GOES-16 (GOES-East) Upper-level Water Vapor (6.2 µm) images (above) revealed the presence of elongated W-E oriented billow clouds, many of which exhibited small-scale ripples that were oriented N-S along the billow cloud tops, over coastal areas of South Carolina and North Carolina on 15 November 2019. An initial SIGMET (November 1) was issued covering airspace over Georgia and South Carolina — Severe Turbulence (plotted in red) was reported at 41,000 feet and at 35,000 feet. A second SIGMET (November 2) was later issued covering airspace over South Carolina and North Carolina.

The same GOES-16 Water Vapor images which include isotachs of RAP40 model maximum wind (at any level) are shown below — most of the Moderate to Severe turbulence reports were occurring within the speed gradient along the poleward (left) edge of a SW-NE oriented jet stream flowing parallel to the coast.

More detailed views of the billow-top ripples were provided by a Terra MODIS Visible image at 1600 UTC, and NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared images as visualized using RealEarth (below).

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Geostationary data from KMA‘s GEOKOMPSAT-2 satellite (over the Equator at 128º E Longitude, shown above at right) and from JMA‘s Himawari-8 Satellite (over the Equator at 140º E Longitude, shown above at left) can be used to create stereoscopic imagery. The imagery above, from 0400 and 0500 UTC on 14 November 2019, centered at 15º N, 150º E, shows Typhoon Fengshen. Visible imagery from both satellites show a well-developed central cluster of thunderstorms with little apparent indication of wind shear. Stereoscopic views of the storm allow the vertical structure of the system to be perceived.

Data processing for these images was accomplished using Geo2Grid, a software package that incorporates Satpy. (Previous Blog posts discussing Geo2Grid are here and here).

Very grateful acknowledgement of these data from KMA and from JMA is extended. Thank you!

Added:  Click here for an animation from 0300 to 0550 UTC on 14 November.  (Warning:  Large animated gif at 159 M).

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During the course of multiple intrusions of arctic air across the Lower 48 states during early November 2019, a variety of lake-effect, river-effect and bay-effect cloud features were generated — many of which produced varying intensities of snowfall. GOES-16 (GOES-East) “Red” Visible (0.64 µm), “Clean:” Infrared Window (10.35 µm) and Day Cloud Phase Distinction Red-Green-Blue (RGB) images on 07 November (above) showed lake-effect clouds streaming south-southeastward across Lake Superior. The Day Cloud Phase Distinction RGB images (in tandem with the Infrared images) helped to highlight which cloud features had glaciated and were therefore more capable of producing moderate to heavy lake-effect snow; the dominant band yielded 5-10 inches of snowfall in the central part of northern Michigan.

On 11 November, GOES-16 Nighttime Microphysics RGB images (below) displayed lake-effect clouds originating from the still-unfrozen waters of Fort Peck Lake in northeastern Montana — these clouds did produce a brief period of light snowfall downstream at Glendive (KGDV). On this particular morning, the lowest temperature in the US occurred in north-central Montana, with -30ºF reported north of Rudyard.

On 12 November, cold air moving southward across the Lower Mississippi Valley produced horizontal convective roll clouds which were evident in GOES-16 Nighttime Microphysics RGB and subsequent Visible images after sunrise (below) — one of these narrow cloud bands was likely enhanced by latent heat fluxes as it passed over the comparatively-warm waters of the Mississippi River, and produced accumulating snowfall in downtown Memphis. Note that since Memphis International Airport KMEM was located just east of the cloud band, no accumulating snow was reported there (only a brief snow flurry around 1430 UTC).

Aqua MODIS Sea Surface Temperature values along parts of the Mississippi River were as warm as the mid-40s F (below).

@memphisweather1 @NWSMemphis Snow showers downtown! Sticking to roads that are ice-less! Unusual sight downtown. #memsnow pic.twitter.com/2t9FVFlRNl

— Andrew (@AndrewAvery_2) November 12, 2019

On 13 November, as the cold air was moving off the US East Coast, GOES-16 Infrared images (below) revealed bay-effect cloud plumes which developed over Chesapeake Bay and Delaware Bay — the Chesapeake Bay plume produced brief periods of light snow at Oceana Naval Air Station in Virginia Beach KNTU from 06-10 UTC (and possibly contributed to snowfall farther south at Elizabeth City, North Carolina KECG).

Terra MODIS Sea Surface Temperature values in Chesapeake Bay and Delaware Bay were in the lower to middle 50s F where the bay-effect cloud plumes were originating (below).

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As noted in this post from October, horizontal fields of thermodynamic variables that have been derived from NUCAPS vertical profiles are now available in AWIPS. The fields give a swath of observations derived from infrared and microwave sounders in regions of the troposphere where observations by Radiosondes happen only occasionally. In this case, NUCAPS observed the strong cold front moving southward into the north Atlantic. Temperatures over eastern Canada at 850 hPa were in the teens below 0 Celsius, and in the teens (Celsius) out over the Atlantic.

Lower-tropospheric temperatures are an important variable to know when early-season cold airmasses are cold enough that the temperature difference between 850 hPa and surface water bodies — such as rivers and lakes — is sufficient to support Lake (or River) Effect clouds and precipitation. River-effect flurries hit mid-town Memphis on the 12th of November, and the 0.86 “Veggie” image (0.86 µm, this wavelength was chosen because land/water contrasts are large in it) image, below, shows a band extending from the Mississippi River in northwest Tennessee southward into central Memphis. NUCAPS data at 850 on this day showed 850-mb temperatures around -10 C at 0900 UTC.

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