Tornado in Luzerne County, Pennsylvania

June 14th, 2018 |

GOES-16 ABI Band 2 (Red Visible, 0.64 µm) over northeastern Pennsylvania. Luzerne County is outlined in Yellow, and Wilkes-Barre’s location is highlighted as a yellow box (Click to animate)

A confirmed tornado struck Wilkes-Barre in Luzerne County in northeastern Pennsylvania shortly after sunset on 13 June 2018 (at about 0215 UTC). Visible imagery, above, shows the line of thunderstorms approaching the region before sunset. This video, from Citizens Voice Reporter Nico Rossi, shows some of the damage.

NOAA/CIMSS ProbTor captured the tornadic cell very well (Click this link for a discussion that includes infrared satellite animations). Click here for real-time access to ProbTor.

1-minute Mesoscale Sector GOES-16 Band 13 (Clean Infrared Window, 10.3 µm) images with plots of SPC storm reports are shown below. The Wilkes-Barre PA tornado is plotted as a red T on the 0200 UTC image.

GOES-16 Band 13 (Clean Infrared Window, 10.3 µm) images, with SPC storm reports plotted in red [click to animate]

GOES-16 Band 13 (Clean Infrared Window, 10.3 µm) images, with SPC storm reports plotted in red [click to animate]

Below is a 1-km resolution Terra MODIS Band 31 (Infrared Window, 11.0 µm) image from shortly after the Luzerne County tornado, showing the line of convection that had developed in advance of a cold front. The 2 overlapping SPC storm reports (listed as damaging winds, with report times of 2008 and 2015 UTC) for the Wilkes-Barre event are in the center of the image. The minimum cloud-top infrared brightness temperature was -66ºC.

Terra MODIS Band 31 (Infrared Window, 11.0 µm) image, with plots of cumulative SPC storm reports and the 03 UTC position of the surface cold front [click to enlarge]

Terra MODIS Band 31 (Infrared Window, 11.0 µm) image, with plots of cumulative SPC storm reports and the 03 UTC position of the surface cold front [click to enlarge]

Why Mesoscale Sectors matter: Tropical Storm Aletta

June 6th, 2018 |

GOES-16 Visible (0.64 µm) Imagery, 1422-1741 UTC on 6 June 2018 (Click to animate)

The first Tropical Storm, Aletta, of the eastern Pacific Ocean basin has been named. One-minute imagery from a moveable Mesoscale Sector, above as an animated gif (or here as an mp4), shows a distinct low-or mid-level circulation center moving out from under higher clouds in the northeast quadrant of the storm at about 1621 UTC, being even more obvious at 1636 UTC.

The GOES-16 CONUS Sector scans at 5-minute intervals. The southern boundary of the CONUS sector (15º N Latitude), however, bisects this tropical storm, as shown at this link, and is therefore unhelpful for center diagnostics. Full Disk imagery captures the storm evolution at a 15-minute time step that is too coarse to provide a smooth animation. (Just two years ago, the time resolution for this storm formation would have been every 3 hours, as that was the time cadence for a Full Disk from GOES-13! GOES-16 really is life-changing for those who view satellite animations.)

The Split Window Difference over Iowa

June 5th, 2018 |

GOES-16 ABI Split Window Difference (10.3 µm – 12.3 µm) at 1402 UTC on 5 June 2018 (Click to enlarge)

The Split Window Difference field (SWD, the 10.3 µm brightness temperature minus the 12.3 µm brightness temperature) can be used to identify regions of moisture and dust in the atmosphere.  (Click here for a previous blog post).  On 5 June 2018, the SWD showed a strong gradient over the upper Midwest, with large values over Iowa and relatively smaller values to the northeast over Wisconsin (and to the south over Missouri). Is this showing a moisture gradient between Iowa and Wisconsin? Do you trust its placement? Given that convection will frequently fire along the gradient of a field (HWT Link; Old HWT link), it’s important to trust the placement of the gradient.

The toggle below shows both the SWD and the (clear sky only) Baseline Derived Stability Lifted Index.  The Lifted Index shows negative values over the southern Plains, and also a lobe of instability stretching WNW-ESE from southwestern Minnesota to Chicago.  If you look carefully, you will note that the axis of instability in the Lifted Index is offset from the Split Window Difference field.  Why?

