Northeast US winter storm

February 9th, 2017

GOES-13 Water Vapor (6.5 µm) images, with surface fronts and MSLP pressure [click to play animation]

GOES-13 Water Vapor (6.5 µm) images, with surface fronts and MSLP pressure [click to play animation]

A strong winter storm impacted much of the Northeast US on 09 February 2017, dropping up to 24 inches of snow in Maine and producing wind gusts of 70 mph in Massachusetts (WPC storm summary). GOES-13 (GOES-East) Water Vapor (6.5 µm) images with surface fronts and Mean Sea Level Pressure (above) showed the rapid intensification of the mid-latitude cyclone.

GOES-13 Visible (0.63 µm) images, with hourly surface weather symbols [click to play animation]

GOES-13 Visible (0.63 µm) images, with hourly surface weather symbols [click to play animation]

GOES-13 Visible images (above) and Water Vapor images (below) with hourly surface weather symbols revealed the extent of thunderstorms in the south and heavy snow in the north. A number of sites in New England also reported thundersnow.

GOES-13 Water Vapor (6.5 Âm) images, with hourly surface weather symbols [click to play animation]

GOES-13 Water Vapor (6.5 Âm) images, with hourly surface weather symbols [click to play animation]

Suomi NPP VIIRS Visible (0.64 µm) and infrared Window (11.45 µm) images (below) provided a high-resolution snapshot of the storm at 1708 UTC. Note the areas of banded convective elements both south of the storm center over the Atlantic, and also inland over parts of New England.

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with surface fronts and MSLP [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with surface fronts and MSLP [click to enlarge]

===== 10 February Update =====

Terra and Aqua MODIS false-color RGB images [click to enlarge]

Terra and Aqua MODIS false-color RGB images [click to enlarge]

As the storm moved northward over Newfoundland and Labrador in eastern Canada on 10 February, a toggle between Terra (1601 UTC) and Aqua (1743 UTC) MODIS false-color “snow/cloud discrimination” Red/Green/Blue (RGB) images (above) showed the extent of the snow cover (darker shades of red), although supercooled water droplet clouds (shades of white) persisted over many areas at the times of the 2 images. Glaciated ice crystal clouds also appeared as shades of red.

Snowfall totals in the Canadian Maritimes were as high as 38 cm (15 inches).


Atmospheric river events bring heavy precipitation to California

January 13th, 2017

MIMIC Total Precipatable Water product [click to play MP4 animation]

MIMIC Total Precipatable Water product [click to play MP4 animation]

A series of 3 atmospheric river events brought heavy rainfall and heavy snowfall to much of California during the first 10 days of January 2017 (NWS San Francisco/Monterey | WeatherMatrix blog). Hourly images of the MIMIC Total Precipitable Water product (above; also available as a 33 Mbyte animated GIF) showed the second and third of these atmospheric river events during the 06 January11 January 2017 period, which were responsible for the bulk of the heavy precipitation; these 2 events appear to have drawn moisture northeastward from the Intertropical Convergence Zone (ITCZ)..

Terra MODIS Visible (0.65 µm) and Near-Infrared

Terra MODIS Visible (0.65 µm) and Near-Infrared “Snow/Ice” (2.1 µm) images [click to enlarge]

A relatively cloud-free day on 13 January provided a good view of the Sacramento Valley and San Francisco Bay regions. A comparison of Terra MODIS Visible (0.65 µm) and Near-Infrared  “Snow/Ice” (2.1 µm) images (above) showed that snow cover in the higher terrain of the Coastal Ranges and the Sierra Nevada appeared darker in the Snow/Ice band image (since snow and ice are strong absorbers of radiation at the 2.1 µm wavelength) — but water is an even stronger absorber, and therefore appeared even darker (which allowed the areas of flooding along the Sacramento River and its tributaries to be easily identified). A similar type of 1.6 µm Near-Infrared “Snow/Ice” Band imagery will be available from the ABI instrument on the GOES-R series, beginning with GOES-16.

Better detail of the flooded areas of the Sacramento River and its tributaries was seen in 250-meter resolution false-color Red/Green/Blue (RGB) imagery from the MODIS Today site — water appears as darker shades of blue, while snow appears as shades of cyan (in contrast to supercooled water droplet clouds, which appear as shades of white). In the corresponding MODIS true-color image, rivers and bays with high amounts of turbidity (tan shades) were evident; the offshore flow of sediment from a few rivers could also be seen.

Terra MODIS true-color and false-color RGB images [click to enlarge]

Terra MODIS true-color and false-color RGB images [click to enlarge]

 

Fires continue in the southeast United States

November 14th, 2016

Terra MODIS (1650 UTC), Aqua MODIS (1829 UTC) and Suomi NPP VIIRS (1913 UTC) true-color images [click to enlarge]

Terra MODIS (1650 UTC), Aqua MODIS (1829 UTC) and Suomi NPP VIIRS (1913 UTC) true-color images [click to enlarge]

Fires (as seen on 07 and 10 November) continued to burn in parts of the southeast US on 14 November 2016. A sequence of 3 consecutive true-color Red/Green/Blue (RGB) images from Terra MODIS (1650 UTC), Aqua MODIS (1829 UTC) and Suomi NPP VIIRS (1913 UTC) viewed using RealEarth, above, showed the aerial extent of the dense smoke that was most concentrated over Tennessee, Georgia, North Carolina and South Carolina. With the aid of some of the 16 spectral bands on the ABI instrument aboard GOES-R, true-color images like these will be available at least once every 5 minutes over the Lower 48 states and adjacent areas.

