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GOES-18 Goes West

Posted by Bill Line on 06/15/2022
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GOES-18 completed it’s drift, which began on May 16, from 89.5W to 136.8W, on June 6, where it will continue its post-launch testing from this very near GOES-West position. NOAA and CI scientists immediately resumed analyzing the new imagery as it began to flow again. NESDIS organized some of the stunning animations into an “Earth from Orbit” video and article. This blog post includes animations from the video that were created at CIRA and STAR/RAMMB. Animations from CIMSS and STAR/ASPB can be found here. All GOES-18 animations remain preliminary and non-operational.

First, a look at the GOES-West “Full Disk” domain using the Geocolor Imagery product.

Next, we focus on OCONUS regions and Geocolor imagery, including Alaska, where wildfire smoke and low clouds were observed, and Hawaii.

In the East Pacific, von karmen vortices were observed off the west coast in Geocolor imagery, and a broad upper low was diagnosed in water vapor imagery.

Over the western CONUS, severe thunderstorms were shown in Geocolor and IR imagery.

Other GOES-18 animations captured from the new position include an animation of 1-min Day Cloud Phase Distinction RGB imagery, which shows a hail swath (green) in the wake of a strong thunderstorm.

Additionally, 1-min Day Cloud Phase Distinction RGB imagery differentiates low clouds (cyan) from mid-upper clouds (green-yellow-red) over Alaska.

Finally, a comparison of GOES-17 VIS (top) and GOES-18 VIS (bottom) show great similarity between the two sensors/band.

Bill Line (NESDIS/STAR), Dan Lindsey (GOES-R), Curtis Seaman and Dakota Smith (CIRA).

High Plains Accumulating Hail – 07 June 2022

Posted by Bill Line on 06/08/2022
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A quick moving shortwave and ample moisture resulted in widespread severe thunderstorms across the high plains on 7 June 2022. The shortwave trough is obvious in GOES-East water vapor imagery digging across the Rockies during the morning, and east into the plains after convective initiation during the afternoon/evening (Fig 1).

Figure 1: 07 June 2022 GOES-East ULWV.

Thunderstorms developing across the southern Colorado I-25 corridor produced large hail, and at times, accumulating hail. The accumulating hail could be diagnosed in satellite imagery, which could be useful for confirming that a storm is producing hail and for identifying potential impacts to travel on roadways. Starting with GOES-East VIS, a keen eye could identify the streak of higher reflectance in the wake of the impressive thunderstorm exiting eastern El Paso County, which had confirmed large hail reports. Also with this storm, classic severe storm signatures could be diagnosed, including inflow feeder bands/clouds, and a long-lived above-anvil cirrus plume.

Figure 2: 07 June 2022 GOES-East 1-min VIS. Annotation

We know we can do better than single-band imagery, though. Combining the VIS with IRW and Snow/Ice band, we can better isolated the hail swaths in the Day Cloud Phase Distinction RGB, as Green against the otherwise dark blue clear sky scene, and lighter blues/reds/yellows of clouds.

Figure 3: 07 June 2022 GOES-East 1-min Day Cloud Phase Distinction RGB. Annotation

GOES-18 ABI began collecting imagery again from the “near” GOES-West position of 136.8W lduring teh previous evening (Transition Plan). A 1-min meso sector was positioned over the region, and provided a better view of the hail swaths on the back edge of the east-moving storms. Specifically, the GOES-18 imagery captured a hail swath with a Pueblo County storm (Fig 4), which was masked by the storm in GOES-East imagery (Fig 5). This is yet another example of the value of leveraging both GOES-East and -West imagery where available.

Figure 4: 07 June 2022 (Preliminary, non-operational) GOES-18 1-min Day Cloud Phase Distinction RGB.
Figure 5: 07 June 2022 GOES-East 1-min Day Cloud Phase Distinction RGB.

JPSS VIIRS imagery provides yet another perspective of the hail swaths. The 375 m resolution and ~direct view from above allows hail swaths to be detected where the task may be more difficult using GOES. In this case, the VIIRS Day Cloud Phase Distinction RGB captured the hail swath from Fig 2-3 slightly earlier than was obvious in GOES imagery.

Figure 6: 07 June 2022 VIIRS Day Cloud Phase Distinction RGB imagery. Annotation

Storms across the region continued to produce large hail into the evening, which can be diagnosed in Nighttime Microphysics RGB imagery. The swaths, compared to the surrounding clear sky background, contain less blue (cooler), and more red (+ vs – 12-10um SWD), resulting in a color near Magenta. In Fig 7, the animation transitions from VIS during the day to NightMicro RGB at night.

Figure 7: 07 June 2022 GOES-East 1-min Day VIS (day) Nighttime Microphysics RGB (night). Two hail swaths are circled.

