SPoRT is planning an assessment of Total Lightning products with several existing and new collaborators from WFOs, CWSUs, and National Centers, ranging in locations from southern Florida to New Mexico and Colorado. From May 15 – July 15, 2014 operational forecasters will evaluate the application of total lightning to support severe storm, public safety, and aviation weather warning responsibilities. To prepare, SPoRT is holding tele-training sessions with collaborators during the week of April 21 and has provided users several training modules as well as a Total Lightning Quick Guide. These can be found via SPoRT’s Training Page and on the NOAA LMS. Experience with total lightning data will prepare users for the GOES-R GLM as well as provide feedback from operations to researchers regarding the types of products users desire.
Archive for the ‘GOES-R Proving Ground’ Category
This was one of those storms that people will talk about for years, especially those that were directly affected by it. It all started with three separate shortwaves that all phased together once off the Mid-Atlantic coast, far enough offshore to limit any direct effects save for some unusual late season snow and gusty winds the next day. The highest impact area included Cape Cod, Nantucket, Nova Scotia, and New Foundland. I’m sure any ships that were in the vicinity were not happy with this situation!
The evolution of the nor’easter can be seen in the GOES Sounder RGB Air Mass animation above. A southern stream system originating in the Gulf of Mexico moved east of Florida while two other shortwaves dropped southeast out of Canada. All of the pieces combined near the North Carolina coastline, but the explosive deepening took place as the combined system moved northeast away from the Mid-Atlantic. There appears to be a few stratospheric intrusions, but the most impressive intrusion occurs with the final shortwave as noted by the dark oranges and reds that appear at the end of the day on 03/25. When models are forecasting a phasing situation, this product can be quite useful in identifying the features and observing the stratospheric drying seemingly “bleed” from one shortwave to the other.
The two MODIS RGB Air Mass products above show the nor’easter near peak intensity. Notice how distinct the gradient between oranges and greens is in this image, almost as though you can see the upper portion of the frontogenesis, well behind the actual front. The intensity of the stratospheric intrusion is quite evident by the dark pinks near the center of the cyclone. The second image shows the wind field overlaid from ASCATB. Notice the large area of hurricane force winds (red wind barbs) near the bent-back front, in the comma-head of the cyclone. This area of wind affected parts of Southeast Massachusetts, including Nantucket where winds gusted from 60-85 mph. Nantucket recorded a wind gust of 82 mph and about 10″ of snow. Meanwhile, Nova Scotia bore the brunt of this beast with wind gusts of 129 mph at the Bay of Fundy and 115 mph in Wreckhouse. Waves were equally impressive with altimeter readings between 40-50 ft and a buoy report of 52.5 ft.
Another interesting aspect of this storm was the two distinct areas of thunderstorms that erupted. I overlaid the OPC and TAFB offshore zones for reference. Notice well east of the Bahamas there are possible supercell thunderstorms associated with the southern shortwave energy. Meanwhile, as the strong northern stream shortwaves exit the NC coastline, two areas of thunderstorms developed with the easternmost storm exhibiting supercell characteristics. Although the lightning was not as intense with this northern area, I would speculate that the storms were associated with very strong wind gusts due to the dry air associated with the stratospheric intrusion.
I’ll finish this entry with two VIIRS Visible images above showing the majestic beauty of this nor’easter. The 18 UTC OPC surface analysis depicts the storm at a maximum intensity of 955 mb, after a 45 mb drop in 24 hours! This qualifies as one of the most explosive cyclones on record. Another tidbit. . .this was the strongest storm in this part of the Atlantic since Hurricane Sandy (2012).
Thanks for reading!
Well, it’s February and it’s the East Pacific off of California, so the short answer is no. But. . .what an amazing structure, right? We haven’t seen anything this good looking in the tropical Atlantic in years! But I digress. . .
The first image was collected four hours before the second image and you can see how the center of the intense storm developed an “eye-like” feature (images courtesy of NASA SPoRT). Notice the distribution of the pinks and reds in both images as well. That is dry, stratospheric air filling the center of the strong upper-level low (~300-500 mb). The second area shows an additional area of pink approaching the southern California coast. This area is associated with strong instability that has led to rare California thunderstorms.
So, how do we know if there is stratospheric air?
