Severe convection « CIMSS Satellite Blog

Using NUCAPS soundings in and around fire locations

September 7th, 2020 | Scott Lindstrom

GOES-16 Visible (0.64 µm) hourly imagery, 1811-2311 UTC on 6 September 2020 (click to enlarge)

GOES-16 Visible imagery, above, during the late afternoon on 6 September, shows an invigoration of the Cameron Peak fire in Larimer County, Colorado, with visible evidence of a pyrocumulus development. Are there tools a forecaster can use to anticipate such extraordinary afternoon fire growth?

NOAA-20 overflew Colorado shortly after (NOAA-20 orbits can be viewed at this website) 2000 UTC on 6 September (see NUCAPS Sounding availability points below; note that the date of these plots — 1951 UTC — corresponds to the time of the first NUCAPS swath is available in AWIPS from this NOAA-20 pass; for this ascending pass, that swath is near 40 S latitude!)

NUCAPS Sounding Points from the 2000 UTC overpass on 6 September 2020 (Click too enlage)

What do the NUCAPS Sounding surrounding Larimer County Colorado look like? The animation below steps through the profiles surrounding the fire. Consider using the LCL and EL information (and other information) in these profiles when diagnosing the likelihood of convection developing in response to an intense fire. On this day, NUCAPS showed steep mid-tropospheric lapse rates that help support pyrocumulonimbus.

Select NUCAPS Soundings and thermodynamic variables (from AWIPS, locations as indicated) on 6 September 2020 (Click to enlarge)

Posted in NOAA-20, NUCAPS, Severe convection | No Comments »

Severe thunderstorms in South Dakota

August 30th, 2020 | Scott Bachmeier

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images — with and without an overlay of GLM Flash Extent Density (above) showed the rapid development of thunderstorms along a cold front across eastern South Dakota on 30 August 2020. One particularly well-defined and long-lived Enhanced-V signature with an Above-Anvil Cirrus Plume (reference | VISIT training) was seen in the Visible and Infrared imagery, which extended northeastward from the core of a thunderstorm where large hail and tornadoes were occurring.

GOES-16 “Red” Visible (0.64 µm) images, with time-matched SPC Storm Reports plotted in red [click to play animation | MP4]

1-minute GOES-16 Visible images with time-matched plots of SPC Storm Reports are displayed above, with the corresponding Infrared images below.

GOES-16 “Clean” Infrared Window (10.35 µm) images, with time-matched SPC Storm Reports plotted in cyan [click to play animation | MP4]

There were some overshooting tops which exhibited infrared brightness temperatures as cold as -72ºC — a plot of 00 UTC rawinsonde data from Aberdeen, South Dakota (below) indicated that this was about 7ºC colder than the tropopause temperature of -66.1ºC.

Plot of 00 UTC rawinsonde data from Aberdeen, South Dakota [click to enlarge]

Posted in GLM, GOES-16, Lightning, Severe convection | No Comments »

Midwest Derecho

August 10th, 2020 | Scott Bachmeier

GOES-16 “Red” Visible (0.64 µm) images, with SPC Storm Reports plotted in red [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the eastward progression of a Mesoscale Convective System (MCS) that produced a long swath of damaging winds (SPC Storm Reports) or derecho from eastern Nebraska to Indiana on 10 August 2020. The highest measured wind gust was 112 mph in eastern Iowa at 1755 UTC.

The corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images are shown below.

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play animation | MP4]

In a comparison of Infrared Window images from Suomi NPP (11.45 µm) and GOES-16 (10.35 µm) at 1931 UTC (below), the higher spatial resolution of the VIIRS instrument detected infrared brightness temperatures as cold as -84ºC, compared to -76ºC with GOES-16 (the same color enhancement is applied to both images). The northwest parallax offset associated with GOES-16 imagery at this location was also evident.

Comparison of Infrared Window images from Suomi NPP (11.45 µm) and GOES-16 (10.35 µm) at 1931 UTC [click to enlarge]

GOES-16 Visible/Infrared Sandwich Red-Green-Blue (RGB) and “Clean” Infrared Window (10.35 µm) images, with “probability of intense convection” contours and SPC Storm Reports, is shown below. The probability contours are produced from a deep-learning algorithm used to identify patterns in ABI and GLM imagery that correspond to intense convection. It is trained to highlight strong convection as humans would identify it. Work is ongoing to incorporate this storm-top information into NOAA/CIMSS ProbSevere.

