Lightning Jump in the North Alabama Lightning Mapping Array

It’s a busy day in North Alabama with NASA and NOAA aircraft in the region supporting a field campaign for GOES-16.  Another instrument supporting activities is the North Alabama Lightning Mapping Array (NALMA), which observes total lightning (both intra-cloud and cloud-to-ground).  SPoRT has been providing NALMA data to local forecast offices for 14 years and has used these data to serve as a proxy for the Geostationary Lightning Mapper on GOES-16 as part of the GOES-R Proving Ground.  The images below show the total lightning activity across southern Tennessee and northern Alabama at 2138 and 2152 UTC on 22 April 2017.  The main storm of interest is right along the Alabama-Tennessee border, just north of Huntsville, Alabama.  The maximum number of flashes per 2 square kilometers in two minutes is about 50 flashes at 2138.  In 14 minutes, that has jumped to nearly 150 flashes over two minutes highlighting a lightning jump.   A long flash extending to the south towards Huntsville is also seen.  This storm already had a severe thunderstorm warning active and the jump here indicates that the storm will maintain it’s intensity.  The weather community will look forward to the Geostationary Lightning Mapper observations when they a made available in the next few months.

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Total lightning observations from the North Alabama Lightning Mapping Array at 2138 UTC on 22 April 2017.

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Total lightning observations from the North Alabama Lightning Mapping Array at 2152 UTC on 22 April 2017.

Dust RGB analyzes “dryline” for 3/23/17

Dust RGB analyzes “dryline” for 3/23/17

 

The Dust RGB, originally from EUMETSAT and a capability of GOES-R/ABI, can be helpful in identifying features other than dust, including drylines. A dryline represents a sharp boundary at the surface between a dry air mass and moist air mass where there is a sudden change in dew point temperatures. In this event from 3/23/17, a dryline in eastern New Mexico and west Texas is distinguishable via the Dust RGB imagery animation from GOES-16 (Fig. 1), while a large dust plume (magenta) is impacting areas further west. Note that the visible imagery (Fig. 2) shows clouds forming along the dryline, but these clouds drift downwind toward the northeast as they mature, away from the dryline itself, making it difficult to monitor the dryline position.  However, the dryline position can easily be seen via the color difference of the Dust RGB across the boundary of dry and moist air, and in fact, the dryline appears fairly stationary or moves in a slight westward direction, opposite of the cloud motion.  In situ observations (Fig. 3) are a primary tool for monitoring the dryline location, but the advantage of satellite imagery is an increased spatial and temporal resolution for forecasters.

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Figure 1. GOES-16 Dust RGB valid from 2022 to 2322 UTC, on 23 March 2017 centered on extreme western Texas.  Dryline seen in color difference of cloud-free area in eastern New Mexico and west Texas while dust plume is in magenta shades.

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Figure 2. GOES-16 Visible (0.64u) channel valid from 2027 to 2322 UTC on 23 March 2017 as in Figure 1.

For the above and subsequent images/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.

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Figure 3. METAR station plot of surface observations at 2143 UTC on 23 March 2017 centered over New Mexico.

The ability to identify drylines using the Dust RGB gives the forecaster the capability to analyze these boundaries in ways not seen before. In the Dust RGB (Fig. 4), the surface area on the dry side is seen as a purple color (i.e. increased red contribution), and the moist side appears more blue (i.e. less red). This dryline can be noted more easily than in visible imagery (Fig. 5) due to the sensitivity of the 12.3 micron channel used in the 12.3 – 10.35 micron difference within the Dust RGB red component.  The 12.3 micron channel goes from warmer to cooler brightness temperatures with changes in density from very dry to very moist air. The blue contribution is consistent on each side of the line because the surface temperature, and hence the 10.35 micron channel, does not change much from either side of the dryline. There is limited ability to identify drylines using high resolution visible imagery, as seen in the Midland WFO Graphicast (Fig. 6) where cumulus clouds are documented forming along the dryline. Unfortunately, visible imagery is only useable during daylight hours and a user is dependent on cloud features along the dryline in order to analyze its position. However, aside from the obvious value of the color difference in cloud free areas to depict the dryline, the Dust RGB, is viable both during daytime and nighttime hours.

