On February 12, 2024, much of inland Alaska is experiencing warnings for wintery precipitation, while coastal Alaska is under warnings for storms, gales, and heavy freezing spray. Southeastern Alaska is also under a small craft advisory.

The low-pressure system associated with this inclement weather is seen easily from the GOES-West imagery. Viewers can see a large hook-shaped rotational system swooping in from the south and affecting much of the state. Figure 2 shows Band 9, the mid-level water vapor channel, from GOES-West, illustrating the low pressure system nicely. On the GOES-West Advanced Baseline Imager (ABI), Band 9 is centered on 6.9 µm and is great for tracking storm systems.

Expectedly, the weather is having unfavorable effects on aviation safety. Marginal visual flight rules (MVFR) cite weather conditions that aircraft pilots can experience at land or ocean surface levels. As seen in Figure 3, satellite and model-derived MVFR probabilities are present throughout inland and coastal areas of Alaska.

The animations in this post are replicable for anyone with web access, using RealEarth. RealEarth is a free weather visualization application. To recreate the animations you see in this post, click the links in the animation captions.

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1-minute Mesoscale Domain Sector GOES-18 (GOES-West) images from all 16 of the ABI spectral bands in addition to a Rocket Plume RGB (above) displayed signatures of a SpaceX Starlink Mission Falcon 9 rocket that was launched from Vandenberg Space Force Base, California at 0034 UTC on 10 February or 4:34 PM Pacific Time on 09 February 2024. A warm thermal signature of the Stage 1 rocket booster was evident in images from most of the Near-Infrared and Infrared spectral bands (Bands 04-16) and the RGB imagery as it quickly moved east-southeastward from the launch site — and either a somewhat bright reflectance signature or a relatively cool thermal signature of the Stage 1 rocket booster condensation cloud was seen in most of the spectral bands as it drifted slowly southward.

In a toggle between Upper-level Water Vapor (6.2 µm) images from GOES-16 (GOES-East) and GOES-18 (GOES-West) at 0036 UTC, both remapped to a common projection (below) note the large offset in apparent location of the Falcon 9 vapor trail — this is due parallax, which was significant due to (1) the altitude of the rocket’s vapor plume at that time, which was around 45 km and (2) the difference between satellite viewing angle magnitude (62.34 degrees for GOES-16 vs. 43.82 degrees for GOES-18) and direction.

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GOES-16 (GOES-East) Upper-level Water Vapor (6.2 µm) images that included plots of Derived Motion Winds along with Pilot Reports (PIREPs) of turbulence (above) showed that there was widespread turbulence in the general vicinity of the axis of an anomalously-strong subtropical jet stream moving across the US on 09 February 2024. Wind speeds along the axis of the subtropical jet were 180-190 knots, with embedded jet streak maxima around 200 knots (RAP40 model MaxWind isotachs at 1500 UTC). A Derived Motion Wind speed of 202 knots was sampled over SW Missouri at 1031 UTC.

There were 4 pilot reports of Severe turbulence during the 14-hour period shown above: over Kentucky around 1026 UTC, over Virginia around 1500 UTC, over Oklahoma around 1700 UTC and over Illinois at 2144 UTC. According to GOES-16 Derived Motion Winds, speed shear was notable in the vicinity of those cases of Severe turbulence: 1501 UTC | 1701 UTC | 2146 UTC.

GOES-16 Upper-level Water Vapor images with contours of Moderate or Greater (MOG) Turbulence Probability within the 38-41 kft layer (below) depicted intermittent pockets of 33% (green) to 50% (yellow) probability along or near the axis of the subtropical jet — and the 2 high-altitude (41-43 kft) Severe turbulence PIREPs occurred in the general proximity of MOG Probability contours in the 33-50% range (1701 UTC | 2146 UTC).

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After an outage of about a week brought on by an anomaly in NOAA-20 (since fixed), NUCAPS profiles have re-appeared in AWIPS workstations, starting with the 1713 UTC overpass over the Eastern United States, shown above. One use for NUCAPS is to gauge how well a forecast is evolving. For example, consider the point near New York City, highlighted by the circle in the image above. The 1200 UTC sounding from OKX (Upton, NY) is shown below.

GFS forecasts for the profile show a considerable change between 1200 and 1800 UTC valid times (i.e., 00h and 06h) as shown above; in particular strong drying aloft is indicated. NUCAPS profiles can help a forecaster understand if the model evolution is occurring in reality. The NUCAPS profile below, from the point circled in black at top (the profile to the right in the figure below), does show significant drying aloft by 1800 UTC that compares favorably aloft with the forecast profile (left). There are discrepancies closer to the boundary layer.

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Welcome back NUCAPS profiles — and gridded NUCAPS fields!

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