Puerto Rico: GOES-13 Super Rapid Scan Operations, and Saharan dust

June 1st, 2010

GOES-13 10.7 µm IR images

GOES-13 10.7 µm IR images

Due to lightning causing a radar outage, and with strong thunderstorms capable of producing heavy rainfall in the area, the National Weather Service Forecast Office in San Juan, Puerto Rico requested that GOES-13 be placed into Super Rapid Scan Operations (SRSO) mode — this made satellite imagery available at 1-minute intervals for short periods of time between 02:04 and 04:15 UTC on 01 June 2010:

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
826 PM AST MON MAY 31 2010

.UPDATE...TDWR TSJU RADAR HAS FAILED LIKELY DUE TO COMMS FAILURE
AS A RESULT OF INTENSE CG LIGHTNING ACTIVITY NEAR THE RADAR SITE.
GIVEN THAT WE HAVE NO RADARS AVAILABLE ATTM...I HAVE REQUESTED TO
NCEP TO PUT GOES IN SUPER RAPID SCAN IMAGERY UNTIL AT LEAST
MIDNIGHT WHEN CONVECTION SHOULD WEAKEN OR WITH START SEEING A
DECREASE IN LIGHTNING DATA.

McIDAS images of the GOES-13 10.7 µm IR channel data (above) showed the widespread cold cloud tops in the vicinity of Puerto Rico during that period — IR brightness temperatures south of the island were as cold as -82º C (purple color enhancement). While the convective complex approaching from the north appeared to be diminishing — an important trend to monitor nonetheless — there was a small cell that later developed very quickly along the extreme eastern end of the island.

Since we’re talking about Puerto Rico, it’s also worth mentioning that there had been a large cloud of Saharan dust  moving westward across the tropical Atlantic Ocean during the past few days of May 2010, and the leading edge of this Saharan dust was approaching the Lesser Antilles island chain on 01 June. The large hazy areas of Saharan dust were very apparent on GOES-13 0.63 µm and GOES-12 0.65 µm visible channel images (below), and getting closer to Puerto Rico (labeled PR on the images).

GOES-12 (bottom) and GOES-13 (top) visible channel images

GOES-12 (bottom) and GOES-13 (top) visible channel images

The dry air mass containing this Saharan dust could also be seen on GOES-12 sounder  Total Precipitable Water (TPW) derived product imagery (below), with TPW values in the 30-40 mm range (green to yellow color enhancement). Real-time GOES-12 Imager and Sounder products are available on the CIMSS GOES-12 (South America) site.

GOES-12 sounder Total Precipitable Water (TPW) derived product images

GOES-12 sounder Total Precipitable Water (TPW) derived product images

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