True Color RGB images — created using Geo2Grid — from GOES-18 (GOES-West), GOES-17 and GOES-16 (GOES-East) (above) displayed dense plumes of blowing dust across parts of New Mexico, Texas and Oklahoma on 14 February 2023. Strong winds (with gusts in the 60-85 mph range) in the wake of a cold front lofted dry topsoil from areas that were experiencing Moderate to Exceptional Drought conditions.

GOES-17 (formerly GOES-West) was temporarily operating from its pre-storage checkout position over the Equator at 104.7 W longitude.

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True- and False-color imagery of Lake Erie from VIIRS data on NOAA-20, above, show a Lake largely clear of ice in mid-February (!). Cyan colors in the False-color imagery do suggest lake ice along the northern shore of Erie, however, to the east of Kingsville Ontario, and to the east of Port Stanley Ontario. The regions with ice are circled in this annotated false color image.

Clear skies meant that the Advanced Clear-Sky Processing for Ocean (ACSPO) algorithm could produce estimates of lake surface temperatures, shown below. The warmest temperatures — near 37^oF, green in the enhancement — are just northeast of Erie, PA.

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In fact, most of the Great Lakes had clear skies at 1836 UTC. Click here to see the SSTs. The mostly clear skies continued overnight on 14 February, and the image below shows ACSPO SSTs and the Day Night Band.

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1-minute Mesoscale Domain Sector GOES-18 (GOES-West) “Red” Visible (0.64 µm) images (above) include plots of Derived Motion Winds (DMW) — and showed the rapid offshore transport of cold arctic air across the southern Cook Inlet, Shelikof Strait and northwestern Gulf of Alaska on 12 February 2023. The fastest low-level (Surface – 900 hPa) DMW speed was 64 knots in the far southern portion of Cook Inlet at 2305 UTC (below).

A Heavy Freezing Spray Warning had been issued for that entire offshore region (light blue), including the Shelikof Strait (above) — and Buoy 46077 in the Shelikof Strait was recording Ice Accretion rates in excess of 1.0 inches per hour (below). Buoy air temperatures had fallen into the 10-12F range during that time, with wind gusts of 40-50 knots — providing ideal conditions for rapid ice accretion.

RCM/Radarsat-2 SAR winds at 1630 UTC on 12 February (source) are shown below — a NW-to-SE oriented swath of strong offshore winds (40-50 knots, darker shades of red) was seen extending from the far southern end of Cook Inlet (where the aforementioned 64-knot GOES-18 DMW speed was located) into the northwestern Gulf of Alaska. Another pocket of similarly-strong wind speeds was evident farther to the north, in the vicinity of Homer, Homer Spit and the mouth of Kachemak Bay.

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Sentinel-1A overflew the Samoan Islands shortly after sunset on 11 February and captured a packet of very strong winds just to the west of Tutuila Island of American Samoa. The toggle above compares Band 13 imagery with two different enhancements of the SAR Winds: one (here) highlighting the different Beaufort Scales, and one (here) showing just gridded fields (from 0-65 knots). Is there a good relationship between the wind structures and the Band 13 brightness temperatures?

The first thing to do is to examine the strong winds to the west of Tutuila for any possible artifacts that might arise from ice within the clouds. The toggle below (between this wind image and this Normalized Radar Cross Section — NRCS — image from this website) shows that features north of Tutuila, between 13.4 and 13.6^oS and around 170.5^oW, for example, have bright white, diffuse NRCS features that suggest ice; such features are absent in the clouds around western Tutuila, however, suggesting they contain little ice to affect the SAR return (with the exception of features at the very southern edge of the domain). The SAR data suggest modest northerly winds (around 10 knots) over most of the domain. That is in agreement with ASCAT data from MetopB (0800 and 2100 UTC on 12 February) and MetopC (2030 UTC on 12 February), taken from this website.

The animation below shows persistent cooler cloud top features moving northward over western Tutuila. The feature over western Tutuila at 0550 UTC spawns the very strong winds that show up in the SAR data. Immediately in the lee of the island (if one assumes southwesterly outflow!), relatively calm winds are diagnosed.

GOES-18 Band 3 Near-infrared (“Veggie Band”, 0.86 µm) imagery, below, also shows the northward motion of cloud features over western Tutuila. The absence of widespread strong winds in other features within this line of enhanced cloudiness suggests that interaction with the topography of Tutuila was a possible contributing factor to the outflow generation.

What was the weather like at Pago Pago International Airport around sunset? The screen capture below (from this site) shows a shower near 7 PM on the 11th (Samoa Standard Time), which is 0600 UTC on 12th.

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