan 2022. Radar beam blockage and distance results in slightly degraded radar coverage in parts of this region. NWS Baltimore/Washington forecasters leveraged the NESDIS Snowfall Rate product to diagnose snowfall across the higher terrain in western areas of their forecast area during the evening. SFR is available in AWIPS at some NWS offices, and can also be found online here (and with more info) and here.
In the overnight near-term forecast update, the NWS forecaster wrote the following, with corresponding imagery included as Fig 1: “NESDIS snowfall rate product from Suomi NPP and NOAA-20 satellites from 0722Z and 0813Z respectively showed snow falling across the mountains west of Frostburg with liquid equivalent rates of around 0.05 in/hr. Another inch of snow is possible before snow ends later this morning behind Arctic frontal passage currently analyzed over southwestern PA.”
A version of the SFR product merges the satellite-based SFR with MRMS radar-based, helping to fill in gaps where radar coverage might be unavailable. That product surrounding the period of discussion is shown in Fig 2.
Figure 2: Early morning 25 Jan 2022 NESDIS merged Snowfall Rate product.
Observed snowfall reports later that morning confirmed up to a few inches of snow total had fallen in the region overnight. This event exemplifies how the NESDIS Snowfall Rate product can be leveraged to boost confidence in a nowcast/short-term forecast of snowfall, particularly in regions of less-than-ideal radar coverage.
Strong northwesterly winds across North Dakota snowpack resulted in widespread blowing snow on 18 Jan 2022. The blowing snow reduced visibility considerably (less than 1 mile) in many areas, as was highlighted by NWS Bismarck, ND here (below) and here. NWS offices leveraged satellite imagery in their forecasts/analyses and communication of blowing snow during this event.
NWS Bismarck leveraged GOES satellite imagery to help shape their understanding of the blowing snow event and influence their forecast products. Specifically during the late morning, satellite imagery of blowing snow resulted in the addition of a county to the Winter Weather Advisory: “Quick update to add Divide County into the Winter Weather Advisory given satellite imagery suggesting significant blowing snow continuing from eastern parts of the county upstream into southern Canada.”
In the early afternoon, NWS/BIS provided a detailed update to the forecast/analysis of blowing snow, shaped by several observational data sources, including trends in satellite imagery: “Web camera trends suggest the lowest visibilities are more variable than ASOS/AWOS sensors alone would suggest, while satellite imagery suggests the most significant blowing snow is related to well-defined plumes that are occurring in Horizontal Convective Roles (HCRs). For the most part, those HCRs are relatively widely-spaced, leading to the variability in visibilities spatially, and temporally as the HCRs shift slightly with the background flow. Satellite imagery does suggest the most widespread blowing snow plumes are centered over Burke County and vicinity, where impacts are likely most significant. In the end, we continue to monitor trends for the need for any Blizzard Warning upgrades, but are holding off for now. Changes with this update cycle were mainly focused on observational trends through the afternoon hours, with no significant adjustments.”
GOES-East satellite imagery referenced in the discussion, specifically the default Day Snow-Fog RGB available in AWIPS, is shown in Fig 1. The plumes of blowing snow organizing into HCRs are easily diagnosed in the imagery streaming south across North Dakota. These are highlighted in the imagery as subtle difference in color (brighter red) compared with the background snow-covered surface, and the shadowing along the northern edges of the tall plumes.
Figure 1: 18 Jan 2022 GOES-East Day Snow-Fog RGB over North Dakota. Click to view
As was introduced in this recent blog post, an attempt to further highlight areas of blowing snow, and associated HCRs, is made with an experimental Blowing Snow RGB (Fig 2). Regions of blowing snow, especially the HCRs, further stand out against non (or weaker)-blowing snow, snow-covered background.
Figure 2: 18 Jan 2022 GOES-East experimental Blowing Snow RGB over North Dakota. Click to view
Afternoon VIIRS passes provide a detailed view of the blowing snow plumes and HCRs via a similar experimental Blowing Snow RGB (Fig 3).
Figure 3: 18 Jan 2022 VIIRS experimental Blowing Snow RGB over North Dakota. 1818 UTC, 1909 UTC, 2002 UTC.
