Target Sector (2.5-minute interval) JMA Himawari-9 AHI Clean Infrared Window (10.4 µm) images (above) showed Tropical Invest 90P as it moved westward across the Coral Sea on 20 January 2024. Intermittent convective bursts within the growing cold cloud canopy contained multiple overshooting tops that exhibited infrared brightness temperatures of -100ºC or colder (internal clusters of red pixels embedded within yellow-to-black regions). In fact, the minimum infrared brightness temperature of -103.83ºC on the 17:09:44 UTC image was colder than the -103.55ºC measured by Himawari-8 with Typhoon Kammuri in 2019 (which at that time was thought to be the coldest cloud-top infrared brightness temperature on record as sensed by a geostationary satellite).

Himawari-9 Infrared Window (11.2 µm) images from the CIMSS Tropical Cyclones site (below) showed that Invest 90P was moving through an environment of high deep-layer wind shear — which was inhibiting its further intensification.

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With the total solar eclipse occurring over parts of the contiguous U.S. on April 8, 2024, there are many wondering what the cloud cover might be on that day. As anticipation builds, we decided to look at the past 28 years of GOES cloud products on April 8. This is not a forecast, but a look back at the cloud climatology. Every spot on the eclipse path has had April 8ths where it was cloudy and every spot has had April 8ths where it was clear. So while you may choose to travel to southwest Texas to see the eclipse because that gives you the best chance historically at clear skies, there is going to be some uncertainty involved for eclipse viewers all along the path as to whether or not they’ll get a clear-sky view of the event. The potentially clearest areas still have at least 30% chance of being cloudy on April 8 based on the historical record. Of course the climatology does not have days with a total solar eclipse, and we have seen in earlier events how some fair-weather cumulus cloud coverage is briefly reduced as a result of the reduced incoming solar radiation. Still, an eclipse can be a fun event if you’re on the path even when it’s partly cloudy. This is an opportunity to discuss the science related to cloud cover on the upcoming eclipse day.

For comparison, see similar images derived from MODIS data and the ERA-5 (re-analysis). In general, climatologically it is more clear in Texas and less clear in New England in early April. Of course that is not a forecast for what will actually happen in 2024.

More information

There is much more information about this event, including this CIMSS Satellite Blog post, and the NWS and NOAA Satellites.

H/T

This image was made by M. Gunshor, UW/CIMSS (who also helped write this blog post) with NOAA geostationary cloud files processed by S. Wanzong, UW/CIMSS, with input files from UW-Madison, SSEC; SSEC Data Services. Thanks also for the Eclipse Predictions by Fred Espenak, NASA’s GSFC. T. Schmit works for NOAA/NESDIS/STAR and is stationed in Madison, WI.

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Morning radar on the morning of 19 January 2024 (shown below from this source) showed a single band of snow squalls moving southward over central Lake Michigan. Then band moved inland over northwestern Indiana, resulting in a winter storm warning over northwestern Indiana (More information from NWS IWX) and hazardous travel conditions through that heavily-traveled corridor between Chicago and Detroit. GOES-16 Clean Window Infrared (Band 13, 10.3 µm) imagery, below, shows a subtle lake-effect band signature emerging as the clouds associated with a system that deposited widespread light snow over the upper Midwest exits to the east. Surface observations, especially of CMAN sites, show convergence over the lake. Note the east/northeast winds at stations LDTM4 (Ludington MI) and BSBM4 (Big Sable Point MI) over central lower Michigan and the northwest winds along Lake Michigan’s western shore. Sometimes lake effect bands are vigorous enough to produce convection. That was not the case for this band; GLM detected no flash events (in addition, LightningCast probabilities were less than 2%!)

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Merged Snowfall rates (source; a field that combines observations from radars and from polar orbiting satellites’ microwave observations of the atmosphere), below, show that the single band started to coalesce shortly after 0700 UTC. Microwave observations over the Great Lakes did not occur at the hourly intervals shown (although some observations are present over the Pacific Northwest, where the gap-filling between radars is more important!); however, there were microwave estimates of snowfall rate at 0850 and 0920 UTC, as shown in this toggle. Light snow in Madison WI was just ending at 0900 UTC/3 AM CST; compare the 0900 mSFR field (radar-only coverage over the midwest) and the 0850 UTC/0920 UTC mSFR fields (here are all 3 in an animation): satellite-based microwave estimates of snow better capture the back edge of the light snow than the radar-only image.

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The single band is increasingly apparent in the animations below of Day Cloud Phase Distinction and Day Cloud Type RGBs. Because the airmass is very cold, the Day Cloud Phase Distinction RGB (that has as its red component the 10.3 brightness temperature) shows low-level snow-cover as much redder than in the Day Cloud Type RGB that has as it red component the 1.38 reflectance. (There is sufficient water vapor in the atmosphere that a surface reflectance signal is absorbed). Both RGBs show the mid-lake convective band as a series of discrete convective towers forming a sinuous band as it approaches the southern Lake Michigan shoreline. Shortly the end of the animation one of the towers over north central Lake Michigan is vigorous enough that LightningCast probabilities have reached 10% (click here to see the Day Cloud Type RGB at 1601 UTC) .

A bit more zoomed in Cloud Phase Distinction RGB, as well as ABI “red” visible band 2 (still and movie). These images were made with the geo2grid software.

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MetopC overflew the western Great Lakes shortly before 0200 UTC on 19 January 2024. Advanced Scatterometer (ASCAT) imagery from that time (source) show northeasterly winds, suggesting mid-lake convergence, along the southeast edge of the swath.

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Overlapping 1-minute Mesoscale Domain Sectors provided GOES-16 (GOES-East) images at 30-second intervals from all 16 of the ABI spectral bands in addition to a Rocket Plume RGB (above), which displayed the northeast-moving warm thermal signature of a SpaceX Falcon 9 stage 1 rocket booster as the Ax-3 Mission was launched from NASA Kennedy Space Center in Florida at 2149 UTC (4:49 PM EST) on 18 January 2024. Due to the presence of widespread lower-tropospheric and upper-tropospheric clouds off the coast — note the moist layers seen in a plot of morning Cape Canaveral rawinsonde data (the high-altitude clouds were due to a subtropical jet stream over the Southeast US) — the rocket’s thermal signature was apparent in a more limited subset of Near-Infrared (ABI spectral bands 04/05/06) and Infrared (ABI spectral bands 07/08/09/10) images compared to many previous rocket launches.

One noteworthy feature seen in GOES-16 Water Vapor and Rocket Plume RGB imagery was the subtle trail of hot water vapor in the wake of the departing Falcon 9 stage 1 rocket booster, which could be seen drifting to the north-northwest in 30-second images from 2152-2153 UTC (below).

A comparison of GOES-16 Rocket Plume RGB, Upper-level Water Vapor, Mid-level Water Vapor and Shortwave Infrared images at 21:55:25 UTC (below) revealed a warm thermal signature of the Falcon 9 stage 1 entry burn — which slowed the rocket’s rate of descent as it re-entered the Earth’s atmosphere — to prepare it for a landing at Cape Canaveral Space Force Station.

GOES-16 Visible images (below) showed the brighter white Falcon 9 rocket condensation cloud as it emerged from the low-level cloudiness, and was subsequently sheared eastward by westerly winds of 40-70 kts.

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