NUCAPS profiles from NOAA-21 are now flowing into AWIPS, joining NUCAPS from NOAA-20 and Metop-C. NOAA-21 and NOAA-20 orbits are similar, and the combination of the two satellites means complete coverage twice daily. That is demonstrated in the animation above over Hawai’i that shows gridded NUCAPS fields of 500-mb temperatures between 1134 and 1331 UTC on 10 May 2024, from two NOAA-21 overpasses and one NOAA-20 overpass. There are no gaps in data coverage! The data shows unseasonably cold 500-mb temperatures (-16^oC) to the north of the Hawai’ian Islands. The cold temperatures are associated with a region of convection to the north of Hawai’i as shown in the image below taken from the Geosphere site.

View only this post Read Less

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) included plots of Severe Thunderstorm Warning and Tornado Warning polygons — which showed the supercell thunderstorm that produced EF3 damage and was responsible for 1 fatality in the Columbia area (just southwest of Nashville) on 08 May 2024 (SPC Storm Reports). Pulses of thunderstorm overshooting tops were evident in the Visible and Infrared imagery. One sequence of the images also included an overlay of GOES-16 GLM Flash Extent Density — which revealed a few brief lightning jumps (the peak Flash Extent Density rate was 172 at 2156 UTC).

1-minute GOES-16 Visible/Infrared Sandwich RGB images (below) began to exhibit an Above-Anvil Cirrus Plume or AACP (reference | VISIT training | blog posts) about an hour before the tornado began near Columbia around 2237 UTC (damage survey). A Tornado Emergency (bold red polygon) was then issued for the Spring Hill area (and downstream locations) at 2253 UTC.

As the AACP was becoming established, the cloud-top cold/warm couplet infrared brightness temperature values at 2143 UTC were -72.1ºC/-49.1ºC (darker black enhancement/brighter green enhancement), respectively (above). According to a plot (source) of rawinsonde data from Nashville, Tennessee at 1800 UTC on 08 May (below), the -72.1ºC value represented a significant (~1 km) overshoot of the Most Unstable (MU) air parcel Equilibrium Level (EL) value of -60.9ºC.

In a comparison of cursor-sampled GOES-16 “Clean” Infrared Window (10.3 µm) infrared brightness temperature along with the corresponding Cloud Top Temperature and Cloud Top Height derived products for the cloud-top cold/warm couplet at 2143 UTC (below), there was an even greater range in Cloud Top Temperature values (-75.5ºC vs -47.4ºC), at Cloud Top Height values of 44222 ft (13.5 km) and 37757 ft (11.5 km), respectively. This implied that the small cluster of warm pixels immediately downwind of the cold overshooting top represented a ~6465 ft (2.0 km) depression of the cloud-top topography (likely a result of compensating subsidence).

View only this post Read Less

The Storm Prediction Center in Norman OK issued a Moderate Risk of severe weather over the lower Ohio River Valley/mid-Mississippi River Valley on 8 May 2024, as shown below. (Here are the storm reports for that day). The orbits for MetopC and NOAA-20 on the 8th sampled the region well, as shown in the toggle above of NUCAPS Sounding Availability with timestamps of 1605 UTC (Metop-C) and 1902 UTC (NOAA-20). Note the purple box in the toggle. Both MetopC NUCAPS and NOAA-20 NUCAPS retrievals at that location converged to a solution. How might the thermodynamic information within just those two profiles help?

---

The toggle below compares the MetopC NUCAPS and NOAA-20 NUCAPS profiles within the purple box in the toggle at the top of this blog post. The atmosphere at this location destabilizes in these three hours: diagnosed MUCAPE has more than doubled, mid-level lapse rates have steepened, the LFC has dropped, total precipitable water has increased. These indicators (derived from satellite-sensed radiances) all suggest that development of strong convection might proceed.

---

This blog post just shows you two profiles showing how a small volume of the atmosphere over southeastern Missouri is changing. Gridded thermodynanic fields derived from all the NUCAPS profiles are also available and are especially useful in diagnosing gradients and changes in stability over a large area.

View only this post Read Less

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed widespread thunderstorms that produced tornadoes, large hail and damaging winds (SPC Storm Reports) across parts of Nebraska, Kansas and Oklahoma (as well as far western Iowa, Missouri and Arkansas) on 06 May 2024. This was declared a rare High Risk day for severe weather by the SPC (as also discussed in this blog post).

A longer animation of 1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images (below) extended several hours past sunset. The coldest overshooting top infrared brightness temperatures were in the -70 to -75ºC range (darker black to embedded shades of white). These thunderstorms produced the deadly EF4-rated tornado in Barnsdall, Oklahoma around 0240 UTC, hail as large as 4.00″ in diameter near Moonlight, Kansas around 0126 UTC and a wind gust as high as 82 mph near Chester, Oklahoma around 2209 UTC.

5-minute CONUS Sector GOES-16 Visible (and after 1911 UTC, Infrared) images combined with GOES-16 Convective Available Potential Energy (CAPE) and Lifted Index (LI) Derived Stability Indices and the Total Precipitable Water (TPW) derived product (below) showed the instability and moisture within the warm sector of a large midlatitude cyclone that was centered over the Northern Plains — ingredients which helped to fuel the development of the severe thunderstorms.

View only this post Read Less