The afternoon NWS/BIS forecast discussion included further analysis blowing snow in satellite imagery. “Satellite shows well-defined blowing snow plumes embedded in Horizontal Convective Rolls (HCRs), which have been becoming somewhat more widespread in that corridor as temperatures fall to 0 F or below, increasing the ability for snow to be lofted, especially in areas where the heavy snow fell late last week and strong winds today eroded any crust….We will however continue to monitor the situation, especially since satellite trends do suggest some increase in HCRs and related blowing snow plumes recently, perhaps as the boundary layer depth shrinks a bit. Interestingly, those satellite images also suggest blowing snow is being transported as far south as Burleigh County, where the pre-existing snowpack on the ground is indeed sufficiently crusted to not be broken even with the winds today.”
NWS Grand Forks, ND also leveraged satellite imagery during this blowing snow event, discussing: “… along with horizontal convective rolls are producing snow showers and based on satellite trends, have increased in coverage, pushing into the central valley.” Downstream, NWS Aberdeen was monitoring satellite imagery for blowing snow: “Based off of satellite, we are seeing blowing snow in North Dakota continuing to push southeast. With the snow in our area crusted over, that should limit any lofting of snow from the strong winds…”
NWS/FGF further took advantage of satellite imagery by including it in their public messaging of the hazard (also below).
Compare the above RGBs with single-band VIS and IR imagery in Figs 4 and 5, respectively. While the presence of blowing snow/HCRs can be realized given the shadowing in the VIS and slight temperature difference in the IR, the exact location and extent of blowing snow, especially non-HCR areas, is much more difficult compared to in the multi-spectral, RGB images.
Figure 4: 18 Jan 2022 GOES-East VIS over North Dakota.Figure 5: 18 Jan 2022 GOES-East IR over North Dakota.
Low, thin clouds and fog developed across northern Illinois snowpack overnight into the morning hours of 13 Jan 2022. Comparison of single band imagery with multispectral Imagery and level-2 products remind us of the advanced methods we have for analyzing low clouds and fog in complex scenes, in this case, during the day. One-minute imagery was available over the region during the period, which is quite valuable when monitoring the real-time evolution of low clouds near TAF sites.
Starting off with visible imagery, the scene is encompassed with a lot of light gray to white, representing both snow and cloud cover, diagnosed by stationary and non-stationary movement, and shadows (Fig 1). Near the IA/IL border, some movement is noted representing likely low clouds, but the delineation between low clouds and snow cover is difficult.
Figure 1: 13 Jan 2021 GOES-East VIS.
While Geocolor establishes a more familiar scene from space, including adding color to non-snow surface features, it doesn’t do much to help to separate clouds from snow cover (Fig 2).
Figure 2: 13 Jan 2021 GOES-East Geocolor.
IR Window imagery helps capture the higher (colder clouds), but again doesn’t help much with differentiating potential low clouds from the similar-temperature snow surface (Fig 3).
Figure 3: 13 Jan 2021 GOES-East IRW.
By combining the VIS, IR and Snow/Ice bands, we are left with a picture that separates snow cover (green) from low (liquid) clouds (cyan, light blue) from high (ice) clouds (pink/red) in the Day Cloud Phase Distinction RGB (Fig 4). High detail is maintained in the features with the inclusion of the 0.5 km VIS. The reflectance components can easily/quickly be adjusted in AWIPS (lower max) to draw out features during low light situations. The nearly stationary and semi-transparent low clouds across northwest Illinois, which could not be diagnosed in previous imagery, is easily observed in the RGB against the snowy background.
Figure 4: 13 Jan 2021 GOES-East Day Cloud Phase Distinction RGB.
Similarly, the Day Snow-Fog RGB combines the Veggie Band, Snow/ice Band, and Fog Difference to separate snow cover from clouds (Fig 5).
Figure 5: 13 Jan 2021 GOES-East Day Snow-Fog RGB.
The FLS Probability level-2 product, now available in AWIPS, combines satellite and NWP information to give a probability of MVFR, IFR, and LIFR conditions (and Cloud Thickness). During the day, the areal extent of coverage matches well with appearance in imagery, though with reduced spatial detail and some difficulty in multi-layer cloud scenes (Fig 6).
Figure 6: 1622 UTC 13 Jan 2021 GOES-East Day Cloud Phase Distinction RGB (left) and MVFR Probability (right).
One method for incorporating the quantitative fog products into AWIPS workflow is to underlay the three fog probability products in your typical Cloud imagery display. In the example shown, sampling the area will not only show the RGB readout information, but also the probabilities of the various restrictions, for that location (Fig 7). This type of display allows one to view the imagery but still get the benefit of the quantitative information without taking away valuable screen real estate, while also helping to connect the quantitative product to the imagery.
