Nighttime Microphysics RGB: Stratus and Fog Cover much of the Great Plains and South, March 2017

The development of low clouds and fog over wide areas of the Gulf Coast states and the Great Plains began in the early morning around 0600 UTC on 22 March 2017.  Expansion of these features by 1200 UTC stretched from Texas to Florida in the South and from Oklahoma into the Dakotas along the Great Plains.  These features are easily distinguished in the Nighttime Microphysics (NtMicro) RGB imagery (Fig. 1) from the newly launched GOES-16 imager.  The low cloud/fog range from aqua coloring in the south and become more lime colored toward the colder portions of the Great Plains.  The Pueblo Colorado NWS Weather Forecast Office (PUB) commented on the use of GOES-16 to monitor these low cloud and fog features when considering possible impacts to the public and aviation users.

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Figure 1. Nighttime Microphysics RGB imagery from GOES-16 at 1207 UTC, 22 March 2017 over the CONUS.

For the above image and subsequent animations: NOAA’s GOES-16 satellite has not been declared operational and its data are preliminary and undergoing testing. Users receiving these data through any dissemination means  (including, but not limited to, PDA and GRB) assume all risk related to their use of GOES-16 data and NOAA disclaims any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose.

The forecast discussion from PUB included this paragraph in the aviation portion:

“GOES-R fog loop shows stratus deck expanding over the plains as of 10z, and expect at least patchy MVFR stratus along and east of I-25 until midday. Western fringe of the cloud deck will likely produce some IFR cigs/vis near the mountains and Palmer divide as clouds push up against higher terrain.”

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Figure 2. GOES-16 “Fog” product (i.e. 3.9 – 11 micron difference) and ceiling/visibility observations.   A default color enhancement is applied to the “Fog” product.  The animated GIF is from 0812 – 1207 UTC, 22 March 2017

The “fog” loop product mentioned above is the channel difference of 3.9-11 microns , and it is shown in the default AWIPS color curve (Fig 2.) where one can see the pink to nearly white features representing negative differences that correspond to low clouds and/or fog.  As anticipated, some MVFR conditions did occur due to ceilings below 3000 ft, and many parts of the Palmer Divide and the Raton Ridge became surrounded by these features.

While the “fog” product shows the various low cloud and fog features, this same capability is found in the “green” component of the Nighttime Microphysics RGB.  This event of low clouds and fog can also be seen in the NtMicro RGB below (Fig. 3) where the land surface and various mid/high clouds are more easily distinguished from the low clouds and fog. This differentiation of features occurs due to additional infrared channels/differences that help to classify cloud thickness and height.  While the event mostly involved low stratus, fog can be seen developing in the low lying areas of southeast Colorado and northeast New Mexico.  Given the improved resolution of GOES-16 in space and time and the availability of more channels compared to legacy GOES imagers, monitoring the fog between in situ observations becomes easier with the NtMicro RGB, and thus allows forecasters to better anticipate impacts to aviation sites and public roadways.

 

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Figure 3. Nighttime Microphysics RGB imagery from GOES-16 from 0812 – 1207 UTC, 22 March 2017 centered on west Kansas.

For more information regarding the Nighttime Microphysics RGB, including interpretation guides for the color features in the imagery:

SPoRT Quick Guide: Nighttime Microphysics RGB in the SPoRT Training Site

SPoRT Nighttime Microphysics RGB Fundamentals (Module) ~20 minutes

 

 

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