GOES-16 Visible/Infrared Sandwich RGB and “Clean” Infrared Window (10.35 µm) images, with “probability of intense convection” contours and SPC Storm Reports (credit: John Cintineo, CIMSS) [click to play animation | MP4]

A comparison of Terra MODIS True Color RGB images (source) from before (28 July) and after (11 August) the derecho (below) revealed very large swaths of wind-damaged crops (lighter shades of green) across Iowa. It is estimated that around 10 million acres of corn and soybean crops were flattened by the strong winds.

Comparison of before (28 July) / after (11 August) Terra MODIS True Color RGB images centered over Iowa [click to enlarge]

A toggle between VIIRS True Color RGB images from Suomi NPP and NOAA-20 visualized using RealEarth (below) also displayed the crop damage swath.

VIIRS True Color RGB images from Suomi NPP and NOAA-20 — with and without map labels [click to enlarge]

Shown below is a before/after (28 July/11 August) comparison of VIIRS Day/Night Band (DNB) imagery (source), where many of the areas across Iowa that suffered significant power outages — appearing darker (due to a lack of city lights) on the nighttime DNB images — corresponded to the large swaths of crop damage seen on the 11 August MODIS True Color image. Around 550,000 households lost power across the state.

VIIRS Day/Night Band (0.7 µm) images on 28 July and 11 August, along with a MODIS True Color RGB image on 11 August [click to enlarge]

Even 2 days later (on 12 August), many customers remained without power across Iowa (below), especially in Marshall County (where peak winds of 106 mph were recorded), Tama County (where peak winds of 90 mph were recorded) and Linn County (where peak winds of 112 mph were recorded).

Iowa counties with power outages on 12 August [click to enlarge]

Updated estimated wind speed map for the #derecho2020. #iawx #IowaDerecho pic.twitter.com/XMaAgc6oHT

— NWS Des Moines (@NWSDesMoines) August 20, 2020

Posted in GOES-16, MODIS, NOAA-20, RealEarth, Red-Green-Blue (RGB) images, Severe convection, Suomi NPP, Terra, VIIRS | No Comments »

Severe thunderstorms in Minnesota

August 8th, 2020 | Scott Bachmeier

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed clusters of thunderstorms that developed along and just behind a cold front moving eastward across Minnesota on 08 August 2020. The northernmost hail-producing thunderstorm in Minnesota exhibited an Above-Anvil Cirrus Plume (reference | VISIT training); in addition, a decaying thunderstorm complex in southeastern North Dakota eventually revealed the cyclonic circulation associated with a Mesoscale Convective Vortex.

GOES-16 “Red” Visible (0.64 µm) images, with SPC Storm Reports plotted in red [click to play animation | MP4]

GOES-16 Visible images (above) and Infrared images (below) included time-matched SPC Storm Reports.

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play animation | MP4]

A toggle between time-matched NOAA-20 VIIRS Infrared Window (11.45 µm) and GOES-16 “Clean” Infrared Window (10.35 µm) images (below) demonstrated the northwestward parallax displacement of GOES-16 cloud-top features (note: the same color enhancement enhancement has been applied to both images). Due to the 375-meter spatial resolution of VIIRS imagery, it was able to sense overshooting top infrared brightness temperatures as cold as -77.8ºC (compared to -65.7ºC with GOES-16). The higher resolution VIIRS image also provided a clearer depiction of the cloud-top gravity waves and tendrils of transverse banding.

NOAA-20 VIIRS Infrared Window (11.45 µm) and GOES-16 “Clean” Infrared Window (10.35 µm) images [click to enlarge]

A GOES-16 Infrared image with parallax displacement vectors and magnitudes (in km) from this site is shown below. For a 50,000 foot cloud top over southern Minnesota, the parallax adjustment was to the southeast at a distance of 21 km (13 miles) — this corresponded well to what was seen in the NOAA-20/GOES-16 comparison above.