Figure 7: 1622 UTC 13 Jan 2022 GOES-East Day Cloud Phase Distinction RGB. Readout includes probability of MVFR (yellow), IFR (violet), and LIFR (khaki).
Previous blogposts and presentations have introduced the ability to diagnose plumes of blowing snow in GOES ABI imagery. In particular, the feature becomes apparent in the Day Snow-Fog RGB, primarily due to contrast of the plumes with surrounding environment in the Snow/Ice band and Fog Difference, and shadowing. Recent snowfall and strong winds resulted in a widespread blowing snow event across southern Saskatchewan/Manitoba into North Dakota on Jan 8. Surface observations and webcams reported considerable visibility reductions within the region of blowing snow as detected by ABI and VIIRS, including some areas to less than 1 mile. The blowing snow was pointed out by Carl Jones (NWS/FGF) on Twitter:
An experimental Blowing Snow RGB captured the blowing snow well across the region, as a shade of gold to dark yellow compared to the red snow-covered background and blue of clouds. Some plumes of blowing snow appear to develop into HCRs at times (as was documented in this paper), and have shadows associated with them in the imagery. Recall, this experimental RGB is similar to the Day Snow-Fog RGB available in AWIPS, but with the higher resolution 0.64 um band replacing the 0.87 um band, and with ranges tweaked to better highlight the blowing snow feature.
Figure 1: 08 Jan 2022 GOES-East experimental Blowing Snow RGB.
Compare the Blowing Snow RGB in Fig 1 with the Day-Snow-Fog RGB in Fig 2.
Figure 2: 08 Jan 2022 GOES-East Day Snow-Fog RGB.
A similar experimental Blowing Snow RGB can be applied to VIIRS 375 m I band imagery, providing excellent spatial detail (Fig 3 and Fig 4). The individual plumes/HCRs of blowing snow can better be observed, as well as more subtle areas of blowing snow. Combining NOAA-20 and S-NPP, an animation of four VIIRS swaths can be created within a period of ~2.5 hours. Of course, ABI has the advantage in showing the longer evolution of blowing snow with time. Utilized together, one gains an ideal understanding of the feature and its evolution.
Fig 3: 08 Jan 2022 VIIRS experimental Blowing Snow RGB. Fig 3: 08 Jan 2022 VIIRS experimental Blowing Snow RGB (zoomed in version of Fig 3).
A strengthening shortwave trough ejecting into the central US plains resulted in widespread damaging winds, wildfires, and visibility-reducing blowing dust on 15 Dec 2021.
NWS forecast offices leveraged satellite imagery throughout the event. In particular, water vapor imagery was used to track the progression of the mid-upper low, including areas of most pronounced subsidence (drying), where strong synoptic winds were most likely (Figure 1). Water vapor imagery also showed abundant gravity waves emanating from the center of circulation, helping to characterize the turbulent system. During the early afternoon from NWS CYS:
“Mesmerizing GOES WV loop for Windsday as a strong, progressive low continues to deepen and move off to the northeast into central KS/NE. Back edge of this system continues to move through the CWA with drying starting to become evident along the South Laramie Range aided by downsloping winds.”
“Winds have clamed down in most areas. However, satellite data shows enhanced subsidence in the nrn foothills. This is allowing for wind gusts in the 50 to 60 mph range in the normal windy areas.”
NWS Pueblo forecasters mentioned they used “all 3 water vapor channel’s to get a good feel of the intensity of the system.”
Figure 1: 15 Dec 2021 GOES-East UL Water Vapor Imagery. Link
The system brought widespread wind gusts over 60 mph across the plains, including several reports over 100 mph. NWS Pueblo provides a great summary of the event. Some of the strongest wind gusts for southern Colorado occurred during the morning hours as the surface low deepened and strong subsidence developed across the area. GOES-East 1-min Geocolor imagery with NWS LSRs overlayed captures this period in Figure 2, just prior to the lofting of widespread blowing dust.
Figure 2: 15 Dec 2021 GOES-East 1-min Geocolor Imagery, NWS LSRs. Link
Over the next couple of hours, GOES-East 1-min Geocolor imagery captured widespread lofting of dust, particularly in the Pueblo area, and over the far eastern CO plains (Fig 3). Forecasters leveraged GOES-East satellite imagery to detect and track the blowing dust: “Satellite imagery shows more widespread blowing dust over the eastern plains with some roads closed due to winds and visibility. Issued dust storm warning for the plains east of the Interstate 25 corridor. The I25 corridor remains in a blowing dust advisory with some areas reporting visibilities below 1 mile.”
