Water Vapor Imagery

Strong thunderstorms erupted on the evening of 04/28/17 and continued into the overnight, expanding in coverage and producing prolific lightning in spots. The Weather Prediction Center’s Metwatch Desk was particularly busy issuing multiple Mesoscale Precipitation Discussions (MPD) to stay ahead of the flash flood threat.

WPC MPD #0150 issued by forecaster, Greg Gallina, at 0015 UTC on 04/28/17. Click to enlarge

NWS Forecaster, Greg Gallina, indicated the following:

“GOES-16/EAST WV LOOP SHOWS A RELATIVELY FLAT
SHORTWAVE ACROSS NW OH WITH THE TRAILING TROF SW ACROSS CENTRAL
IND/IL WITH A MCS TRACKING ACROSS CENTRAL IND. THIS MCS IS AT THE
APEX OF SOUTHWESTERLY LOW LEVEL JET/WAA REGIME OVERRUNNING A WARM
FRONT THAT EXTENDS FROM LWV…N OF LOU AND S OF CVG. THIS COMPLEX
HAS BEEN PRODUCING 1.5-2.5″ RAIN AS IT TRACKED THROUGH WEST
CENTRAL IND…AND WILL LIKELY MAINTAIN AS IT CROSSES INTO LOWER
FFG VALUES ACROSS SE IND/SW OH IN THE NEXT HOUR OR SO.”

GOES-16 6.9 um “mid-level” water vapor animation valid from 1800 UTC – 2357 UTC on 04/28/17. *Preliminary, Non-Operation Data* Click to enlarge

As Greg mentioned, GOES-16 6.9 μm “mid-level” water vapor imagery shows a relatively flat shortwave aiding in the maintenance of the Mesoscale Convective System (MCS) over Indiana and Ohio, while a stronger shortwave can be seen moving out of Iowa into southeastern Minnesota. What other features can you identify in this animation?

GOES-16 1-minute 0.64 um “Red” visible animation valid from 2130 UTC 04/28/17 to 0059 UTC 04/29/17. *Preliminary, Non-Operational Data* Click to enlarge

The GOES-16 1-minute 0.64 μm “Red” visible animation shows the incredible detail in the cloud top environment (0.5 km resolution) of the aforementioned MCS moving through Indiana and Ohio. Note the persistent overshooting tops and their subsequent gravity waves rippling across the cirrus shield. This is indicative of healthy, organized updrafts which a forecaster can then make a decision on whether the activity will persist, strength, or weaken with time.

GOES-16 1-minute 10.3 um “Clean” infrared animation valid from 2130 UTC 04/28/17 to 0259 UTC 04/29/17. *Preliminary, Non-Operational Data* Click to enlarge

Once again, the 1-minute imagery proves valuable here as the trend of the cold cloud tops can be seen expanding with the MCS, while new convection fires near the Illinois, Kentucky, and Indiana borders. Note the dark pixels indicating very cold overshooting tops. Can you spot the enhanced-V structures down-stream from those towers?

WPC MPD #0151 issued by forecaster, Andrew Orrison, at 0300 UTC on 04/29/17. Click to enlarge

As noted by NWS forecaster, Andrew Orrison:

“EXPERIMENTAL GOES-16 IR IMAGERY CONFIRMS THAT
CONVECTIVE INITIATION IS UNDERWAY IN AN ELEVATED FASHION ACROSS
AREAS OF SOUTHERN MO…FAR NORTHWEST AR AND PARTS OF EASTERN OK. A
STRENGTHENING AND VERY MOIST LOW LEVEL JET COUPLED WITH GRADUALLY
IMPROVING RIGHT-ENTRANCE REGION JET DYNAMICS IN VICINITY OF A
WELL-DEFINED QUASI-STATIONARY FRONTAL ZONE SHOULD FACILITATE A
SW/NE AXIS OF STRONG THUNDERSTORMS WITH INTENSE RAINFALL RATES
OVER THE NEXT FEW HOURS.”

