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.
Archive for the ‘GOES-R Proving Ground’ Category
An image captured this morning by the MODIS Terra instrument shows an impressive cyclone off the eastern coast of the US. The image on the left shows the cyclone in SPoRT’s Air Mass RGB and the image on the right shows the 11.0 µm from Terra (from 8 February 2016 at 1427 UTC). The deep red color on the RGB shows the intrusion of ozone-rich stratospheric air, which is an indication of deformation zones, jet streaks, and potential vorticity anomalies associated with rapid cyclogenesis, which itself indicates strong winds at the surface. This RGB is also limb-corrected for cooling at the edges of the swath, so we can assume the cyclone in this imagery is every bit as intense as it looks.
The new generation of geostationary satellites being deployed globally, such as Himawari, MTG, and GOES-R, will allow us to observe imagery like the Air Mass RGB several times an hour, enabling us to watch the cyclogenesis as it happens.
So, here at NWS HUN, I’ve recently begun ingesting and looking at the GOES-R Fog and Low Stratus (GOES-R FLS) Product. True, while this is not a SPoRT product, it is a part of the GOES-R Proving Ground and is certainly worthy of operational evaluation and comparison with other GOES-R and JPSS Proving Ground products provided by SPoRT and other entities. So, this morning, I noticed a relatively extensive patch of what appeared to be mid and high clouds streaming across southern Texas in advance of a weak, sheared trough in the SW CONUS and NW Mexico (Image 1).
Observations show that most cloud bases in the region were above ~6500 ft AGL. A look at the GOES-R FLS MVFR Probability product also indicated low chances for MVFR conditions within the cloud shield across the region…with the exception of portions of far southern Texas (Image 2).
So, how is this value added to the operational weather forecaster? Easy…it offers a more efficient look at clouds that are impactful…especially to aviation forecast concerns. The FLS MVFR Probability product in this situation would have shown a forecaster in rather quick fashion that the developing band of clouds upstream from his/her area were generally VFR. Sure, an interrogation of ground observations would have suggested the same thing, but only at point locations of course. Forecasters are usually wanting to know what’s going on in between ground observation sites. Homogeneity may be safely assumed in some cases, but it’s always good to have other sources of information that may verify these assumptions or reduce risk in assumptions.
I have some other thoughts about these data/imagery and will be taking more looks at these data and comparing with other legacy and GOES-R/JPSS Proving Ground products in the future…especially when I have the opportunity to use them operationally in my own area.
Over the last few days Himawari-8 AHI Air Mass RGB imagery has captured an impressive view of Severe Tropical Storm Choi-wan near Japan. The storm began as a tropical depression near Wake Island and the Japan Meteorological Agency upgraded the depression to a tropical storm on October 2nd. The tropical storm continued to move north-northwest toward Japan and the Sea of Okhotsh but weakened as it evolved. Yesterday and today (October 8th) the storm began to take on more extratropical characteristics and look like a strong mid-latitude low pressure system (click on Fig. 1 animation).
Currently, SPoRT is investigating the utility of NOAA Unique CrIS/ATMS Processing System (NUCAPS) satellite retrieved soundings for hurricane tropical to extratropical transition events. Soundings are typically used to anticipate severe weather and analyze the pre-convective environment; however, they can be just as valuable for analyzing and understanding the environment surrounding complex extratropical transition events, especially over data sparse oceanic regions. National Center forecasters at the National Hurricane Center and Ocean Prediction Center routinely use the Air Mass RGB for forecasting such events, especially for identifying the influence of warm, dry stratospheric air during extratropical transition. Although the Air Mass RGB provides a wealth of information about the upper-level horizontal distribution of temperature and moisture characteristics surrounding a storm, it does not provide insight about the vertical distribution of thermodynamic characteristics. With Next-Generation S-NPP/JPSS NUCAPS Soundings now available in AWIPS-II, they can be used in conjunction with the Air Mass RGB to anticipate extratropical transition events.
Here are a few examples of NUCAPS Soundings compared to the Air Mass RGB. Let’s take a look at NUCAPS Soundings in three locations in the environment surrounding Severe Tropical Storm Choi-wan (Fig. 2).
Location 1, red/orange coloring, represents upper-level dry air on the Air Mass RGB. To no surprise, the NUCAPS Sounding (Fig. 3) reveals dry upper-levels and dry conditions throughout the atmospheric column.
Now Location 2 is also in an orange colored region and representative of upper-level dry air, but take note the coloring is not as “red tinted” as Location 1 and there are more mid-level clouds. Mid-level clouds tend to be light tan or ocher colored in the Air Mass RGB. The NUCAPS Sounding (Fig. 3) does confirm a mid-level moisture layer from about 800-600 mb. Seeing ocher clouds in the RGB only means that qualitatively mid-level clouds are present (one can’t get a quantitative height from the RGB), but inspection of the NUCAPS Sounding would give a quantitative height estimate of the mid-level clouds. Although this sounding is in the region right over the mid-level cloud, looking at more soundings in the same orange region (but not right over a cloud) do show the atmospheric column is not completely dry (like Location 1) but there is low- to mid-level moisture present throughout the region surrounding Location 2. Just by looking at the RGB one may not realize a mid- to low-level moisture layer is present since the interpretation of the orange coloring in the Air Mass RGB is upper-level dry air.