Figure 3: 15 Dec 2021 GOES-East 1-min Geocolor Imagery, NWS LSRs. Link
A day long Geocolor animation shows continuing evacuation of dust from southeast Colorado and surrounding areas, and transportation across the central plains (Fig 4).
Figure 4: 15 Dec 2021 GOES-East Geocolor Imagery. Link
In the infrared, the 10.3 minus 12.3 um split window difference (SWD), discussed numerous times on this blog, depicts the dense blowing dust plume clearly as areas of relatively dark gray to black (negative values; Fig 5). The SWD is available to forecasters in AWIPS with a different default color range and table. However, a grayscale color table such as what is shown can easily be employed.
Figure 5: 15 Dec 2021 GOES-East Split Window Difference Imagery. Link
The Dust RGB, which includes the SWD and is available in AWIPS, reveals the blowing dust as pinks/reds, along with information about clouds (Fig 6).
Figure 6: 15 Dec 2021 GOES-East Dust RGB Imagery. Link
The Dust-Fire RGB, available in AWIPS on request, similarly includes both the SWD and IRW, but also adds the 3.9 um SWIR in order to reveal wildfire hot spots as well (Fig 7). The RGB is also able to differentiate dust from clouds. Given the strong gusty winds, numerous hot spots developed and spread across the plains, appearing as red pixels amongst the blowing dust (green). Note that the infrared dust products continue to capture dust after sunset, which is not possible with the vis/nir methods, such as Geocolor.
Figure 7: 15 Dec 2021 GOES-East Dust-Fire RGB Imagery. Link
The DEBRA-Dust product, available online and in AWIPS upon request, was leveraged by both NWS PUB and BOU for dust detection during the event (Fig 8). This product also leverages the SWD, along with more advanced techniques, to highlight blowing dust. From NWS/PUB: “the dust -DEBRA (CIRA) product on Colorada State’s RAMMB/CIRA Slider page was very helpful to monitor how bad the dust was getting across the far eastern plains.” And NWS/BOU wrote in an AFD: “The DEBRA dust satellite product shows the extent of the dust across SE CO and all of W. KS. There is a fair amount of dust across the northeast corner of Colorado, but with mid level clouds we can’t see it on satellite but ASOS and trained spotters have been all over it. Will keep dust in the forecast through this evening across mainly the northeast corner.” DEBRA-Dust also works at night.
Figure 8: 15 Dec 2021 GOES-East DEBRA-Dust Imagery. Link
Another useful “windy day” display that can be made in AWIPS combines the Geocolor product with below zero SWD (yellow), SWIR hot spots (red), and GLM flash points (blue), resulting in a multipurpose display that captures blowing dust, wildfires, smoke, and thunderstorm details (Fig 9).
Figure 9: 15 Dec 2021 GOES-East Geocolor, SWD, SWIR, GLM flash points, NWS LSRs. Link
Finally, VIIRS providing even more detailed views of the blowing dust and wildfire hot spots in the early afternoon via the Natural Fire Color RGB (Fig 10). The exact locations of dust initiation, and the thickest plumes, can be diagnosed in the imagery, along with a detail of the wildfire hot spot location and size.
Figure 10: 15 Dec 2021 VIIRS Natural Fire Color RGB. Link
Bill Line, NESDIS and CIRA
Input from NWS/PUB forecasters, and NWS text products
A broad mid-upper level trough and associated shortwaves moving across the country resulted in numerous weather impacts, including but not limited to heavy snow, blowing dust, and severe storms. A detailed analysis of GOES water vapor imagery is provided by NWS/LUB, with associated imagery shown in Fig 1 and Fig 2.
“08Z analysis indicates a gradually amplifying, positively-tilted trough pivoting over the Great Basin with a shortwave trough embedded within the broader flow and rounding the base over southern Nevada, with the infant stages of a developing baroclinic leaf ahead of it as mid-level frontogenesis intensifies over the Intermountain West. A secondary, more-compact shortwave trough was analyzed over northern Sonora with a pair of vorticity lobes (induced via horizontal shearing instability due to the largely barotropic state of the atmosphere over the eastern two-thirds of the CONUS) rotating northeastward over the Texas Panhandle and the east-central Great Plains; all of which is seen on water vapor imagery.”