The first image above is the AIRS Total Column Ozone product developed at NASA SPoRT. The color bar on the left is not correct. The main idea is that the warmer (cooler) the colors, the more (less) ozone is in the atmospheric column. The green colors indicate ozone levels above 200 Dobson Units (ozone unit of measurement) with the magenta areas indicating ~500 Dobson Units. The second image shows the AIRS Ozone Anomaly product with the first level of blue indicating 125% of normal, while the yellow region indicates >200% of normal ozone at that latitude and geographic location. Stratospheric air is associated with high levels of ozone and potential vorticity which can help identify the strength of the upper-level low. These images show the connection of this ozone pocket with the “reservoir” of ozone located in the northern latitudes at this time of year.
As the upper-low cut off and became stacked over the surface low (~971 mb), you can see how the high concentration of ozone becomes more focused over the storm. Once again, the magenta coloring indicates ozone levels >500 Dobson Units. The anomalies are more incredible with a large area of >200% of normal directly west of southern California.
I will continue to work with forecasters at OPC, TAFB, SAB, and WPC on discovering ways to use these products in conjunction with the RGB Air Mass products to gauge storm strength and look for signals upstream of developing tropopause folds and stratospheric intrusions.
The ozone isn’t the only impressive part of this storm. Notice the occasional bursts of lightning within the spiral bands of the parent storm. Although not completely unusual, this is a great indicator of how much energy is available to this storm.
I put together a longer animation of the GOES-Sounder RGB Air Mass product with the GLD-360 lightning strikes overlaid. Note the first system that came ashore in California earlier this week, then moved over the four-corners regions with plenty of lightning, especially for this time of year. The current storm is seen lurking offshore with more lightning developing in a band of thunderstorms that moved from Los Angeles to just north of San Diego. This system will be responsible for the next bought of winter weather for the Midwest to the Mid-Atlantic next week.
Thanks for reading and as always, feel free to contact me with questions and feedback!
SPoRT is conducting an assessment of RGB imagery for Aviation and Cloud Analysis with Alaska WFO partners. A 17 minute training module for high-latitude application of nighttime RGBs with an Alaska example was created by SPoRT to support this assessment (see SPoRT training page to download or launch module). The Juneau WFO provided feedback for 1/24/14. Here is a part of their feedback regarding the value of the Nighttime Microphysics RGB imagery from MODIS and VIIRS and an example image from AWIPS/D2d.
WFO Juneau feedback:
“… the microphysics image was very helpful in picking out where the fog and low clouds were in the complex terrain that is the SE panhandle. most of the fog this morning was confined to the narrower valleys and channels while the wider channels were mostly clear. This is possibly due to higher winds still present in the wider channels limiting fog formation there. It also showed little or no fog and low clouds out in the gulf. The microphysics image was very helpful with figuring out fog for zone and marine forecasts. It also helped out with the TAFs with seeing if there were any higher clouds layers above the fog layer.”
A well defined TROWAL feature that set up over the high plains from eastern NM into western TX and KS on December 21, 2013 was captured very well by the NESDIS snowfall rate product. A composite radar reflectivity loop in the first image below summarizes the overall evolution of this feature between 12 UTC on December 21st and 00 UTC on the 22nd (click image to loop and enlarge). Initially temperatures were too warm for snow across much of the area however as a potent cold front shifted south over the region rain changed over to snow. In the area of greatest instability the snow became heavy at times from near Tucumcari, NM (KTCC) to Dalhart, TX (KDHT).
The following series of images compare hourly precipitation reports at several sites across western TX and KS with the NESDIS snowfall rate product. The first image was captured at 2040UTC and the AWIPS cursor readout at KDUX (Dumas, TX) is shown. Note the observation is reporting an hourly precipitation accumulation of 0.05 (P0005) with moderate snowfall and a visibility of 1/2SM. The cursor readout comparison with the QPE product is 0.0544 in/hr. The following sample point valid for KPYX (Perryton, TX) is reporting a visibility of 1/4SM however no weather or precipitation is available since it is only an AWOS. However, the QPE product is sampling a precipitation rate of 0.1064 in/hr which converting with a simple 10:1 snow ratio would equate to heavy snow at 1″ per hour. The next image was captured at 2236UTC and the cursor readout at KDDC (Dodge City, KS) is shown. Note the observation is reporting an hourly precipitation accumulation of 0.07 (P0007) with moderate snowfall and a visibility of 1/2SM. The QPE comparison in the readout shows a rate of 0.092 in/hr. These values are exceptionally representative of the current conditions and the latency is less than 30 minutes.
