SPoRT used the MODIS and VIIRS imagers (on NASA’s Aqua & Terra satellites, and NOAA’s S-NPP satellite, respectively) within the NOAA’s Satellite Proving Ground to assess the value of a “Dust RGB Imagery” product for potential use with GOES-R (now GOES-16). The Dust RGB proved useful on 13 April 2018 (animation above) where many dust plumes developed in the U.S. Southwest and Mexico. Forecasters were able to monitor dust plume initiation and issue advisories and warnings. In addition, several plumes continued to have impacts after sunset, and the Dust RGB, which uses only IR window channels (see Dust RGB Quick Guide), was able to continue monitoring the event at night while the visible imagery was no longer valuable. Some advisories were extended beyond their original expiration time. NASA SPoRT is using the NASA CALIPSO satellite and associated CALIOP lidar on board to validate and categorize dust signatures seen in the RGB and examine quantitative aspects like plume height and thickness. The image below shows an event from 3 April 2018 where forecasters from the NWS Albuquerque WFO and CWSU evaluated the Dust RGB impact to operations as part of SPoRT’s assessment activities, and the CALIOP lidar backscatter captured the dust plume over west Texas. From CALIOP the dust plume appears to be about 2 km thick in most locations, but the most concentrated region reached a height of about 3 km above ground.
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.
A methane explosion occurred last Friday, January 20, in rural northwest Alabama (story from WAFF-TV). NWS Huntsville provided decision support services to the incident, which posed significant risks to emergency personnel. The active pattern last weekend created additional concerns, since several rounds of rain and thunderstorms were forecast to move across the area (though fortunately the significant severe weather from that weekend remained well to the south).
One such event arrived Saturday morning as stratiform rain pushed back into the area. Forecasters noted that there were indications of cloud-to-ground lightning from the National Lightning Detection Network along the leading edge of the rainfall, so we leveraged flash extent density data from the North Alabama Lightning Mapping Array to investigate further. Strangely, when loaded as an image in AWIPS-2, this showed little.
It took some time to discover why. The flash rates were so low (1 flash per ‘scan’) that the FED image interpolation was smoothing the data below what the color curve could visualize. After the interpolation was turned off or the color curve edited again, the flashes were much more apparent, as seen in the following GIF loop from AWIPS.
Adding the full flash extent density information from the NALMA helped the forecasters to visualize the lightning threat beyond what was otherwise available in AWIPS. This helped when it came time to brief emergency personnel on the approaching threat.
This event also helps to reinforce the potential utility of the Geostationary Lightning Mapper (GLM) aboard GOES-16 as it becomes available this spring. However, forecasters will have to visualize the GLM data wisely. It will likely more important to view low flash rates for an IDSS or safety mindset, versus higher flash rate changes for severe weather. Even with total lightning, context is everything.
A potent winter storm system impacted portions of New Mexico on March 26, 2016, ending an extended stretch of very dry weather. Snowfall amounts of 3 to 9 inches were reported from the Sangre de Cristo Mountains eastward across the northeast plains. The MODIS and VIIRS satellite products proved useful for illustrating the extent of snow cover in both the daytime and nighttime scenes. The images below are graphical briefings posted to the NWS Albuquerque web page and shared via Twitter after this much needed snowfall event.
A powerful jet stream approached NM from the Pacific Northwest on February 23, 2016 and carved out a large scale upper level trough over the southern Rockies. Meanwhile, a strong area of surface high pressure raced southward down the front range of the Rockies and provided an influx of moist, cold air into eastern NM. Winter storm warnings were issued for several counties in northeastern NM with winter weather advisories in a few surrounding zones. Forecasters were eagerly anticipating how the event would unfold on the merged SFR product given the recent stretch of very dry and exceptionally warm weather. Figure 1 below is a Graphical Briefing issued prior to the event with expected snowfall totals.
Rain and high terrain snow developed from north to south late on the 22nd before transitioning to all snow early on the 23rd. Forecast models from the 21st indicated that an area of heavy snow would impact northeastern NM on the 23rd. Figure 2 shows a well-defined axis of higher snowfall rates stretching from Trinidad, CO to Capulin, NM and Tucumcari, NM in the stand-alone SFR product from 0912 UTC 23 February 2016. Sampling this area showed peak liquid equivalent values near 0.07″/hr. The 0900 UTC observation at Trinidad showed the visibility had fallen to 1/2 mile within the snow band while the observation at Raton, NM showed no snowfall where the SFR product had near zero values. Farther south near Tucumcari the observation showed unknown precipitation falling at a temperature of 36° south of the main snow band.
The following merged SFR image at 0940 UTC showed the area of higher snowfall rates persisting (Figure 3 (left)). A merged SFR product from 0950 UTC is shown to note the extent of the radar void area (Figure 3 (right)). The following stand alone SFR product at 1245 UTC indicated the higher rates had shifted farther south but were still impacting at least portions of this same area (Figure 4). In this example the observation at Las Vegas, NM was indicating snowfall with visibilities down to 1 1/4 miles while Tucumcari showed very light snow with no values on the SFR product.
