Bore features over Lake Michigan

May 20th, 2022 |
GOES-16 True Color Imagery from the CSPP Geosphere site, 1111 – 1421 UTC on 20 May 2022

The true-color animation above, produced from the CSPP Geosphere site, shows bore-like cloud features over northern Lake Michigan shortly after sunrise on 20 May 2022. These parallel lines of clouds are mostly likely to persist in regions where a low-level inversion is present. NUCAPS profiles from the 0800 UTC overpass of NOAA-20, shown below, show an inversion below 850 mb over the central parts of the Upper Peninsula of Michigan. The cold waters over the lake would likely amplify the strength of this inversion. The Green Bay soundings from 1200 UTC (here, from this site), also shows a low-level stable layer.

NUCAPS Profiles over Upper Michigan as indicated, ca. 0800 UTC on 20 May 2022. NUCAPS Sounding Availability points also shown (click to enlarge).

Thanks to Rick Mamrosh, WFO GRB, for bringing these cloud features to our attention! Check out the link on their Facebook page.

Satellite-derived instability ahead of widespread severe winds over South Dakota and Minnesota

May 12th, 2022 |
GOES-16 Visible imagery, 1841 – 2356 UTC, 12 May 2022

Storm Reports from SPC for 12 May 2022, (also shown below), show an extraordinary number of severe wind reports over eastern South Dakota and western Minnesota. Visible imagery from the CSPP Geosphere site, above, shows the convective system responsible for the widespread winds lifting northeastward out of Nebraska and moving over the Missouri River Valley.

Storm Prediction Center Storm Reports, 12 May 2022 (click to enlarge)

The animation below shows Clean Window infrared imagery (10.3 µm) overlain on top of Clear-sky only GOES-16 Derived Convective Available Potential Energy (CAPE). CAPE values increase into the mid-2000s (J/Kg) as the convection lifts toward the South Dakota/Minnesota border: abundant instability is present.

GOES-16 Band 13 Infrared Imagery (10.3 µm) and GOES-16 Derived CAPE, 1821 – 2316 UTC on 12 May 2022 (Click to enlarge)

NOAA-20 overflew this area just after 1800 UTC, and the NUCAPS profiles derived from CrIS and ATMS on board that satellite tell a similar story of instability. Gridded fields of the 850-500 mb Lapse Rate, of Total Precipitable Water (TPW) and of the Total Totals Index, below, show a corridor of instability and moisture over extreme southeast South Dakota. Lapse rates are between 8 and 9o C/km, TPW values are near 1.5″, and Total Total Index values exceed 55! Convection moving towards this region and along this axis of instability would not be inhibited by the environment. NUCAPS Sounding Availability points shown in the image below are mostly green: the infrared retrievals converged to a solution.

Gridded Values of 850-500 mb Lapse Rate, Total Precipitable Water, and Total Totals Index, ca. 1830 UTC on 12 May 2022. Also shown: NUCAPS Sounding Availability points (click to enlarge)

What do the individual NUCAPS Profiles look like? Two lines of profiles over eastern Nebraska are shown below. Sounding readout values from NSharp in AWIPS show large MUCAPS values, and a very well-mixed atmosphere.

NUCAPS profiles over eastern Nebraska/southeastern South Dakota, at the points indicated, ca. 1840 UTC on 12 May 2022 (Click to enlarge)
NUCAPS profiles over central Nebraska, at the points indicated, ca. 1840 UTC on 12 May 2022 (Click to enlarge)

AWIPS imagery in this post was created using the NOAA/TOWR-S AWIPS Cloud Instance.


GOES-18 “Red” Visible (0.64 µm) images, with time-matched SPC Storm Reports plotted in red [click to play animated GIF | MP4]

1-minute Mesoscale Domain Sector GOES-18 “Red” Visible (0.64 µm) images with time-matched plots of SPC Storm Reports (above) showed the northeastward propagation of the derecho — along with a second Mesoscale Convective System in its wake — as it produced wind gusts as high as 107 mph in South Dakota (at 2125 UTC), hail as large as 2.50 inches in diameter in Nebraska (at 0007 UTC) and several tornadoes. Note that this early GOES-18 imagery is preliminary and non-operational.

