Thunderstorms northeast of Guam

April 2nd, 2021 |

Himawari-8 Band 13 Clean Window infrared imagery (10.41 µm) from 2300 UTC on 1 April through 1100 UTC 2 April (Click to enlarge)

The animation above shows Himawari full-disk imagery from 2300 UTC on 1 April through 1140 UTC on 2 April and depicts a cluster of thunderstorms over the Pacific Ocean far to the northeast of Guam.  A particular challenge in diagnosing atmospheric events over the open Pacific is the lack of data.  In this case, a timely NOAA-20 overpass (around 0300 UTC), below, allowed for the use of NOAA-Unique Combined Atmospheric Processing System (NUCAPS) profiles to describe the atmosphere in and around this ongoing convection.

NOAA-20 NUCAPS Sounding Availability points, 0300 UTC on 2 April 2020 (click to enlarge)

The toggles below shows Total totals index and Tropopause heights over the Pacific Ocean around Guam and northeastward over the developing convection.  Modest instability surrounds the convective cluster (TT values from 40-44);  somewhat more unstable air (TT > 46) is diagnosed to the northwest of the convection.   Tropopause heights surrounding the convection are high, around 200 mb.  Much lower tropopause heights are diagnosed over the northern part of the domain, and the more unstable TT values are in a region where the tropopause height is sloping.

HImawari-8 Clean Window infrared imagery (10.41 µm) overlain with NUCAPS-derived Total Totals indices (with and without labels) at 0312 UTC on 2 April 2021 (click to enlarge)

Himawari-8 Clean Window infrared imagery (10.41 µm) overlain with NUCAPS-derived estimates of tropopause heights, 0312 UTC on 2 April 2021 (Click to enlarge)


Himawari-8 infrared (Clean Window, 10.41 µm) imagery and NUCAPS-derived lapse rates, 925-700 mb, 0312 UTC on 2 April 2021

NUCAPS can also show you lapse rates within the atmosphere.  It is important when viewing lapse rates to consider that the vertical resolution of NUCAPS profiles is typically not greater than 10 layers within the tropopause.  The toggle above shows lapse rates from 925-700 mb; lapse rates from 850-500 mb are shown below. These domains are is a bit larger than the domain used in showing the tropopause height and Total Totals index above.  The 925-700 mb lapse rates show two regions:  relatively weak stability, with lapse rates around 5 or 6 C/km south of 30 N Latitude, and much stronger stability (Lapse rates closer to 3 C / km ) north of that latitude, to the east of Japan.

The 850-500 mb lapse rates similarly show two general regions:  not as stable south of 30 N, much more stable east of Japan.  There is a more concentrated region of lower stability, however, along the leading edge of the sloped tropopause, at 850-500 mb compared to 925-700 mb, and the 850-500 mb values show larger lapse rates in the air to the east of Japan.  This toggle shows the 925-700 and 850-500 mb lapse rates directly.

Himawari-8 infrared (Clean Window, 10.41 µm) imagery and NUCAPS-derived lapse rates, 850-500 mb, 0312 UTC on 2 April 2021

 


This region of the Pacific Ocean is scanned by both the Advanced Himawari Imager (AHI) on JMA’s Himawari-8 satellite and the similar Advanced Meteorological Imager (AMI) on KMA’s GK2A satellite.  The animation below combines visible imagery from the two satellites at 0100, 0110, 0230 and 0400 UTC to create a pseudostereocopic image of the convection.

Himawari-8 (left) and GK2A (right) visible imagery (0.64 µm) at 0100, 0110, 0230 and 0400 UTC 2 April (Click to enlarge)


Developing (and ongoing) thunderstorms are usually locations of turbulence. The CIMSS Turbulence product, shown below for the region from 0000 UTC to 0350 UTC, and available online here, does show elevated turbulence probabilities over the convection (located over the western part of the domain shown below).