GOES-13 (GOES-East) Visible (0.63 µm) images with plots of surface weather and visibility (below; also available as an MP4 animation) revealed that visibility was restricted to 3 miles or less at one or more sites in all of the aforementioned states. A pair of pilot reports in eastern Tennessee indicated that he top of the smoke layer was at 6000 feet above ground level.

GOES-13 Visible (0.63 µm) images, with hourly plots of surface weather (yellow) and visibility (statute miles, in cyan) [click to animate]

GOES-13 Visible (0.63 µm) images, with hourly plots of surface weather (yellow) and visibility (statute miles, in cyan) [click to animate]

High loading of particulate matter (PM) due to smoke led to AIRNow Air Quality Index ratings of Unhealthy (red)  to Very Unhealthy (purple) over much of that 4-state region (below).

Hourly AIRNow Particulate Matter (PM) Air Quality Index (AQI)

Hourly AIRNow Particulate Matter (PM) Air Quality Index (AQI)

===== 15 November Update =====

Suomi NPP VIIRS Shortwave Infrared (3.74 um) and Day/Night Band (0.7 um) images, plus METAR surface reports [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 um) and Day/Night Band (0.7 um) images, plus METAR surface reports [click to enlarge]

A toggle between Suomi NPP VIIRS Shortwave Infrared (3.74 um) and Day/Night Band (0.7 um) images (with and without METAR surface reports) at 0735 UTC or 3:35 am local time on 15 November (above) showed the “hot spot” signatures and bright glow from the larger fires that were burning in northern Georgia and western North Carolina. With ample illumination from the Moon — which was in the Waning Gibbous phase, at 99% of Full — smoke plumes from some of these fires could be seen drifting southward or southeastward,  thanks to the “visible image at night” capability of the Day/Night Band.

During the subsequent daytime hours, Terra MODIS and Suomi NPP VIIRS true-color RGB images (below) again revealed the vast coverage of the thick smoke — and VIIRS Aerosol Optical Depth values were quite high over South Carolina. Unhealthy AQI values persisted during much of the day across parts of Tennessee, Georgia and South Carolina.

Terra MODIS and Suomi NPP VIIRS true-color images, with VIIRS Aerosol Optical Depth (click to enlarge]

Terra MODIS and Suomi NPP VIIRS true-color images, with VIIRS Aerosol Optical Depth (click to enlarge]

A sampling of pilot reports (PIREPS) showed some of the impacts that the smoke was having on aviation (below).

Suomi NPP VIIRS Visible (0.64 µm) image with a PIREP over South Carolina [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) image with a PIREP over South Carolina [click to enlarge]

Aqua MODIS Visible (0.65 µm) image with a PIREP over Georgia [click to enlarge]

Aqua MODIS Visible (0.65 µm) image with a PIREP over Georgia [click to enlarge]

GOES-13 Visible (0.63 µm) image with a PIREP over North Carolina [click to enlarge]

GOES-13 Visible (0.63 µm) image with a PIREP over North Carolina [click to enlarge]

===== 16 November Update =====

Terra/Aqua MODIS and Suomi NPP VIIRS true- color images [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS true- color images [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS true-color images (above) showed that much of the smoke had moved over the adjacent offshore waters of the Atlantic Ocean on 16 November.

 

Halos due to the presence of ice crystal clouds

November 14th, 2016
Photo showing an Upper Tangent Arc, a Parhelia (Sun Dog), a Parhelic Circle segment and a faint 46 degree segment (upper right).

Photo showing an Upper Tangent Arc, a Parhelia (Sun Dog), a Parhelic Circle segment and a faint 46 degree segment (upper right).

Photos taken by SSEC scientist Claire Pettersen at 1615 UTC (above) and 1623 UTC (below) revealed several examples of ice crystal cloud optics over Madison, Wisconsin on 14 November 2016.  More information on the various types of ice cloud halos can be found here and here.

Photo showing a Circumzenithal Arc with a Supralateral Arc, in addition to an Upper Tangent Arc.

Photo showing a Circumzenithal Arc with a Supralateral Arc, in addition to an Upper Tangent Arc.

1650 UTC Terra MODIS Visible (0.65 µm), near-infrared Cirrus (1.375 µm) and Infrared Window (11.0 µm) images (below) showed the patches of cirrus clouds that were over southern Wisconsin not long after the photos above were taken. Many of the cirrus cloud features over the Madison (KMSN) area appeared very thin and nearly transparent on the Visible image; they also exhibited very warm Infrared Window brightness temperature values (warmer than -20ºC), since a great deal of radiation from the warmer surface of the Earth was reaching the MODIS detectors through the thin clouds. The 1.375 µm Cirrus band is able to detect the presence of airborne particles that are efficient scatterers of light — such as cirrus cloud ice crystals, dust, volcanic ash, smoke, haze — so the thin cirrus clouds exhibited a good signature on that image.

Terra MODIS Visible (0.65 µm), Cirrus (1.375 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Terra MODIS Visible (0.65 µm), Cirrus (1.375 µm) and Infrared Window (11.0 µm) images [click to enlarge]

A similar 1.37 µm Cirrus Band will be on the ABI instrument aboard GOES-R.