GOES-16 ABI and GOES-R CI aid IDSS over the weekend

Once again, NWS Huntsville provided impact-based decision support services (IDSS) for the Panoply Arts Festival in downtown Huntsville.  Since it occurs in late April every year, Panoply has a long history of coping with challenging weather conditions, and NWS Huntsville has staffed the event every year to help with those challenges.  This year was no exception.

 

Saturday was a summer-like day, with the main forecast challenge being convective initiation from a field of cumulus clouds.  The UAH-developed GOES-R Convective Initiation algorithm output was helpful with this process as it correctly forecast low probabilities for much of the day.

 

We also decided to look at GOES-16 ABI data to see if it added any value.  In addition to monitoring the low (7.3um) and mid-level (6.9um) water vapor channels on a larger scale, the Red Visible (0.64 micron) was most beneficial.  A mesoscale domain sector was in place over the region at the time, enabling forecasters to easily look for growing cumulus clouds (though there were not many of these).  (Apologies for the quick and small screen captures!)

GOES-16 ABI 0.64um imagery – valid 29 April 2017 1950 UTC

During the mid-afternoon, forecasters staffing the emergency operations center noticed an interesting trend in the visible imagery: areas to the south that were shrouded by thicker cirrus were seeing clearly-suppressed cumulus development, and the cumulus clouds were developing again once the cirrus had passed by. This almost created a “moving shadow” effect.

GOES-16 ABI 0.64um imagery – valid 29 April 2017 2013 UTC

GOES-16 ABI 0.64um imagery – valid 29 April 2017 2029 UTC

The forecasters were able to use this to determine that convective initiation–and thus impacts to Panoply and downtown Huntsville–were very unlikely, since the cirrus clouds were moving into the area.
There is a great deal of promise for IDSS using the new GOES-16 data, particularly once the Geostationary Lightning Mapper begins flowing on a preliminary basis.
Note The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. Users bear all responsibility for inspecting the data prior to use and for the manner in which the data are utilized.
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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GOES-16 Advanced Baseline Imager Data Observes Severe Weather Event on Day 1!

Today marks the first day that the beta-mode Advanced Baseline Imager (ABI) data have been made available from GOES-16.  NASA SPoRT is obtaining the ABI data via the GOES Rebroadcast (GRB) data transmission system receiver located at the NASA Marshall Space Flight Center in Huntsville, Alabama.

Mother Nature provided some active weather through the Tennessee River Valley today as SPoRT team members worked to produce imagery from the receiver.  Below is a one hour animation of ABI data from 1817 to 1917 UTC updating every 5 minutes.  This shows Band 2 visible 0.64 µm imagery at a resolution of 0.5 km.  The imagery shows the line of storms as it entered northern Alabama.

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GOES-16 ABI 0.64 um visible imagery from 1817 to 1917 UTC on 1 March 2017.  These data come from the GOES Rebroadcast (GRB) data transmission system receiver located at the NASA Marshall Space Flight Center in Huntsville, Alabama. (Full resolution)

Please note, the GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. Users bear all responsibility for inspecting the data prior to use and for the manner in which the data are utilized.

For comparison, the following figure below shows the same ABI 0.64 µm imagery at 2006 UTC (0.5 km) side-by-side with the existing GOES-13 visible data at 2007 UTC (1 km).  Notice the impressive detail observed with the higher resolution GOES-16 imagery!

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Comparison of GOES-16 ABI 0.64 um (left, 2006 UTC – 0.5 km) and the GOES-13 Imager (right, 2007 UTC – 1 km) on 1 March 2017.  The yellow circle highlights an overshooting top in Jackson County, Alabama.  These data come from the GOES Rebroadcast (GRB) data transmission system receiver and the GVAR receiver, both located at the NASA Marshall Space Flight Center in Huntsville, Alabama. (Full resolution)

Please note, the GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. Users bear all responsibility for inspecting the data prior to use and for the manner in which the data are utilized.

NUCAPS Soundings and Hurricane Matthew

CrIS/ATMS soundings processed through the NOAA Unique Combine Processing System (NUCAPS) are available in AWIPS.  SPoRT is working with the Joint Polar Satellite System (JPSS) Proving Ground to testbed the utility of NUCAPS soundings to anticipate hurricane tropical to extratropical transition.  Although satellite derived soundings are “smoother” than radiosondes they can provide valuable information about the depth of moist or dry layers in data sparse regions. Forecasters can anticipate extratropical transition by identifying the dry slot and upstream potential vorticity anomalies on satellite imagery that may interact with a storm while also considering many other factors that lead to extratropical transition.  Although Hurricane Matthew is not expected to undergo extratropical transition for quite a few days, the NUCAPS Soundings can be used to diagnose the temperature and moisture characteristics surrounding the hurricane as highlighted below.