After the storm system pulled out of the region the Snow-Cloud RGB product provided a stellar view of this mesoscale band of snowfall. Modifying temperatures over the following days significantly eroded snowpack in most areas except where the heaviest snow fell. Local storm reports obtained from the Iowa State website indicated between 6 and 11 inches of snow impacted the area within the central axis of the TROWAL feature.
Late yesterday evening (Dec 17th) fog began forming along coastal areas of Lousiana and Texas. By 10 pm CST, visibilities at some locations along the coast had already dropped to less than 1 SM. The fog continued to intensify, with visibilities falling to around 1/4 SM or less at many locations during the early morning hours this morning (Dec 18th). By 2 am CST (0800 UTC), the visibility had fallen to near 0 SM in portions of SW Louisiana as noted by the observation at Jennings (3R7, near Fenton in the image, image 1).
In this standard GOES spectral difference imagery however, the fog is very diffcult to visually discern, likely due to it’s very shallow depth. There is some indication of the fog, with slightly brighter pixels in areas of southern LA and SE Texas. However, notice the better (albeit slightly) detection of the fog in the Nighttime Microphysics RGB products from the VIIRS and MODIS instruments below (images 2 and 3, respectively). The fog in these images appears as a pinkish-gray color.
I think the fog is a little easier to see in the MODIS image, which may be due to higher resolution and small differences in channel wavelengths between the VIIRS and MODIS instruments. Nevertheless, the fog in all of the imagery is rather subtle and will require development of pattern recognition by forecasters. Sampling the color contributions, I found that the primary changes between areas of fog and areas without occurred in the green color (assigned the ~10.8-3.9/3.7 channel difference), which would be expected. For example, when taking a color sample from the pinkish-gray band of fog in SW Louisiana (near Jennings) from the MODIS image, I came up with: Red-180, Green-137, Blue-165. Meanwhile, sampling of a pixel in central Louisiana without fog: Red-167, Green-99, Blue-150.
So, how did the fog appear in the Day-Night Band RGBs? Not very well at all, as you can see in the next couple of images…
I wasn’t able to detect any fog at all in the Day-Night Band RGB imagery. However, there is still potentially important information to glean from all of this. If the fog is evident (even slightly) in the NT Microphysics RGB imagery mainly due to the 10.8-3.7/3.9 channel difference, but is essentially translucent in the visible spectrum (Day-Night Band), then it is likely very shallow. This could be helpful for determining the duration of the fog during a change of conditions, such as the development of mixing after sunrise (i.e. shallow fog dissipation will be quicker than thick fog dissipation).
Notice in the GOES visible loop below (images at 0445 UTC and 0601 UTC) that the fog dissipated very quickly after sunrise (click the expanded image to obtain the loop).
The Corpus Christi, Houston and Slidell offices all issued Dense Fog Advisories or Special Weather Statements concerning the fog in their respective County Warning/Forecast Areas during the early morning hours.
The RGB Imagery for Aviation and Cloud Analysis got underway on December 1st with SPoRT’s collaborative coastal NWS offices in Southern Region. These offices include Corpus Christi, Houston, Slidell, Mobile, Melbourne, and Miami. A separate evaluation with AK offices and CA/OR coastal offices has also begun recently. The SR coastal office evaluation will run through the end of January, where offices will be evaluating the VIIRS and MODIS Nighttime Microsphysics RGB imagery, VIIRS Day-Night Band Reflectance and Radiance RGBs, in addition to the hybrid GOES/MODIS/VIIRS 11-3.9 um looped product. SPoRT personnel have conducted training for the offices and will be helping during the evaluation with questions and/or technical issues. Although RGBs have been used in the European forecast community for years, they are quite new to most U.S. forecasters. However, and importantly, the imagery available from the Aqua/Terra satellites (MODIS imager) and the Suomi NPP satellite (VIIRS imager) are a part of GOES-R and JPSS Proving Ground activities and will serve as educational tools for forecasters before the GOES-R and JPSS eras. As a part of the evaluation, forecasters will answer a short survey about the operational impact of these imagery on aviation forecasts in particular, but may of course include impacts for other operational products (i.e. advisories, fire weather, public, hydrologic, etc).
