Significant rainfall event in California

December 2nd, 2014 |
MIMIC Total Precipitable Water product, with surface analysis overlays

MIMIC Total Precipitable Water product, with surface analysis overlays

As of 25 November 2014, much of the state of California was experiencing extreme to exceptional drought conditions.  However, the development of a large occluded mid-latitude cyclone over the far eastern Pacific Ocean during the 01 December – 02 December time period began to draw high values (up to 60 mm or 2.4 inches, darker red color enhancement) of total precipitable water (TPW) northward from the Inter-Tropical Convergence Zone (ITCZ), as seen on AWIPS images of the MIMIC TPW product (above). While the rainfall was beneficial in terms of drought mitigation, amounts of up to 12 inches did cause flooding and mudslide problems in some locations.

An animation of hourly MIMIC TPW images from 30 November – 02 December (below; click image to play animation) showed the northward surge of moisture toward the California coast, and also hinted at a complex inner structure associated with the occluded low.

MIMIC Total Precipitable Water product (click image to play animation)

MIMIC Total Precipitable Water product (click image to play animation

Comparison of MODIS 6.7 um and GOES-15 6.5 µm water vapor channel images

Comparison of MODIS 6.7 um and GOES-15 6.5 µm water vapor channel images

On 02 December, comparisons of AWIPS II images of 1-km resolution MODIS 6.7 µm and 4-km resolution GOES-15 6.5 µm water vapor channel data around 11 UTC (above) and around 22 UTC (below) demonstrated the importance of improved spatial resolution for more clearly identifying some of the smaller-scale structure features within the core of the occluded low.

Comparison of MODIS 6.7 µm and GOES-15 6.5 µm water vapor channel images

Comparison of MODIS 6.7 µm and GOES-15 6.5 µm water vapor channel images

A comparison of Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 22:18 UTC (below) shows a few areas of embedded convection, some of which had produced cloud-to-ground lightning strikes in the hour preceding the images.

Suomi NPP VIIS 0.64 µm visible channel and 11.45 µm IR channel images, with cloud-to-ground lightning strikes

Suomi NPP VIIS 0.64 µm visible channel and 11.45 µm IR channel images, with cloud-to-ground lightning strikes