Strong Thunderstorms move through Washington DC.

May 14th, 2018 |

GOES-16 ABI Channel 13 “Clean Window” (10.3 µm) at 1-minute time-steps from 1607-2359 UTC on 14 May 2018 (Click to animate)

A GOES-16 Mesoscale Sector produced 1-minute imagery as a strong thunderstorm complex approached Washington DC late in the afternoon/early evening of 14 May 2018.  The (150-megabyte (!!)) animated gif above shows overshooting tops quickly developing and decaying as the complex moved over the Potomac Basin.  Winds in excess of 60 knots were reported around the Washington DC metropolitan area, with widespread tree damage. (Smaller MP4 animations with plots of SPC storm reports are also available: Infrared | Visible)

NOAA/CIMSS ProbSevere All Hazards (Source), below, showed very high ProbHail and ProbWind with this cell as it approached Washington DC.

NOAA/CIMSS ProbSevere All Hazards, 2200 UTC on 14 May 2018 (Click to enlarge)

GOES-16 Geostationary Lightning Mapper (GLM) data from Real Earth (Link for animation), below, shows an increase in electrical activity to the storms as they moved through Washington DC.

CONUS Hybrid Radar Reflectivity overlain with GLM observations, 2200-2330 UTC 14 May 2018 with 15-minute timestep.

Hail-producing storm on the High Plains of Colorado and Kansas

May 14th, 2018 |

GOES-16 Red Visible (0.64 µm) from 1212 on 14 May 2018 through 0037 UTC on 15 May 2018 (Click to animate)

A Thunderstorm complex moved through eastern CO into western Kansas on 14 May 2018, producing 2 to 3 inch hail in Kit Carson and Cheyenne Counties in east-central Colorado and in Wallace County in northwest Kansas (SPC Storm Reports). Visible animation (0.64 µm) from GOES-16, above, shows the storms initiating near metropolitan Denver before moving eastward across the Plains.

GOES-16 ABI Clean Window imagery (10.3 µm), below, shows very cold overshooting  tops associated with these storms, with brightness temperatures colder than -60º C.  The area of coldest cloud tops shows a pronounced southeastward motion.

GOES-16 ABI “Clean Window” Infrared Imagery (10.3 µm), 1212 UTC 14 May 2018 to 0037 UTC on 15 May 2018 (Click to animate)

The GOES-16 ABI “Snow/Ice” Channel (at 1.61 µm) is important in diagnosing cloud-top properties in convection, in particular because glaciated clouds absorb solar energy at 1.61 µm (rather than reflecting it).  Thus, glaciated cloud tops will look dark.  That is the case with this system, shown below.  Note that above-anvil cirrus banners are apparent in this animation as well towards the end, stretching west-southwest to east-northeast.  These above-anvil banners are very well correlated with severe weather. This link shows a toggle between the Visible (0.64 µm) and Snow/Ice (1.61 µm) bands at 2302 UTC on 14 May, during the time when hail was occurring in eastern Colorado.

GOES-16 ABI “Snow/Ice” Near-Infrared Imagery (1.61 µm), 1212 UTC 14 May 2018 to 0037 UTC on 15 May 2018 (Click to animate)

One of the Derived Products available from GOES-16 is Lifted Index. This animation, from 1212 UTC on 14 May through 0037 UTC on 15 May shows widespread Lifted Indices of -3º to -5º in the inflow into this thunderstorm. (The clear-sky only Lifted Index is plotted on top of the Snow/Ice 1.61 µm Imagery). Note also that dewpoints over the High Plains of Colorado and Kansas were fairly high for that region: 40s and 50s Fahrenheit. (Click to view 2007 UTC “Veggie” Band 0.86 µm imagery with surface metars plotted).

NOAA/CIMSS ProbSevere All Hazards showed very high probabilities for this cell at 2330 UTC, when it was over eastern Colorado, as shown below (Source).

NOAA/CIMSS ProbSevere All Hazards, 2330 UTC on 14 May 2018 (Click to enlarge)

As noted elsewhere (link, link), hail deposited by this storm in central Colorado (in Douglas and Elbert counties) was widespread enough to be visible from satellite, below.  The hail appears white in the visible (0.64 µm) imagery and dark in the 1.61 µm Snow/Ice imagery because ice strongly absorbs energy with wavelengths of 1.61 µm.

GOES-16 Band 2 (“Red Visible”, 0.64 µm) and Band 5 (“Snow/Ice”, 1.61 µm) imagery at 2217 UTC on 15 May 2018 showing hail on the ground in Douglas and Elbert counties, Colorado (Click to enlarge)

GOES-16 Band 2 (“Red Visible”, 0.64 µm) and Band 5 (“Snow/Ice”, 1.61 µm) imagery at 2217 UTC on 15 May 2018 showing hail on the ground in Douglas and Elbert counties, Colorado (Click to enlarge)

Once the severe convection moved closer to the Colorado/Kansas border, a second hail swath was later seen to the east-northeast, below.

