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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EUMETSAT Meteosat-11 Visible (0.8 µm) images (above) showed the circulation and eye-like feature of Medicane “Trudy” (named “DETLEF” by Free University Berlin) as it moved southeastward across the Mediterranean Sea toward the coast of Algeria on 11 November 2019.

VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP (as visualized using RealEarth) are shown below.

At 0630 UTC, a northerly wind gust of 52 knots was recorded at Menorca, Spain (LEMH) as the medicane passed near the Balearic Islands — and several hours later as the system moved inland just after sunset, a northwesterly wind gust of 43 knots occurred at Jijel, Algeria (DAAV) at 18 UTC (below).

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JMA Himawari-8 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and Longwave Infrared Window (10.4 µm) imagery (below) showed the evolution of smoke plumes, hot 3.9 µm fire thermal anomalies (red pixels) and cloud-top infrared brightness temperatures of isolated pyrocumulus associated with bush fires that were burning in far eastern parts of New South Wales and Queensland, Australia from 1900 UTC on 07 November to 0800 UTC on 08 November 2019. With strong northwesterly surface winds, many of the fire thermal anomalies exhibited rapid southeastward runs toward the coast. That region of Australia had just experienced severe to record 3-month rainfall deficiencies — which included the driest October on record for the southern third of the country.

Himawari-8 True Color Red-Green-Blue (RGB) images created using McIDAS-V (below) provided another view of the dense smoke plumes from 0000-0610 UTC. Toward the end of the animation — in the upper left portion of the satellite scene — plumes of blowing dust could be seen moving eastward from farther inland.

A combination of Suomi NPP VIIRS True Color RGB and Shortwave Infrared (4.1 µm) imagery at 0328 UTC (below) revealed hot thermal signatures of the fires (yellow to red enhancement) at the source of the smoke plumes.

A toggle between a Suomi NPP VIIRS True Color RGB image and a display of Sentinel-5 TROPOMI Tropospheric Vertical Column NO2 (below) indicated high NO2 concentrations immediately downwind of these fires.

The dense smoke plumes were also evident in a sequence of 3 VIIRS True Color RGB images from NOAA-20 and Suomi NPP, as visualized using RealEarth (below).

Smoke reduced the surface visibility to 3 miles or less at Grafton (YGFN) from 03-05 UTC (below).

At 5.30pm, there are 96 fires burning across the state, with 57 yet to be contained. 17 fires remain at Emergency Warning, mostly across the north coast and northern NSW. If you are near a fire at Emergency Warning level, take action now to protect your life. #nswrfs #nswfires pic.twitter.com/FWIQs2o0ES

— NSW RFS (@NSWRFS) November 8, 2019

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