Fires in Alaska, Canadian smoke over the Lower 48

June 29th, 2015
Suomi NPP VIIRS 3.74 µm infrared channel images, times as indicated (click to enlarge)

Suomi NPP VIIRS 3.74 µm infrared channel images, times as indicated (click to enlarge)

Suomi NPP 0.64 µm visible channel images, times as indicated (click to enlarge)

Suomi NPP 0.64 µm visible channel images, times as indicated (click to enlarge)

The 2015 Wildfire Season is off to a quick start in Alaska (continuing an observed trend). This map (from this site) shows more than 300 active fires over Alaska at 2000 UTC on 29 June 2015. This graph (from the Alaska Climate Info Facebook page) compares early burn acreage in 2015 to that in 2004 (the year with the most acreage burned — see this graph, courtesy of Uma Bhatt, University of Alaska-Fairbanks).

Soumi NPP VIIRS 3.74 µm infrared imagery from early morning on 29 June 2015 (top) shows numerous wildfire hot spots (dark black pixels) in the region surrounding the Yukon River (the middle portion of the imagery, south of Kotzebue Sound). VIIRS visible imagery from the same time, above, shows an extensive pall of smoke over much of central Alaska.

GOES-13 Visible (0.63 µm) imagery (click to play animation)

GOES-13 Visible (0.63 µm) imagery (click to play animation)

Meanwhile, thick smoke from fires burning over northern Canada (comparison of VIIRS visible and shortwave IR images from 28 June) was drifting southward over central portions of the Lower 48 states. The smoke plume on 28 June (above) was fairly narrow; however, a much broader and thicker plume was seen moving south on 29 June (GOES visible imagery below, then MODIS/VIIRS true-color RGB imagery as displayed using the SSEC RealEarth web map server). SSEC MODIS Today true-color imagery of this smoke plume is also available here. Pilot reports placed the lower and upper bounds of the thick smoke at 5000 and 17500 feet, with flight visibilities as low as 2 miles at 5000 feet. Some of the smoke subsided to the surface in southeastern South Dakota, restricting the surface visibility at Sioux Falls to 5 miles and raising the Air Quality Index there into the Unhealthy category. In fact, the smoke was so thick over far eastern South Dakota that it had the effect of reducing surface heating and slowing the rise of afternoon temperatures, such that convective temperatures were not being reached and probabilities of precipitation had to be scaled back:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
356 PM CDT MON JUN 29 2015

.SHORT TERM…(THIS EVENING THROUGH TUESDAY)
ISSUED AT 356 PM CDT MON JUN 29 2015

IN ADDITION…THICK PLUME OF SMOKE CONTINUES TO DRIFT SOUTHWARD IMPACTING NEARLY ALL OF THE FORECAST AREA…BUT MOST   NOTABLE ALONG AND EAST OF THE JAMES RIVER VALLEY. BECAUSE OF THIS…AFTERNOON TEMPERATURES ARE ABOUT 2 TO 4 DEGREES
COOLER THAN FORECAST AND WE ARE HAVING A HECK OF A TIME REACHING OUR CONVECTIVE TEMPERATURE. THEREFORE LOWERED THE LATE AFTERNOON AND EVENING POPS IN OUR EASTERN ZONES TO ONLY SLIGHT CHANCE POPS. BUT EVEN THOSE MAY BE TOO HIGH AND IF NOTHING DEVELOPS OVER THE NEXT COUPLE OF HOURS…THEY MAY NEED TO BE REMOVED ENTIRELY.

GOES-13 Visible (0.63 µm) imagery (click to play animation)

GOES-13 Visible (0.63 µm) imagery (click to play animation)

MODIS and VIIRS true-color imagery (click to enlarge)

MODIS and VIIRS true-color imagery (click to enlarge)

Daytime detection of smoke plumes is not difficult with visible (or true-color) imagery. At night, however, smoke detection is a challenge. The VIIRS Day/Night Band on Suomi NPP can detect smoke when Lunar Illumination is high (although detection is limited to one or sometimes two passes per night). Smoke is otherwise mostly transparent to infrared channels on the GOES Imager. Websites such as the NOAA/NESDIS IDEA and the GASP are helpful; however, the GASP product uses single-channel (visible) detection only.

