Himawari-8 Imagery, above (courtesy JMA, the Japan Meteorological Agency, from this site), shows a cyclonically rotating feature over the western Pacific, approaching the northern Marianas Islands by the end of the animation. Periodic weak convection is forming within the center of the circulation, with more widespread convection developing to its east. Gridded NUCAPS fields, below, from this site, show that the cyclonic feature is associated with relatively cool temperatures at 500 mb. At the beginning of the animation, the cool temperatures are near Wake Island; the cool temperatures progress steadily westward just south of 20^o N latitude over the following days and are over the Marianas at the end of the animation.

---

Examination of surface-based winds (from scatterometers, at this site) suggests that the mid-level circulation does not extend all the way to the surface.

---

Update, 14 July 2022

By 0333 UTC on 14 July 2022, the cool region at 500 mb was centered just west of 20^oN, 150^oE. (Its westward progress has slowed significantly) The cool region overlaps a ‘green’ Quality Control Region, meaning the retrieval there converged to a solution. Yellow regions likely correspond with clouds, and the infrared retrieval did not converge (but the microwave one did); red points depict a lack of convergence in the infrared and microwave retrievals. For more information on the retrieval, check out this training video on NUCAPS profiles.

Did the cold pool aloft have a surface signature? Scatterometry overlain on top of Himawari-8 Visible (0.64 µm) imagery, along with a streamline analysis from the NOAA/NWS/NCEP Global Forecasting System (GFS) model, shown below (courtesy Brandon Aydlett, WFO Guam), shows anticyclonic flow underneath the region of the upper-level cold pool. Upper-level (300-mb) streamline (shown here overlain on top of Himawari-8 Upper Level water vapor imagery (Band 8, 6.24 µm), also courtesy Brandon Aydlett) shows an upper-level cyclonic circulation associated with the cold pool.

View only this post Read Less

1-minute Mesoscale Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Fire Temperature RGB images (above) showed a wildfire just southwest of Yellowknife (CYZF) in Canada’s Northwest Territories, which produced a pyrocumulonimbus (pyroCb) cloud during the afternoon hours on 12 July 2022.

This large fire burned very hot, with 3.9 µm Shortwave Infrared brightness temperatures reaching 138.71ºC — which is the saturation temperature of ABI Band 7 detectors. The coldest pyroCb cloud-top 10.35 µm Infrared Window brightness temperatures were around -49ºC (lighter shades of blue).

View only this post Read Less

CSPP True Color imagery (link) above suggests a region of apparent dust over the eastern Caribbean Sea. That is, there is a hazy look to the imagery that persists even as the region of sun glint moves past. Suspended dust in the tropical Atlantic is known to suppress convection. Other products besides true-color imagery can be used to show dry the air (qualitatively and quantitatively) over the Caribbean. For example, the toggle below (from this site) of the Saharan Air Layer analysis (via the Split Window Difference) and the Airmass RGB shows very dry air south of Hispaniola and Puerto Rico — orange in the Split Window Difference, and also an orange tint to the Airmass RGB.

Air over the eastern Caribbean also shows large values of Aerosol Optical Depth (from the AerosolWatch site); the enhanced values are most likely a result of suspended dust from the Sahara. AOD is not computed in the region of sun glint — that’s the cause of the smooth curved line that arcs through extreme eastern Cuba.

Total Precipitable Water (TPW) from the MIMIC site (link) shows dry air over the eastern Caribbean (and over much of the tropical Atlantic Ocean north of 10^oN). Total precipitable water derived from gridded NUCAPS fields (here), and relative humidity at 700 mb (here), also show dry air over the eastern Caribbean; they are also shown in a toggle with NUCAPS Quality Flags below.

An interesting feature in the animation at the top of this blog post is the development of convection over Hispaniola, over the topography, even in the presence of fairly dry air. NUCAPS analyses of 500-mb air temperature (here), show a cold pocket of air over Puerto Rico and Hispaniola, helping the development of convection there.

---

When assessing the environment of a region with sparse conventional data, such as the Atlantic (or Pacific) Ocean, or the Caribbean Sea, take advantage of information that satellite observations can give you.

View only this post Read Less

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed the evolution of the eye of Hurricane Darby as it moved westward across the East Pacific Ocean on 11 July 2022. Mesovortices were evident within the eye, along with a stadium effect eye structure — as Darby ended its period of rapid intensification and leveled off as a Category 4 storm (ADT | SATCON). Darby was moving through an environment of low wind shear and across relatively warm water (SST | OHC), factors which favored intensification.

A NOAA-20 VIIRS Infrared Window (11.45 µm) image from RealEarth (below) revealed an arc of slightly colder cloud tops (shades of white within dark black) in the northern portion of the eyewall.

A NOAA-20 ATMS Microwave (183 GHz) image from the CIMSS Tropical Cyclones site (below) also showed the compact eye, along with a band of precipitation spiraling northward.

View only this post Read Less