Figure 1: 10 Dec 2021 GOES-East WV. Figure LinkFigure 2: 10 Dec 2021 GOES-East WV with labels from LUB discussion.
VIIRS Day Cloud Phase Distinction RGB imagery provided a high resolution (375 m) look at the snow cover (green) before (Dec 3) and after (Dec 11) the snowstorm over Colorado (Fig 3). The Colorado mountain snowpack had been well below normal prior to the storm.
Figure 3: 03 and 11 Dec 2021 VIIRS Day Cloud Phase Distinction RGB over Colorado.
Strong gusty winds (widespread over 35 knots, localized over 50 knots) developed across the southern Plains south of the surface low as the mid-upper level jet advanced over the region and deep vertical mixing set in during the afternoon. The relative position of the this jet core can be analyzed in water vapor imagery as strong cold to warm poleward temperature gradient extending southwest from the main shortwave. The 250 mb Jet as analyzed by the RAP NWP model aligns with that per the water vapor analysis (Fig 4).
Figure 4: 10 Dec 2021 GOES-East WV, RAP analysis 250 mb wind speed 100 knot (green) and 120 knots (yellow) contours, and surface obs.
The strong winds across dry antecedent lands resutled in widespread blowing dust across the southern plains. As has been discussed numerous times on this blog, the GOES 10.3 – 12.3 um Split Window Difference (SWD) captured lofted dust as near zero to slightly negative values compared to otherwise mostly positive values. The SWD in this case captures numerous large and long lasting dust plumes during the day, lasting into the early evening (Fig 5). Dust is not only diagnosed by the values, but also by the unique motion and streaky appearance of said values. Visibility was periodically reduced significantly within the blowing dust plumes.
Figure 5: 10 Dec 2021 GOES-East 10.3 – 12.3 um Split Window Difference. Dark gray (low positive to negative values) to light gray (high positive values). Figure Link
Given the dry and windy conditions, rapid growth and spread of wildfires, should any develop, was also a concern. Several wildfires did indeed develop, including within the NWS/OUN forecast area. Forecasters at NWS/OUN were motioning GOES Imagery for wildfire hot spots, and blowing dust, writing:
“Several hot spots associated with wildfires have been observed on satellite so far this afternoon, as strong winds and low RH continue to lead to near-critical fire weather conditions. Clouds have been a bit more extensive than forecast across western portions of the area, with fires most prevalent so far within clearing across central into southwest Oklahoma and western north Texas, on the western edge of the low-level thermal ridge. Expect fire risk to continue through the afternoon ahead of a cold front currently advancing into far northwestern Oklahoma….For this forecast, will mention MVFR restrictions in blowing dust at KLAW and KSPS ahead of the front closest to dust plume evident on satellite.”
Since wildfires and blowing dust often occur together, a Dust-Fire RGB was developed to highlight both in a single image, in addition to masking out clouds. The Dust-Fire RGB is shown over parts of OK and TX during the afternoon of the 10th (Fig 6). Blowing dust appears as relatively bright green, clouds generally as blue, and wildfire hot spots as red. The cold front is also diagnosed pushing south through the Panhandles and N OK by the end of the animation.
Figure 6: 10 Dec 2021 GOES-East Dust-Fire RGB. Figure Link
One-minute Imagery from GOES-East was available to forecasters to monitor the wildfire threat. Geocolor imagery also captured the blowing dust (and smoke plumes) well during the day, and can be combined with SWIR imagery to also highlight wildfire hot spots (Fig 7).
Figure 7: 10 Dec 2021 GOES-East Geocolor, hot SWIR (yellow). Figure Link
Natural Color Fire RGB imagery from VIIRS provides a detailed view of a wildfire, its smoke plume, and a large dust plume in North Texas near the S OK border (Fig 8).
Figure 8: 10 Dec 2021 VIIRS Natural Color Fire RGB.
Further east across the southeast, severe thunderstorms developed as the broader system brought anomalously moist low level air into the region along with favorable wind shear. GOES-East 1-min imagery was also available over this region to aid forecasters in tracking thunderstorm development and evolution. The thunderstorm associated with the Quad State tornado (moving from southwest to northeast across domain) exhibited a consistent and strong updraft per the cold OT, periodic AACP, and persistently high GLM flash rate (Fig 9).
Figure 9: 10 Dec 2021 GOES-East 1-min IRW, GLM Flash Points (black dots), NWS warnings. Figure Link