GOES-13 water vapor imagery shows dry upper levels west of Hurricane Matthew and abundant moisture surrounding the system (Fig. 1).  Since water vapor imagery can only detect moisture characteristics in the mid-to upper- levels of the atmosphere, the NUCAPS soundings (green dots on Fig. 1) can be analyzed to provide more information about the vertical extent of the dry air and whether it is in close proximity to the hurricane in the mid- to lower- levels.

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Fig. 1. 5 October 2016 1830 UTC GOES-13 water vapor imagery and 1811 UTC NUCAPS Soundings. Green dots represent point and click soundings. Blue numbers label location of example soundings highlighted below.

Scroll down through the example Soundings to compare the changes in moisture conditions west of Hurricane Matthew. Soundings 1 and 2 (Fig. 2 and 3), taken in a region of dry air as identified by the orange color enhancement on the water vapor imagery, confirm a dry column throughout the depth of the atmosphere. Sounding 3 (Fig. 4) shows the drying is not as intense in the upper-levels and mid-level drying extends down to about 600 mb. Sounding 4 and 5 (Fig. 5 and 6) show upper level conditions are more moist closer to the hurricane, as expected from the water vapor imagery. While Sounding 4 (Fig. 5) shows moist conditions throughout the atmospheric column, Sounding 5 (Fig. 6) does show mid-level dry air is present.  Previous analysis of Sandy 2012 and Arthur 2014 showed the same signature (e. g., similar to Sounding 5) became more abundant surrounding the systems as upper-level dry air intruded.  Currently, there are very few soundings with this signature surrounding Hurricane Matthew.  The NUCAPS soundings confirm dry atmospheric conditions are well west of the system and there is very little mid- to low- level dry air in the proximity of the system.  This preliminary example is presented but as Hurricane Matthew continues to evolve NUCAPS Soundings and SPoRT Ozone Products will be analyzed to discern the utility for anticipating dry air intrusion and associated hurricane tropical to extratropical transition.

Sounding 1

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Fig. 2. 5 October 2016 1811 UTC NUCAPS Sounding at Location 1.

 

Sounding 2

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Fig. 3. 5 October 2016 1811 UTC NUCAPS Sounding at Location 2.

Sounding 3

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Fig. 4. 5 October 2016 1811 UTC NUCAPS Sounding at Location 3.

Sounding 4

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Fig. 5. 5 October 2016 1811 UTC NUCAPS Sounding at Location 4.

Sounding 5

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Fig. 6. 5 October 2016 1811 UTC NUCAPS Sounding at Location 5.

 

 

Recent VIIRS DNB Observation of Snow Cover in the TN/OH Valley Region…

Yet another bout of snow, sleet and ice recently affected much of the Tennessee and Ohio Valley regions.  Although clouds were clearing in western portions of this region, allowing for a broad scale satellite view of the newly laid snow/ice field, eastern portions remained cloud-covered until sunset.  While ground reports contain valuable information about the depth of snow and/or ice, they’re only point measurements, so assumptions often have to be made about the spatial extent of the snow, until satellite observations are available (unless clouds obscure).  So, those observations would have to wait until the next day, during visible sunlight hours…or would they?  Well, not exactly…which is the point of this blog post.

The image below (Image 1) is a Snow/Cloud RGB produced by SPoRT and disseminated to collaborative NWS field offices.  The green colors represent the background surface (grass, trees, cities, etc.), while the deeper reds represent snow/ice cover.  White colors depict clouds, while reddish-white represents very cold clouds containing ice crystal clouds.  Notice the swath of snow that is visible from NE Texas into the Midwest.  Meanwhile, clouds obscure any snow/ice in eastern areas.

Image 1.  MODIS  Snow/Cloud RGB 1631 UTC 5 March 2015

Image 1. MODIS Snow/Cloud RGB 1631 UTC 5 March 2015

Clouds had pushed eastward by sunset, but did still not move far enough to provide a clear indication of the eastward extent of the snow/ice field that had just fallen.  However, once the VIIRS Day-Night Band imagery became available later that night, the spatial extent of the snow and ice could be fairly easily observed.  Notice in the next image (Image 2) the snow and ice cover that was apparent over portions of the Tennessee and Ohio Valley region.

Image 2.  Suomi-NPP VIIRS Day-Night Band Radiance RGB, 0805 UTC 6 March 2015.  The solid white line indicates the extent of the snow/ice cover.  Clouds are also in the image over portions of the southern Appalachians and the Gulf into the Atlantic Coastal Plain.

Image 2. Suomi-NPP VIIRS Day-Night Band Radiance RGB, 0805 UTC 6 March 2015. The solid white line indicates the extent of the snow/ice cover. Clouds are also in the image over portions of the southern Appalachians and the Gulf into the Atlantic Coastal Plain.

This type of imagery can be helpful for operational forecasters when trying to assess the potential societal impacts of lingering snow and ice, and also the impacts on sensible parameters such as temperatures and relative humidity, which can help improve weather forecasts.

