True Color RGB mages — created using Geo2Grid — from GOES-18 (GOES-West), GOES-17 and GOES-16 (GOES-East) (above) displayed the hazy signature of blowing dust associated with a Tehuano wind event, which was spreading south-southwestward from the Gulf of Tehuantepec across the Pacific Ocean on 18 February 2023. A narrow rope cloud marked the edges of this outflow.

GOES-16 “Red” Visible (0.64 µm) images (above) include plots of surface/ship/buoy reports and the 18 UTC surface analysis — a region with the risk of Gale Force winds was outlined in the Gulf of Tehuantepec.

In a closer view of regional topography (below), the narrow Chivela Pass could be seen north-northeast of Ixtepec (station identifier MMIT), through which the northerly flow of cold air is accelerated.

A sequence of ASCAT wind barbs (source) from Metop-B and Metop-C (below) helped to highlight the pulse of gap winds as they emerged from the Isthmus of Tehuantepec and spread south-southwestward across the Gulf of Tehuantepec.

View only this post Read Less

Sentinel-1A SAR data just before sunrise captured a very narrow region of enhanced winds just south of the Rio Grande delta on 18 February 2023, as shown above in a toggle with the 1226 UTC GOES-16 Band 13 Clean Window infrared (10.3 µm) imagery. There appears to be no obvious relationship between the wind structures and the brightness temperatures at this time. However, an animation of the infrared imagery for the 3 hours before sunset, below, shows a similar north-south linear feature, in about the same place as the SAR winds, between 1000 and 1100 UTC. (Here’s a toggle of the 1224 UTC Sentinel winds and the 1036 UTC Band 13 imagery).

The 1200 UTC surface analysis (click here) from the 18th shows the Texas Gulf Coast near a ridge axis with easterly winds indicated. However, the Sentinel-1A wind analysis, shown below (from this website; direct link to image), shows convergence into the line of stronger winds. The normalized radar cross-section (NRCS) image (here, or here at the NOAA/STAR website), from that same website, shows evidence of small-scale gravity waves on the western edge of the wind maxima. Those fields are visible in the AWIPS imagery as well.

View only this post Read Less

New software now in use at CIMSS combines JPSS Raw Data Records (RDRs) from Suomi-NPP or from NOAA-20, created at different direct broadcast antenna sites (for example, at CIMSS (data link for NOAA-20; data link for Suomi NPP) — and at AOML in Miami), into a single RDR that includes data that can span roughly 1/4 of a JPSS orbit. Polar2Grid software then produces exceptional (and exceptionally long!) imagery, such as the True Color image from Suomi NPP shown below, from 1811 UTC on 17 February (also available at the CIMSS Direct Broadcast site here, or at the VIIRS Image Viewer). The view below extends from northern Canada to the Equator and includes the Pacific Ocean south of Mexico and also Lake Maracaibo in Venezuela. VIIRS single-channel and True- and False-Color imagery are produced over the larger domain; ATMS imagery is also produced over a larger domain (here’s an example 88.2 GHz image, for example, from 1811 UTC on 17 February) and extended Advanced Clear-Sky Processor for Ocean (ACSPO) SST fields are also produced that include data over the Pacific ocean southwest of Mexico, as in this example from NOAA-20 from 1918 UTC on 16 February.

View only this post Read Less

GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Day Cloud Phase Distinction RGB images (above) showed widespread elevated convective banding that was helping to enhance snowfall rates — with some locations reporting 1.5 to 2.0 inches per hour — across parts of Minnesota, Wisconsin, Lower Michigan, Iowa and Illinois on 16 February 2023. There was no GLM indication of lightning activity associated with any of these convective bands.

On the Day Cloud Phase Distinction RGB images, shades of yellow to green suggested that cloud tops along many of the convective bands were either glaciated or were mixed phase (composed of ice crystals and supercooled water droplets). The ability to load select GOES RGB images combined with various GOES Level 2 Derived Products (using Satellite > Local Menu Items > Satellite Sector) provides the ability to use AWIPS cursor sampling to determine specific quantitative properties associated with the various RGB shades — for example, the GOES-16 Day Cloud Phase Distinction RGB image at 1731 UTC (below) includes cursor sampling of the individual RGB components in addition to the associated Cloud Top Phase (Ice) and Cloud Top Height (19,658 feet) derived products at that cursor location, which was along a convective band that was enhancing snowfall rates and reducing the surface visibility to 1/4 mile at Middleton (KC29) just west of Madison, Wisconsin (KMSN). The GOES-16 “Clean” Infrared Window (10.3 µm) cloud-top infrared brightness temperature — the Red component of the RGB image — at that particular cursor location was -24.73ºC.

View only this post Read Less