Record daily rainfall in southern California

September 15th, 2015 |

Time series plot of weather conditions for Los Angeles International Airport [click to enlarge]

Time series plot of weather conditions for Los Angeles International Airport [click to enlarge]

Some locations in southern California received record daily precipitation on 15 September 2015. A time series plot of weather conditions for Los Angeles International Airport is shown above; the 1.80 inches of rainfall received there made it the wettest September day on record.

As mentioned in the NWS Los Angeles record event report, the moisture source for this heavy rainfall event was the remnants of Hurricane Linda (storm path); the MIMIC Total Precipitable Water product covering the period 06-15 September (below) showed the evolution of the moisture associated with Linda, which originally tapped rich moisture from the Intertropical Convergence Zone (ITCZ).

MIMIC Total Precipitable Water product [click to play animation]

MIMIC Total Precipitable Water product [click to play animation]

A closer look at the MIMIC Total Preciptable Water product (below) showed how the moisture was becoming more concentrated just offshore, in advance of an approaching upper level trough and a decaying surface cold front.

MIMIC Total Precipitable Water product [click to play animation]

MIMIC Total Precipitable Water product [click to play animation]

GOES-15 Infrared (10.7 µm) images (below) revealed that the cloud-top IR brightness temperatures were actually quite warm (> -20º C) over coastal southern California during the period of the heavy rainfall event.

GOES-15 Infrared (10.7 µm) images [click to play animation]

GOES-15 Infrared (10.7 µm) images [click to play animation]

Aurora Borealis as seen by VIIRS Day/Night Band imagery

September 9th, 2015 |
Aurora Forecast issued by the Space Weather Prediction Center

Aurora Forecast issued by the Space Weather Prediction Center

The Aurora Forecast shown above was issued on the night of 08 September 2015 by the NOAA Space Weather Prediction Center, with the accompanying text:

Following the G2 (moderate) geomagnetic storms from last night, observations of the solar wind at the ACE spacecraft near L1 indicate the potential again this evening for more activity. G1 (minor) conditions have already been observed by the global network of ground-based near real-time magnetometers. A forecast warning for G2 has been issue from 09/0500 – 09/1000 UTC (1am to 6am EST). These could be some prime hours to possibly see the Aurora in the northern most regions of the lower 48 states.

Suomi NPP VIIRS Day/Night Band (0.7 µm) image composite [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image composite [click to enlarge]

A composite of Suomi NPP VIIRS Day/Night Band (0.7 µm) images viewed using the SSEC RealEarth web map server (above) showed the bright and complex signature of the aurora borealis across southern Canada and the northern United States during the subsequent nighttime hours. Two of the individual Day/Night Band image swaths as viewed using AWIPS-2 are shown below.

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0756 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0756 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0939 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0939 UTC [click to enlarge]

Tropical Storm Jimena

September 8th, 2015 |

GOES-15 Visible (0.63 um) images [click to play animation]

GOES-15 Visible (0.63 um) images [click to play animation]

GOES-15 Visible (0.63 µm) images (above; click image to play animation) showed the low-level circulation center (LLCC) of Tropical Storm Jimena becoming exposed as the tropical cyclone encountered increasing amounts of westerly deep-layer wind shear. Jimena had rapidly intensified to a Category 4 hurricane over the East Pacific Ocean in late August and early September (path | ADT plot).

Before sunrise, Suomi NPP VIIRS imagery (below; click to enlarge) was useful to help locate the LLCC, as was noted in a discussion issued by the Central Pacific Hurricane Center.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared (11.45 µm) images [click to enlarge]

A DMSP-18 SSMIS Microwave (85 GHz) image at 1733 UTC (below; click to enlarge) showed a signature of significant rainfall rates (orange to red color enhancement) within the deep convection that remained well to the east of the LLCC.

DMSP-18 SSMIS Microwave (85 GHz) image [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) image [click to enlarge]

Supercell thunderstorm producing large hail in the Naples, Italy area

September 5th, 2015 |

Meteosat-10 Infrared (10.8 µm) images [click to play animation]

Meteosat-10 Infrared (10.8 µm) images [click to play animation]

EUMETSAT Meteosat-10 Infrared (10.8 µm) images (above; click image to play animation) showed an isolated supercell thunderstorm which quickly developed over the eastern Mediterranean Sea and moved eastward across central Italy on 05 September 2015. This storm produced large in the Naples area (station identifier LIRN); hail was as large as 10 cm (3.94 inches) in diameter in the city of Pozzouli, which was just south of the vertex of the well-defined “enhanced-V” storm-top signature as seen in IR images from the SSEC RealEarth web map server site (below; click images to play animation). The coldest cloud-top IR brightness temperature was -73.5º C at 0900 UTC.

Meteosat-10 Infrared (10.8 µm) images [click to play animation]

Meteosat-10 Infrared (10.8 µm) images [click to play animation]

Meteosat-10 High Resolution Visible (0.8 µm) images (below; click image to play animation) revealed the tell-tale shadows cast by overshooting tops associated with the vigorous updrafts within this large and intense thunderstorm.

Meteosat-10 Visible (0.8 µm) images [click to play animation]

Meteosat-10 Visible (0.8 µm) images [click to play animation]