Further north in Nebraska, numerous storms also produced narrow hail swaths, and were captured to varying degrees in both GOES-16 (Fig 8) and GOES-18 (Fig 9) Day Cloud Phase Distinction RGB imagery.

Figure 8: 07 June 2022 GOES-East 1-min Day Cloud Phase Distinction RGB. Annotation
Figure 9: 07 June 2022 (Preliminary, non-operational) GOES-18 1-min Day Cloud Phase Distinction RGB.

Bill Line, NESDIS/STAR

Memorial Day 2022 Severe

Posted by Bill Line on 05/31/2022
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Severe weather developed across the central Plains to upper Midwest on Memorial Day 2022 (May 30). Storms were forced by a potent shortwave trough rounding the base of a broad central US upper trough, and associated surface boundaries.

Per SPC 13Z Day 1 Outlook: “A large field of mid/upper-level cyclonic flow covers most of the
western/central CONUS, anchored by a broad, complex cyclone covering much of the northern/central Rockies and Intermountain region. Primary vorticity maxima are evident in moisture-channel imagery over ID and central/eastern CO. The latter will eject northeastward today, become a compact, closed cyclone in its own right, and deepen considerably, with the 500-mb low reaching east-central SD by 00Z.”

The aforementioned shortwave originating in Southern Colorado around 10Z is analyzed in the following water vapor animation as a west-to-east couplet of warm (drying, descending) and cold (moistening, ascending, cloud development) lifting northeast into the central plains along the southeast periphery of broad cyclonic flow. The drying on the backside and leading moistening/convective activity become more pronounced later in the day as the wave strengthens and lifts into the upper midwest. Overlaying model analysis fields can bolster ones understanding of the water vapor imagery observations, with height fields capturing the broad upper trough and, sometimes, smaller-scale shortwaves, wind field revealing upper level wind jet structure, and surface fields showing the patterns influence on the surface pressure pattern.

Figure 1: 30 May 2022 GOES-East UL WV, RAP analysis 500 mb Height, sfc MSLP.

Locally, NWS Omaha, NW discusses: “Recent surface analysis and satellite observations place a deepening surface low north of Yankton, South Dakota, with a southward extending dryline that is draped along the Nebraska/Iowa border and strong gradient winds have been observed on both sides of the feature (with gusts up to 46 kts). Water vapor imagery highlights the deepening mid-level support with a strong punch of dry air moving northward behind the aforementioned surface low.”

NWS, Des Moines, Iowa provided a great analysis of satellite imagery in a mid-day AFD: “Lots of goodies one can pick up on satellite ahead of the strong to severe weather potential later today/tonight. As of early this afternoon you can clearly pick up on the potent shortwave rounding the base of the negatively tilted trough that is responsible for aiding a deepening surface low, a strong dry slot/dry air intrusion moving northward through portions of C/E Nebraska and E South Dakota, and the explosive convection along its leading edge. Additionally on visible satellite imagery, a sharp surface dry line is seen sliding into E Nebraska and drops back into C Kansas. Ahead of the surface dry line, satellite imagery corroborates hi-res guidance depictions of an area of potent low- mid level moisture transport with mid-level cellular cloud cover. Many of the aforementioned goodies will affect portions of Iowa tonight as the parent trough continues to translate northeastward, leading to the potential for strong to severe storms as well as a potential sting jet.”

Associated visible imagery is shown in Figure 2, along with Day Cloud Phase Distinction RGB Imagery in Figure 3. The DCPD RGB imagery provides a little more context to the VIS, including areas where cu are beginning to glaciate/initiate. Slightly earlier, SPC also discussed development along the northern part of the dryline here.

Figure 2: 30 May 2022 GOES-East VIS, sfc obs.
Figure 3: 30 May 2022 GOES-East DCPD RGB, sfc obs

Northward moisture transport ahead of the dryline is also diagnosed in GOES-16 TPW imagery as a narrow corridor of 1.25″+ TPW.

Figure 4: 30 May 2022 GOES-East VIS, TPW.

Convection continued to develop south along the dryline, as analyzed in satellite imagery and discussed in a later SPC MCD here. This evolution was captured in a 1-min sector.

Figure 5: 30 May 2022 GOES-East 1-min VIS.

Later around and following sunset, the cold front caught up with the retreating dryline, leading to another round of convective initiation. While surface obs provide some information about the evolution of these boundaries, satellite imagery captures their movement in much more detail, temporally and spatially. In this case, the GOES-16 Split Window Difference appears to have captured both boundaries quite well leading up to and through their interaction.

Figure 6: 30 May 2022 GOES-East SWD, cold IR, sfc obs.

One could also follow the evolution of the boundary interaction in Nighttime Microphysics RGB imagery (which forecasters would want to be viewing anyway post transition to night), which includes the SWD along with the IRW and Night Fog Diff. In this RGB, convective evolution is analyzed by transition from Blue to Pale Cyan (development of liquid cloud), and then to Red (glaciation/cooling). Using satellite imagery to track boundaries in this manner helps forecasters better anticipate where and when convection will develop, important for mesoanalysis, and which could be communicated in forecast discussions, social media, and other DSS means.