G16_10p3_LTNGDEN05_CONUS_OHValley_20170428

GOES-16 CONUS (5-minute) 10.3 um “Clean” infrared imagery with the 5-minute GLD-360 lightning density product overlaid, valid from 2130 UTC 04/28/17 to 0256 UTC 04/29/17. *Preliminary, Non-Operational Data* Click to enlarge

The ongoing MCS in the above GOES-16 10.3 μm “Clean” infrared animation with GLD-360 5-minute lightning density overlaid appears to weaken a bit as new convection farther southwest takes advantage of a stout low-level jet. Notice how the lightning cores are exceeding the color scale that was set by the developers at OPC and NESDIS. Grant it, the color scales are somewhat limited by the GEMPAK software (6.5 bit or 96 colors), yet it’s safe to assume the lightning activity is very intense.

WPC MPD #0154 issued by forecaster, Andrew Orrison, at 0500 UTC on 04/29/17. Click to enlarge

Finally, around 0500 UTC on 04/29/17, Andrew Orrison again referenced GOES-16 in his analysis of the well-defined (new) MCS which developed overnight:

“THE SATELLITE PRESENTATION OF THE CONVECTION IS VERY IMPRESSIVE
WITH THE EXPERIMENTAL GOES-16 10.3 MICRON/IR IMAGERY DEPICTING A
VERY LARGE AREA OF VERY COLD CONVECTIVE CLOUD TOPS…REACHING
NEARLY -80C…WITH NUMEROUS OVERSHOOTING TOPS EMBEDDED WITHIN THE
CONVECTIVE MASS. THIS IS INDICATIVE OF VERY STRONG FORCING WHICH
IS ENHANCED NOT ONLY IN THE LOW LEVELS GIVEN THE LOW LEVEL JET AND
ISENTROPIC ASCENT…BUT ALSO BROADLY DIFFLUENT FLOW ALOFT
ASSOCIATED WITH RIGHT-ENTRANCE REGION JET DYNAMICS.”

GOES-16 CONUS (5-minute) 10.3 um “Clean” infrared animation valid from 2202 UTC 04/28/17 to 0857 UTC 04/29/17. *Preliminary, Non-Operational Data* Click to enlarge

As Andrew referenced in his MPD, as the night progressed, the convection along the Midwest through Ohio Valley erupted into an elongated MCS with embedded Mesoscale Convective Vortices (MCVs) that will have to be watched later in the day.

WPC Day 1 QPF issued at 2032 UTC on 04/28/17. Click to enlarge

WPC Day 1-3 QPF issued at 2040 UTC on 04/28/17 and valid from 0000 UTC 04/29/17 to 0000 UTC 05/02/17. Click to enlarge

As you can see in the above Quantitative Precipitation Forecasts for Day 1 (top) and Days 1-3 (bottom), this was only the beginning of a prolonged flood threat for the Mid-Mississippi Valley and eventually farther north to western Michigan.

GOES-16 is certainly proving to be useful in operations as the increased temporal and spatial resolutions when compared to GOES-E (13) and GOES-W (15), provides more detail, fluidity, and trend monitoring to assist in the forecast decision-making process. Additional channels, multispectral imagery (RGBs), band-differences, and derived products will be explored throughout 2017, so please stay tuned for more posts!

Thanks for reading!

GOES-16 Contrails in the Southwest on 04/10/17

Posted by Michael Folmer on 04/13/2017

Posted in: ABI, Aviation, G16-CH02_0.64_VIS-Red, G16-CH04_1.37_NIR-Cirrus, G16-CH05_1.6_NIR-SnowIce, G16-CH09_6.9_WV-Mid-Level, Uncategorized, Water Vapor Imagery. Tagged: #G16, #GOES16, Contrails, Southwest Weather. Leave a comment

Contrails_20170410

Traffic camera view of contrails from Mesa, AZ, courtesy Arizona Department of Transportation. Full Resolution

Top-Left: Red Band (Ch 2, 0.64 um); Top-Right: Cirrus Band (Ch 4, 1.38 um); Bottom-Right: Snow/Ice Band (Ch 5, 1.61 um); Bottom-Left: Mid-Level Water Vapor (Ch 9, 6.9 um). *Preliminary, Non-Operational Data* Full Resolution

This morning there were a lot of contrails evident on the GOES-16 data. Looking at the VEF 12Z 10 APR 2017 sounding (see below), conditions look good for them – lots of high-level moisture. From this, we expect most of the contrails to be in the 200-300 mb (which is around a cruising altitude of ~30,000 ft).

