Hurricane Arthur

July 3rd, 2014
Terra MODIS 11.0 µm IR channel image

Terra MODIS 11.0 µm IR channel image

04 July Update: a 1-km resolution Terra MODIS 11.0 µm IR image (above) showed the eye of Category 2 Hurricane Arthur making landfall along the coast of North Carolina around 03:13 UTC or 11:15 pm Eastern Time. Arthur was the earliest hurricane to make landfall in North Carolina since records began in 1851 (the previous record was 11 July, 1901).

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

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

[5:45 PM EDT 3 July 2014 Update: The animation of GOES-13 visible images above, ending at 21:45 UTC or 5:45 PM Eastern Daylight Time, shows Hurricane Arthur very close to the North Carolina coast. Convection continues redeveloping in the circulation close to the eye.]

Suomi NPP VIIRS True Color Image of Arthur at 1800 UTC 3 July 2014

Suomi NPP VIIRS True Color Image of Arthur at 1800 UTC 3 July 2014

The original VIIRS image, above (courtesy of Russ Dengel), was clipped from this link. An animation of VIIRS True-Color imagery of Arthur (courtesy of Kathy Strabala), taken from the Webmap server at SSEC is shown below.

Suomi NPP VIIRS True Color Imagery of Arthur, 30 June - 3 July 2014 (click to enlarge)

Suomi NPP True Color Imagery of Arthur, 30 June – 3 July 2014 (click to enlarge)

GOES-13 10.7 µm infrared channel images (click to play animation)

GOES-13 10.7 µm infrared channel images (click to play animation)

Tropical Storm Arthur has strengthened overnight to become the first hurricane of the Atlantic Tropical Season. The storm-centered animation above, from GOES-East, (click here for an animation without the map) shows evidence of the relaxation in wind shear that has allowed intensification. At the beginning of the animation, most convection is to the east and south of the system. By 3 July, convection is much closer to the center of the strengthening storm and an outflow channel to the southeast has developed; a distinct eye is present by 2045 UTC on 3 July. Note that in the color enhancement that the coldest cloud tops — purple — are cooler than -80° C. This image (from this website) shows Arthur, at 1500 UTC on 3 July 2014, under a minimum in wind shear. (Zoomed-in version of wind shear).

The tropical cyclone has been moving due north over the past 24 hours, but the National Hurricane Center notes that a recurvature to the northeast is occurring now. Interests along the South and North Carolina coasts should pay special attention to forecasts for today and tomorrow.

GOES-13 0.63 µm visible channel image with surface observations, 1400 UTC 3 July 2014 (click to enlarge)

GOES-13 0.63 µm visible channel image with surface observations, 1400 UTC 3 July 2014 (click to enlarge)

Visible imagery from 1400 UTC, above, does not yet show an eye, and strongest winds at that time remained offshore. Moored Buoy 41004 (41 miles southeast of Charleston, SC, at 32°30’2″ N 79°5’58″ W) shows tropical-storm force-winds; a plot of the pressure and winds at the station, below, suggests an approaching storm.

Surface Pressure and Winds at Moored Buoy 41004 (click to enlarge)

Surface Pressure and Winds at Moored Buoy 41004 (click to enlarge)

Toggle between Suomi NPP VIIRS 11.45µm Infrared Imagery and Day/Night Band at 0639 UTC 3 July (click to enlarge)

Toggle between Suomi NPP VIIRS 11.45µm Infrared Imagery and Day/Night Band at 0639 UTC 3 July (click to enlarge)

Suomi NPP overflew Arthur in the early morning of July 3rd, affording a high-resolution view of the convective clouds. The coldest overshooting tops, around -85°C are far to the east of the surface circulation, but a large cirrus shield with temperatures near -75°C is over the storm center. The Day/Night band shows little contrast because the Quarter Moon set at 0400 UTC and therefore no lunar illumination is available. A few lightning streaks in the convection around Arthur are present. Lightning is far more common in the convection over the northeast Gulf of Mexico.

MODIS Imagery over Arthur at 1613 UTC 3 July (click to cycle through channels)

MODIS Imagery over Arthur at 1613 UTC 3 July (click to cycle through channels)

MODIS imagery over Arthur was available from Terra at 1613 UTC today. A variety of channels are shown above — Visible imagery (0.64 µm), the Snow/Ice Channel (a wavelength of 1.6 µm, at which snow/ice strongly absorb radiation and therefore appear dark), the Cirrus channel (a wavelength of 1.38 µm, at which cirrus clouds are strongly reflective and are therefore highlighted), the Water Vapor channel (6.7 µm, showing the height of the top of the moist layer) and the Infrared channel near 11 µm.

Previous Tropical Storm Arthurs passed near the North Carolina coast in 1996 (a swirl in mid-level clouds with little deep convection) and in 2002 (a mass of convection that obscured any circulation).

