GOES-11 0.65 µm visible and 10.7 µm IR images (click image to play animation)

Strong thunderstorm outflow winds (gusting as high as 69 mph) created a severe dust storm (or “haboob“) in the Phoenix, Arizona area around 02:00 to 03:00 UTC on 06 July 2011 (or 7pm to 8pm local time on 05 July 2011), restricting the surface visibility to near zero with blowing dust and forcing a 45-minute Ground Stop at Phoenix Sky Harbor Airport (an interesting YouTube video of the approaching dust storm is available here). The Phoenix National Weather Service forecast office published a summary of the event, and additional information and 3D radar animations are available on the AccuWeather WeatherMatrix blog. A high-resolution GOES image can be found at the NOAA Environmental Visualization Laboratory.

McIDAS images of GOES-11 0.65 µm visible channel data during the day and GOES-11 10.7 µm IR channel data at night (above; click image to play animation) show how the Mesoscale Convective System over Arizona on 05 July evolved into a Mesoscale Convective Vortex (MCV) on the following morning over the deserts of southern California, as the cirrus canopy of the convective system eroded to reveal the mid-level circulation. The MCV then appeared to play a role in helping to initiate new convective activity over California later in the afternoon on 06 July.

AWIPS image comparison from 18:00 UTC on 06 July

MCVs maintain their structure through the release of latent heat associated with condensation when clouds form and especially when precipitation forms. This release of heat alters the stability of the atmosphere, inducing the formation of a cyclonic potential vorticity anomaly. MCVs erode when they encounter high wind shear.

An AWIPS image comparison (above) shows GOES visible channel data (the seam in the middle of the images demarcates data from GOES-11 or GOES-West and GOES-13 or GOES-East; note that the older GOES-11 data is darker because of the age and degradation of that satellite’s visible sensors), GOES 10.7 µm IR channel data, the Blended Total Precipitable Water (TPW) Percent of Normal product, and 850-300 hPa layer wind shear from the GFS and RUC models. In the present example, the MCV exists in an axis of low values of 850-300 hPa wind shear, as noted by model forecasts from the RUC and from the GFS. Abnormally high values of precipitable water are also present, exceeding 200% of normal according to the ‘Blended Product’ that combines observations from the GOES Sounder and ground-based GPS stations. Rawinsonde reports from Phoenix (00 UTC and 12 UTC on 06 July) and from Yuma (12 UTC and 14 UTC on the 06 July) show abundant moisture and relatively low shear. All of these data show environmental conditions that support MCVs.

GOES-11 Sounder TPW and LI derived product images

In the pre-convective environment across southern Arizona on 05 July, GOES-11 Sounder derived product images (above) showed Total Precipitable Water (TPW) values in the 40-50 mm (1.6 to 2.0 inch) range, and Lifted Index (LI) values as low as -5º to -8º C.

MODIS 11.0 µm IR image + negative and positive cloud-to-ground lightning strikes

As the MCS continued to move westward across Arizona, an AWIPS image of 1-km resolution MODIS 11.0 µm IR data at 05:33 UTC (above) showed cloud top IR brightness temperatures as cold as -72º C (black color enhancement), along with numerous negative and positive cloud-to-ground lightning strikes. At that time, the thunderstorm outflow winds were moving through Blythe, California (station identifier KBLH) producing wind gusts of 46 knots (52 mph) with a reduction in visibility to 1.5 miles, and also through Yuma, Arizona (station identifier KNYL) producing wind gusts of 40 knots (46 mph) with a reduction in visibility to 1.25 miles.

View only this post Read Less

POES AVHRR 10.8 µm IR image + resulting hail and damaging winds reports

Severe thunderstorms produced a long swath of large hail and damaging winds (SPC storm reports) across much of the Upper Midwest region from eastern South Dakota to northwestern Wisconsin on 01 July 2011. In addition, there were tornadoes that produced EF-1 and EF-2 damage in southwestern Minnesota (NWS Sioux Falls summary), EF-1 rated tornadoes in central Minnesota (NWS Minneapolis summary), and a tornado that produced EF-2 damage in northwestern Wisconsin (NWS Duluth tornado event summary). At a campground in northwestern Wisconsin there was one fatality and 39 injuries as a result of falling trees from severe straight-line winds.

An AWIPS image of POES AVHRR 10.8 µm IR data at 20:21 UTC or 3:21 PM local time (above) showed the initial thunderstorm as it was intensifying near the South Dakota / Minnesota border, along with the resulting widespread reports of hail and wind damage as the thunderstorm complex grew and moved northeastward (NWS Duluth event summary). The coldest cloud top IR brightness temperature on the AVHRR image was -81ºC (violet color enhancement).

