CIMSS Satellite Blog

Mesoscale Convective Vortex in the Gulf of Mexico

May 3rd, 2012

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

AWIPS images of 4-km resolution GOES-13 10.7 µm IR channel data (above; click image to play animation) showed the development of large thunderstorms over the far eastern Gulf of Mexico during the pre-dawn hours on 03 May 2012.

Better detail of the cold convective cloud tops could be seen in a series of 1-km resolution POES AVHRR 10.8 µm IR and MODIS 11.0 µm IR channel images (below).

POES AVHRR 10.8 µm IR and MODIS 11.0 µm IR images

McIDAS images of 1-km resolution GOES-13 0.63 µm visible channel data (below; click image to play animation) revealed the formation of a mesoscale convective vortex (MCV) after the night-time convection dissipated.

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

A GOES-13 10.7 µm IR image at 16:10 UTC with an overlay of ASCAT scatterometer surface winds at 16:05 UTC (below) suggested that the MCV was causing a perturbation in the general southeasterly flow as it was beginning to organize.

GOES-13 10.7 µm IR image + ASCAT scatterometer surface winds

Posted in AVHRR, GOES-13, MODIS, Other Satellites, POES, Satellite winds | No Comments »

Undular bore over northeastern North Dakota and northwestern Minnesota

May 2nd, 2012

GOES-13 10.7 µm IR channel + 0.63 µm visible channel images (click image to play animation)

Surface outflow from dissipating convection over southern Manitoba, Canada during the pre-dawn hours on 02 May 2012 created an undular bore, which then propagated southeastward across northeastern North Dakota and northwestern Minnesota. AWIPS images of 4-km resolution GOES-13 10.7 µm IR channel data followed by 1-km resolution GOES-13 0.63 µm visible channel data after sunrise (above) showed the undular bore wave clouds. Surface winds associated with this convective outflow gusted to 30 knots in southern Manitoba at 12 UTC and 27 knots in northwestern Minnesota at 13 UTC.

POES AVHRR 12.0 µm IR image

An AWIPS image of 1-km resolution POES AVHRR 12.0 µm data (above) indicated that the wave cloud top IR brightness temperature was in the +2 to +3 C range. According to the 12 UTC rawinsonde data from International Falls, Minnesota (below), a temperature inversion located between 683 hPa and 693 hPa was likely acting to duct the undular bore as it moved southeastward.

International Falls, Minnesota rawinsonde data (12 UTC)

Posted in AVHRR, General interpretation, GOES-13, POES | No Comments »

Suomi NPP VIIRS images showing Arctic Ocean ice movement

April 28th, 2012

Suomi NPP VIIRS 0.64 µm visible channel images

AWIPS images of Suomi NPP VIIRS 0.64 µm visible channel data (above) and 11.45 µm IR channel data (below) showed cloud and ice features over the Arctic Ocean on 28 April 2012. For geographic reference, station identifier CWMD is Mould Bay, located on Prince Patrick Island in the far northwestern portion of the Canadian Arctic Archipelago.

The meteorological cloud features at this time were fairly benign, with some low stratus seen over the northern portion of the satellite scene, and multi-level clouds associated with a cyclone developing to the south. Of particular interest was the amount of sea ice motion during this relatively short 8-hour period — several ice leads opened up and became very prominent features on both the visible and the IR imagery.

Suomi NPP VIIRS 11.45 µm IR channel images

Suomi NPP VIIRS 1.61 µm near-IR images (below) revealed a number of narrow “streaks” of supercooled water droplet clouds (which appear as brighter white features) moving away from the islands, suggesting that there were strong winds across the region helping to move the sea ice. Water (and cloud shadows) appear black on the near-IR images, while ice and snow cover appear as darker shades of gray.

Suomi NPP VIIRS 1.61 µm near-IR images

Surface analyses at 12 UTC and 18 UTC (below) indicated that there was a strong pressure gradient over the region, between the High over the Arctic Ocean and a deepening Low over far northern Canada. The effect of this tightening pressure gradient was strong offshore (easterly) winds — the closest available observation site was Sachs Harbour on Banks Island, where they had easterly winds of 25 knots with gusts to 30 knots, and zero visibility with heavy snow and heavy blowing snow at 22 UTC.