The corresponding 1-minute GOES-18 “Clean” Infrared Window (10.35 µm) images (below) extend a bit past sunset — and revealed pulsing overshooting tops as cold as -70 to -75ºC (white pixels embedded within areas of black).

GOES-18 “Clean” Infrared Window (10.35 µm) images, with time-matched SPC Storm Reports plotted in cyan [click to play animated GIF | MP4]

Using the Night Microphysics RGB and LightningCast probabilities to anticipate nighttime convection and Lightning

May 11th, 2022 |
Nighttime MIcrophysics RGB, 0616 – 0811 UTC on 11 May 2022 (click to enlarge)

The Nighttime Microphysics RGB, above, over central Wisconsin (that’s Green Bay at the northeastern edge, and southeast Minnesota/northeast Iowa over the southwestern part, of the animation), shows a field of low clouds stretching west-southwest to east-northeast. Note however, the occasional appearance of redder pixels within the field (as shown in this annotated image from 0806 UTC), especially in Wood and Portage counties (Click here for a map of Wisconsin counties). That kind of signal suggests that vertical cloud growth is occurring. Do you think convection will occur shortly? What about lightning?

NOAA-20 overflew this region shortly after 0730 UTC, and NUCAPS profiles would have become available in AWIPS at about the time of the end of the animation. What do they show? The image below shows 850-mb Temperature and the 850-500 mb lapse rates computed from gridded NUCAPS fields. The steepest lapse rates and strongest instability is centered on a NUCAPS profiles in central WI (in Adams County) which is just south of the band of clouds identifiable in the Night Microphysics RGB shown above: NUCAPS profiles show ample instability just south of this line (and winds are southerly: 0000 UTC Green Bay sounding).

850-mb Temperatures, 850-500 mb Lapse Rate, and Total Totals Index, 0730 UTC on 11 May 2022 (click to enlage)

The individual NUCAPS soundings in Adams County and Green Lake County, below, show very steep mid-level lapse rates.

NUCAPS Profiles in Adams County (left) and Green Lake County (right) at 0735 UTC on 11 May 2022 (Click to enlarge)

The GOES animation of Nighttime Microphysics above ended at 0811 UTC. What happened in the next 15 minutes? Note a continued development in the amount of reddish pixels! During these 15 minutes, radar is also showing increasing returns.

Nighttime Microphsyics RGB, 0811-0826 UTC on 11 May 2022 (Click to enlarge)

If convection is expected, lightning might also occur. Lightning Cast is a product in the NOAA/CIMSS ProbSevere portfolio, and it’s available online here, and a short training video is here. LightningCast probabilities for the same 15-minute span as above are shown below. Low probabilites are present until 0826 UTC. When do you think lightning might occur with this developing line?

LightningCast probabilities, 0811-0826 UTC on 11 May 2022 (click to enlarge)

The animation below follows the developing cells through the next 15 minutes — from 0826 to 0841 UTC. Nighttime Microphysics (overlain by radar: note the parallax shift, and also note the continued reddening of pixels in the RGB where convection is occurring) is on the left, and LightningCast Probabilities are on the right. Do you think lightning is imminent?

Nighttime Microphysics RGB overlain with 0.5 Base Reflectivity (left) and LIghtningCast Probability (right), 0826 – 0841 UTC (Click to enlarge)

The first GLM observations (with a CONUS time cadence of every 5 minutes) of lightning occurred at 0846 UTC, as shown in the animation of the Nighttime Microphysics RGB below. (Here is LightningCast at 0846 UTC).

Nighttime Microphysics RGB and GLM Flash Extent Density (FED), 0616 – 0851 UTC on 11 May 2022 (click to enlarge)

The animation below shows the NightMicrophysics RGB overlain with LightningCast Probabilities, from 0816 to 0846 UTC.

GOES-16 Nighttime Microphysics RGB with LightningCast Probabilities and GLM FED observations, 0816 – 0846 UTC on 11 May 2022 (click to enlarge)

Gridded NUCAPS fields for this blog post were created using the NOAA/TOWR-S Cloud Instance of AWIPS. Thank you! And here is a link to a presentation detailing how the Nighttime Microphysics RGB can be used in winter!