Figure 7: 30 May 2022 GOES-East Nighttime Microphysics RGB, sfc obs.

Bill Line, NESDIS/STAR

GOES-18 Captures Fires and Severe Thunderstorms

Posted by Bill Line on 05/12/2022
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GOES-18 data is preliminary and non-operational.

GOES-18 captured intense wildfires and widespread severe thunderstorms across the central US on 11 May 2022. GOES-18 mesoscale sector 2 was positioned over the southern high plains, encompassing large wildfires in New Mexico, and thunderstorm development in west Texas. A GOES-18 VIS/SWIR combo animations displays the large wildfire hot spots and associated smoke plumes, along with connective initiation along the west Texas dryline.

11 May 2022 GOES-18 1-min VIS/SWIR combo over southern high plains

In fact, GOES-16 and GOES-17 also had mesoscale sectors positioned over that location, allowing for a comparison between the three. GOES-18 imagery appears very similar to that from GOES-16 and GOES-17, as it should, aside from parallax differences due to the varied viewing angles between the three satellites.

11 May 2022 GOES-17 (top), GOES-18 (middle), GOES-16 (bottom) VIS/SWIR combo over southern high plains

Focusing east on the thunderstorms along the dryline, 1-min 500-m visible imagery provides excellent detail into convective initiation and storm top features.

11 May 2022 GOES-18 VIS over southern high plains, storm-relative

Combining the VIs (Ch02) channel with NIR (Ch05) and IR (Ch13) channels, we get the popular Day Cloud Phase Distinction RGB from GOES-18. The multispectral product provides information about storm top glaciation and cooling, indicators of convective initiation, that are not apparent in a single channel alone.

11 May 2022 GOES-18 Day Cloud Phase Distinction RGB over southern high plains

Focusing further north in Kansas, the details of a rapidly development thunderstorm are revealed in a rocking animation of GOES-18 1-min VIS.

11 May 2022 GOES-18 VIS over Kansas, storm-relative rocking animation

Severe thunderstorms also developed across the upper midwest, where another GOES-18 mesoscale sector was positioned. This time, we observe storm top characteristics, such as overshooting tops and above anvil cirrus plumes, along with additional convective development and decay, using the GOES-18 VIS-IR sandwich combo imagery.

11 May 2022 GOES-18 VIS/IR combo over upper midwest, storm-relative

GOES-18 CONUS sector (5-min) IR imagery shows the longer-period evolution of the severe convection across the upper midwest from the 11th through the morning of the 12th.

11-12 May 2022 GOES-18 10.3 um IR imagery

Zooming way out, we get a full disk view of GOES-18 UL WV imagery from last night through this morning.

12 May 2022 GOES-18 6.2 um water vapor imagery

Comparing water vapor imagery from the three GOES-R series satellites, we see that while GOES-17 WV imagery suffers from the Cooling System issue at times, corresponding GOES-16 and GOES-18 imagery appears great! GOES-18 is scheduled to begin it’s drift west to the GOES-West position in a few days, and eventually will become the operational GOES-West satellite early next year.

12 May 2022 GOES-17 (left), GOES-18 (middle), GOES-16 (right) 6.2 um water vapor imagery.

Bill Line, NESDIS and CIRA

First Light GOES-18 Imagery

Posted by Bill Line on 05/12/2022
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GOES-18 images and animations in this blog post are considered preliminary and non-operational.

On 11 May 2020, NESDIS released an “Earth From Orbit” GOES-18 Advanced Baseline Imager (ABI) first light video and associated article, which can be found here. The images and animations included in the video are some of the first captured by the GOES-18 ABI, including imagery from 5-8 May 2022. This blog post includes several of the animations from the video such that they can be viewed individually and with context. Included are an array of 10-min full disk, 5-min CONUS, and 1-min Mesoscale sector imagery. Additional animations and images from the first light video can be found in this blog post from CIMSS. Be sure to view the 1080p version of the videos!

First, a full disk Geocolor imagery from the day on the 5 May 2022, capturing the full hemisphere from the satellite currently at the 89.5W degree longitude position. The satellite is scheduled to begin drifting west toward the 136.8W position, near GOES-West, on May 16, arriving on June 6. A full schedule of the GOES-West transition can be found here.

5 May 2022 GOES-18 Full-Disk Geocolor Imagery.

Most of the first light imagery included in the video is from May 5, when a variety of active weather occurred across the US. GOES-18 provided incredible images of severe thunderstorms developing from Texas east into the southern MS valley area. First, GOES-18 upper-level water vapor imagery reveals the upper level features responsible for the development of widespread convection.