Turbulence probability plotted on top of Himawari-8 grey-scale water vapor imagery, 0000 – 0350 UTC on 2 April 2021 (Click to enlarge)

Himawari-8 imagery in this blog post courtesy of JMA; GK2A imagery in the blog post courtesy of KMA. Thanks to Brandon Aydlett, WFO Guam, for alerting us to this interesting case.

Turbulence detection near Alaska

March 22nd, 2021 |

GOES-17 Upper Level Water Vapor infrared (6.19 µm) at 1310 UTC on 22 March 2021. The plot also shows pilot reports of turbulence, ISIG turbulence predictions, and Turbulence Probability fields. (Click to enlarge)

CIMSS now has a real-time product designed to warn (probabilistically) against regions where Moderate Or Greater (MOG) turbulence might occur for aircraft cruising at levels between 30- and 41,000 feet, which is the standard range for commercial airliners. This product was developed using machine learning with satellite data (water vapor and infrared data) and Global Forecast System (GFS) meteorological variables as input, and is an improvement on a previous product that used only satellite data. On 22 March, an important case of prevalent turbulence occurred across the North Pacific and the coast of Alaska.  A training video on the product is available here.

The toggle above includes GOES-17 Upper-Level Water Vapor infrared imagery (6.19 µm) with and without Pilot Reports of turbulence, as well as ISIG turbulence polygons. In addition, the Turbulence Probability product is shown. The Turbulence Probability product (which uses GOES-17, GOES-16, Himawari-8, Meteosat-11 or Meteosat-8 data) is also available online here.  A screen capture from the website, shown below, shows 1450 UTC data on 22 March 2021. There are many different choices available in the drop-down menus.

Moderate or Greater (MOG) Turbulence Probability plotted over Upper Level Water Vapor infrared imagery (6.19 ), 1450 UTC on 22 MArch 2021 (click to enlarge)

Turbulence over the Tennessee River Valley

February 11th, 2021 |

GOES-16 Band 4 (1.38 µm) “Cirrus Channel” imagery, along with Derived Motion Wind Vectors at 250-350 mb (red), 350-450 mb (yellow) and 450-600 mb *green). Pilot Reports of Turbulence are also plotted (Click to play animated gif)

The animation above shows GOES-16 Band 4 (1.38 µm, “Cirrus Channel) Imagery along with GOES-16 Derived Motion Wind vectors and Turbulence observations. Significant and widespread turbulence occurred. Of particular interest is a arced feature that appears in the GOES-16 imagery from northern Mississippi through western Tennessee and into south-central Kentucky.  Turbulence occurs along this feature, where strong downward motion is likely present. Note this raw PIREP, for example, showing a very large vertical change!

UUA /OV RQZ/TM 1801/FL 410/TP C25M/TB SEV CAT/RM + OR - 1000 FT AND +60 KNOTS NO INJURIES NO DAMAGE

GOES-16 “Cirrus” Channel (Band 4, 1.38 µm) imagery, along with Derived Motion Winds and Pilot Reports (PIREPs) of turbulence, 2001 UTC on 11 February 2021 (Click to enlarge)

The curved structure is also prominent in the GOES-16 Band 8 (6.19 µm, Upper Level Water Vapor) infrared imagery shown below in a rocking animation.  It emerges out of convection along the Gulf Coast and subsequently races to the northeast.  The feature is less obvious in the Band 10 animation, suggesting that it is fairly high in the atmosphere. The 1200 UTC sounding from Jackson MS (link, from this website) shows a strong inversion at 500 mb; this might be the vertical boundary under which this feature is trapped. The weighting function for the Jackson sounding (here, from this site), shows peak values for all three water vapor channels very close to 500 mb.

Note that the arcing feature is apparent first in the upper-level water vapor imagery, then in the lower-level water vapor and cirrus channel imagery.