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NtMicro RGB: Fog vs Stratus

NtMicro RGB: Fog vs Stratus

A veritable buffet of things to digest are occurring in this Nighttime Microphysics RGB animation from 0600 to 1000 UTC in the early morning of 3/28/17 where multi-state impacts of stratus and fog are seen (Fig 1). In blue/aqua to gray shades, the low cloud features are developing over the central CONUS while being sandwiched between Spring-time cyclones in the East and West.  The massive spreading of the stratus and fog can’t be missed and numerous METAR observations across the central CONUS verified the aviation hazards.

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Figure 1. Nighttime Microphysics RGB from GOES-16 at 0602 to 0957 UTC on 28 March 2017 over the U.S.

For the above and subsequent images/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.

Focusing on the Tennessee and Lower Mississippi Valley regions, the fast motion of the animation from 0900 to 1130 UTC allows one to see the development of fog while other stratus clouds  pass to the east/northeast (Fig 2.).  Note that fog develops in the various low-lying areas, particularly eastern Tennessee valleys.  There is also a separate push of fog, noted by the black dotted oval of Figure 3, that moves southward along the back side of the eastern cyclone.  The METAR stations in the oval show the lowest visibility observations occurring in this area of southern and western Tennessee as well as northern Alabama.  A bit further upstream (north) from the push of fog there is a layer of very low stratus also moving southward and causing MFVR to IFR conditions.  With the large amount of precipitation from the previous day and relatively light winds overnight, a variety of fog and stratus developed over a wide area as the cyclone passed.  While not extremely common there are instances where fog develops even with  low stratus present overhead.  One can see this in central Missouri where fog is reported but the RGB shows stratus with large water droplets at their tops.  Fog below stratus was experienced at times in northern Alabama as well.

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Figure 2. Nighttime Microphysics RGB from GOES-16 at 0902 to 1122 UTC on 28 March 2017 centered over western Tennessee and covering the Tennessee and Upper Mississippi Valleys.

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Figure 3. METAR station plot from the Aviation Weather Center ADDS site (left) and the Nighttime Microphysics RGB.  Both from near 1100 UTC with annotations of fog and stratus locations and movement.  Blue arrow in METAR shows direction of movement and shared black dotted oval notes locations of lowest visibility reports.

It’s Dust (RGB) Season!

It’s Dust (RGB) Season!

A large dust plume occurred over the southwest CONUS on 23 March 2017 as high winds lofted surface materials from the Mexican plateau across the border toward Texas and New Mexico.  Blowing dust events are common in the Spring in this region given the frequency of strong cyclones passing over dry land with sparse vegetation at this time.  For this event the dust plume could be detected during the day in visible imagery and even infrared single channel imagery from the newly launched GOES-16 satellite; however, the high resolution visible imagery traditionally used to monitor dust is not valid after sunset and through the overnight period.  The nighttime impacts of the dust plume eventually extended to locations downstream in Colorado, Oklahoma, and Kansas. Fortunately, a combination of infrared channels from GOES-16 can be used within an red, green, and blue (i.e. RGB) imagery product to highlight the dust location (bright magenta coloring) both day and night.

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Dust RGB Imagery from GOES-16 at 0257 UTC (~9:57 PM Central) on 23 March 2017 centered on northwestern Texas of the U.S.  Dust plume is identified by magenta coloring while thick cloud features are mostly in tans to reds with other thin clouds in dark shades ranging from purples and blues to black.

 

For the above and subsequent images/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.

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Dust RGB Imagery from 0002 to 0357 UTC, 23 March 2017 centered over western Texas of the U.S.  Blowing dust is colored in magenta.