5 May 2022 GOES-East CONUS sector 5-min Channel 8 (upper-level) water vapor imagery.

GOES-18 visible and IR satellite imagery captured important storm top details, such as overshooting tops and above anvil cirrus plumes, in addition to cumulus cloud evolution, convective initiation and decay, and boundary movement.

5 May 2022 GOES-18 CONUS sector 5-min channel 13 (clean window) IR imagery.
5 May 2022 GOES-18 Mesoscale sector 1-min channel 2 (red) visible imagery over ArkLaTex region, with NWS severe thunderstorm and tornado warning polygons.
5 May 2022 GOES-18 Mesoscale sector 1-min channel 2 (red) visible imagery over southeast Texas, storm relative.

Further east, GOES-18 Geocolor imagery captured wildfire smoke over Florida, along with cumulus cloud development and eventual convective initiation.

5 May 2022 GOES-18 CONUS sector 5-min Geocolor imagery over south Florida.

Elsewhere on the 5th, GOES-18 Geocolor imagery revealed cu streaming across the Yucatan Peninsula, and stratus clouds sloshing along the Chile coast.

5 May 2022 GOES-18 CONUS sector 5-min Geocolor Imagery over Yucatan Peninsula.
5 May 2022 GOES-18 Full Disk sector 10-min Geocolor Imagery over Chile coast.

On 8 May 2022, critical fire weather conditions across the southwest resulted in ongoing wildfires across New Mexico to grow and generate large smoke plumes, which were captured in detail by GOES-18 Geocolor imagery. Also evident in the imagery is a dense region of blowing dust coming out of northwest New Mexico.

8 May 2022 GOES-18 Mesoscale sector 1-min Geocolor imagery over New Mexico wildfires and blowing dust.

Bill Line, NESDIS/STAR. Non-Geocolor Imagery created in AWIPS.

Geocolor Imagery created by Dan Lindsey (GOES-R), Curtis Seaman (CIRA), Steve Miller (CIRA), and Dakota Smith (CIRA).

Thanks to Natalie Tourville (CIRA) for managing GOES-18 dataflow to CIRA, and to many many others for making GOES-18 ABI possible!.

8 May 2022 Blowing Dust

Posted by Bill Line on 05/09/2022
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A broad upper trough digging across the western US and associated 60+ knot mid-level jet yielded gusty winds and low RH across a broad portion of the southwest US on Sunday. Not only did widespread critical fire weather conditions exist, but numerous areas of blowing dust developed during the day amidst winds gusting over 50 mph at the surface. GOES Water Vapor imagery with RAP analysis fields captures the evolution of the system on Sunday (Fig 1). Downward momentum transfer across the southwest can be visualized in the WV imagery as darkening/warming (drying). Further, the tightening pressure gradient is apparent in the RAP MSLP field. Both GOES-West Mesoscale sectors were positioned across the Southwest to capture the blowing dust and wildfire threat.

Figure 1: 8 May 2022 GOES-East UL WV Imagery, 500 mb height (white contour) and wind speed (Color contour), and sfc MSLP.

A broad view from GOES-East Geocolor and IR SWD imagery during the afternoon provides a nice overview of the event (Fig 2 and 3). Blowing dust developed across soCA, NV, AZ, NM, CO, and wTx, with impressive smoke plumes also coming out of New Mexico and Arizona. Quite a few NWS Dust Storm Warnings were issued across the Southwest during the day, highlighting locations where blowing dust was restricting visibility considerably. As has been noted in past posts, these warning polygons are typically issued and shaped with some combination of, depending on availability, surface obs, webcams, other visual, satellite imagery. Satellite imagery was utilized by NWS offices in the issuance of the Dust Storm Warnings, discussion of the forecast in Area Forecast Discussions, and on Social Media, by impacted NWS offices.

Figure 2: 8 May 2022 GOES-East 5-min Geocolor+SWIR imagery, NWS Dust Storm Warning polygons. GIF
Figure 3: 8 May 2022 GOES-East 5-min Split Window Difference Imagery, NWS Dust Storm Warning polygons.

Focusing on early blowing dust in New Mexico, NWS Albuquerque noted in an AFD at 2059 UTC: “A prominent dust plume is already evident on RGB satellite imagery over San Juan county where a Dust Storm Warning has been issued, and subsequent statements will likely follow.” The Dust Storm Warning, issued earlier at 1826 UTC, mentions Satellite imagery as the source of the warning. The NWS ABQ Twitter account communicated the location of the hazard using GOES Dust RGB imagery. One-minute Geocolor (Fig 4) and Dust RGB (Fig 5) imagery capture the blowing dust and smoke plumes in detail.

