GOES-16 Clean Window imagery from 1800 UTC on 7 May 2020, above, suggests a frontal zone from the central Atlantic southwestward through the Florida Straits.  What products can be used to diagnose the moisture differences between the dry airmass over the southeast United States/Florida and the far moister airmass over the central and western Caribbean Sea?

Total Precipitable Water is a Baseline Level-2 GOES-16 Product that is produced in clear air, and the toggle of it, with the Clean Window Imagery (and also overlain on top of the Clean Window Imagery), below, shows abundant moisture to the south and east of Florida.  The cloud-free demand of this Level 2 product makes it difficult to determine exactly where the moisture gradient sits.

NOAA-20 overflew the east coast of the United States shortly after 1800 UTC on 7 May 2020 (map, from this site).  The gridded field of Total Precipitable Water that was derived from the different vertical profiles (shown below in a toggle with the TPW and the points) shows a tight gradient over central Cuba.

A strength of the NUCAPS-derived TPW is that it is produced in regions of clear and cloudy skies because it can rely on microwave sounder data in regions where clouds prevent the infrared sounder from giving a complete solution. The toggle below compares the GOES-16 Total Precipitable Water (a global product that gives cloud-free values every hour) with the NUCAPS product that gives an image along the swath).  Both products give similar values of TPW.

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A cold front with ample moisture and instability ahead of it spawned numerous strong storms in the Southeast U.S. yesterday; particularly one long-lived supercell in South Carolina. A convolutional neural network model (CNN) was deployed in realtime on the 1-min GOES-16 mesoscale sector imagery. The model produces an “Intense Convection Probability” (ICP). The inputs for the model are the GOES-16 ABI 0.64 µm reflectance, 10.3 µm brightness temperature, and GLM flash extent density. It was trained to identify “intense” convection as humans do, associating features with intense convection such as strong overshooting tops, thermal couplets (“cold-U/V”), above anvil cirrus plumes (AACP), and strong cores of total lightning.

The animation below shows the ICP contours overlaid ABI 0.64 µm + 10.3 µm sandwich imagery, annotated with preliminary severe storm reports.

The long-lived supercell in South Carolina exhibited AACP and cold-U features, and produced numerous severe wind and hail reports (up to the size of tennis balls). While the NOAA/CIMSS ProbSevere models handled this storm well, the ICP ramped up on a couple of severe storms in northern Georgia before ProbSevere did. ICP for these cells exceeded 90% 15-18 min before ProbWind reached 50%. The ICP may be able to provide additional lead time and confidence to ProbSevere guidance for certain storms, utilizing spectral and electrical information from geostationary satellites. Incorporating ICP into ProbSevere is an active area of current research.

ProbSevere storm contours and MRMS MergedReflectivity for storms in GA and SC. The main or “inner” ProbSevere contour is shaded by the probability of any severe weather, while the outer contour is shaded by the probability of tornado, which appeared when that value was at least 3%, in this example.

An accumulation of ProbSevere storm centroids (white to pink squares, 50% –> 100%), NWS severe weather warnings, and SPC severe local storm reports from 12Z on May 5th to 12Z on May 6th [click to enlarge]

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Visible Infrared Imaging Radiometer Suite (VIIRS) data from Suomi NPP and NOAA-20 can be used to create accurate sea-surface temperature (SST) fields using the Advanced Clear-Sky Processor for Ocean (ACSPO) algorithms.  The toggle above shows ACSPO SSTs over the Gulf of Maine from Suomi NPP (at 0620 UTC) and from NOAA-20 (at 0710 UTC) — orbital paths can be found here.  Waters over the Gulf of Maine are relatively warm (around 41ºF) compared to the very cold waters (about 38ºF) southeast of Nova Scotia!

VIIRS’ view of the Gulf Stream is shown below — with the colorbar range from 59º to 86º F (compared to 20º to 100º for the Gulf of Maine image above).  Warmest Gulf Stream waters are around 85º, but more uniformly near 82º F, with shelf waters near 74º F and tropical Atlantic waters near 77º.

VIIRS-based ACSPO SSTs are available via an LDM feed from CIMSS. Previous blog posts on ACSPO SSTs are here and here.

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GOES-16 (GOES-East) Dust Red-Green-Blue (RGB) images (above) showed a pink plume of blowing dust – created by northwesterly surface  winds gusting as high as 49 knots or 56 mph – moving over parts of Interstates 29, 35 and 70 in Nebraska, Iowa and Missouri on 05 May 2020. The visibility briefly dropped to 8 miles at St. Joseph, Missouri (KSTJ) — but was greatly reduced along portions of Interstate 29 in Nebraska/Iowa.

Gusty winds in western Iowa are creating areas of blowing dust, which is causing reduced visibility on roadways. This is I-29 south of Pacific Junction. #iawx https://t.co/K7kDkTHKN2

— NWS Des Moines (@NWSDesMoines) May 5, 2020

Due to the winds I was Driving thru a mini haboob going to Fremont on Hwy 275. pic.twitter.com/f1WpFr7k1V

— ElPerron (@panchoRF887) May 5, 2020

GOES-16 Mid-level Water Vapor (6.9 µm) images (below) revealed north-south oriented gravity waves over the same region. These were either vertically-propagating waves initiated by the strong surface winds, or waves that were forced by decelerating flow in the wake of a lower/middle tropospheric jet streak that was rotating through the Lower Missouri River Valley. Although turbulence AIRMETs had been issued for the area, there were no pilot reports confirming the presence of turbulence.

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