GOES-16 (GOES-East) Low-level Water Vapor (7.3 µm) images (above) showed that this spectral band was able to sense the surface due to the presence of a cold and dry arctic air mass over the Upper Midwest on 13 February 2020 (the coldest surface air temperature that morning was -39ºF at Kabetogama in northern Minnesota). In North Dakota and South Dakota, the outline of the Missouri River was very evident — as well as surface warming in the western part of those states due to the onset of downslope (southwesterly) winds. Across the eastern Dakotas and Minnesota, the warmer (darker blue) “urban heat islands” of several cities and towns became more evident toward the end of the animation at 18 UTC.

The arctic air mass was so dry that Total Precipitable Water derived from rawinsonde data set record low values for the date/time (source) at a few regional sounding sites such as Bismarck ND (KBIS), Aberdeen SD (KABR) and Minneapolis/Chanhassen MN (KMPX) — and this shifted the 7.3 µm water vapor weighting functions to altitudes low enough to sense a significant amount of upwelling surface radiation (below). In fact, at KMPX the 7.3 µm water vapor weighting function actually peaked at the surface!

 

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GOES-17 IFR Probability fields are being evaluated at CIMSS (the Cooperative Institute for Meteorological Satellite Studies), with a plan to release them to the field via an LDM request in the near future.  The toggle above compares GOES-16 IFR Probability and GOES-17 IFR Probability for the same time over central California. Differences in resolution and parallax shifts are apparent (You can investigate the effect of parallax in a WebApp here).  A similar comparison is shown for Oregon, below, and for Washington, at bottom. GOES-17 IFR Probability fields for CONUS are also available at this website.

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Gridded NUCAPS fields include a wide range of thermodynamic variables. The plot above shows the 900-mb temperature field. Is it possible to use this data to diagnose a rain/snow transition line?

Over southern New England, the relationship between 900-mb temperatures and surface precipitation observations seems robust: snow is restricted to most (but not all!) places where 900-mb temperatures are cooler than 0ºC. and rain falls where temperatures exceed 0ºC. Where terrain might be an influence in trapping cold air near the surface — the Catskills, for example, or the Alleghenies over New York and Pennsylvania, the relationship is not so straightforward. This data source warrants future investigations on its utility in these situations.

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GOES-16 (GOES-East) Air Mass RGB images (above) displayed the characteristic pale yellow hues associated with cold arctic air that was moving southward behind a deep area of low pressure centered over Hudson Bay and northern Quebec, Canada on 12 February 2020.

A sequence of GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Day Snow-Fog RGB images (below) revealed north-to-south oriented horizontal convective rolls that highlighted areas where blowing snow was creating ground blizzard conditions across the Red River Valley of North Dakota/Minnesota (the strongest winds were being channeled southward through the lower terrain of the RRV).  The surface visibility was reduced to near zero in rural areas — and in eastern North Dakota, Interstate 29 was closed from the Canadian border to the South Dakota border. Toward the end of the day, conditions slowly began to improve in the northern portion of the Red River Valley — from Grand Forks (KGFK) northward — as surface winds decreased, horizontal convective rolls dissipated, and visibility started to increase. More information on this event is available from NWS Grand Forks and the Satellite Liaison Blog.

High res view of the ground blizzard over Fargo ND on Feb 12 as viewed by Sentinel-2’s 10 meter resolution (30ft!).

Notice tightly packed horizontal convective rolls organize blowing snow plumes (white) right over Fargo. Processed w/ @sentinel_hub @CopernicusEU #ndwx #mnwx #blsn pic.twitter.com/GwynOZITrh

— Carl Jones (@northflwx) February 13, 2020

Another feature of interest was the rapidly intensifying Hurricane Force low pressure system just south of the Canadian Maritime Provinces (surface analyses) — with a lowering tropopause along the western edge of the storm, a swath of the NOAA-20 Gridded NUCAPS Total Column Ozone product (below) showed a lobe of higher ozone extending southward behind the surface low (and along the axis of its 500 hPa trough). That region of higher ozone was also apparent the day before, on 11 February, as shown in this blog post.

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