Based on the peak values depicted in the SFR product and the persistence of the snow band in the area forecasters were anticipating snowfall reports in the 2 to 6 inch range. The Snow-Cloud RGB product later in the day in Figure 5 verified this area of snowfall very well (red shades). Spotters reports are overlaid on the RGB imagery. Feedback from forecasters during this event supported accurate observations of the SFR product during the transition from rain to snow as well.
The NESDIS Snowfall Rate (SFR) product assessment is in full swing at NWS Albuquerque and forecasters are already capturing some good cases over data sparse regions. The first week of January 2016 was very active across New Mexico as back to back winter storm systems crossed the area. The second system in the series crossed over the Four Corners region on 4 January 2016, producing light to moderate snowfall rates for several hours. The forecaster on shift noted the observation at Farmington, NM (KFMN) indicated light snow with a visibility of 5 statute miles. A quick glance at the SFR procedure used in Figure 1a shows the extent of any precipitation echoes well to the east of KFMN at 0000 UTC 5 January 2016. The nearest radar (KABX, not shown) is located roughly 150 miles southeast of KFMN near Albuquerque, NM. The arrival of a SFR product at 0010 UTC 5 January 2016 showed the extent of the precipitation was much greater with the merged POES image overlaid on the radar data (Figure 1b). Sampled liquid equivalent values in the light green areas to the east of KFMN were near 0.03″/hour.
The Terminal Aerodrome Forecast (TAF) issued for KFMN shortly before the receipt of this image indicated temporary fluctuations in the visibility to 1 statute mile with light snow and an overcast ceiling near 1,200 ft between 0000 UTC and 0400 UTC (Instrument Flight Rules, IFR). It is not clear whether any operational changes occurred based on the receipt of the merged SFR product or whether the product increased confidence on the IFR forecast. However, it is entirely possible given the improvement in product latency compared to the 2015 assessment that the imagery could be used in this way.
The webcam available at San Juan College just a short distance from the KFMN observation showed significant decreases in the visibility between 330pm and shortly after sunset (Figure 2a and 2b). The two images below show the decrease in surface visibility as well as notable accumulations on grassy surfaces in front of the college. An observer 3 miles southeast of Farmington did report a total accumulation of 1″ from this event. The merged SFR product did in fact show higher rates immediately to the east of KFMN. The last image in the series shows the impact on travel conditions noted by the NM Department of Transportation web page (Figure 3). The areal coverage of the difficult travel impacts (yellow highlights) was greater than that depicted by what can be seen based on poor radar coverage.
A slow-moving upper level storm system tracked east across northern NM and southern CO on 14-15 December 2015. A weak tap of subtropical moisture ahead of this system provided light to moderate snowfall mainly along the Continental Divide of western NM and the higher terrain running north-south through central and northern NM. Snow accumulations of 3 to 8 inches were reported ahead of and immediately behind the surface front and the mid level trough passage. A classic westerly,upslope flow event developed behind the upper wave as moist, unstable flow interacted with the north-south oriented higher terrain. Winter weather advisories and winter storm warnings were in effect over much of northern NM for the expectation of storm total snowfall of 8 to 12″ with locally higher amounts. Figure 1 depicts the distribution of advisories and warnings over northern NM on the Albuquerque National Weather Service public page.
Poor radar coverage over northern and western NM makes it a challenge for assessing winter precipitation patterns and snowfall rates. Figure 2 shows a radar mosaic valid 1800 UTC 15 December 2015 utilizing an enhanced color curve to identify areas of lighter snowfall. Automated surface observations are sparse in this area however there are at least a few observations reporting snow where nothing is present in the radar reflectivity. Webcams at ski resorts serve as an excellent near real-time proxy for visualizing active snow accumulations in these poor radar coverage regions. Additionally, once daily snow accumulation reports from ski resorts aid the verification process following the winter event.
The integration of satellite data allows forecasters to supplement these data void areas. The most recent interation of the NESDIS snowfall rate products available at WFO Albuquerque illustrate the snowfall rate derived from radar (Figure 3a) and the snowfall rate available from merging the POES satellite data with the radar data (Figure 3b). Note the grey areas overlaid on the map in Figure 3a indicate areas of reliable radar coverage. The snowfall rate derived from satellite data in Figure 3b clearly shows coverage outside of the area with reliable radar coverage. A very cold and unstable airmass in association with this precipitation suggested snowfall rates in the higher terrain would average between 20-30:1. The 18:1 image in the lower right of Figure 3b indicated rates around 0.4/hr.
Although there is sparse coverage of automated surface observations around the higher terrain, webcams from ski resorts can verify the existence of moderate to heavy snowfall. Visibilities in the webcams below suggest snowfall rates higher than those depicted in the NESDIS products – visually, rates look closer to perhaps 1″/hr in the upper right and lower right images (Figure 4). One of our goals of this assessment is to combine information from the webcams with the more quantitative snowfall rate product to better estimate snowfall in data void areas. Snowfall reports from the Chama Railyard indicated 8.5″, Taos Ski Valley 6″, Ski Santa Fe 12″, and Pajarito Mountain 10″.