While many potential positive impacts to various forecast products have been related on this blog, I’ll be watching and posting those which forecasters at these offices (and myself) observe during the evaluation period (time permitting of course). Take the following case from yesterday, December 9th, for example…
In the image above, notice the swath of light purple colors that extend across a good portion of the TX Gulf Coast. Further north, in north central and northeastern TX extending to include portions of Oklahoma, Missouri and Arkansas, an area of low clouds with colors closer to dull reds to greenish-white are apparent. In Image 1, a small area near Corpus Christi, TX has been sampled, with the contributions from Red (183), Green (132) and Blue (209) included in the image (This was sampled in Microsoft Paint). At about the same time, observations across this region of coastal TX were nearly uniform. Ceilings were around 300-400 ft from Houston, to Port Lavaca and Corpus Christi, with visibilities ranging from 1.5 to 2.5 SM.
Thus, the colors represented by the shades of light purple represented an extensive low stratus/fog deck encompassing the area. Notice that a swath of this color/cloud type also extended into northern Louisiana and Mississippi. Low visibilities ranging from 2.5 to 3 SM and low ceilings around 400 ft were observed in both areas.
Herein lies the power of the RGB imagery. Since the combination of colors are related to several physical characteristics (i.e. red – optical depth, green – particle phase and size, blue – temperature), then it is easier to make assessments about cloud homogeneity or inhomogeneity. While other satellite observations generally just relate one physical characteristic (usually temperature), or in the case of the standard 11-3.9 channel (particle phase/size), they don’t have the ability to tie together several physical characteristics together in one image like the RGBs can. It is thus much easier, with RGB imagery, to assess locations where cloud characteristics are the same and make inferences about the similarity of ceilings and visibility in areas without direct observations.
This next image shows a sample of the color taken from the Texarkana site in NE Texas at the same time, underneath the area of low stratus containing more dull red colors.
As the difference in colors suggests, the cloud characteristics are different here than in SE coastal TX. Referring to image 2, the ceiling and visibility at Texarkana were 1100 ft and 6 SM, respectively. Ceilings were still relatively low, but were higher than in coastal TX, as was the visibility. Essentially, this was a slightly higher stratus deck. The red color contibutions were very similar in each location, suggesting clouds of similar depth. However, differences in green and blue are clearly discernible. The cloud deck near the coast certainly contained more blue, indicating warmer temperatures, which makes physical sense. The clouds in NE TX contained more green however, which would suggest smaller water particle size. But, emssions in the 3.9 channel from the surface beneath the low/thin cloud deck near the coast may also be contributing to less green color there. Taking a look at proximity soundings in this area of clouds from Forth Worth (FWD) and Little Rock (LZK), cloud tops decreased during the 00-12 UTC period, but contained super-cooled water droplets by the 12 UTC sounding.
As an aside, forecasters have expressed the desire (including myself) to have the specific values from the red, green, blue color contributions available in AWIPS when sampling the imagery. This is a valuable part of the feedback and evaluation process. Unfortunately, this is not possible in AWIPS I, but will be in AWIPS II.
A ridge of high pressure moved into the desert southwest in the wake of a strong winter storm system that impacted the region last weekend. Strong low level inversions beneath the ridge and melting snow cover increased the potential for an extended period of low clouds and freezing fog. The MODIS Nighttime Micropyhsics product valid at 0501 UTC November 29, 2013 showed low clouds and possible areas of freezing fog along the I-70 corridor over and west of Grand Junction. Observations at Grand Junction verified IFR low clouds at 900′ with visibilities above 6 miles. The following VIIRS Nighttime Microphysics product at 0904 UTC November 29, 2013 showed low clouds and freezing fog expanding eastward into the Colorado, Gunnison, and Uncompahgre River Basins and the Grande Valley south of Grand Junction. Visibilities have been significantly reduced to 1/4 mile at Montrose and farther south at Cortez. The ceiling at Montrose is 200′ with visibility at 3/4 mile. The nighttime microphysics product shows exceptional detail within the narrow valleys along Roan Creek to the northeast of Grand Junction. Notice the fog and low cloud deck is very close to Rifle at 0904 UTC but the observation still suggests clear skies. 31 minutes later at 0935 UTC the observation at Rifle dropped to LIFR at 400′ however visibilities remained at or above 6 miles.