Figure 4: 8 May 2022 GOES-West 1-min Geocolor + SWIR Imagery, NWS Dust Storm Warning Polygons. GIF
Figure 5: 8 May 2022 GOES-West 1-min Dust RGB Imagery, NWS Dust Storm Warning Polygons. GIF

Further West NWS Las Vegas issued numerous Dust Storm Warnings across their CWA, with one reading: “At 417 PM PDT, dust channel moving across Death Valley Road near Dumont Dunes continues to be impressive on satellite imagery and is likely producing less than a quarter mile visibility.” By later in the afternoon, while dust could be diagnosed in GOES-West visible imagery (such as Geocolor), the lack of forward scattering from this location during the afternoon toward GOES-West makes it more difficult, compared to from GOES-East (Fig 6).

Figure 6: 8 May 2022 GOES-West 1-min Geocolor Imagery, NWS Dust Storm Warning Polygons. GIF

Therefore, bringing in IR-based products, such as SWD, to enhance dust appearance in the imagery is recommended (Fig 7), and/or viewing the IR-based RGBs (Fig 8).

Figure 7: 8 May 2022 GOES-West 1-min Geocolor Imagery, SWD overlay, NWS Dust Storm Warning Polygons. GIF
Figure 8: 8 May 2022 GOES-West 1-min Geocolor Imagery, Dust 2 RGB, NWS Dust Storm Warning Polygons. GIF

Additional mentions of satellite imagery in AFDs for dust detection during this event included:

From NWS Phoenix, AZ at 2132 UTC: “Meanwhile, further west across the Imperial Valley blowing dust has already been detected on visible satellite imagery and local web cams, and this threat will continue into this evening.”

From NWS Reno, NV at 2133 UTC: “For now, we will keep an eye on gusts of 60-70 mph with wind prone areas possibly gusting to 80+ mph. Driving along N-S oriented roads such as US 395 and US 95 will be difficult for high-profile vehicles through the afternoon. Blowing dust is visible on satellite imagery near Lovelock, and this is likely to persist throughout Monday.”

From NWS Pueblo, CO at 2315 UTC: “Satellite imagery depicts a narrow channel of dust extending from northwest New Mexico northeastward into south-central Colorado. While much of this dust in southern Colorado appears to be concentrated aloft, surface visibilities have been lowering across the San Luis Valley, and may continue to fall this evening as additional dust is transported into the region. As a result, a Blowing Dust Advisory has been issued for the San Luis Valley, in addition to the eastern San Juan Mountains — specifically applying to southern areas of the mountains close to the Colorado-New Mexico border.”

Additional examples of NWS offices communicating the blowing dust hazard using satellite imagery from NWS Grand Junction, CO (DEBRA Dust) and El Paso, TX (Geocolor) are shown below.

Satellite imagery is showing a decent plume of dust heading into the southeast San Juan range as winds gusts in the 45 to 65 mph range. #cowx pic.twitter.com/4XFNzec8eg

— NWS Grand Junction (@NWSGJT) May 8, 2022

6:30 pm: A look at satellite imagery this evening quickly shows the impact the strong winds have on the Borderland, bringing in smoke from a fire in AZ, and lofting dust and gypsum (from White Stands). #txwx #NMwx pic.twitter.com/FroamUY3JT

— NWS El Paso (@NWSElPaso) May 9, 2022

Bill Line, NESDIS and CIRA

Oklahoma Supercells at Sunset from GOES-16

Posted by Kevin Thiel (CIWRO) on 04/26/2022
Posted in: Day Cloud Phase Distinction RGB, G16-CH13_10.3_IR-Clean, GLM, RGB, SPC, Tornado. Leave a comment

Supercells were expected to initiate along a dryline in west-central Oklahoma during Saturday evening on April 23rd. The Storm Prediction Center had issued a slight risk of severe storms in their 1630 Z (1:30 PM CDT) outlook, with the risk tornadoes (5%), damaging hail (15%), and damaging wind (15%). Thunderstorms initiated around 2200 Z (5:00 PM CDT) as shown from the Day Cloud Phase Distinction RGB animation below. As the sun began to set near the end of the animation, decreasing contributions from the green (Channel 2, visible) and blue (Channel 5, near-IR) bands created a shift to more red colors in the imagery (Channel 13, clean-IR).

Animation of the Day Cloud Phase Distinction RGB from 2130 to 2300 Z (4:30-6:00 PM CDT).

An SPC Mesoscale Discussion and Tornado Watch, along with NWS Norman Public Information Graphics show the transition from the initial SPC Convective Outlook to the warnings that would later be issued that evening. (Images below in chronological order)

As convection matured into supercells after sundown, satellite imagery became confined to the infrared bands (Channels 7-16), with Clean-IR imagery most often used. Additionally, rapidly updating (1 minute) lightning data from the GLM Flash Extent Density product can provide information about thunderstorm trends between NEXRAD full-volume scans (4-5 minute updates). At night, the GOES-16 GLM detection efficiency often exceeds 90% across the south-central United States.

