Hurricane Tomas

November 5th, 2010 |
Storm track of Tomas (during the period 29 September - 05 November 2010)

Storm track of Tomas (during the period 29 September - 05 November 2010)

Tropical Storm Tomas became the 19th named storm of the 2010 Atlantic tropical cyclone season on 29 September 2010 (NHC advisory archive). The path of Tomas from the CIMSS Tropical Cyclones site can be seen above, along with a plot of the Advanced Dvorak Technique (ADT) intensity estimate (below) which showed that there were a number of fluctuations in the intensity of Tomas: it initially intensified into a Category 1 and then a Category 2 hurricane as it crossed the Windward Islands of the Lesser Antilles on 30-31 August, but then was degraded to a Tropical Storm due to unfavorable deep layer wind shear on 01 November. Atmospheric steering currents then helped Tomas turn to the north, and the storm re-intensified into a Category 1 hurricane as it passed between Cuba and Hispaniola on 05 November.

Automated Dvorak Technique (ADT) plot for Tomas

Automated Dvorak Technique (ADT) plot for Tomas

Animations of GOES-13 0.63 µm visible channel imagery and GOES-13 10.7 µm IR channel imagery (below) revealed a number of convective bursts as Tomas intensified into a Category 1 hurricane on 30 August.

GOES-13 0.63 µm visible channel images

GOES-13 0.63 µm visible channel images

GOES-13 10.7 µm IR images

GOES-13 10.7 µm IR images

A comparison of a GOES-13 10.7 µm IR image with the corresponding SSMI/S 85 GHz microwave image around 22:45 UTC on 30 August (below) showed that Hurricane Tomas had a large closed eye and a well-defined spiral band extending northward as the storm passed to the west of the Windward Islands of St. Lucia and St. Vincent.

Hurricane Tomas GOES-13 10.7 µm IR + SSMI/S 85 GHz microwave images

Hurricane Tomas GOES-13 10.7 µm IR + SSMI/S 85 GHz microwave images

On 05 November, AWIPS images of POES AVHRR 10.8 µm IR data (below) showed that Hurricane Tomas was exhibiting IR brightness temperatures as cold as -93º C (darker purple color enhancement) as the storm passed between Jamaica and Hispaniola.

POES AVHRR 10.8 µm IR images

POES AVHRR 10.8 µm IR images

Note the improvement in cloud top temperature structure that can be seen on the 1-km resolution POES AVHRR IR image, compared to the corresponding 4-km resolution GOES-13 IR image (below). On the POES AVHRR image, subtle storm top gravity waves can be seen emanating southward away from the region of coldest cloud tops, and the transverse banding structure along the western and southwestern edge of the storm are better resolved.

POES AVHRR 10.8 µm IR image + GOES-13 10.7 µm IR image

POES AVHRR 10.8 µm IR image + GOES-13 10.7 µm IR image

Note to NWS users: POES AVHRR images and products can be added to your local AWIPS workstations (via Unidata LDM subscription): for more details, see the AVHRR Imagery and Products in D-2D site.

Snow cover in northern Wisconsin

November 5th, 2010 |
250-meter resolution MODIS true color and false color RGB images

250-meter resolution MODIS true color and false color RGB images

A comparison of a 250-meter resolution MODIS true color Red/Green/Blue (RGB) image (created using Bands 1/4/3) with the corresponding MODIS false color image (created using Bands 7/2/1) obtained from the SSEC MODIS Today site confirmed that the brighter white area seen in far north-central Wisconsin on 05 November 2010 was a patch of snow that remained on the ground following a period of lake-effect snow 1-2 days earlier. Snow cover and/or ice appears as cyan-colored features in the MODIS 7/2/1 RGB false color image.

AWIPS images showing another set of MODIS false color RGB images (below, created using Bands 1/7/7) showed that the patch of snow cover — which appeared as a red-colored feature in these particular RGB images — remained stationary between the times of the Terra satellite overpass (around 16:58 UTC, or 11:58 am local time) and the Aqua satellite overpass (around 18:40 UTC, or 1:40 pm local time), which again confirmed that this was snow cover rather than a cloud feature. Upson in Iron county had received 3 inches of snow during the preceding 48 hours, with Butternut in Ashland county receiving 1.0 inch of snowfall.

MODIS false color RGB images

MODIS false color RGB images