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.
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.
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.
During the early morning hours of 14 March 2022, a plume of moisture from the Gulf of Mexico was advected northward prior to a severe weather setup later that day. Along with surface observations and RAP surface analysis data, imagery from the GOES-16 Nighttime Microphysics RGB provided conformation of this moisture advection with stratus clouds developing across eastern Texas and southern Oklahoma (green-yellow) from Figure 1. Strong contributions in the red and green bands signify thick clouds that mostly contain water, helping to determine that these are low level stratus clouds driven by the synoptic scale advection of low level moisture across the region.
The NWS Storm Prediction Center issued a Slight Risk for northeast Texas and the Ark-La-Tex region, with all hazards (tornadoes, large hail, and damaging winds) possible (see slideshow below). Use of the Nighttime Microphysics RGB in this scenario may provide conformation of the moisture advection, along with its current spatial extent in regions where few surface observations exist. Monitoring the extent of these stratus clouds also provides a ‘first look’ at which areas will receive more or less solar heating during the morning, which may impact the initiation time, coverage, and maximum strength of convection later in the day.
A broad trough and embedded shortwaves digging east across the southern US brought severe weather, including tornadoes, to parts of the south and southeast US on 21-22 March 2022. The evolution of the trough across the country is shown well in 6.2 um GOES-East Water Vapor Imagery in Figure 1. GLM FED is also included in the animation as progressively more opaque yellow atop the green cold clouds.
Adding RAP sfc and upper level analysis fields onto the water help one to better understand features in the imagery by associating them with familiar fields, such as 500 mb height and wind speed, and sfc pressure (Figure 2).
Partially overlapped GOES-East 1-min mesoscale sectors resulted in a corridor of 30-second imagery across central Texas. The difference between 30-second imagery and 1-min imagery may not sound like a lot, put processes that are occurring on such small timescales do appear notably smoother to the human eye in the side-by-side comparison. This is exemplified in an animation of visible imagery over a tornado-producing severe thunderstorm on the border of 30-sec and 1-min imagery (Fig 3).
Further south near San Antonio, the evolution of the cu field leading up to eventual convective initiation is captured in 30-second Day Cloud Phase Distinction imagery. The 2.5 hour animation (300 images) reveals a cumulus field becoming increasingly agitated with the growth of cumulus clouds into towering cu, eventual glaciation with the colors changing from blue/cyan to green, to convective initiation diagnosed by vertical growth and transition of colors from green to yellow/red (Fig 4). The growth of the eventual first severe-warned storm occurs under high cirrus (red), but can be followed in the very high temporal resolution imagery.
Post convective initiation, 30-second imagery of storm maturation captured the evolution of storm top features, such as overshooting tops and an above anvil cirrus plume, in much detail (Fig 5). The imagery is extremely fluid, and ensures forecasters are receiving updates about the storm faster than ever. The animation is 240 images, or 2 hours long.
During the same period of 30-second imagery, adding a semitransparent 10.3 um overlay, resulting in the VIS/IR Sandwich, helps to capture the storm top features a little better by including the quantitative brightness temperature information (Fig 6).
After viewing the 30-sec animation a few times, take a peak at the 1-min animation of the same scene. It is fascinating how 1-min imagery appears relatively “choppy” (Fig 7)!
The most impressive storm developing near San Antonio exhibited an exposed updraft in the GOES-East 30-second imagery. Rocking a 30-sec visible imagery animation of this storm over a 25 minute period reveals counterclockwise rotation of the updraft (Fig 8). Extending west of the updraft is the more horizontally oriented flanking line. Inflow feeder clouds are also analyzed southeast of the updraft, as well as an overshooting top and above anvil cirrus plume at the storm top. Given the presence of high clouds, and rapid evolution, some of these features can easily be missed in coarser temporal resolution imagery.
As was shown in Figure 1+2, the convective threat shifted east to the southeast on the 22nd as the broad upper trough shifted east and another shortwave and associated strong jet streak spread across the region. Two strong thunderstorms passed through the New Orleans area just after sundown, and were captured in GOES-East 1-min ABI and GLM imagery. The northern storm produced an EF1 tornado, while the thunderstorm produced an EF3 tornado. The 1-min IR imagery revealed rapidly cooling cloud tops just prior to the initial tornado reports between 0024 UTC and 0029 UTC (Fig 9).
GLM FED associated with the storms included rapid upticks in total lightning activity leading up to tornado development (Fig 10). The FED data highlights the location and movement of the most intense storm updrafts, as well as the presence of lightning flashes and resulting lightning danger well removed of the storm core.
Finally, combining the GLM Flash Extent Density with Minimum Flash Area into a single RGB reveals where an abundance of small flashes (indicative of strengthening updraft) were occurring, as bright shades of yellow (Fig 11). Red represents low FED and small flashes, so a transition from Red to Orange to yellow in this RGB indicates increasing numbers of small flashes. Shades of blue represent long flashes, which are often present with the anvil regions of the thunderstorms, as well as with decaying updrafts.