A closer view of the tornadic supercell is shown below, with overlays of surface reports (metric units). The pulsing nature of the overshooting tops is evident in the fluctuation of the coldest cloud-top IR brightness temperatures (the coldest of which was -69º C, darker black color enhancement, on the 0300 UTC GOES-15 and 0315 UTC GOES-13 images). There are different apparent positions of the storms based on the satellite that views them because of parallax shifts. Such shifts are especially pronounced at higher latitudes with very tall storms.A 1-km resolution Terra MODIS 11.0 µm Infrared image at 0331 UTC is shown below; the minimum cloud-top IR brightness temperature was -73º C. Visible imagery from GOES-13 (above) and GOES-15 (below) showed the overshooting tops associated with the tornadic thunderstorm, as well as the rapidly expanding cirrus shield. A closer view of the tornadic supercell from GOES-15 vs GOES-13 is shown below, with overlays of surface reports (metric units). The overshooting tops are again apparent on the images, along with an above-anvil plume (which is easier seen on the GOES-13 images, due to a more favorable forward-scattering viewing geometry). The robust convective development was first seen on the 2030 UTC images, in the vicinity of the Saskatchewan/Manitoba/North Dakota border region. As an area of low pressure was deepening over eastern Montana, warm and humid air was surging northward into far southern Saskatchewan and Manitoba (surface analyses). GOES sounder derived product images (available from this site) of Convective Available Potential Energy (CAPE), Lifted Index, and Total Precipitable Water (below) showed that the environment across southern Manitoba was becoming increasingly unstable and moist leading up to the time of convective initiation.
A more detailed view of the fire hot spots was provided by 375-meter resolution (mapped onto a 1-km AWIPS grid) Suomi NPP VIIRS 3.74 µm shortwave IR images (below; click to play animation).Many of the fires were burning in the general vicinity of the Utopia Creek, Indian Mountain airport (station identifier PAIM); a time series of surface observation from that site (below) showed that visibility was 1 mile or less due to smoke at times on 25 July. Daily composites of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images viewed using the SSEC RealEarth web map server are shown below.
Another sequence of GOES-15 visible channel images is shown below (click image to play animation; also available as a MP4 movie file). Another smaller smoke plume can be seen originating from a fire in far southeastern British Columbia.As it continued to burn into the following night; a comparison of Suomi NPP VIIRS 3.74 µm shortwave IR and 0.8 µm Day/Night Band images at 0958 UTC or 3:58 am local time (below) revealed the hot spot (yellow to red to black pixels) and the bright glow of the fire.
—————————————————————————On the following day (22 July), consecutive afternoon (1944 and 2122 UTC) Suomi NPP VIIRS 3.74 µm shortwave IR channel images (above) revealed changes in the shape and areal coverage of the fire hot spot (dark black pixels); the corresponding VIIRS Red/Green/Blue (RGB) true-color images (below) still showed a smoke plume, though is was not as large as that seen on the GOES visible imagery from the previous day.
On 23 July, daytime (1925 and 2104 UTC) Suomi NPP VIIRS 3.74 µm shortwave IR and true-color RGB images (below) continued to display large fire hot spots and a smoke plume drifting toward the east-northeast. The size of the Reynolds Creek Fire was estimated to have increased to 4000 acres.
Unusual rains causing flooding and mudslides hit southern California (San Diego in particular) on 18-19 July 2015. The two-day rain total (1.69″) at Lindbergh Field broke the monthly record for July (previous record, 1.29″) and exceeded the January-April 2015 rainfall (the typical wet season) at the station. The San Diego Padres had their first July rainout ever, and the Anaheim Angels had their first rainout since 1995! What caused the rains? The water vapor imagery, above, shows the three systems that contributed. Pacific Hurricane Dolores (Track) was declared post-tropical off the coast of Baja California at 0300 UTC on 19 July. Farther to the west, Pacific Tropical Storm Enrique was declared post-tropical at 0300 on 18 July. High pressure aloft was helping support a Gulf Surge, a surge of moisture up the Gulf of California towards the desert southwest. Two animations of MIMIC Total Precipitable Water, below, show the surge and also show that moisture associated with main circulation of Dolores remains mostly offshore until late on the 19th, after the heavy rains had ended.
The Blended Precipitable Water Product (data collected from this site), below, also shows evidence of a Gulf Surge of moisture moving northward through the Gulf of California in the few days preceding the rains.
The animation of 10.7 µm imagery, below, suggests that the precipitation on Saturday the 18th was associated more with the Gulf Surge of moisture (which surge was likely influenced both by the large scale synoptic flow and by the circulation of Dolores); precipitation on Sunday the 19th seems more directly influenced by Dolores.
What part did the upper-level outflow jets from the two tropical cyclones play in this event? Consider the water vapor animation below, zoomed in from the larger-scale view at the top of this post. Outflow from Enrique moves from the southwest part of the domain towards the southern California coast (the low-level circulation of Enrique are at the southwest edge of the domain), moving inland as convection develops on Saturday 18 July 2015. The Total Precipitable Water imagery suggests that convection starts as the leading edge of the Gulf Surge arrives; water vapor imagery suggests a tie to Enrique.
GOES-15 Visible Imagery, below, from Saturday the 18th and from Saturday the 19th suggest rain on 19 July was more directly tied to the circulation of Dolores. On both days, the convective nature of the precipitation is apparent, with numerous overshooting tops present. Convection on Sunday the 19th started over higher terrain first, and then was joined by tropical convection moving in from the ocean.
As might be expected, the San Diego sounding (source) shows deep tropical moisture late on the 18th and late on the 19th as the heavy rains occurred. The precipitable water value of 2.10″ at 0000 UTC on 20 July was a top 5 value for July (Source). The rains caused two spikes in the flow of the San Diego River (Link, courtesy Alex Tardy, NWS San Diego).
The convection over San Diego produced many lightning strikes on Saturday, as shown on the map below, courtesy of Alex Tardy, NWS San Diego.