Using NUCAPS to diagnose threats in a region of Enhanced/Moderate risk

October 13th, 2021 |
GOES-16 Low-Level water vapor infrared imagery (Band 10, 7.34 µm) at 1931 UTC on 12 October 2021 (Click to enlarge). NOAA-20 NUCAPS Sounding Availability points are indicated as colored dots. METAR plots are also included.

The Storm Prediction Center in Norman issued a convective outlook on 12 October 2021 that included a large area of Enhanced Risk over western Kansas and Oklahoma, noting the expected development of a strong low-level jet creating favorable shear profiles for supercells. (SPC increased the threat to a Moderate Risk for a small part of southwestern Kansas and parts of the Oklahoma and Texas panhandles at 2000 UTC). The Band 10 low-level water vapor image above, from 1931 UTC. An initial round of convection is moving eastward over central Kansas. Did that convection stabilize the atmosphere? NUCAPS profiles can give information on that, information that is not dependent on numerical model simulations.

The plot below, taken from RealEarth, shows the Lifted Index computed from NUCAPS soundings blended with MADIS surface observations. The greatest instability, shaded in red, lies along the Kansas/Colorado border, and it extends to the southeast along the western Oklahoma/north Texas border. (Click here to see surface-based CAPE at the same time).

NUCAPS/MADIS Surface-based Lifted Index, 1952 UTC on 12 October 2021 (Click to enlarge)

What do individual profiles show? 20 different profiles over southwestern Kansas are in the stepped animation below. Steep mid-level lapse rates (greater than 8 K/km) are indicated in the soundings, and Most Unstable Convective Available Potential Energy (MUCAPE) values persist in the lower troposphere. It also appears that moisture is pooling along the Kansas/Colorado border: precipitable water values from two soundings (at 38.42 N/102.60 N and 38.04 N /101.89 W) and are greater than surrounding values. So: instability is present, and moisture is available. Model-independent information like this can help a forecaster during the wait for initiation.

GOES-16 Day Cloud Phase Distinction image at 1931 UTC, along with NUCAPS Sounding Availability plots. Individual profiles as indicated are shown in the inset; values from those soundings are shown in the grey box in upper left (Click to enlarge)

It can be time-consuming in AWIPS to look through multiple soundings (the Pop-up SkewT functionality can be helpful, but for subtle changes in precipitable water, or in lapse rate, that use is limited). Gridded NUCAPS fields are available in AWIPS, and also online. The 700-500 mb lapse rate, shown below, from this website, diagnoses the steep lapse rates that were present (perhaps to be expected given the suggestion of an elevated mixed layer in the water vapor imagery at the top of this blog post!)

Lapse Rate (700-500 mb) diagnosed from NOAA-20 NUCAPS, 1949 UTC on 12 October 2021 (Click to enlarge)

So what happened with this event? Convection developed along the Colorado/Kansas border, and spawned severe weather over western Kansas, western Oklahoma, and western Texas. GOES-16 clean window infrared imagery (10.3 µm), below, shown on top of the Level 2 stability Lifted index product, shows the instability and the development of the convection (Click here for a Band 13 animation only).

GOES-16 clean window infrared imagery (Band 13, 10.3 µm) and Level 2 Derived Stability Index (Lifted Index, clear sky only) from 2201 UTC on 12 October 2021 through 0646 UTC on 13 October 2021 (Click to enlarge).

Ongoing eruption of Cumbre Vieja (La Palma) in the Canary Islands

October 9th, 2021 |

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 (GOES-East) True Color RGB images created using Geo2Grid (above) showed the south-southeastward drift of an ash-laden volcanic cloud from Cumbre Vieja on La Palma in the Canary Islands on 09 October 2021. Since this most recent ongoing eruptive period began on 19 September, intermittent periods of volcanic clouds with an elevated ash content have been observed — and on this day, the darker tan to light brown appearance was an indication that higher ash concentrations were likely.     

In the corresponding GOES-16 Ash RGB  images (below), increasing shades of pink — which suggest a higher ash content — became apparent within a semi-circular volcanic cloud element after 1100 UTC.  

GOES-16 Ash RGB images [click to play animation | MP4]

A NOAA-20 VIIRS True Color image as viewed using RealEarth (below) also showed the darker tan to light brown shades of the ash-laden volcanic cloud.

NOAA-20 VIIRS True Color RGB image [click to enlarge]

GOES-16 retrieved products from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) indicated that the more distinct pulse of ash-laden volcanic cloud had a maximum height in the 5-6 km range, and was composed of ash particles having an effective radius 10 µm and smaller. 

GOES-16 Ash Probability [click to play animation | MP4]

GOES-16 Ash Loading [click to play animation | MP4]

GOES-16 Ash Height [click to play animation | MP4]

GOES-16 Ash Effective Radius [click to play animation | MP4]

Displaying NUCAPS data with Matlab

October 1st, 2021 |
NOAA-20 NUCAPS Temperature values at 853 mb, 1817-1819 UTC on 01 October 2021 (Click to enlarge)

Alexa Ross, a scientist at CIMSS (and CIMSS Blog contributor) has created a Matlab program that reads in NUCAPS EDR data from any Direct Broadcast datastream (here, for example), or from NOAA CLASS, and creates color-coded plots at NUCAPS data levels (that is, at any one of the 100 pressure levels used in the Radiative Transfer Model that drives the retrieval). Output from the program for four separate granules between 1817 and 1819 UTC is shown above. Temperatures are notably warmer over land than over the Atlantic Ocean, a temperature distribution in agreement with GFS model output (GFS model imagery from the College of Dupage website).

This program does not (as yet) indicate whether or not the retrieved profile has converged to a solution. It is up to a user to apply some quality control to the data. The very warm pixel at 1817 UTC over the Atlantic Ocean, for example, looks suspect. Cloud imagery is an important tool for anticipating whether a retrieval will converge — click here to see an 1820 UTC GOES-16 True-Color imagery over the scene, taken from the CSPP Geosphere site.

Gridded NUCAPS (available from this NASA SPoRT website) can also be used to view the horizontal distribution of temperatures across the NUCAPS data swath. The toggle below shows the 850-mb Temperature field and also the Quality Control flags.

850-mb gridded NUCAPS temperatures and Quality Flags from the NOAA-20 overpass at ~1815 UTC on 1 October 2021 (Click to enlarge)

Kilauea is active again

October 1st, 2021 |
GOES-17 Shortwave Infrared, 0126 – 1156 UTC on 1 October 2021 (Click to enlarge)

GOES-17 Shortwave Infrared imagery, above, shows the hot-spot associated with the latest eruptive phase of the Halema’uma’u Crater on Kilauea’s southern slope. (Click here for webcams).

The Day Night band from VIIRS on board Suomi NPP and NOAA-20 show the light source from the eruption as well, as shown in the toggle below (imagery from the Honolulu Direct Broadcast site, here)

VIIRS Day Night Band imagery from Suomi NPP (1111 UTC) and NOAA-20 (1200 UTC), 1 October 2021 (Click to enlarge)

The NOAA/CIMSS Volcanic Cloud Monitoring Web Portal (i.e., VOLCAT — link) include a Kilauea sector under the Washington DC VAAC tab; an imagery example is here.

FDCA — the Fire Detection and Characterization Algorithm — should have a signal here but does not. The landcover dataset used for the product is missing Hawaii. Fires aren’t looked for when land does not exist, even if its absence is in error. NOAA/NESDIS Scientists and their partners at CIMSS are working to correct this oversight.