The VEF 12Z 10 APR 2017 sounding. Full Resolution

Of course we can’t see the contrails until the sun comes up in the visible and near-IR bands. However, using the different water vapor bands, we can still see them (the improved resolution helps too!). Using this website to learn about weighting functions, we can get a general idea of the level at which the weighting function for each water vapor channel peaks. Since contrails are typically located high in the troposphere, they will appear similarly visible in all three water vapor channels. In other words, most water vapor absorption for the three water vapor channels (see weighting functions below) takes place below the level at which a typical contrail will be located. The 7.34 um channel will be slightly better than the other two water vapor channels at detecting upper level cloud features such as contrails since it is the least sensitive to water vapor absorption.

GOES-16 ABI for Ch 8 (Upper-Level Water Vapor, 6.2 um)

GOES-16 ABI for Ch 9 (Mid-Level Water Vapor, 6.9 um)

GOES-16 ABI for Ch 10 (Low-Level Water Vapor, 7.3 um)

Comparison of three GOES-16 water vapor channels at 1657 UTC (same time as Mesa webcam image) on April 10, 2017. *Preliminary, Non-Operational Data* Full resolution: https://satelliteliaisonblog.files.wordpress.com/2017/04/20170416_wv_contrails.gif

The “split-window” (10.35 – 12.3) moisture difference does an especially good job at detecting high, thin clouds such as contrails:

1642 UTC 10 April 17 10.35 um – 12.3 um split window difference. *Preliminary, Non-Operational Data* Full resolution: https://satelliteliaisonblog.files.wordpress.com/2017/04/20170410_wv_swd.gif

Once the sun does come up, we can use our other bands. In this loop, I have the Red Band (Ch 2, 0.64 um) in the top-left, the Cirrus Band (Ch 4, 1.38 um) in the top-right, and the Snow/Ice Band (Ch 5, 1.61 um) in the bottom-right. First thing I notice is that the contrails don’t show up the best in the Red Band, the Cirrus band pops them the best. According to the GOES-R ABI Fact Sheet for the Cirrus Band,

The “cirrus” near-infrared band at 1.37 μm will detect very thin cirrus clouds during the day. This band is centered in a strong water vapor absorption spectral region. It does not routinely sense the lower troposphere, where there is substantial water vapor, and thus provides excellent daytime sensitivity to high, very thin cirrus under most circumstances, especially in warm, moist atmospheres.

Thus the high-clouds pop against a muted background of the lower troposphere. If you watch this loop, you can also see the contrails increase in abundance as we progress from 12Z through 1530Z. That is due to the increase in air traffice, which is confirmed with this loop (from Planefinder.net).

Air traffic during morning of 10 April 2017, courtesy Planefinder.net. Click here for animation.

Thanks for reading!

Paul Iniguez (SOO-Phoenix WFO)

Post edited on 4/16 (Bill Line, NWS)

“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.”

Atlantic Mesoscale Oceanic Low in late March 2017

Posted by Michael Folmer on 04/11/2017

Posted in: ABI, G16-CH07_3.9_SWIR, G16-CH08_6.2_WV-Upper-Level, G16-CH09_6.9_WV-Mid-Level, G16-CH10_7.3_WV-Low-Level, OPC, Uncategorized, Water Vapor Imagery. Tagged: #G16, #GOES16, ABI, Ocean Storms, OPC. 4 Comments

During the overnight hours of March 19-20, 2017, an amplifying upper level shortwave moved off the Mid Atlantic coast and led to the rapid development of a mesoscale oceanic cyclone across the Gulf Stream east and southeast of Cape Hatteras. The upper level feature moved south and southeast along the backside of a deep upper level long wave trough near 68W. The global models including the GFS and ECMWF were not well initialized with the upper level shortwave and consistently, over the previous several model runs, were only indicating a weak trough would develop at the surface. Conversely, the 4km NAM and HRRR were each showing surface low development and significantly higher associated surface winds than shown by the coarser global models. OPC forecasters had been carrying storm warnings across a few offshore zones through 00 UTC March 20, 2017.