Location 3 is the most interesting (at least to me since the sounding gives more information about the atmosphere than one could extrapolate from just looking at the Air Mass RGB). The green coloring around Location 3 represents a warm, moist air mass. The NUCAPS Sounding (Fig. 4) does reveal a more moist sounding about 300 mb and above, but note there is mid-level dry air present and a low level moist layer. Again the NUCAPS Soundings provide more information about mid- and low- level characteristics that one can’t infer from the RGB imagery. This is just one example that highlights the utility of analyzing Next-Generation satellite data sets for complex weather events in data sparse regions.
Recently, I had the opportunity to travel to the Tucson NWS office and work with forecasters there concerning a number of experimental data sets transitioned by the SPoRT group. Primarily, this involved the SPoRT LIS, GPM Constellation and IMERG, and NESDIS QPE data sets. However, I also had the opportunity to see how other products were being utilized by forecasters. While taking a look at the Nighttime Microphysics RGB image, I was initially perplexed by the apparent presence of fog and low clouds in parts of the desert southwest. The first image below is a 4-panel image from AWIPS, showing the Longwave (LW) and Shortwave (SW) IR, the LW-SW IR channel difference, and the Nighttime Microphysics RGB from the VIIRS instrument on the morning of Sept 23rd.
The difference in brightness temperatures between the LW and SW IR channels in parts of SW Arizona, SE California and areas of NW Mexico around the Gulf of California, results in relatively large positive values. Notice the yellow colors that appear in these areas in the channel difference imagery (image 1, lower right), and the corresponding appearance of white-aqua colors in the Nighttime Microphysics RGB (the 10.8-3.9 channel difference represents the green color component of the RGB recipe). For a forecaster accustomed to looking at these imagery in other parts of the country (and those will less sandy surfaces), these channel difference values and colors in the RGB would suggest the presence of low stratus and/or fog. However, no clouds or fog were present in those locations during the morning. You can, however, see some low clouds in portions of central and eastern New Mexico, as indicated by the brighter white-aqua colors.
So, what is going on here? Well, as eluded to above, it’s the presence of dry sand. The image below (courtesy of COMET) shows the IR emissivity over several different surface features: tree leaves, red clay, dry sand, and water.
Notice that the emissivity over dry sand changes fairly substantially through portions of the SW and LW portion of the spectrum, and is lower at 3.9 µm than at 10.8 µm. The channel difference between 10.8 and 3.9 µm will result in positive values (given clear sky conditions of course) over dry sandy areas, thus mimicking the presence of low clouds and/or fog, as would be the interpretation in other areas. The next image below demonstrates the LW and SW IR brightness temperatures and differences, along with the Nighttime Microphysics RGB, as sampled over a clear, dry sandy area.
Notice the substantial resulting green color contribution in the Nighttime Microphysics RGB (lower right in above image). These colors are very similar to colors that would be indicative of fog and other low cloud features as they traditionally appear under similar temperature conditions in other areas outside of dry, sandy areas (image 4 below).
NWS Albuquerque recently began ingesting the updated SPoRT CONUS LIS products in our new AWIPS II system as part of our continued collaboration with SPoRT. These products have already peaked the interest of several local, state, and federal partners. Short-term drought conditions have improved steadily since late winter as more frequent and widespread precipitation events impacted the state. Overall, deep-layer soil moisture conditions have improved substantially compared to this time last year (Fig. 1).
The SPoRT LIS products have become a valuable tool for drought monitoring during our monthly drought workshops. Several state and federal partners noted on our most recent call in late July that these new products provided an additional layer of situational awareness and infuse more science into the drought monitoring process. These products have also peaked the interest of our fire weather community, in particular Incident Meteorologist Brent Wachter. New Mexico during late July is generally under the influence of higher humidity with periodic wetting rainfall events. The convective nature of the precipitation however tends to bring about a patchwork of “have’s and have-nots”. The Fort Craig wildfire broke out in a dry pocket of south central Socorro County within the middle Rio Grande Valley during the afternoon of 26 July 2015. The New Mexico State Climatologist, Dave DuBois, captured the wildfire on camera and posted the image to Twitter shortly thereafter (Fig. 2).
The SPoRT LIS 0-10cm volumetric soil moisture at 12Z 28 July 2015 showed the corresponding dry area where the wildfire developed (Fig. 3). Les Owen from the New Mexico Department of Agriculture also noted this area of drying within Socorro County in what he called his “windshield survey” in mid to late July. The Fort Craig fire grew to nearly 700 acres over the course of two days. The NASA SPoRT soil moisture imagery showed the dry area quite well and the fire was located smack dab in the middle of it.
Several storms then impacted the area late on the 28th and the 29th leading to some natural fire suppression and reduction in active fire behavior. The follow-up SPoRT imagery at 12Z 30 July 2015 showed the increase in 0-10cm relative soil moisture over the same area (Fig. 4). The high resolution imagery could be useful in determining fuel dryness for potential fire starts from human activities, cloud to ground lightning ignitions, as well as highlight potential active fire behavior areas. We will continue to assess the possible applications of the SPoRT LIS products as we move through the remainder of the 2015 monsoon season.
Low clouds and fog in the N. Gulf and Texas regions caused MVFR/IFR/LIFR conditions over a large area. The VIIRS Nighttime Microphysics RGB shows aqua to gray coloring to represent these features. In the RGB the scene is fairly complex with high and middle clouds (reds, blues, purples, tans …..). The RGB composite uses the traditional 11-3.9um difference (seen below) and combines other channels to better illustrate the low cloud features between the middle/high clouds. The RGB also improves the characterization of the thick, cold cloud tops associated with the cutoff low producing precipitation along the coast and southern states when compared to the simple 11-3.9um. Other “microphysical” RGBs are possible during the day or in a form that can be applied both day and night (i.e. 24hr product).