Intensification of two supercells and tightening of their low level mesocyclones, southwest of Oklahoma City and southwest of Stillwater, as indicated by radar prompted the NWS Norman office to issue tornado warnings for both storms. The Tornado Warning for the Stillwater supercell was issued at 2359 Z (6:59 PM CDT), and the Tornado Warning for the Oklahoma City supercell was issued at 0003 Z (7:03 PM CDT).

5-minute ABI and GLM data from 2330 to 0030 Z (6:30 – 7:30 PM CDT)
Left: GLM Flash Extent Density (5 minute total) overlaid on the ABI Clean-IR band.
Right: ABI Clean-IR Band.

The animation above is from 2330 Z to 0030 Z (5 minute intervals), and shows how both storms intensified from the perspective of the GLM FED and ABI Clean-IR products. Deep overshooting tops were observed from the ABI along with notable increases in GLM flash rates. In this scenario satellite information may have provided a ‘heads-up’ on which storms to monitor, along with additional confirmation of trends observed from NEXRAD.

One-minute data was observed from the GOES-East Mesoscale Domain for both products (below). In this scenario NWS Norman also had access to the Terminal Doppler Weather Radar at the Oklahoma City Airport (TOKC), providing 1-minute radar reflectivity and doppler velocity data within the vicinity of the airport. For the supercell near Oklahoma City, this may make a forecaster less reliant on one-minute satellite data when making warning decisions. However, for the storm southwest of Stillwater no TDWR data was available. The rapid increase in lightning flash rates identified by the GLM FED product for this storm can provide additional verification for an NWS forecaster that the updraft was intensifying, and tightening of the low level mesocyclone prior to tornadogenesis may be imminent.

1-minute data from the GOES-East ABI (Clean-IR) and GLM (FED) within the mesoscale domain. Imagery is from 2350 – 0010 Z (6:50-7:10 PM CDT) (Click animation to view at full size)

Kevin Thiel (OU CIWRO)

Dense Fog in Ohio Viewed from the Nighttime Microphysics RGB

Posted by Kevin Thiel (CIWRO) on 04/22/2022
Posted in: Nighttime Microphysics RGB, RGB. Leave a comment

During the early morning hours of April 22nd, fog began to form across southern Ohio, West Virginia, and Pennsylvania. In anticipation of the fog, the NWS Weather Forecast Office in Wilmington OH issued a Dense Fog Advisory for a portion of their forecast area.

Latest guidance increases confidence in development of areas of dense fog late tonight. Based on this, have hoisted Dense Fog Advisory south of Interstate 71.

NWS ILN, AFD Issued at 0133 UTC (9:33 EDT)

pic.twitter.com/BbwYSueh93

— NWS Wilmington OH (@NWSILN) April 22, 2022

Confirmation of the dense fog can be observed via satellite from the Nighttime Microphysics RGB starting around 0500 Z (1:00 AM EDT), with greater contributions from the Green Band (10.3 um – 3.9 um band difference) and minor contributions from the Blue Band (10.3 um band). The stationary, more faint, and highly localized appearance of the fog stands in contrast to the low level clouds in southwest Pennsylvania and central West Virginia, which often have a similar color due to similarities in their composition. Additionally the movement of cirrus and stratocumulus clouds into the area, from precipitation over Indiana, did obscure the extent of the fog in western Ohio by 1000 Z (6:00 AM EDT). This is one limitation of the product, as skies have to be fairly clear in order to properly identify fog.

Based on surface observations and imagery from the Nighttime Microphysics RGB, it was apparent by 0830 Z (4:30 AM EDT) that the dense fog was expanding north of Interstate 71. This confirms NWS Wilmington expanding the Dense Fog Advisory north into the Cincinnati and Dayton metro areas, prior to the increase of traffic during the morning rush. In this case the combination of surface observations and the Nighttime Microphysics RGB can provide confirmation of developing fog and its spread overnight for the Dense Fog Advisory. Using satellite RGBs in tandem with other observations can help maximize situational awareness, especially when satellite data cannot be relied on exclusively as shown in this example.

The fog is becoming dense in many locations across northern KY, southern Ohio, and southeast Indiana. Have expanded the dense fog advisory north to about I-70.

NWS ILN, AFD Issued at 0831 Z (4:31 AM EDT).

[12:56 AM] The dense fog advisory has been expanded northwest to include most of the Cincinnati metro. Areas of reduced visibilities are likely into the morning rush.

