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)

Hot tempertures in the Desert Southwest of the US

July 12th, 2012 |
MODIS 0.65 µm visible channel image + MODIS Land Surface Temperature product

MODIS 0.65 µm visible channel image + MODIS Land Surface Temperature product

The daily maximum temperature at Death Valley, California was 128º F (53.3º C) on 11 July 2012. A comparison of AWIPS images of 1-km resolution MODIS 0.65 µm visible channel data and the corresponding Land Surface Temperature (LST) product (above) showed that LST values were in the 150-160º F range (darker red color enhancement) in parts of the Death Valley region (which is generally oriented north to south, just to the east of station identifier K4SU).

The following morning, the surface air temperature at Death Valley only dropped to 107º F (41.7º C), which was the second warmest daily minimum temperature on record for that location:

RECORD EVENT REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
950 AM PDT THU JUL 12 2012

…SECOND WARMEST LOW TEMPERATURE EVER RECORDED AT DEATH VALLEY ON RECORD…

THE LOW TEMPERATURE AT THE OFFICIAL DEATH VALLEY WEATHER STATION IN FURNACE CREEK THIS MORNING ONLY FELL TO 107 DEGREES. THIS BREAKS THE RECORD FOR THE HIGHEST MINIMUM TEMPERATURE FOR JULY 12TH OF 100 DEGREES SET IN 1931.

THE LOW OF 107 DEGREES THIS MORNING IS THE SECOND WARMEST MINIMUM TEMPERATURE EVER RECORDED AT DEATH VALLEY SINCE RECORDS STARTED IN JUNE 1911. ONLY JULY 5TH 1918…WHEN THE LOW TEMPERATURE FELL TO 110 DEGREES HAS BEEN WARMER. THE LAST TIME DEATH VALLEY RECORDED A LOW OF 105 DEGREES OR GREATER WAS ON JULY 11TH 1920. A LOW OF 101 WAS RECORDED ON JULY 19TH 2010 AND THIS WAS THE LAST TIME A MINIMUM IN THE TRIPLE DIGITS WAS RECORDED IN DEATH VALLEY.

THE ABOVE INFORMATION IS PRELIMINARY AND IS SUBJECT TO A FINAL REVIEW BEFORE BEING CERTIFIED BY THE NATIONAL CLIMATIC DATA CENTER.

$$

STACHELSKI

Hurricane Emilia in the East Pacific Ocean

July 10th, 2012 |
GOES-15 0.63 µm visible channel images (click image to play animation)

GOES-15 0.63 µm visible channel images (click image to play animation)

McIDAS images of 1-km resolution GOES-15 0.63 µm visible channel data (above; click image to play animation) showed that Hurricane Emilia was beginning to exhibit as well-defined eye as it rapidly intensified over the East Pacific Ocean on 09 July 2012.

During the subsequent night-time hours, an eye signature was still evident on 4-km resolution GOES-15 1-.7 µm IR channel images (below; click image to play animation). Cloud top IR brightness temperatures were as cold as -82 C (violet color enhancement) at 06:00 UTC.

GOES-15 10.7 µm IR channel images (click image to play animation)

GOES-15 10.7 µm IR channel images (click image to play animation)

Emilia was in an environment of low deep-layer (850-200 hPa) wind shear (below), which was one factor that favored intensification.

GOES-15 10.7 µm IR images + Deep layer wind shear

GOES-15 10.7 µm IR images + Deep layer wind shear

 

Mesoscale Convective System exhibiting cloud-top gravity waves and transverse banding

July 6th, 2012 |
Suomi NPP VIIRS 11.45 µm IR  + 0.7 µm Day/Night Band images

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

A comparison of AWIPS images of 375-meter resolution (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 11.45 µm IR channel data with the corresponding 0.7 µm VIIRS Day/Night Band (above) showed a large Mesocale Convective System (MCS) with an expansive cold cloud shield (exihibiting IR brightness temperatures as cold as -84 C) over parts of North Dakota and South Dakota at 08:43 UTC (3:43 AM local time) on 06 July 2012. A number of well-defined cloud-top gravity waves could also be seen propagating northward and northeastward outward away from the core of the storm. There was a damaging wind report at 09:03 UTC in south-central North Dakota:  SW WIND GUST OF 68 MPH AT 403 AM CDT...AND N WIND GUST OF 68 MPH AT 408 AM CDT. Illumination from a full moon made convective overshooting tops and some of these cloud-top gravity waves easy to see on the Day/Night Band image.

About 2 hours later, these cloud-top gravity waves wee more difficult to identify on a 1-km resolution POES AVHRR 10.8 µm IR image (below) at 10.32 UTC (5:32 AM local time), although a few could still be seen in eastern North Dakota, western Minnesota and southern Manitoba. There was a wind gust to 51 knots (59 mph) reported at 10:40 UTC in southeastern North Dakota.

POES AVHRR 10.8 µm IR channel image + METAR surface reports and severe wind reports

POES AVHRR 10.8 µm IR channel image + METAR surface reports and severe wind reports

As the MCS began to dissipate around sunrise, a vivid display of transverse banding cirrus filaments could be seen on 1-km resolution GOES-13 0.63 µm visible channel images (below; click image to play animation) forming along the southern periphery of the storm over eastern South Dakota, southern Minnesota, and far northern Iowa. This transverse banding is a satellite signature of potential high-altitude turbulence — and there was one pilot report of moderate turbulence at 38,00 feet in eastern South Dakota.

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

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