Visible imagery from GOES-15, below, highlights the expansive region covered by smoke over northern Canada. Note that the smoke becomes less distinct with time as the sun rises higher in the sky, because forward scattering of visible light by smoke particles is more effective than backward scattering.

GOES-15 Visible (0.62 µm) imagery, times as indicated (click to animate)

GOES-15 Visible (0.62 µm) imagery, times as indicated (click to animate)

Natural gas pipeline explosion in Texas

June 15th, 2015

GOES-15 (left) and GOES-13 (right) 3.9 µm shortwave IR channel images [click to play animation]

GOES-15 (left) and GOES-13 (right) 3.9 µm shortwave IR channel images [click to play animation]

An explosion occurred along a natural gas pipeline near Lindenau, Texas just after 01 UTC on 15 June 2015 (8:00 pm local time on 14 June). The thermal signature or “hot spot” of the resulting fire was detected on both GOES-15 (GOES-West) and GOES-13 (GOES-East)  3.9 µm shortwave IR imagery (above; click image play animation). The images have overlays of surface reporting stations (yellow), Interstate highways (cyan), and primary highways (gray). The relatively small but very hot fire exhibited IR brightness temperatures as high as 341.1 K on GOES-13 and 340.0 K on GOES-15, which is close to the saturation temperature for the 3.9 µm detectors on those satellites. Since GOES-13 was in Rapid Scan Operations (RSO) mode at the time, the fire hot spot was first detected by that satellite (at 0107 UTC) — and the IR brightness temperature remained at 341.0 K for another 40 minutes after initial detection (0115 to 0155 UTC).

A subtle signature of the fire’s smoke plume (lighter gray enhancement) could be seen moving northwestward and then northward away from the fire hot spot. On the 0125 UTC GOES-13 shortwave IR image (below), and overlay of the CRAS model winds showed them turning from southeastward at the surface (in agreement with regional METAR surface reports) to southerly at an altitude of 3 km, suggesting that the smoke plume may have reached that height.

GOES-13 3.9 µm shortwave IR image (with METAR surface reports and CRAS surface. 1km, 2km, and 3km winds)

GOES-13 3.9 µm shortwave IR image (with METAR surface reports and CRAS surface. 1km, 2km, and 3km winds)

Hurricane Blanca in the eastern Pacific Ocean

June 4th, 2015
Suomi NPP VIIRS Day Night Band 0.70 µm Visible and 11.35 µm infrared imagery over Blanca, 0829 UTC 4 June 2015 (Click to enlarge)

Suomi NPP VIIRS Day Night Band 0.70 µm Visible and 11.35 µm infrared imagery over Blanca, 0829 UTC 4 June 2015 (Click to enlarge)

Suomi NPP overflew Hurricane Blanca early in the morning on 4 June, during a near-full Moon, and the Day Night Band imagery, above, toggled with the 11.35 µm imagery, show the hurricane. (Day/night band imagery of the eye is here, the entire storm is here, and zoomed out is here; click for 11.35 µm imagery of the eye, the entire storm, and zoomed out). Deep convection overnight did not wrap all the way around the storm. Evidence of dry air entrained into the circulation is apparent.

GOES-15 Imager 10.7 µm infrared channel images (click to play animation)

GOES-15 Imager 10.7 µm infrared channel images (click to play animation)

The 3-hourly animation of 10.7 micron imagery, above, from 3-4 June 2015 shows Hurricane Blanca southwest of the Mexican coast, drifting southwestward. Cold cloud tops that were apparent at the start of the loop warm by the end, perhaps because convection is being suppressed by the presence of dry air. MIMIC Total Precipitable Water (below) suggests that dry air is being entrained into Blanca’s circulation from the north. (Update on Andres, also apparent in the MIMIC Total Precipitable Water animation: This overlay of Metop ASCAT winds on top of GOES 10.7 imagery from ~0530 UTC on June 4 shows a swirl that is offset from the convection. Andres is forecast to become post-tropical later on June 4.)