The mp4 animations below are also available as animated gifs: 6.19 µm, 7.34 µm and 1.38 µm)


GOES-16 6.19 µm (Band 8, “Upper-Level Water Vapor”) Infrared Imagery, 1236 UTC 11 February – 0001 UTC 12 February 2021 (Click to play mp4 animation)

 

GOES-16 7.34 µm (Band 10, “Low-Level Water Vapor”) Infrared Imagery, 1236 UTC 11 February – 0001 UTC 12 February 2021 (Click to play mp4 animation)

GOES-16 1.38 µm (Band 4, “Cirrus Channel”) near-infrared Imagery, 1401 UTC – 2201 UTC 11 February 2021 (Click to play mp4 animation)


CIMSS scientists have recently upgraded a turbulence detection product that was developed using machine learning, combining Satellite Data, principally GOES-R Band 8 (6.19 µm, a “water vapor” band on GOES-R) and Band 13 (the Clean Window infrared, 10.3 µm) and trained on observations of EDR (Eddy Dissipation Rate). These mappings of Probabilities of Moderate or Greater (MOG) turbulence are available online at this website. How did this product fare on this day of active turbulence.

Animations below show predictions of MOG from 1200 to 2350 UTC on 11 February 2021. Predictions of MOG at 30000-31000 feet, 36000-37000 feet and 40000-41000 feet are shown.  The probability contours are shown on top of a grey-scaled 6.19 µm water vapor image, and observations of turbulence are included.

Probabilities of Moderate or Greater (MOG) turbulence at 30000-31000 feet, from 1200 – 2350 UTC on 11 February 2021 (Click to animate)

Probabilities of Moderate or Greater (MOG) turbulence at 36000-37000 feet, from 1200 – 2350 UTC on 11 February 2021 (Click to animate)

Probabilities of Moderate or Greater (MOG) turbulence at 40000-41000 feet, from 1200 – 2350 UTC on 11 February 2021 (Click to animate)

Blowing snow across the Upper Midwest

February 6th, 2021 |

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 (GOES-East) Day Snow-Fog RGB images (above) showed widespread horizontal convective rolls (HCRs) which highlighted areas where blowing snow was more concentrated across parts of southern Manitoba and the Upper Midwest on 06 February 2021. Snow cover (and glaciated clouds) appeared as shades of red, with bare ground exhibiting lighter shades of green and low-level water droplet clouds appearing as brighter shades of white.

Closer views of the northern, central and southern portions of the region where blowing snow was most prevalent are shown below. The HCRs were evident during the early to late morning hours across southern Manitoba, far eastern North Dakota and northwestern Minnesota — and then became more apparent across western/southern Minnesota extending into far northern Iowa as the day progressed. Surface reports showed that the visibility fluctuated dramatically at some sites as HCRs moved through.

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

Terra MODIS True Color and False Color RGB images [click to enlarge]

Terra MODIS True Color and False Color RGB images [click to enlarge]

In comparisons of MODIS True Color and False Color RGB images from Terra (above) and Aqua (below), the areal coverage of HCRs could be seen in the False Color imagery.

Aqua MODIS True Color and False Color RGB images [click to enlarge]

Aqua MODIS True Color and False Color RGB images [click to enlarge]

Farthest to the north, one cluster of HCRs appeared to originate over Lake Manitoba — as seen in 30-meter resolution Landsat-8 False Color imagery from RealEarth (below).

Landsat-8 False Color RGB image [click to enlarge]

Lansdsat-8 False Color RGB image [click to enlarge]

Two notable pilot reports across southern Minnesota (below) showed that flight visibility was restricted to 4 miles at an elevation of 3000 feet, and the tops of HCRs extended to 5000 feet.

GOES-16 Day Snow-Fog RGB images, with plots of Pilot Reports [click to enlarge]

GOES-16 Day Snow-Fog RGB images, with plots of Pilot Reports [click to enlarge]

GOES-16 Day Snow-Fog RGB images, with plots of Pilot Reports [click to enlarge]

GOES-16 Day Snow-Fog RGB images, with plots of Pilot Reports [click to enlarge]

Additional material on satellite identification of blowing snow is available here and here.