500 mb analysis valid 00 UTC 20 March 2017 issued by the Ocean Prediction Center. Click here to open in a new window.

Animation of the 20 March 2017 00 UTC 4 km NAM pmsl and surface winds. Yellow boundaries delineate the OPC offshore forecast zones. Click here to open in a new window.

The GOES-16 water vapor imagery, including the 6.9 um mid-level and 6.2 um upper-level, suggested that the mid/upper shortwave was more amplified than initialized by the global models. The feature was also apparent in the GOES-16 7.3 um lower-level water vapor imagery, indicating it may be vertically stacked or at least extend through the lower levels. The three water vapor channels alone indicated there was likely adequate forcing through the upper and mid levels, and even into the lower levels, to support the development of a surface low. However, the low level circulation analyzed in the GOES-16 3.9 um shortwave infrared imagery confirmed the presence of the surface low. In addition, the enhanced baroclinicity the system encountered as it tracked across the Gulf Stream likely played a big role in the storm’s intensification. The sea surface temperature (SST) gradient along the north wall of the Gulf Stream can be seen in the GOES-16 3.9 um shortwave infrared animation.

GOES-16 6.2 um upper-level water vapor animation valid 2102 UTC 19 March 2017 – 0902 UTC 20 March 2017. *Preliminary, Non-Operational Data* Click here to open in a new window.

GOES-16 6.9 um mid-level water vapor animation valid 2102 UTC 19 March 2017 – 0902 UTC 20 March 2017. *Preliminary, Non-Operational Data* Click here to open in a new window.

GOES-16 7.3 um lower-level water vapor animation valid 2102 UTC 19 March 2017 – 0902 UTC 20 March 2017. *Preliminary, Non-Operational Data* Click here to open in a new window.

GOES-16 3.9 um shortwave infrared animation valid 2102 UTC 19 March 2017 – 0902 UTC 20 March 2017. *Preliminary, Non-Operational Data* Click here to open in a new window.

Upon reviewing the GOES-16 imagery and evaluating the most recent model guidance, the overnight OPC forecaster extended the storm warning through the night period, and also expanded the warning to include the outer mid Atlantic offshore waters. The significantly improved temporal and spatial resolution of the GOES-16 imagery, along with the additional water vapor channels, allowed forecasters to better diagnose the strength of the upper level shortwave and also, the presence of the surface low, which then gave forecasters more confidence in amending the warnings. Even as the both the upper level feature and the surface low appear to shear and weaken in the three GOES-16 water vapor channels and 3.9 um shortwave infrared band around 06 UTC, there was a ship which reported gale force winds (35 kt) at 06 UTC well southwest of the surface low.

Thanks for reading!

James Clark (OPC) and Michael Folmer (CICS)

GOES-16 perspective on April 2 Severe Weather Event

Posted by Bill Line on 04/03/2017

Posted in: ABI, G16-CH02_0.64_VIS-Red, G16-CH13_10.3_IR-Clean, Lightning, SPC, SRSOR, Super Rapid Scan, Tornado, Uncategorized, Water Vapor Imagery. Tagged: #GOES16, GOES-16, Louisiana, Louisiana tornadoes, Texas. Leave a comment

A significant severe weather event impacted E TX, LA, and MS on Sunday, April 2. A SPC Moderate Risk for severe had a region upgraded to High at the 1630 UTC Day 1 outlook for the tornado threat. Given the threat, GOES-East RSO was requested by SRH, and Mesoscale Domain Sector 1 granted over the region. The early day setup included a closed upper low moving NE across central Texas towards Arkansas. At the surface, an MCS and associated cold pool from the previous evening was traversing eastward through Texas. Ahead of this feature, strong southerly flow drew up warm, moist Gulf air.

