ACSPO SSTs off the Oregon Coast

September 14th, 2021 |
ACSPO SST values derived from VIIRS data, 12-14 September 2021, at times indicated (Click to enlarge)

Clear skies to the west of Oregon and California in the past two days have allowed VIIRS data (VIIRS — the Visible-Infrared Imaging Radiometer Suite flying on both Suomi-NPP and NOAA-20) to produce compelling imagery of the Sea Surface using Advanced Clear Sky Processing for Ocean (ACSPO) algorithms. VIIRS imagery is downlinked at the Direct Broadcast site at the UW-Madison; data are processed using CSPP. Purple values are just a bit cooler than 50º F; Yellow values are in the mid-60s ºF.

ACSPO estimates of SSTs are important over the Pacific Northwest because the Level 2 SST GOES-16 product is not computed near the GOES-16 limb. Level 2 Clear Sky mask is not computed out to the limb, as shown below, and GOES-16 SSTs (Full-Disk only products) are not computed out to the edge of the Clear Sky mask! So, if you want satellite-derived SSTs (GOES-17 Level 2 products are not yet widely available), Polar-Orbiting data are the way to go.

GOES-16 Level Clear Sky Mask (white=clouds; black=no clouds) and derived SSTs, 1600 UTC on 14 September 2021 (Click to enlarge)

AWIPS-ready ACSPO SST files are available from via an LDM feed from CIMSS.

Hurricane Nicholas makes landfall in Texas

September 14th, 2021 |
GOES-16 Mesoscale Sector infrared imagery (Band 13, 10.3), 0321-0844 UTC on 14 September 2021

Hurricane Nicholas made landfall on the Gulf Coast shortly after 0530 UTC on 14 September. It is a challenge to determine the storm center from the animation above, although deep convection is suggestive of its location. Note the collapse of deep convection as well at the end of the animation. Radar imagery, below (from this site), is helpful in placing the storm center.

NEXRAD Composite Reflectivity, 0524, 0534, 0544, 0554 UTC on 14 September 2021 (Click to enlarge)

MetOp-B overflew Nicholas at 0315 UTC shortly before landfall. ASCAT winds (from this site) at 0315 UTC show the circulation center very close to the shoreline. A similar image from the OSI SAF Multiplatform viewer is here.

Metop-B ASCAT winds, 0314 UTC on 14 September 2021 (Click to enlarge)

Nicholas is embedded in very moist air. A 24-hour MIMIC Total Precipitable Water animation, below, shows the moisture plume. Heavy rain is forecast for the central Gulf Coast.

Total Precipitable Water, 1000 UTC on 13 September – 0900 UTC 14 September (click to enlarge)

Nicholas has weakened to a Tropical Storm as of 0900 UTC on 14 September. Refer to the National Hurricane Center website for more information.