NUCAPS estimates of temperature and dewpoint give swaths of information over the Arctic — a region where conventional observations are uncommon and widely spaced. The toggle above shows a disorganized low pressure system over central Alaska — light snow is widespread as shown by the surface observations, below (and in the toggle above).

The toggle above includes swaths of temperature and of relative humidity (derived from all NUCAPS profiles at that time) that are shown individually below. The color bar for 850-mb temperature has been modified so that temperatures of 0^oC and -10^oC are contoured in solid black. The >0^oC warmer region (yellow and red in the color curve) is south of the Aleutians. There is a relatively cold patch just northeast of the warm patch, and a stronger boundary between warmer and -10^oC and colder than -10^oC across central Alaska. There is good agreement between the NUCAPS analysis and the GFS analysis of 850-mb temperature at that time (here, from the TropicalTidbit website)

Kodiak Island is very near a region of dry air as indicated by the NUCAPS profiles; relative humidity in the 850-500 mb layer is <20% per the gridded NUCAPS analysis. The toggle below compares the NUCAPS profiles near Kodiak Island (a green profile, at 1323 UTC) with the 1200 UTC sounding at Kodiak. In this case the soundings tell similar stories: a largely dry atmopshere, and the diagnosed levels (FZL, -20^oC and -30^oC) are similar.

The NUCAPS swath also includes Fairbanks and Utqiagvik, both with 1200 UTC soundings. Comparisons at those two sites are shown below. NUCAPS near Fairbanks does capture the near-saturation in the snow-growth region of the atmosphere, and the tropopause height is in agreement; however, the low-level saturation and low-level inversion in the rawinsonde is not in the NUCAPS profile. If a forecaster had access to AMDAR/MADIS profiles from aircraft at the same time, that near-surface NUCAPS deficiency could be mitigated.

The comparison at Barrow/Utqiagvik, below, shows some similarities: the dry slot at mid-levels with relatively moist regions near the surface and below the tropopause. As you make the comparison between NUCAPS and rawinsondes, always recall the very coarse vertical resolution in NUCAPS profiles.

Gridded NUCAPS fields are also available at this SPoRT site, supplying views as shown below.

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The SPoRT site above also contains microwave estimates of snowfall rate, derived using MIRS algorithms and (for the time shown) ATMS data from NOAA-20. Widespread light snow is indicated, as might be expected by the saturation in the snow growth region within the Fairbanks sounding.

Snowfall rate is also available at this UMD site where data from more satellites are available. Note the similarities in the two fields of snowfall rate from the two sites for the same overpass.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) showed thunderstorms that produced several tornadoes and damaging wind gusts (SPC Storm Reports) across parts of central Oklahoma on 03 November 2024. Pulses of thunderstorm overshooting tops exhibited 10.3 µm brightness temperatures as cold as -78.6ºC (brighter white pixels embedded within dark black regions) — and Enhanced-V cloud-top signatures were evident with some of the storms; the interior warm portion of the Enhanced-V signature (shades of red, in this particular color enhancement) often highlights where an Above-Anvil Cirrus Plume might be present.

1-minute GOES-16 GLM Flash Points depicted abundant lightning activity associated with these thunderstorms.

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To the CIMSS Inbox, From to the Alaska Ice Desk:

I noticed what I think are a pair of mesoscale convective vorticies forming on a boundary in the southeastern Beaufort Sea between the Mackenzie River Delta and the ice pack where there's still open water. I don't think there's much impactful going on, and there's no SAR to see the wind field yet but an interesting feature none the less. This is adaptive day/night band and overall the imagery wasn't great, but wanted to pass it along as an interesting feature to look at.

Indeed, the feature is very hard to see in the Day Night Band because of a lack of lunar illumination (the moon is a New Moon on November 1st). How did this feature evolve with time (can that be viewed?), and what did other VIIRS Imager Bands show?

In AWIPS, the Day Night Band imagery is shown as the Near Constant Contrast (NCC) product. The animation below shows Day Night Band imagery for the five hours between 1028 and 1528 UTC on 1 November. You will immediately note that the brightness of the scene varies considerably – because of the appearance and disappearance of Aurora on this date! It proved very difficult to enhance this NCC product to match the Adapative DNB shown above! (Note the position of Kaktovik in the image up top and the image below).

The I04 data below, at 3.74 µm, however, shows (faintly!) the two circulation centers at 1209 UTC.

The animation of the I05 data (infrared imagery at 11.45 µm), rescaled so that brightness temperatures are between 0 and -80^oC, below, shows the feature at 1209 UTC, and maybe you can infer its movement (I cannot) from these widely-spaced snapshots. But it’s an interesting feature to investigate.

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Added, Bill Line, NOAA/NESDIS at CIRA, forwarded along the following animation of Day Night Band images from two JPSS Satellites (NOAA-20 and NOAA-21). The swirls are near the western edge of the animation below and appear to be moving to the west. But the lack of illumination is making interpretation a challenge. Thanks for the imagery Bill!

Thanks to Mike Lawson at the Alaska Ice Desk for highlighting this ice-edge feature.

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GOES-East airmass RGB imagery, above, shows the evolution of a strong system that brought heavy rain to the central United States as well as snow over the western Great Lakes. The Potential Vorticity Anomaly that supported the surface cyclone, orange in the RGB shown above, starts over the Rocky Mountains and moves northeastward to the northern Plains before shifting more eastward across the Great Lakes at the end of the animation. Total Precipitable water fields from MIMIC, below (archived here), show the deep moisture drawn northward from the Gulf of Mexico that the system could access. Madison, WI, set a daily record rainfall — 2.21″ — on 30 October. You might also infer deep moisture in the airmass RGB where the field is a deep green color.

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The images below compare GFS pressures on the 2 PVU surface (source) to the airmass RGB fields at the same time. There is good (but not perfect) spatial agreement between the modeled initial pressure maximum on the 2 PVU surface (that is, a lowered tropopause associated with the Potential Vorticity Anomaly) and the orange-hued region in the airmass RGB.

GOES Imagery with its excellent temporal resolution is what a forecaster is going to use to monitor the evolution of a system. Polar Orbiter data offers unique fields that aren’t really available from basic GOES imagery. Suomi-NPP overflew the region and Microwave-derived estimates of rain rate are shown below (the data are mislabeled as coming from NOAA-20) in a toggle with various GOES-16 bands at the same time. The band of heavier precipitation is associated with strong low-level frontogenesis (here is a 12-h NAM forecast of 700-mb Frontogenesis — source — at 1800 UTC on 31 October). In the toggle below, one of the Band 13 images has been rescaled to allow the display to use the entire color bar. It is time to make that adjustment in the upper midwest as very cold cloud tops that accompany strong convection are not likely until next Spring!

GOES data can also be used to estimate rain rate. In addition to the level 2 rain rate product, GREMLIN (GOES Radar Estimation via Machine Learning to Inform Numerical Modeling), which field is shown below in a toggle with ATMS estimates of Rain Rate from NOAA-20 (as labeled this time), is available. There is excellent agreement between the two estimates especially regions of heavier precipitation.

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Microwave data can also give snowfall estimates, as displayed at this website. Estimates from a variety of Low Earth Orbit (LEO) satellites that have Microwave Sounders on board are shown below for times between 1500 and 1900 UTC on 31 October 2024.

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