40 years of Satellite Imagery

June 27th, 2014
Synchronous Meteorological Satellite (SMS-1) 11 µm infrared channel image, 2130 UTC 27 June 1974 (click to enlarge)

Synchronous Meteorological Satellite (SMS-1) 11 µm infrared channel image, 2130 UTC 27 June 1974 (click to enlarge)

The oldest satellite image in the SSEC data archive is shown above, taken 40 years ago on 27 June 1974, from SMS-1 (the corresponding visible image can be seen here). The infrared channel sensed radiation in a broad spectrum between 10.5 and 12.6 µm (source). The SMS-1 satellite (launched on 17 May 1974) was positioned over the Equator over eastern South America, at about 45 degrees West Longitude.

More information on the SSEC Datacenter archive is here.

The Memphis Derecho of July 22 2003

July 31st, 2013
GOES-12 10.7 µm IR imagery (Click Image to play animation)

GOES-12 10.7 µm IR imagery (Click Image to play animation)

On the morning of July 22, 2003, a strong derecho moved through metropolitan Memphis, TN, with winds exceeding hurricane-force. The most significant impact of this storm was a loss of power caused in part by the many trees that were downed by the winds. The Storm Report for the day from the Storm Prediction Center shows a cluster of wind reports in and around Memphis and Shelby County. The National Weather Service office in Memphis produced a report on this event that includes radar imagery and a discussion of surface and upper-air observations. More information on this derecho is here. What do satellite data show for this event?

The animation of 10.7 µm imagery, above, shows the development of convection in southeast Kansas and northwest Arkansas that then moves eastward into the mid-South, hitting Memphis around 1200 UTC. Several overshooting tops are evident as the storms pass near Memphis, with the coldest brightness temperatures at 196K! Past derechosdiscussed on this blog (such as the one that hit the East Coast in 2012) were characterized by a channel of moisture and instability aligned with the storm motion, allowing the propagating thunderstorm complex access to a rich source of moisture and instability. This event in 2003 was no different. GOES-12 Sounder retrievals — during that year, 3×3 fields-of-view were used (versus single pixels now) — of Total Precipitable Water, Convective Available Potential Energy (CAPE) and Lifted Index (LI), show abundant moisture and instability aligned west-to-east across northern Arkansas. CAPE values exceeded 3000 J/kg, Total Precipitable Water was greater than 2 inches, and Lifted Indices were near -10.

GOES-10/GOES-12 Sounder-Derived Total Precipitable Water (3x3 Field of View) (Click Image to play animation)

GOES-10/GOES-12 Sounder-Derived Total Precipitable Water (3×3 Field of View) (Click Image to play animation)

GOES-10/GOES-12 Sounder-Derived Convective Available Potential Energy (CAPE) (3x3 Field of View) (Click Image to play animation)

GOES-10/GOES-12 Sounder-Derived Convective Available Potential Energy (CAPE) (3×3 Field of View) (Click Image to play animation)

GOES-10/GOES-12 Sounder-Derived Lifted Index (3x3 Field of View) (Click Image to play animation)

GOES-10/GOES-12 Sounder-Derived Lifted Index (3×3 Field of View) (Click Image to play animation)

GOES-12 Visible Imagery (Click Image to play animation)

GOES-12 Visible Imagery (Click Image to play animation)

Visible imagery, above, from GOES-12 shows the convection continuing to develop as it moves across the Mississippi River into Memphis. Several Overshooting tops are evident, as well as parallel cloud lines at the cirrus level that are usually associated with turbulence. GOES-10, as GOES-West, was also able to capture the convection as it moved through Memphis (below).

GOES-10 Visible Imagery (Click Image to play animation)

GOES-10 Visible Imagery (Click Image to play animation)

53rd anniversary of the first image from a meteorological satellite

April 1st, 2013

 

TIROS-1 visible image

TIROS-1 visible image

Today marks the 53rd anniversary of the first image from the meteorological satellite TIROS-1, which was available on 01 April 1960 (above). While TIROS-1 was only operational for 78 days, it provided a number of images of the Earth and cloud systems (including the first image of a tropical cyclone, over the South Pacific Ocean on 10 April 1960).

One example that demonstrates how satellite imagery has improved over the past 53 years is a night-time comparison of AWIPS images of Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel  data (below), covering the same general region as shown on the first TIROS-1 image (Maine, and the Canadian Maritime provinces). With ample illumination from the moon (Waning Gibbous phase, 67% of full), the Day/Night Band offered a “visible image at night” which showed such features as the extent of sea ice in the channels between Nova Scotia, Prince Edward Island, and New Brunswick, as well as a series of banded wave clouds associated with an undular bore off the southern coast of Nova Scotia. Subtle details regarding the location and cloud-top IR brightness temperature of overshooting tops could also be seen in the convective clouds off the coast of Maine.

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

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

UPDATE: Hat-tip to AccuWeather’s Jesse Ferrell, who found this information which indicates that the TIROS-1 image shown above was actually taken on 02 April 1960! The actual first image from TIROS-1 (taken on 01 April 1960) is shown below (courtesy of Rick Kohrs, SSEC).

The actual first TIROS-1 image (taken on 01 April 1960)

The actual first TIROS-1 image (taken on 01 April 1960)