20170402 1630 UTC Day 1 Outlook Graphic

The evolution of the overnight MCS is depicted in 5-min GOES-16 ABI 10.4 um clean window IR imagery below. This channel is the “cleanest” of the IR channels because it is least sensitive to absorption by atmospheric constituents such as water vapor. The development of thunderstorms during the evening of the 1st is seen as rapid cooling of the cloud tops in SW Texas. The rapid expansion of the cold cloud tops signals the continued maintenance of convection, and development of an MCS. By early morning on the 2nd, rapid warming becomes evident, especially on the southern end of the MCS, signaling a weakening and dissipation of thunderstorm activity. The higher spatial (2km vs 4 km) and temporal (5-min vs 15-min over CONUS) resolution of the GOES-16 satellite allows for these cloud top temperature trends to be more easily and promptly diagnosed.

GOES-16 10.4 um IR from the evening of April 1 to the early afternoon of April 2. For full resolution, view: https://satelliteliaisonblog.files.wordpress.com/2017/04/20170402_early_ir_mcs_long_anno.gif

By late morning, convection began to develop within the warm sector in E Texas and Louisiana ahead of the previous evening’s weakening cluster of thunderstorms. These storms quickly became severe, producing large hail, wind and tornadoes. Detection of convective initiation is significantly improved in the 1-min, 0.5 km visible imagery, as was shown in a previous blog post that compared GOES-16 data with GOES-13 data for initial storm development.

Storm top features of mature convection are also easier to discern in the GOES-16 imagery compared to current GOES satellites. Below is a side-by-side comparison of 0.5 km, 1-min VIS from GOES-16 and 1 km, Rapid Scan (5-15 min) VIS from GOES-13. Additionally, GOES-16 2 km, 1-min IR is compared with GOES-13 4 km, Rapid Scan IR. The time period is 2145 UTC to 2315 UTC. Storm top features apparent that are associated with strong-severe weather at the surface include overshooting tops, enhanced-V’s, and above-anvil cirrus plumes. Gravity waves emanating from the updrafts, indicators of turbulence and caused by strong updrafts, are also more obvious in the GOES-16 data.

2145 – 2315 UTC 02 April 2017 GOES-16 1-min 0.5 km 0.64 um VIS (left), GOES-13 5-15-min 1 km 0.63 um VIS (right). Full resolution: https://satelliteliaisonblog.files.wordpress.com/2017/04/20170402_vis_compare2_anno.gif

2145 – 2315 UTC 02 April 2017 GOES-16 1-min 2 km 10.4 um IR (left), GOES-13 5-15-min 4 km 10.7 um IR (right). Full resolution: https://satelliteliaisonblog.files.wordpress.com/2017/04/20170402_ir_compare_anno.gif

The Geostationary Lightning Mapper (GLM) is the other new earth-pointing instrument aboard the GOES-R series of satellites, and can detect total lightning activity with uniform detection efficiency. Data from the GLM are not yet available, however ground-based networks can be used to get a feel for how GLM data will generally look in AWIPS. Plotted is GOES-16 2-min visible imagery with Earth Networks 1-min Total Lightning Pulse density data, binned in 8-km grid boxes to match the resolution of the GLM, overlaid as semi-transparent. Pulses are a very basic variable, and when binned into grid boxes over a time period, provide a good measure of fluctuations in lightning activity. Max’s in total lightning density activity signify the core updraft regions of thunderstorms, which are also represented in visible imagery by a high degree of texture and overshooting tops. Rapid increases in lightning density signify rapid upticks in updraft strength, and thunderstorm intensification. Similarly, decreasing trends in total lightning activity will signify a weakening storm.

GOES-16 2-min, 0.5 km visible imagery with ENI 1-min, 8km Pulse Density overlaid. Full resolution: https://satelliteliaisonblog.files.wordpress.com/2017/04/20170402_1-min_w_lightning_anno.gif

By early evening, the strong/severe storms had organized into a linear system, and while the severe threat had lessened, a flash flood threat had begun. A separate post will be written with details about the flood event.

– Bill Line, NWS

Satellite Liaison Blog

GOES-R & JPSS: The Future of Weather Satellites

Water Vapor Imagery

Explosive Thunderstorms, Heavy Rain Threat, and GOES-16

GOES-16 Contrails in the Southwest on 04/10/17

Atlantic Mesoscale Oceanic Low in late March 2017

GOES-16 perspective on April 2 Severe Weather Event

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