MODIS and VIIRS Products for Fog Detection in the TN Valley

I didn’t have a chance to make this post last week when the imagery were more time-relevant.  Nevertheless, I wanted to point out another example of the usefulness of MODIS and VIIRS imagery over current GOES imagery and show the usefulness of exciting products and imagery to come!  First, let’s take a look at the color-enhanced GOES-IR image below from the morning (0715 UTC) of June 20th.

Color-enhanced GOES-IR (11um) image valid 0715 UTC 20 June 2014

Image 1.  Color-enhanced GOES-IR (11 µm) image valid 0715 UTC 20 June 2014

 

I’ve placed the yellow circles in the image for a reason, which you’ll see below.  Further down, I’m going to show areas of fog displayed in the MODIS and VIIRS imagery, and granted, this is not the standard GOES channel difference (11-3.9 µm) typically used for making fog assessments.   However, this post is meant to show current (MODIS / VIIRS) and future capabilities (GOES-R / JPSS) that will make fog detection and cloud differentiation much more easy for the operational forecaster.  So, in the image above, fog is nearly unidentifiable as it was in the 11-3.9 µm channel difference image that morning (not shown).  Mainly high cirrus clouds can be observed scattered across the region.  Now, let’s take a look at the MODIS “fog” product, or channel difference (11-3.9 um) product valid at about the same time (Image 2).

Color-enhanced MODIS 11-3.9 u m product valid 0718 UTC 20 June 2014

Image 2.  Color-enhanced MODIS 11-3.9 µm image valid 0718 UTC 20 June 2014

Notice that in the same areas we can now begin to see low clouds (indicated by yellow colors) scattered around the valleys of the southern Appalachian region.  While the GOES-East imager is capable of detecting larger scale fog often in the valleys in the eastern circle, fog in the valleys in the western circle present challenges for the current GOES-East instrument, and is often not shown very well (even in the standard 11-3.9 µm channel difference).    Next, let’s take a look at a VIIRS Nighttime Microphysics RGB valid at about the same time.

VIIRS Nighttime Microphysics RGB valid 0723 UTC 20 June 2014

Image 3.  VIIRS Nighttime Microphysics RGB valid 0723 UTC 20 June 2014

In the RGB imagery it is much easier to detect the extent of the fog, making the operational forecast process much more effective.  Notice also that it is possible to see the fog through the higher clouds around the TN/GA/NC border region.  Not only does the resolution of the VIIRS and MODIS instruments allow for superior fog detection, but the RGBs in particular offer tremendous operational advantages.  As a user of RGBs for about 2 years now, I am convinced that this type of imagery has a relevant and needed place in future operational forecasting.  Of course, it will take time for forecasters to become accustomed and adjust to the new imagery, but it will happen.

 

GOES-R CI and Total Lightning Products Prove Useful Again in HUN Operations

Shortly after arriving for my evening shift today, I was called by a representative from an organization hosting an outdoor event in downtown Huntsville.  She was inquiring about the chances for shower or thunderstorm development into the early evening hours during the outdoor event (movie in the park night).  As I have grown quite accustomed to loading the GOES-R CI and total lightning products to be used for situational awareness, especially during the convective season, I referred to those to help with my assessment…in addition to radar data of course.  The image below shows GOES Visible channel imagery overlaid with GOES-R CI, total lightning data, and NLDN (the latter of which may be hard to see).  The location of Huntsville is labeled, and cloud motion is analyzed in the image.  Notice that the GOES-R CI product indicates generally low probabilities of convection in the area of clouds to the northwest (and upstream) of Huntsville.  The blue colors indicated CI probabilities of around 10-40%.

GOES Vis imagery overlaid with GOES-R CI, Total Lightning, and 15-min NLDN, approx. 2015 UTC June 13, 2014

GOES Vis imagery overlaid with GOES-R CI, Total Lightning, and 15-min NLDN, approx. 2015 UTC June 13, 2014

The next image shows lightning data overlaying the GOES Vis imagery…

GOES Vis imagery overlaid with KHTX 0.5 reflectivity (dZB) ~2015 UTC June 13, 2014

GOES Vis imagery overlaid with KHTX 0.5 reflectivity (dZB) ~2015 UTC June 13, 2014

 

Notice that only a few showers were located to the NW of Huntsville, but the GOES-R CI suggested further development was not likely and the total lightning (available from the North Alabama LMA) suggested these were only showers and thus not electrically active (I had looked over the previous ~20-30 mins).   Notice that lightning activity was relegated mainly to the South and East of the area.  This was a situation in which the GOES-R CI and total lightning data both served to provide a more complete assessment of the situation, allowing for a better forecast for one of our customers.

By the way…my forecast to her?  Well, based on the evidence from the observational imagery/data…I said very small chances for any shower activity, so let the show go on!  No showers ended up impacting the downtown area.