Lightning

GOES-16 Helps TAFB Analyze Strong Convection in the Gulf of Mexico

Posted by Michael Folmer on 05/01/2017

Posted in: ABI, G16-CH02_0.64_VIS-Red, G16-CH13_10.3_IR-Clean, Lightning, NHC, TAFB, Tropics, Uncategorized. Tagged: #G16, #GOES16, Convection, Gulf of Mexico, Hurricane Center, thunderstorms. Leave a comment

On the morning early of 04/06/17, TAFB forecasters noted a nice V-pattern to convection at the tail end of a front in the northeast Gulf of Mexico. The increased temporal and spatial resolution of GOES-16 compared to the GOES-13 (east) provided more details on the organization and maintenance of the convective line that would otherwise have been analyzed.

GOES-16 0.64 um “Red” visible animation showing strong convection in the eastern Gulf of Mexico, valid 0900 UTC – 1600 UTC on 04/06/17. *Preliminary, Non-Operational Data* Click to Enlarge

Hugh Cobb (TAFB Branch Chief) noted: “We also looked at the Red VIS Band 2 for this event. The VIS imagery was more striking in that you could see the shadows of the high cirrus cast on the lower cloud deck in the animation and the “beavertail” of of the low clouds feeding into and maintaining the deep convection.”

GOES-16 10.3 um “Clean” infrared animation (same as above), valid from 0900 UTC – 1600 UTC on 04/06/17. *Preliminary, Non-Operational Data* Click to Enlarge

GOES-16 10.3 “Clean” infrared imagery with 5-minute GLD-360 lightning density overlaid, valid 0900 UTC – 1600 UTC on 04/06/17. *Preliminary, Non-Operational Data* Click to Enlarge

Jorge Aguirre-Echevarria (TAFB Forecaster) noted that “the striking cloud/convective signature and associate lightning activity observed that day over the waters of the far southern Gulf of Mexico.” In particular, these events are rather rare at such a low latitude in the TAFB Offshore Zones. The GOES-16 10.3 μm infrared imagery proved to be very helpful in seeing the overshooting tops and the cold cloud canopy temperatures which signified the activity would persist west of Key West, FL.

Thanks for reading!

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 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

“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.”

On the afternoon of 03/31/17, severe thunderstorms, including a couple long-lived supercells, moved across the southeastern most part of Virginia leaving behind a path of hail, wind damage, and at least one tornado, with two more reported in northeast North Carolina. These storms developed in association with a mid-level trough and related surface cyclone and cold front.

GOES-16 10.3 um “Clean” infrared animation valid on 03/31/17. Made using GEMPAK. *Preliminary, Non-Operaitonal Data* Click here to open in a new window.

The 10.3 µm “Clean” infrared channel on GOES-16 shows the large storm system transitioning to the East Coast with a dry slot that moves into eastern NC/VA quickly erupting into thunderstorms. Note how the cloud tops associated with the secondary band that develops in the afternoon quickly cool, then appear to jump to the Gulf Stream. This becomes a forecast challenge for the local National Weather Service offices as the storms transition from the land, to nearshore water, then to OPC’s offshore zones.

GOES-16 6.9 um mid-level water vapor animation valid on 03/31/17. Made using GEMPAK. *Preliminary, Non-Operational Data* Click here to open in a new window.

GOES-16 7.3 um low-level water vapor animation valid on 03/31/17. Made using GEMPAK. *Preliminary, Non-Operational Data* Click here to open in a new window.

The 6.9 µm and 7.3 µm water vapor channels show the enhanced warming (drying) in the mid to low levels where the atmosphere becomes unstable in the presence of near-surface warming/moistening and strong forcing with the upper-low coming in from the west. The supercell ahead of the main forcing remains isolated until later in its lifecycle with the dry slot aiding in the instability.

GOES-16 7.3 um low-level water vapor valid on 3/31/17. Made using McIDAS V. Click here to open in a new window.

Zooming in on the area of thunderstorm development in the 7.3 µm low-level water vapor channel (~700 mb), the region of enhanced mid/low-level drying/warming ahead of the cold front within which isolated thunderstorms developed is apparent. Behind the cold front, that region of the atmosphere is expectedly cooler. The 7.3 µm channel is new with the GOES-R series, and when combined with the higher spatial and temporal resolution, allows forecasters to track (for the first time) low/mid-level features such as elevated mixed layers and cold fronts aloft.

00z 01 April 2017 Weighting Function at Moorhead City, NC. Click here to open in a new window.

00Z Weighting functions (UW/CIMSS) from the GOES Sounder 7.4 µm channel (very similar to ABI 7.3 µm) at MHX (just south of strongest t-storms) confirms that the drying/warming we are seeing is centered around 700 mb.

Radiosonde profiles at Morehead City, NC (left, ahead of cold front) and Roanoke, VA (right, behind cold front). Click here to open in a new window.

Looking at 00z soundings for comparison, mid-level drying was indeed present above near surface warming/moistening ahead of the cold front in Morhead City, NC leading to an unstable atmosphere. Meanwhile behind the cold front at Roanoke, VA, the cooler surface and moistening aloft led to a significantly less unstable environment.

GOES-16 10.3 um “Clean” infrared with the GLD-360 15 minute Lightning Density product overlaid, valid 0000 UTC 03/31/17 – 0645 UTC 04/01/17. Made using GEMPAK. *Preliminary, Non-Operational Data* Click here to open in a new window.

The 10.3 µm “Clean window” infrared channel overlaid with the 15-minute GLD-360 lightning density product produced at OPC, shows the rapid increase in lightning activity as the storms in the dry slot mature. This lightning density has proven quite useful to forecasters as a proxy to the Geostationary Lightning Mapper (GLM) that is located on GOES-16. The OPC forecasters can then use this information to characterize the thunderstorms as they move offshore into active shipping and fishing areas.

Storm Prediction Center Storm Reports for 03/31/17. Click here to open in a new window.

AKQ Base Reflectivity valid from 1800 UTC to 2358 UTC on 03/31/17. Click here to open in a new window.

AKQ Base Velocity valid from 1800 UTC to 2358 UTC on 03/31/17. Click here to open in a new window.

GOES-16 0.64 um “Red” visible animation (500 m) valid on 03/31/17. Made using McIDAS V. Click here to open in a new window.

These storms developed within mesoscale domain sector (MDS) 1. This meant that 1-min imagery was available for this event even though no domain was requested, and because a domain was not requested elsewhere. The 1-minute, 0.5 km 0.64 µm “Red” visible imagery shows isolated supercell thunderstorms developing out ahead of the cold front in a warm, moist atmosphere. Additional development is noted along the cold front, which raced towards and caught up to the isolated thunderstorms by sun down.

GOES-16 0.64 um “Red” visible, 1-minute imagery with the GLD-360 2-minute Lightning Density overlaid, valid from 2000 UTC to 2358 UTC on 03/31/17. Made using GEMPAK. *Preliminary, Non-Operational Data* Click here to open in a new window.

The 1-minute 0.64 µm “Red” visible imagery with the 2-minute GLD-360 lightning density overlaid shows the uptick in lightning associated with the isolated supercell that moves through Chesapeake, VA and exits around Virginia Beach. Note the increased lightning intensity around the time of the tornado.

Forecasters are looking forward to using the GLM data with the imagery to help better forecast thunderstorm over land and especially over the oceans.

The preliminary storm surveys from the Wakefield, VA NWS Weather Forecast Office are included below for your convenience.

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Thanks for reading!

Michael Folmer (CICS) and Bill Line (NWS)

Satellite Liaison Blog

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