— NWS Wilmington OH (@NWSILN) April 22, 2022

Dense fog has developed across much of the area especially along and south of I-70. Fog will likely persist into the first part of the morning commute. Watch for low visibilities while driving. Image credit: OH DOT. pic.twitter.com/DAe4J4Ngst

— NWS Wilmington OH (@NWSILN) April 22, 2022

Kevin Thiel (OU CIWRO)

Thunderstorms Initiating Overnight in Kansas and Oklahoma

Posted by Kevin Thiel (CIWRO) on 04/13/2022
Posted in: G16-CH13_10.3_IR-Clean, Nighttime Microphysics RGB, RGB. Leave a comment

During the late evening hours on April 12th, 2022, convection initiated along a retreating dryline and advancing cold front in southern Nebraska and central Kansas. Initiation across the line can be observed from the Clean-IR band (Ch 13) from GOES-16 and the NEXRAD mosaic below. The near-uniform initiation of these thunderstorms along the dryline provided a unique example of how GOES imagery can be combined with radar data to monitor rapid thunderstorm development and dissipation.

Additionally, the initiation and subsequent outflow boundary along the leading edge of the front produced an undular bore, which traveled across central Oklahoma from 0600 Z to 1000 Z and initiated convection just after 1030 Z. Tracking the bore/front in this scenario could have been done by the Clean-IR band or radar (as seen below). However, the Nighttime Microphysics RGB can provide additional information not observed from a single ABI band or from radar.

Strong contributions from the Green band (Ch 13 – Ch 7) and moderate contributions from the Red band (Ch 15 – Ch 13) in the RGB recipe make the green-yellow clouds formed along the bore stand out from the magenta surface. Early signs of initiation along from the front can also be observed from strong contributions by both the Red and Green band, with low contributions from the Blue band (Ch 13), and the development of stratus clouds in central and eastern Oklahoma indicate an environment with greater low level moisture. In this scenario, the Nighttime Microphysics can provide an early ‘heads up’ that CI may be coming soon as the front moves into a more favorable environment for severe weather in southeast Oklahoma, southwest Arkansas, and northeast Texas. This coincides with the SPC Mesoscale Discussion issued just after 1200 Z.

Kevin Thiel (OU CIWRO)

Early April 2022 Blowing Dust

Posted by Bill Line on 04/11/2022
Posted in: Uncategorized. Leave a comment

An active weather pattern involving a persistent mid-level jet over US high plains resulting in several days of widespread hazardous blowing dust. As has been captured previously on this blog, NWS offices leverage satellite imagery to detect and track blowing dust, specifically for diagnosing the spatial extent of blowing dust, which is important for the issuance of advisories and warnings, and for including blowing dust in forecast grids. Further, satellite imagery is used to communicate the threat to the public via social media, as well as to partners in decision support service briefings. NWS Area Forecast Discussions provide some insight into how blowing dust appearance in satellite imagery influences forecaster thinking and decision making. This blog post captures some of these applications from 06-07 April 2022.

GOES-East water vapor imagery from 6-7 April capture a very broad upper low meandering over the upper mid-west (Fig 1). It’s western periphery over the high plains resulted in considerable northwesterly upper flow across the region, along with the embedded periodic and subtle shortwaves.

Figure 1: 06-07 April 2022 GOES-East Ul Water Vapor Imagery

Gusty winds developed early in the day on the 6th, resulting in morning blowing dust and associated considerations by impacted NWS offices:

From NWS Cheyenne, WY at 1609 UTC: Only minor forecast change is related to blowing dust. Latest satellite observations has indicated a few isolated patches of blowing dust in the southern Nebraska Panhandle near Sidney. Nearby locations across central NE and eastern CO have reported areas of blowing dust. Updated the forecast to include patchy blowing dust through the afternoon which could locally reduce visibility at times.

From NWS Goodland, KS at 1600 UTC: Widespread dust developing across the area now. A couple distinct larger areas are showing themselves on satellite… For the moment, issued a blowing dust advisory for the locations of the bigger plumes. However, it’s quite possible that warnings will be needed soon as we’re starting to get a few reports of near zero visibility. And then 1624 UTC: Went ahead with blowing dust warning across SW Nebraska and a large portion of NW Kansas. Started getting several reports of
zero visibility and decided an upgrade to a warning was necessary. Expanded the advisory to include Graham and Norton counties as dust being observed both at Norton AWOS (7 miles) and satellite.

From Dodge City, KS at 1650 UTC: Up to 50-60 mph likely for much of the CWA during peak heating of the afternoon with temperatures in the upper 50s to near 60 degrees. Blowing dust during this time will be an issue as already seen on satellite for western counties in the driest ground conditions.

From NWS Pueblo, CO at 1655 UTC: Blowing Dust Satellite products are showing blowing dust occurring over the far eastern plains, so a blowing dust advisory has been issued until late afternoon for the far eastern counties.

From NWS Boulder, CO at 1710 UTC: The second change was to add in additional blowing dust into the
far northeastern corner of the state. Webcams and surface observations have indicated some areas of reduced visibility due to blowing dust. CIRA’s DEBRA dust product also shows blowing dust has increased quite a bit over the past couple of hours. Have joined our neighbors to the east with a Blowing Dust Advisory for Sedgwick and Phillips counties where dust could impact travel.