MIMIC Total Precipitable Water animation for the 72 hours ending 1300 UTC on 4 June 2015 (click to enlarge)

MIMIC Total Precipitable Water animation for the 72 hours ending 1300 UTC on 4 June 2015 (click to enlarge)

Visible imagery from GOES-13 from June 3 and June 4, below, show a less distinct/cloudier eye on 4 June compared to 3 June. Multiple overshooting tops persist in the circulation of the system, but the coarse 30-minute temporal resolution of the imagery cannot capture the lifecycle of these quickly evolving events.

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

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

Water vapor imagery from GOES-13 from June and June 4, below, also confirm a consistently less organized storm. The dry air penetrating from the north is apparent in the imagery, but it appears not to have entered into the circulation of the storm, at least not at levels detected by the water vapor channel.

GOES-13 Imager 6.5 µm infrared water vapor channel images (click to play animation)

GOES-13 Imager 6.5 µm infrared water vapor channel images (click to play animation)

Morphed Microwave Imagery (MIMIC) from this website shows the evolution of the central eye structure, below. The eyewall that was much closer to the storm center at the start of the animation has been replaced by a weaker, larger eyewall.

Morphed Microwave Imagery, 48 hours ending 1500 UTC 4 June 2015 (click to enlarge)

Morphed Microwave Imagery, 48 hours ending 1500 UTC 4 June 2015 (click to enlarge)

For more information on this storm, please visit the National Hurricane Center website or the SSEC/CIMSS Tropical Weather website.

Andres and Blanca in the eastern Pacific

June 2nd, 2015
GOES-15 Imager 0.64 µm visible channel images (click to play animation)

GOES-15 Imager 0.64 µm visible channel images (click to play animation)

Hurricane Andres (above) in the eastern tropical Pacific was on 2 June 2015 joined by Tropical Storm Blanca (below). Blanca was forecast to become a Hurricane later on 2 June as Andres weakens. The circulation of Andres, above, is well-established, with good anti-cyclonic outflow and curved inflow bands. Shear values are low. (Graphics come from this site). However, Andres has moved over relatively cool Sea Surface Temperatures that spell weakening.

GOES-15 Imager 0.64 µm visible channel images (click to play animation)

GOES-15 Imager 0.64 µm visible channel images (click to play animation)

Blanca, in contrast, has a circulation that is not so well-defined. However, the storm is over very warm water, and also in a region of relatively low shear. Strengthening is forecast.

The animation of Andres at top shows a ragged appearance as dry air intrudes upon the circulation from the south and west. This dry air is apparent in the MIMIC Total Precipitable Water animation below. The circulation of Blanca appears at the end of the animation, embedded within a rich source of tropical moisture.

3-day animation of MIMIC Total Precipitable Water over the eastern Pacific (click to enlarge)

3-day animation of MIMIC Total Precipitable Water over the eastern Pacific (click to enlarge)

Sea-surface temperatures off the Pacific Coast of Mexico have been warmer than normal for much of this year (Map, data from here). Warmer-than-normal sea-surface temperatures argue for stronger hurricanes, and Andres was a Category 4 storm on 1 June with a well-developed eye. Andres is one of only 5 May storms in the eastern Pacific since 1970 to achieve Major Hurricane status (Link).

Aqua overflew Andres shortly before 1800 UTC on 1 June, and the water vapor imagery of the storm at that time is here. The True-Color imagery is shown below.

Aqua True-Color Imagery, 1748 UTC on 1 June 2015 (click to enlarge)

Aqua True-Color Imagery, 1748 UTC on 1 June 2015 (click to enlarge)

A storm-centered animation over Andres’ lifecycle is shown below. The storm starts in the moisture-rich ITCZ and ends as an isolated region of moisture surrounded by dryness.

GOES-15 Water Vapor Infrared Imagery (6.5µm) centered on Andres' center (click to animate)

GOES-15 Water Vapor Infrared Imagery (6.5µm) centered on Andres’ center (click to enlarge)

For further information on these storms, consult the National Hurricane Center website.