GOES-16 ABI Baseline Derived Stability Index Lifted Index and GOES-16 Split Window Difference (10.3 µm – 12.3 µm) at 1402 UTC on 5 June 2018 (Click to enlarge)

The toggles below show the Split Window Difference field and the Rapid Refresh Model estimates of moisture in the lowest 3 km of the atmosphere, followed by the Split Window Difference toggled with the Baseline Land Surface Temperature field. The maximum in moisture is along the northern edge of the Split Window Difference field, and aligns well with the Lifted Index (Toggle between those two is here).

The Split Window Difference better matches the Land Surface Temperature Baseline product, and that reinforces an important caveat in the use of the SWD to detect moisture: SWD is greatly influenced by the skin temperature. Gradients in surface temperature and gradients in moisture both will affect the Split Window Difference. Make sure you understand the underlying cause of the gradient in the Split Window Difference field.

Toggle between the GOES-16 ABI Split Window Difference (10.3 µm – 12.3 µm) and Mean 0-3km AGL Dewpoint from the Rapid Refresh Model, 1402 UTC on 5 June (Click to enlarge)

GOES-16 ABI Split Window Difference (10.3 µm – 12.3 µm) and Land Surface Temperature Baseline Product, 1402 UTC on 5 June 2018 (Click to enlarge)

By 2002 UTC on 5 June, the GOES-16 Lifted Index fields and the SWD more closely align, in part because the axis of moisture has shifted southward. See the toggle below.

GOES-16 ABI Baseline Lifted Index, Split Window Difference (10.3 µm – 12.3 µm) and 0-3 km AGL Rapid Refresh Dewpoint, 2002 UTC on 5 June 2018 (Click to enlarge)

American Airlines Flight 1897 Diverted due to Hail Damage

June 4th, 2018 |

GOES-16 ABI Band 2 Imagery (0.64 µm), 0002-0202 UTC on 4 June 2018 (Click to animate)

American Airlines Flight 1897 pushed back from the gate San Antonio (SAT) Texas at 6:45 PM CDT (and lifted off at 6:58 PM CDT) (2358 UTC) on 3 June, bound for Phoenix. An encounter with convection over southeastern New Mexico cause windshield and nosecone damage, and the flight landed safely at 8:03 PM (0203 UTC) MDT in El Paso, TX. Click here and here (from Twitter user Tom Podolec) for flight paths. The Flight Tracking Log from FlightAware suggests the damage occurred at sometime between 0109 and 0116 UTC.

Visible Imagery, above, near sunset revealed strong convection developing over the southern Plains of Texas and New Mexico. In particular a strong convective tower with overshooting tops is apparent over southeast New Mexico. This could be the hail-producing cell that damaged the aircraft. (Note also the fires that continue to burn in western New Mexico!) The photograph below, from Scott Cruse/KTVK (Source), shows the substantial aircraft damage. (Original Photo from KTVK wesbite). This link shows an Incident Report from avherald.com.

Nosecone and Windshield Damage on AA1897. (Source: Scott Cruse/KTVK)

GOES-16 Clean Window Infrared (10.3 µm) imagery, below, also suggests strong convection, with very cold cloud tops over southeastern New Mexico. A complete animation spanning the flight is here: Note how two general areas of convection from the west and from the east appear to converge on southeastern New Mexico; the animation below focuses on the 0032 – 0157 UTC time frame when ongoing strong convection over southeastern New Mexico is spawning multiple overshooting tops. Near the end of this animation the flight diverts to El Paso.

GOES-16 ABI Band 13 Clean Window (10.3 µm) Infrared Imagery, 0032 – 0157 UTC on 4 June 2018 (Click to animate)

A GOES-16 Mesoscale Domain Sector was positioned over the region, providing 1-minute data — Infrared (11.2 µm) and Visible (0.64 µm) images, below (courtesy of Rick Kohrs, SSEC), include plots of the location of the aircraft. The storm in far southeastern New Mexico did produce hail of 2.5 inches in diameter, but there were no SPC storm reports farther northwest near the aircraft encounter with damaging hail. In addition, there was a pilot report of severe turbulence around the same time and location of the Flight 1897 hail damage (albeit at a higher altitude).

GOES-16 Infrared (11.2 µm, left) and Visible (0.64 µm, right) images, with plots of the aircraft location [click to play animation]

GOES-16 Infrared (11.2 µm, left) and Visible (0.64 µm, right) images, with plots of the aircraft location [click to play animation]

A GOES-16 Visible/Infrared Sandwich product is shown below (courtesy of Joleen Feltz, CIMSS)

GOES-16 Visible/Infrared Sandwich product [click to play MP4 animation]

GOES-16 Visible/Infrared Sandwich product [click to play MP4 animation]

Kudos to the crew for landing this hail-damaged aircraft.