This “Dust RGB” was originally created by EUMETSAT nearly a decade ago during initial use of the MSG/SEVIRI instrument in order to more efficiently utilize the 3-fold increase of infrared channels available to forecasters. NASA/SPoRT transitioned this Dust RGB to U.S. forecasters via MODIS and VIIRS starting in 2011 in preparation for GOES-16, and this is the first look at geostationary Dust RGB imagery of a major blowing dust event over the southwest CONUS. This event continued into the night when visible imagery was no longer useful.  For this post note the Dust RGB and visible animations below and how the initial development of dust plumes in Mexico are more easily noticed in the Dust RGB around 1700 UTC in magenta while the plume is not readily evident in the visible imagery even at the end of the animation at 1842 UTC.  In addition, the visible imagery shows the thin clouds (orographically-induced) in northern Mexico as very similar in nature to the dust plumes themselves.  However, the Dust RGB shows the thin clouds in blue to black coloring and easily differentiates the dust from the clouds as well as land surface features.

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Dust RGB and visible 0.64 micron imagery from 1617 to 1842 UTC on 23 March 2017 centered over western Texas near the U.S./Mexico border (click on animation to enlarge)

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

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

 

 

A GOES-16 Multispectral View of the Late Season Nor’easter

A high impact late season Nor’easter is unfolding across the Mid-Atlantic and New England today.  An enhanced view of the impressive storm is possible with multispectral (i.e. RGB) imagery since GOES-16 ABI has 16 bands available compared to legacy GOES sensors. Both the Day Land Cloud RGB (Fig. 1) and Air Mass RGB (Fig. 2) were developed by EUMETSAT and provided to European forecasters with the launch of Meteosat-8 SEVIRI in the early 2000s. These RGBs are part of the set of EUMETSAT RGB best practices that was later adopted by the WMO and today are widely used by other countries such as Japan and Australia who have access to Himawari-8 AHI derived RGB products.  NASA SPoRT has worked closely with the GOES-R/JPSS Proving Grounds to provide RGB products derived from MODIS, VIIRS, AVHRR, and AHI to NWS offices, National Centers, and the Operations Proving Ground to prepare forecasters for multispectral capabilities with GOES-16.  More recently, NASA SPoRT has been working with the Total Operational Weather Readiness – Satellites (TOWR-S) and the Satellite Enhancement Team to provide client-side RGB imagery to the National Weather Service for use in operations.  These are just two examples of GOES-16 ABI RGB imagery that will be available to NWS forecasters in the near future.  A brief explanation of each product is found in the caption and links to training resources are below.

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Fig. 1 Day Land Cloud RGB 14 March 2017 15:52 UTC.  Provides the ability to distinguish snow from clouds.  Snow appears cyan, low water clouds appear gray to dull white, and high ice clouds appear cyan.  Although snow and high ice clouds both appear cyan, snow can be distinguished since it remains stationary.

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.

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Fig. 2 Air Mass RGB 14 March 2017 15:52 UTC.  The Air Mass RGB was designed to anticipate rapid cyclogenesis by enhancing regions of anomalous potential vorticity near the jet stream in orange/red tones.  These regions indicate where warm, dry, ozone-rich stratospheric air is being pull downward by the jet stream, which can be in indication of rapid cyclogenesis.  Low-, mid-, and high-clouds can also be identified in the RGB. Low clouds appear blue/green, mid clouds appear tan, and high clouds appear bright white.  Compare the clouds in the Air Mass RGB with the clouds in the Day Land Cloud RGB above to identify cloud height.

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.

For more information on the Day Land Cloud and Air Mass RGBs, including interpretation please see:

NASA SPoRT Natural Color RGB Quick Guide (PDF and Interactive)

EUMETSAT Natural Color RGB Interpretation Guide

NASA SPoRT Air Mass RGB Quick Guide (PDF and Interactive)

EUMETSAT Air Mass RGB Interpretation Guide

SPoRT-created training material now available via the new AIR Tool within AWIPS

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Training material now available for use by NWS forecasters via the new AIR tool within AWIPS. This example shows the SPoRT-created Nighttime Microphysics RGB Quick Guide.

NASA SPoRT has been working to get training materials available to NWS forecasters via the new AWIPS Integrated Reference (AIR) tool.  This Twitter post and attached video details how NWS forecasters can access the new training material.  This training is now available with the current POES RGB imagery, but will also be available once RGB imagery from GOES-16 is available in AWIPS. SPoRT will be working to add new training content within Vlab and accessible via the AIR tool in the coming months.