GOES-17 ABI Imagery on 6 February suggests the presence of a cold front over the Pacific Ocean northeast of Hawaii. The Clean Window imagery shows a flat region between 30º N and 40º N around 140º W. The Night Fog Brightness temperature difference shows a signal — cyan — in that region consistent with low stratus. The Night Microphysics RGB (shown here in a toggle with Night Fog Brightness Temperature) shows a strong signal there as well (with some noise that can be attributed to Loop Heat Pipe issues with the GOES-17 ABI).

NOAA-20 overflew this region around 1200 UTC on 6 February (Click this link to see all NOAA-20 orbit paths).  The Gridded NUCAPS field of the 900-700 mb Lapse Rate shows small values (around 2º for a temperature change, the darker cyan color in the enhancement), as might be expected over the stratus deck.  Note also how the air mass is less stable in the cold air behind the front (yellow and orange in the enhancement to the west west of the front, green to the east of the front).  Gridded NUCAPS data are created with all vertical retrievals.  The toggle with NUCAPS Vertical sounding points (here), shows how the profiles that failed to converge (i.e., red and yellow points) can affect the gridded fields.

 

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1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.37 µm) images (above) displayed widespread “transverse banding” — elongated cirrus elements oriented perpendicular to the ambient jet stream flow — that was migrating southward across California on 04 February 2020. This satellite signature is an indicator of potential turbulence, which in this case did indeed result in several pilot reports of light to moderate turbulence.

One of the pilot reports over Salinas, California at 2150 UTC (below) indicated Clear Air Turbulence (CAT) at an altitude of 30,000 feet — this suggests that the aircraft might have been flying just above or below the actual cirrus bands.

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GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) showed numerous orographic waves over eastern Arizona and western New Mexico on 03 February 2020. There were several high-altitude pilot reports of turbulence across that region, including severe turbulence associated with mountain waves at 43,000 feet and at 39,000 feet (below). The turbulence encounter at 39,000 feet noted an aircraft speed fluctuation of +/- 20 knots, along with a drop in altitude of 1600 feet.

 

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2.5-miute Rapid Scan JMA Himawari-8 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and Infrared Window (10.4 µm) images (above) showed the formation of 2 small, fairly short-lived pyrocumulonimbus (pyroCb) clouds spawned by large, hot bushfires in southern New South Wales, Australia on 01 February 2020. The pyroCb clouds developed in advance of an approaching cold front (surface analyses), exhibiting 10.4 µm cloud-top infrared brightness temperatures in the -40 to -49ºC range (shades of blue). The first pyroCb formed at at 0311 UTC to the northeast of Cooma (YCOM), with the second formed at 0559 UTC just southwest of Merimbula (YMER).

NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images at 0426 UTC as viewed using RealEarth (below) revealed cloud-top infrared brightness temperatures near -60ºC (darker red enhancement).

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 1454 UTC or 1:54 am AEDT (below) displayed the nighttime glow and hot thermal signatures of large bushfires south and southeast of Canberra.

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