As for DSS and social media, NWS Goodland analyzed GOES-East DEBRA Dust imagery in a morning web briefing posted to social media. NWS Dodge City highlighted problem areas in GOES-East Dust RGB imagery in early day social media posts.

NWS offices were confirmed to have used the CIRA DEBRA Dust product (available on CIRA Slider and in some NWS office AWIPS), as well as the AWIPS Dust RGB, shown in Figures 2 and 3, respectively.

Figure 2: 06 April 2022 GOES-East DEBRA Dust Imagery.
Figure 3: 06 April 2022 GOES-East Dust RGB Imagery.

One can also easily diagnose the blowing dust in the simple Split Window Difference with grayscale colormap, as regions of relative dark gray to black (Fig 4). The Split Window Difference is a key ingredient to satellite-based blowing dust detection products.

Figure 4: 06 April 2022 GOES-East Split Window Difference Imagery.

Geocolor imagery with blowing dust highlighted by the SWD is shown in Fig 5, which also overlays wildfires via the Fire/Hot Spot product. Finally, an experimental Blowing Dust RGB highlights lofted dust as dull to bright yellow (Fig 6).

Figure 5: 06 April 2022 GOES-East Geocolor+SWD Imagery.
Figure 6: 06 April 2022 GOES-East experimental Blowing Dust RGB Imagery.

On the 7th, with the same pattern in place, blowing dust developed across much of the same area, again early in the day. One-minute satellite imagery was available to forecasters to help analyze early development of blowing dust

From NWS Goodland, KS at 1513 UTC: Satellite is already indicating dust plumes developing across
portions of the area. The first area is between Sterling, CO, Akron, CO, and Wray, CO with 4 mile visibility already being reported in Yuma, CO. The other area of dust is south of Burlington, CO extending southeast towards Tribune, KS. Decided it was necessary to extend the blowing dust advisory across the rest of the forecast area as a result of the dust plumes viewable on satellite as well as observations. Will be monitoring for and looking for reports of near zero visibility and that will determine if Blowing Dust Warnings are needed once again. And at 1724 UTC: Received a couple reports of near zero visibility, and along with the impressive dust plume observed on satellite imagery, was pushed over the edge to issue the blowing dust warning for eastern Colorado (Yuma, Kit Carson, and Cheyenne Counties) and extreme northwestern Kansas (Cheyenne, Sherman, Wallace, and Greeley counties). This is currently the most impressive signal we’ve seen so far.

From NWS Boulder, CO at 1520 UTC: Blowing dust will be an additional hazard through the afternoon, and current satellite imagery depicts a few dust plumes beginning to surface over Washington County. May consider Blowing Dust Advisories down the line depending on how widespread/persistent the blowing dust looks to be.

A blowing dust advisory was eventually issued for Washington County.

From NWS Hastings, NE at 1544 UTC: The Blowing Dust Advisory has been extended to include more of the forecast area today. This is due in part to expected potential strong winds and suggestions of dust showing up on satellite imagery.

From NWS Pueblo, CO at 1726 UTC: Updated to issue a Dust Advisory for the far Eastern Plains
through this afternoon. Satellite imagery indicates widespread blowing dust moving into the far Eastern Plains.

On social media, NWS offices communicated the blowing dust threat with satellite imagery, including these posts from Goodland, Hastings, Pueblo, and Boulder. Various NWS personnel have commented that DEBRA Dust is a preferred product for public-sharing (blowing dust information) given it’s easy-to-understand nature.

DEBRA Dust imagery for the full day again captured the lofted dust quite well (Fig 7).

Figure 7: 07 April 2022 GOES-East DEBRA Dust Imagery.

Focusing on 1-min imagery over E CO and W KS during the morning, we can analyze the period of blowing dust initiation in detail. The grayscale Split Window Difference can sometimes be difficult to interpret on such fine scales (Fig 8).

Figure 8: 07 April 2022 GOES-East 1-min Split Window Difference Imagery.

Geocolor (and other reflectance imagery) from GOES-East will not highlight lofted dust and other aerosols too well from GOES-East in the morning due to lack of forward scattering (Fig 9). Enhancing the imagery with Split Window Difference helps (Fig 10).

Figure 9: 07 April 2022 GOES-East 1-min Geocolor Imagery.
Figure 10: 07 April 2022 GOES-East 1-min Geocolor+SWD Imagery.

During this time of day from GOES-East, and especially when clouds are present, IR-based products might be best for blowing dust detection, such as with the experimental blowing dust RGB (Fig 11) or traditional Dust RGB.

Figure 11: 07 April 2022 GOES-East 1-min experimental Blowing Dust RGB Imagery.

Viewing the 10-min GOES-West Geocolor, we see how forward scattering helps produce the dust signal in reflectance-based imagery.

Figure 12: 07 April 2022 GOES-West 10-min Geocolor Imagery.

Bill Line, NESDIS and CIRA

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