McIDAS images of GOES-13 0.63 µm visible channel data (below; click image to play animation; also available as a QuickTime movie) showed numerous overshooting tops associated with the severe thunderstorms as they moved from eastern South Dakota across Minnesota and into northwestern Wisconsin. Early in the animation, it is also interesting to note the persistent low-level fog/stratus cloud bank that covered the western portion of Lake Superior as the warm, humid air moved across the still-cold waters of the lake.

GOES-13 0.63 µm visible channel images (click image to play animation)

The corresponding GOES-13 10.7 µm IR images (below; click image to play animation; also available as a QuickTime movie) showed the cold cloud top IR brightness temperatures with these storms, which reached a minimum value of -72ºC at 21:15 over Minnesota.Several storm top IR cold/warm thermal couplets were seen, along with subtle “enhanced-V” storm top signatures over the Minnesota/Wisconsin border region.

GOES-13 10.7 µm IR images (click image to play animation)

View only this post Read Less

GOES-13 0.63 µm visible channel images (click image to play animation)

McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed that there was still a great deal of ice remaining in much of Hudson Bay, Canada on 29 June 2011. However, it is interesting to note the motion of the ice on the high-speed animation — some of the ice features move in one direction, stop, and then move in a nearly opposite direction during the course of the day. A ridge of high pressure was in place across the region, with surface winds generally from the northeast over the eastern portion of Hudson Bay, and surface winds from the southwest over the western portion of Hudson Bay (ASCAT winds).

A comparison of AWIPS images of the MODIS 0.65 µm visible channel and a false color Red/Green/Blue (RGB) image (created using MODIS bands 01/07/07 as the R/G/B components of the image) confirmed that it was ice occupying the majority of Hudson Bay — ice features (as well as glaciated clouds) appear as shades of red on the false color image. According to an analysis performed by the Canadian Ice Service, this consisted of thick to medium first year ice.

MODIS 0.65 µm visible channel image + MODIS false color RGB image

Toward the end of the GOES-13 visible channel animation above, the hazy signature of smoke aloft could be seen drifting south-southwestward over the far eastern part of Hudson Bay. This smoke — a result of wildfires burning in northern and western Canada — also showed up well in a MODIS true color RGB image (below) from the SSEC Direct Broadcast site.

MODIS true color RGB image

An AWIPS image of the MODIS Sea Surface Temperature (SST) product (below) revealed that SST values were still in the 30s F (darker blue color enhancement) across much of Hudson Bay, with a few pockets of warmer water seen in various locations.

MODIS Sea Surface Temperature product

CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS images and products available for National Weather Service offices to add to their local AWIPS workstations. The VISIT training lesson  “MODIS Products in AWIPS” is available to help users understand these products and their applications to weather analysis and forecasting.

View only this post Read Less

MODIS Land Surface Temperature product

Record heat was experienced across parts of the Texas and Oklahoma panhandle regions and southwestern Kansas on 26 June 2011 — all-time record high temperatures in Texas included 117ºF at Childress (record tied), 113ºF at Borger, 111ºF at Amarillo, and 110ºF at Dalhart; in Oklahoma, 113ºF at Gage; and in Kansas 110ºF at Dodge City. An AWIPS image of the MODIS Land Surface Temperature (LST) product in the late morning at 16:52 UTC or 11:52 am local time (above) showed a large area exhibiting LST values of 125-130ºF (darker red color enhancement) at that time (although shelter air temperatures 5 feet above the surface were only in the 102ºF to 104ºF range).

GOES-13 3.9 µm shortwave IR images (below; click image to play animation) showed how after sunset the areas with drier air (lower dew points) tended to cool off faster than adjacent areas with more moisture in the air (higher dew points).

GOES-13 3.9 µm shortwave IR images + METAR surface reports (click image to play animation)

Farther to the west, a large wildfire was burning near Los Alamos National Laboratory in New Mexico. A sequence of daytime GOES-13 0.63 µm visible channel images followed by night-time GOES-13 3.9 µm shortwave IR images (below; click image to play animation) revealed a very large smoke plume spreading northeastward during the day on 26 June, along with a very large fire “hot spot” (black to yellow pixels) on the shortwave IR images. The large smoke plume was still apparent on the first few visible images on the next morning (27 June).

GOES-13 0.63 µm visible images + GOES-13 3.9 µm shortwave IR images (click image to play animation)

A comparison of 1-km resolution POES AVHRR 0.63 µm visible channel and 3.74 µm shortwave IR channel images (below) showed a better view of the fire hot spot and associated smoke plume at 01:32 UTC.

POES AVHRR 0.63 µm visible channel and 3.74 µm shortwave IR channel images

View only this post Read Less