The event in this blog post was provided by Amanda Terborg, satellite champion at the Aviation Weather Center.
SPoRT has been coordinating with the Aviation Weather Center (AWC) for a little over a year to incorporate the pseudo-geostationary lightning mapper (PGLM) mosaic demonstration product in operations, derived from ground-based lightning mapping arrays and part of the GOES-R Proving Ground. This work culminated with the transition from demonstration mode to the AWC’s operations floor in September, thanks to Amanda’s coordination. Shortly thereafter we received this particular event from October 7th.
On this day, one of the major items of interest was a line of storms moving through Washington D.C. and northern/western Virginia (Fig. 1). The storms were not creating major disruptions as flights were able to remain ahead of the line or work their way behind the line of storms. Figure 2 shows the aircraft tracks from 1402 UTC, which corresponds to the radar image in Fig. 1. Due to the different projection types in N-AWIPs, the primary point of interest is circled in each image. The major item of note is that there are no National Lightning Detection Network (NLDN) cloud-to-ground strike observations in the entire image. However, the circled region shows a cluster of 3-4 flashes observed by the PGLM product. As there are no corresponding NLDN strikes, these are solely intra-cloud flashes. By observing the flight tracks, the aircraft were flying behind the main line of highest reflectivities. Although the aircraft were behind the main line, Fig. 2 shows that approximately five aircraft flew into the region where the PGLM flashes were observed. At around 1400 UTC one of those flights was struck by lightning. The best news was that, while struck, the aircraft suffered no damage and continued safely on to its destination.
This example shows one of the major benefits of the future GOES-R Geostationary Lightning Mapper (GLM), as a space-borne instrument capable of observing total lightning (both intra-cloud and cloud-to-ground). Radar is an excellent tool for helping develop safe flight tracks. The ability of total lightning to observe intra-cloud flashes, as well as the spatial extent of these flashes, gives aviation planners additional information as to how to route aircraft, particularly in storms that have no cloud-to-ground observations. This will be very important in data sparse regions were radar and total lightning are currently not available.
As the Satellite Proving Ground for Marine, Precipitation, and Hazardous Weather Applications at the NOAA Center for Weather and Climate Prediction (NCWCP) prepares for the winter 2013-2014 demonstrations, it’s always nice when Mother Nature provides some examples, albeit we prefer non-life threatening. The Ocean Prediction Center (OPC), Weather Prediction Center (WPC), NESDIS Satellite Analysis Branch (SAB), and the NHC Tropical Analysis and Forecast Branch (TAFB) will be evaluating the RGB Air Mass product once again and the storm that affected northern Europe this morning is a great case of product utility!
The animation above shows the evolution of a Shapiro-Keyser (1990) type storm that affected the UK, France, Belgium, the Netherlands, Germany, and Denmark with strong winds early this morning. The highest observed wind gust was 99 mph on the Isle of Wight in the English Channel. Wind gusts ranged from 50-90 mph on average with multiple trees down. some structural damage, and at least 3 deaths. So, what in this storm caused the strong winds? The Air Mass product may have a clue.
At this first time step (0700 UTC on 10/28/13), the white circle on the Air Mass product (first image) shows an intruding area of reddish/pink coloring mixing into the blues and greens to the east. The reddish/pink coloring indicates dry, stratospheric air intruding into the deepening cyclone’s core. The water vapor image (2nd image) shows the drying (blue) and along with the Air Mass product, suggests a strong stratospheric intrusion that would help to transport high moment air (winds aloft) to the surface with deep mixing. This is the approximate time that high wind gusts were affecting southern England and northern France. It is tough to gauge the depth of the stratospheric intrusion in these images.
Five hours later, the intrusion appears to intensify (based on imagery) with a stronger/deeper reddish/pink coloring developing near and over Denmark on the Air Mass product, while the water vapor image really accents the drying with deep blues and even a bit of brown coloring along the western Denmark coastline. Now, this suggests that the stratospheric drying increased over this time, possibly helping to further mix down high moment air from the mid-troposphere, especially where there is clearing allowing the sun’s heat to aid in deep mixing of the atmosphere.
I’m sure this is not going to be the last example as we are just starting our winter storm season. I will be sure to include more updates in the next few months.
I leave you with this great photo of waves crashing around a lighthouse in South Wales. Thanks for reading!