First thunderstorm at Barrow, Alaska since 2004

July 15th, 2012 |

NOAA-15 AVHRR 0.6 µm visible channel and 10.8 µm IR channel images [click to enlarge]

NOAA-15 AVHRR Visible (0.6 µm) and Infrared (10.8 µm) images [click to enlarge]

McIDAS images of 1-km resolution NOAA-15 0.6 µm visible channel and 10.8 µm IR channel images from 01:30 UTC on 16 July 2012 or 5:30 PM local time on 15 July (above) showed the development of the first thunderstorm recorded at Barrow, Alaska since July 2004:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
556 PM AKDT SUN JUL 15 2012

…FIRST THUNDERSTORM IN BARROW SINCE 2004…

A LINE OF THUNDERSTORMS DEVELOPED JUST EAST OF BARROW LATE THIS AFTERNOON. A FEW RUMBLES OF THUNDER WERE HEARD AT THE NATIONAL WEATHER SERVICE OFFICE IN BARROW BETWEEN 515PM AND 535PM. THE ALASKA FIRE SERVICES LIGHTNING DETECTION NETWORK RECORDED FEW STRIKES JUST SOUTHEAST OF DEASE INLET.

THIS IS THE FIRST THUNDERSTORM AT BARROW SINCE JULY 3RD 2004.

$$
RT JUL 12

The coldest thunderstorm cloud-top IR brightness temperature on the 01:22 UTC NOAA-15 image was -37º C (green color enhancement). The surface winds at Barrow had switched to light northerly at the time of the thunderstorm, but a few hours prior to that had been from the southeast at 15-20 mph (helping to increase dew point temperatures into the low 50s F).

Due to the extreme viewing angle from the GOES-15 (GOES-West) satellite, the narrow line of weak thunderstorms was poorly resolved on Infrared (10.7 µm) images (below), and the apparent location was shifted to the north over the Arctic Ocean due to the parallax effect.

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

GOES-15 Infrared (10.7 µm) IR images [click to enlarge]

Aurora Borealis signature seen on VIIRS Day/Night Band imagery

July 15th, 2012 |
Suomi NPP VIIRS 0.7 µm Day/Night Band image + 11.45 µm IR channel image

Suomi NPP VIIRS 0.7 µm Day/Night Band image + 11.45 µm IR channel image

An AWIPS image of Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) data (above) revealed the bright signature of the Aurora Borealis along the US/Canadian border region at 07:33 UTC (1:33/2:33 AM local time) on 15 July 2012 (NOAA Space Weather Prediction Center auroral oval map). While the corresponding VIIRS 11.45 µm IR image did show some areas of clouds (particularly over North/South Dakota and southern Manitoba/Saskatchewan), there was very little cloud illumination from the waning crescent phase of the Moon (only 9% of the moon was visible) — so the vast majority of the bright DNB signal was from the Northern Lights activity.

A few of the smaller bright spots seen on the DNB image across parts of eastern Manitoba and western Ontario were due to flames from wildfires that were burning in that region, as seen in a comparison of VIIRS DNB and 3.74 µm shortwave IR images (below). The larger fires exhibited a small “hot spot” (yellow to red color enhanced pixels) on the shortwave IR image.

Suomi NPP VIIRS 0.7 µm Day/Night Band image + 3.74 µm shortwave IR channel image

Suomi NPP VIIRS 0.7 µm Day/Night Band image + 3.74 µm shortwave IR channel image

Brief glimpses of the Aurora Borealis activity could be seen from the northwest-facing camera on top of the SSEC/AOS building on the University of Wisconsin – Madison campus (below; night-time images provided by Pete Pokrandt, AOS).

SSEC/AOS rooftop camera images (click to play QuickTime movie)

SSEC/AOS rooftop camera images (click to play QuickTime movie)

===== 16 July Update =====

The bright auroral oval was again seen on VIIRS Day/Night band imagery the following night, at 07:14 UTC on 16 July. A comparison of the 15 July and 16 July DNB images (below) shows that the auroral oval was retreating northward on 16 July, as the impact of the geomagnetic storm triggered by a Coronal Mass Ejection (CME) from the sun was beginning to subside.

 

Suomi NPP VIIRS 0.7 µm Day/Night Band images (15 and 16 July)

Suomi NPP VIIRS 0.7 µm Day/Night Band images (15 and 16 July)