Outbreak of severe thunderstorms across the Plains

May 17th, 2019 |

GOES-16

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) highlighted the development a large and long-lived supercell thunderstorm that produced tornadoes and large hail (SPC storm reports) from northwestern Kansas to central Nebraska on 17 May 2019. Of note were the large number of tornado and large hail reports around 2259 UTC. Later in the day, concentric gravity waves were seen along the thunderstorm anvil top (for example, at 0022 UTC).

The corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images (below) revealed numerous overshooting tops that exhibited infrared brightness temperatures as cold as -70ºC (black enhancement).

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

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

After the first round of severe weather from Kansas to Nebraska, additional supercell thunderstorms developed which produced tornadoes/hail/winds across southwestern and central Kansas into the nighttime hours (below).

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

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

Mesoscale Convective System in the Midwest

May 16th, 2019 |

GOES-16

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) displayed a Mesoscale Convective System (MCS) that moved southeast across the Midwestern US on 16 May 2019 (surface analyses), producing a variety of severe weather (SPC storm reports). New convection continued to develop along the MCS outflow boundary, whose western edge was marked by parallel cloud bands from eastern Iowa into northwestern Illinois.

The corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images (below) revealed cloud-top infrared brightness temperatures as cold as -72ºC with some of the overshooting tops.

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

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

VIIRS Visible and Infrared images from Suomi NPP (at 1808 UTC) and NOAA-20 (at 1858 UTC) (below) revealed packets of concentric storm-top gravity waves, along with overshooting tops exhibiting infrared brightness temperatures as cold as -78ºC.

VIIRS Visible and Infrared images from Suomi NPP (at 1808 UTC) and NOAA-20 (at 1858 UTC) [click to enlarge]

VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images from Suomi NPP (at 1808 UTC) and NOAA-20 (at 1858 UTC) [click to enlarge]

As the MCS approached Madison, Wisconsin it produced a well-defined shelf cloud:

 

NUCAPS Sounding Availability

May 16th, 2019 |

NUCAPS soundings from NOAA-20 at 0653 UTC on 16 May 2019, 34.4 N, 75.8 W (Click to enlarge)

The Cross-Track Infrared Sounder (CrIS) on Suomi NPP suffered an anomaly back in late March and the mid-wave portion of the detectors are not functioning as designed; the wavelengths affected include those sensitive to water vapor. Because of this data outage, NUCAPS soundings are not being produced from Suomi NPP. Suomi NPP was the sole data source for NUCAPS in National Weather Service offices over the contiguous United States.

As shown above, NUCAPS soundings are being produced by NOAA-20, which, like Suomi NPP, carries both the CrIS and the Advanced Technology Microwave Sounder (ATMS). NOAA-20 NUCAPS soundings are scheduled to replace the Suomi NPP NUCAPS soundings in National Weather Service Forecast Offices in late May 2019. NOAA-20 is in the same orbit as Suomi NPP, but offset by half an orbit; overpasses are offset by about 45 minutes, so the NUCAPS data should show up in forecast offices at about the same time of day. (Compare these Suomi NPP orbits over North America to these from NOAA-20; Orbital tracks for most polar orbiters are here.) Time latency for NOAA-20 soundings is improved over Suomi-NPP however; there will be less wait needed for the soundings.

NUCAPS soundings are also produced from Metop-A and Metop-B, satellites that carry the Infrared Atmospheric Sounding Interferometer (IASI) and the Advanced Microwave Sounding Unit (AMSU) and Microwave Humidity Sensor(MHS) instruments.

NUCAPS soundings from NOAA-20, Metop-A and Metop-B are available at this site. That site includes a map (shown here) To access the soundings, move the map to your desired location, and click on the small box in the upper left of the map (under the +/- that cause the map to zoom in and out).  After clicking the box, use a left click and mouse drag on the map to define a region where sounding points will appear. (Alternatively, click the ‘Thumbnail Viewer’ box above the map; as you mouse over the points, a sounding will appear in the window.) The points are color-coordinated based on how old the latest sounding is. Zoom in, and choose your point.  Three profiles are displayed: The initial regression profile (labeled MW+IR Regr), the microwave-only profile (labeled MW phys) and the final physical retrieval profile (labeled MW+IR phys).  The resultant sounding you see will be the latest, but 10 soundings near that point over the past several days can be accessed as well.

NUCAPS soundings from Suomi NPP are not gone for good, however.  The CrIS has redundant electronics, and ‘A’ side — that has partially failed — and a ‘B’ side that has not been tested since before launch (Suomi NPP was launched on 28 October 2011!  Here is one of its first images).  The ‘B’ side electronics can be activated, and if they work, NUCAPS algorithms would have to be recalibrated for an essentially new data source.  This would take several months.  Alternatively, NUCAPS for Suomi NPP could be reformulated to account for the missing data with the ‘A’ side electrontics, something that also would take several months.  A decision on the path to take is forthcoming.

High pressure centered over Louisiana

May 15th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with plots of Derived Motion Winds [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images, with 5-minute plots of Derived Motion Winds (above) revealed a cumulus cloud field that beautifully outlined the flow around an area of high pressure that was centered over Louisiana on 15 May 2019. Subsidence within the dome of high pressure prevented significant vertical development of these cumulus clouds.