Hail in Portland OR

May 9th, 2022 |
GOES-17 Visible Band 2 (0.64 µm) imagery, 2201 UTC 8 May 2022 – 0311 UTC 9 May 2022 (Click to enlarge)

Here’s a text received late on 8 May from a kid: “Hail today in Portland”. The animation above shows GOES-17 Visible (0.64 µm) imagery between 2201 UTC on 8 May and 0311 UTC on 9 May. The follow-up text answering the obvious question (What time?) was “Around 5 PM” — that is, around 0000 UTC on 9 May. Infrared imagery (Band 13, 10.3 µm) from GOES-17 over the same time period — 2201 – 0311 UTC — is shown below. This loop uses a default enhancement from AWIPS (which enhancement has as its coolest temperature -109oC, perhaps too cold for this airmass; click here to see an animation with a coolest temperature of -90oC; variability in the cold cloud tops is much easier to visualize in that modified color enhancement).

GOES-17 Infrared Band 13 (10.3 µm) imagery, 2201 UTC 8 May 2022 – 0311 UTC 9 May 2022 (Click to enlarge)

The slower animation below, between 0000 UTC and 0100 UTC, highlights the cold cloud tops (west of Portand) of the system that might have produced hail. The eye is drawn to the developing cold cloud tops with the tweaked (non-default) enhancement. (By this time, having examined the imagery, I wonder about the report of the hail occurring around 5 PM; This event was also mentioned on the NWS Portland Facebook page).

GOES-17 Visible Imagery (left), Infrared (center, with default enhancement) and infrared (right, with a smaller range to the enhancement), 0000-0100 UTC on 9 May 2022 (click to enlarge)

LightningCast Probability is a product in the NOAA/CIMSS ProbSevere portfolio that predicts the likelihood of a GLM Flash Event based on a single time of the GOES-17 bands that are used in the Day Cloud Phase Distinction RGB: Bands 2 (0.64 µm), 5 (1.61 µm) and 13 (10.3 µm). The animation of that field is shown below. Contours denote probabilities of 10% (dark blue), 25% (cyan), 50% (green) and 75% (magenta). One lightning flash is shown at the of the animation; note however how the probability contours center on the strongest developing convective cell early in its lifecyle — even though it never produced lightning as detected by the GOES-17 GLM.

LightningCast Probability, 2335 UTC on 8 May 2022 – 0100 UTC on 9 May 2022 (click to enlarge)

NOAA-20 overflew the Pacific Northwest in the afternoon, with two passes over Oregon, as shown in the toggle below that also shows gridded 850-500 mb NUCAPS Lapse Rates at 1933 and 2113 UTC on 8 May. Even though the westernmost NOAA-20 has truncated data, very steep lapse rates — near 8o C/km — are evident.

Gridded 850-500 mb Lapse Rates, 1933 and 2115 UTC on 8 May 2022 (click to enlarge)

500-mb temperatures are shown below, with Portland deep within the cold air (500-mb temperatures are at/below -30o C!). The gridded fields look smooth despite the abundance of yellow and red points in the NUCAPS fields, designating regions where the infrared retrieval did not converge (yellow) or where the infrared and microwave retrievals both failed! This example shows that profiles that do not converge because of low-level clouds/moisture/rain may nevertheless produce useful upper-air information. The 2113 UTC 500-mb temperature field here, shows a red profile in the Willamette Valley in the northernmost row of profiles, and a green profile in the same row just west of the Oregon Coast. The toggle of profiles at those two points is shown below; both have useful information around 500 mb (and above) even though near-surface values in the red profile are of dubious value. Note the steep lower-tropospheric lapse rates in the sounding that is just offshore!

Gridded 500-mb Temperature derived from NUCAPS profiles, 1933 UTC and 2115 UTC on 8 May 2022 (click to enlarge)
NUCAPS profiles at circled (in black) locations, 2138 UTC on 8 May 2022 (click to enlarge)

NUCAPS imagery was created with the NOAA/TOWR-S AWIPS Cloud instance. Thank you!