GOES-16 (GOES-East) Upper-level Water Vapor (6.2 µm), Mid-level Water Vapor (6.9 µm), Low-level Water Vapor (7.3 µm) and “Red” Visible (0.64 µm) images (above) revealed the well-defined signature of a mid-tropospheric lobe of vorticity moving from southeastern South Dakota across Iowa during the day on 19 July 2018 — this feature provided synoptic-scale forcing for ascent which aided in the development of severe thunderstorms in central and eastern Iowa. A number of tornadoes were reported, along with some large hail and damaging winds (SPC storm reports).

A closer look using 1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (above) showed the line of thunderstorms as they developed in advance of an approaching cold/occluded front (surface analyses). Two larger storms were dominant, which produced tornadoes causing significant damage and injuries in Pella KPEA and Marshalltown KMIW — above-anvil cirrus plumes were evident with both of these supercells. In addition, early in the animation a few orphan anvils could be seen along the southern end of the line (southeast and east of Des Moines KDSM).

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) showed cloud-top infrared brightness temperatures of -65ºC to -70ºC with the larger Pella storm, and around -55ºC with the smaller Marshalltown storm to the north.

The NOAA/CIMSS ProbSevere model (viewed using RealEarth) had a ProbTor value of 74% at 2055 UTC for the Pella storm (above) and 83% at 2130 UTC for the Marshalltown storm (below). GOES-derived Cloud-top glaciation rate (from infrared imagery) is one of the predictors used in the model.

ProbSevere time series plots for the Pella and Marshalltown cells are shown below. They indicated that the Pella storm was long-lived, persisting past 0300 UTC — and that ProbTor ramped up quickly and then down quickly, bracketing the time of the tornado in Marshalltown.

A toggle between 375-meter resolution Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 1946 UTC (below) provided a look at the early stage of development of tornado-producing convection.

Additional satellite imagery and analysis of this event can be found on the Satellite Liaison Blog.

The EF-3 damage at the Vermeer Plant in Pella. Preliminary estimated peak winds of 144 mph and a max tornado width of 400 yards. Tornado end time and path length still TBD. #iawx pic.twitter.com/aMMmhdn21N

— NWS Des Moines (@NWSDesMoines) July 21, 2018

Preliminary damage survey…Lennox Warehouse in Marshalltown where the EF-3 damage occurred caused by 144 mph estimated peak winds. #iawx pic.twitter.com/egcNJqBSOE

— NWS Des Moines (@NWSDesMoines) July 21, 2018

As of 4:09 CDT, a tornado debris signature was about 3 miles NE of Pella, IA moving southeast. Radar and webcam shot from @akrherz. #iawx pic.twitter.com/y8erooTml7

— U.S. Tornadoes (@USTornadoes) July 19, 2018

Tornado Emergency for Marshalltown, IA. A damaging tornado is now making it’s way through Marshalltown. Debris from the tornado is being seen by the radar up to 11,000 ft. Indicating a strong tornado is ongoing! #iawx pic.twitter.com/2eKqFlpe2N

— U.S. Tornadoes (@USTornadoes) July 19, 2018

View only this post Read Less

* GOES-17 imagery shown here are preliminary and non-operational *

A 3-panel comparison of Visible images from GOES-15 (GOES-West), GOES-17 and GOES-16 (GOES-East) shown above highlights the dissipation of fog in the Strait of Juan de Fuca during the morning hours on 17 July 2018. The three sets of images are displayed in the native projection of each satellite (with no re-mapping) — GOES-17 was at its post-launch checkout location of 89.5ºW longitude.  Images from GOES-16/17 were at 5-minute intervals, while images from GOES-15 were every 5-15 minutes depending on the operational scan schedule of that GOES-West satellite.

A similar 3-satellite comparison shown below focuses on the development of showers and thunderstorms across western Montana, between Missoula KMSO and Butte KBTM. The improved spatial resolution (0.5 km at satellite sub-point for GOES-16/17, vs 1.0 km for GOES-15) and more frequent images allowed small-scale features of the storms to be more easily identified and followed.

One final comparison, shown below, depicts thunderstorms over western Colorado — outflow boundaries south of these storms produced strong surface winds in the Grand Junction area (SPC storm reports).

 

Yesterday’s peak wind gust of 70 MPH at the @GJAirport set a new record wind speed for the month of July, breaking the old record of 68 MPH set on July 14, 2002! #cowx #climate

— NWS Grand Junction (@NWSGJT) July 18, 2018

 

View only this post Read Less

* GOES-17 images shown here are preliminary and non-operational *

The Ferguson Fire in central California produced a pyrocumulonimbus (pyroCb) cloud during the afternoon hours on 15 July 2018. GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed that the high-altitude portion of the pyroCb cloud then drifted northeastward toward the California/Nevada border, where cloud-top infrared brightness temperatures cooled to near -55ºC (orange enhancement) as it crossed the border around 0005 UTC on 16 July.

A comparison of Visible images from GOES-15 (0.63 µm), GOES-17 (0.64 µm) and GOES-16 (0.64 µm) is shown below — with the imagery displayed in the native projection of each satellite. Images from GOES-16/17 are at 5-minute intervals, while images from GOES-15 are every 5-15 minutes depending on the operational scan schedule of that GOES-West satellite. GOES-17 was at its post-launch checkout position of 89.5ºW longitude, so it offered a more direct view of the pyroCb cloud.

A toggle between NOAA-19 Visible (0.63 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images (below) showed the pyroCb cloud southwest of the California/Nevada border (between Bridgeport KBAN and Mammoth KMMH) at 2327 UTC. In spite of a minimum cloud-top 10.8 µm infrared brightness temperature of -59ºC (red enhancement), note the darker (warmer) appearance of the cloud on the 3.7 µm image — this is due to reflection of solar radiation off the smaller ice particles of the pyroCb anvil. The -59ºC temperature roughly corresponded to an altitude of 13 km or 42.6 kft on the 00 UTC Reno, Nevada rawinsonde report (plot | data)

A time lapse of the pyroCb was created by Sierra Fire Watch (below).

View only this post Read Less

A 4-panel comparison of GOES-16 (GOES-East) “Red” Visible (0.64 µm), Low-level Water Vapor (7.3 µm), Mid-level Water Vapor (6.9 µm) and Upper-level Water Vapor (6.2 µm) images (above) showed a large occluded cyclone (surface analyses) over northern Saskatchewan and northern Manitoba on 15 July 2018. In the cold sector of the storm, morning temperatures were confined to the 40s F — especially at Churchill, Manitoba where strong easterly winds were blowing off Hudson Bay.

A closer examination of the GOES-16 images (below) revealed the presence of waves over southwestern Manitoba on the Water Vapor imagery — these appeared to vertically-propagating waves which formed due to the interaction of strong boundary layer winds with the topography of that area (some land features rise to 2600 feet). These waves then began breaking and propagating slowly westward late in the animation.

A NOAA-20 VIIRS True Color Red-Green-Blue (RGB) image (below) showed numerous smoke plumes from wildfires in southeastern Manitoba and western Ontario, as well as the light cyan color of ice in central and eastern portion of Hudson Bay (ice analysis: northern | southern).

View only this post Read Less