GOES-16 “Red” Visible (0.64 µm, top) and Near-Infrared

GOES-16 “Red” Visible (0.64 µm, top) and Near-Infrared “Snow/Ice” (1.61 µm, bottom) images, with SPC storm reports (red) and hourly plots of surface reports [click to play MP4 animation]

PyroCumulonimbus cloud in Texas

May 11th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.3 µm, bottom) images, with hourly plots of surface reports [click to play MP4 animation]

A large pyroCumulonimbus (pyroCb) cloud developed from the Mallard Fire in the Texas Panhandle on 11 May 2018, aided by warm temperatures and strong winds ahead of an approaching dryline (surface analyses).  1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the large thermal anomaly or “hot spot” (red 3.9 µm pixels) and the rapid development of  the pyroCb cloud beginning shortly after 1900 UTC. Cloud-top infrared brightness temperatures cooled to -60 ºC — the tropopause temperature on the 00 UTC Amarillo sounding — by around 2130 UTC. On the Shortwave Infrared imagery, note the relatively warm (darker gray) appearance of the pyroCb cloud top — a characteristic signature of pyroCb anvils due to enhanced reflection of solar radiation off of smaller cloud-top particles.

4-panel comparisons of Suomi NPP VIIRS Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images at 1936 UTC and 2029 UTC (below) revealed that the maximum differences between 3.74 µm and 11.45 µm cloud-top infrared brightness temperatures — at the same location on the pyroCb anvil — were 86ºC (+26ºC and -59ºC at 1936 UTC) and 91.5ºC (+27.5ºC and -63ºC at 2029 UTC).

Suomi NPP VIIRS Visible (0.64 µm), Near-Infrared

Suomi NPP VIIRS Visible (0.64 µm, upper left), Near-Infrared “Snow/Ice” (1.61 µm, upper right), Shortwave Infrared (3.74 µm, lower left) and Infrared Window (11.45 µm, lower right) images at 1936 UTC and 2029 UTC [click to enlarge]

Lightning was detected from portions of the smoke plume, as well as the core of the pyroCb thunderstorm.

After dark, the thermal signature of the Mallard Fire was also apparent on GOES-16 Near-Infrared “Cloud particle size” (2.24 µm) imagery (below).

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Cloud particle size” (2.24 µm, top), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.3 µm, bottom) images, with hourly plots of surface reports [click to play MP4 animation]

===== 12 May Update =====

Terra MODIS True-color and False-color images [click to enlarge]

Terra MODIS True-color and False-color images [click to enlarge]

In a comparison of 250-meter resolution Terra MODIS True-color and False-color Red-Green-Blue (RGB) images from the MODIS Today site (above), the Mallard Fire burn scar was evident in the False-color. Both images showed a smoke plume from ongoing fire activity, which was drifting northward across the Texas Panhandle.

The corresponding Terra MODIS Land Surface Temperature product (below) indicated that LST values within the burn scar were as high as 137ºF (darker red enhancement), in contrast to values around 100ºF adjacent to the burn scar.

Terra MODIS Land Surface Temperature product [click to enlarge]

Terra MODIS Land Surface Temperature product [click to enlarge]

Severe weather across southern Wisconsin

May 9th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.3 µm, bottom) images, with airport identifiers plotted in yellow and SPC storm reports plotted in red [click to play MP4 animation]

Severe weather (SPC | NWS ARX | NWS MKX) occurred across far southern Wisconsin on the afternoon of 09 May 2018, as a surface low moved eastward across the area. 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) provided a view of the isolated thunderstorm that rapidly developed in far southwestern Wisconsin around 1800 UTC. The evolution of overshooting tops was seen in both Visible and Infrared imagery — cloud-top infrared brightness temperatures cooled into the -50 to -60 ºC range (orange to red enhancement). On the Visible imagery, rear inflow feeder bands could be seen on the southwestern flank of the storm leading up to the time that it produced 1.00-inch diameter hail near Madison at 2045 UTC. SPC storm reports are “parallax corrected” so as to be plotted at a height corresponding to the cloud-top features of the parent storm.

A comparison of Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 1923 UTC (below) showed the isolated thunderstorm as it was moving into northwestern Dane County. The rear inflow feeder bands were evident, and the minimum cloud-top infrared brightness temperature was -62 ºC.

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images [click to enlarge]

GOES-16 Rayleigh-corrected pseudo true color Red-Green-Blue (RGB) images (below; courtesy of Pete Pokrandt, AOS) showed a large Mesoscale Convective Vortex (MCV) that moved through northern Illinois and Wisconsin during the early morning hours, along with the hazy signature of smoke from agricultural burning in the central Plains (which was being drawn northward across eastern Iowa ahead of the surface cold front).

GOES-16 Rayleigh-corrected RGB images [click to play YouTube video]

GOES-16 Rayleigh-corrected RGB images [click to play YouTube video]