GOES-13 (GOES-East ) Visible (0.63 µm) images centered over Lake Erie, Lake Ontario, and central New York state (below) showed a variety of aircraft “hole punch” and “dissipation trails” over the eastern Great Lakes on 03 March 2016.

These cloud features were caused by aircraft that were either ascending or descending through layers of cloud composed of supercooled water droplets, which covered much of the region as shown by the POES AVHRR Cloud Type product at 1545 UTC (below). Cooling from wake turbulence (reference) and/or the particles from the jet engine exhaust acting as ice condensation nuclei cause the small water droplets to turn into larger ice crystals (which then often fall from the cloud layer, creating “fall streak holes“). Similar features have been discussed in previous blog posts.

There were numerous pilot reports of light to moderate icing between FL120 and FL160 (flight level 12,000-16,000 feet) when passing through the supercooled water droplet cloud layers (below). The pilot report altitudes agree well with the POES AVHRR Cloud Top Height product values of 4-5 km over Lake Erie at 1545 UTC.

A comparison of 250-meter resolution Terra MODIS true-color and false-color Red/Green/Blue (RGB) images at 1649 UTC as visualized using RealEarth (below) indicated that the cloud material in the center of the aircraft dissipation trail over the north shore of Lake Erie had glaciated (snow, ice, and ice crystal clouds exhibit a darker cyan appearance on the false-color image).

A panorama photo from the ground was taken in Binghamton, New York (station identifier KBGM, located near the center of the New York GOES-13 images):

#Holepunch cloud (panorama) over Broome & Chenango County from ground & ~22,000 miles above. pic.twitter.com/s0TsCMeBxR

— HowardManges (@HowardManges) March 3, 2016

View only this post Read Less

A strong winter storm produced a swath of winter weather from Arkansas through lower Michigan on 23-24 February. GOES-14 SRSO-R Imagery was centered on the occluded storm on 24 February, and the water vapor animation, above (available here as an animated gif image), shows strong flow north-northwest from the Mid-Atlantic states into the Upper Midwest, where Winter Storm and Blizzard Warnings were widespread. The end of the animation shows strong convection developing over the Mid-Altantic states where multiple reports of Severe Weather occurred. (A water vapor animation with weather symbols included is available here as an mp4 and here as an animated gif).

The thermal structure of the storm as revealed by Rapid Refresh analyses of the 310 Kelvin Equivalent Potential Temperature Surface, above, (and available here with contours of Mean Sea Level Pressure) suggests the presence of a Trough of Warm Air Aloft (TROWAL) that stretches from Tennessee to Michigan. Any dry air that moves northward over this region is likely to eroded from below as low-level moisture (not detected in the water vapor imagery) is forced upwards by frontogenetic circulations along the sloping isentropes. Note how cold cloud tops in the animation above appear with regularity over southern Michigan and northern Indiana. These cold clouds tops in the water vapor imagery could be manifestations of frontal forcings acting on the warm air in the TROWAL airstream. Simulated ABI Water Vapor Channels (available here or here), below, show the blossoming of cold cloud tops in the 7.3 µm channel. This toggle between the 6.2µm and 7.3µm channels at 2100 UTC shows how the different water vapor channels view different levels in the atmosphere because of different sensitivity to water vapor absorption at those two wavelengths: the 7.3µm channel typically sees deeper into the troposphere and therefore has warmer brightness temperatures.

When storms move north to the west of the spine of the Appalachians, downslope winds frequently cause clearing, and this occurred on 24 February, as shown in the half-hourly animation of GOES-13 Visible imagery above. Clear skies are widespread over southeastern Ohio and southwestern Pennsylvania. Cities in the region that cleared saw high temperatures in the mid-60s today. The visible imagery above shows evidence of strong shear in the warm sector (where SPC had issued a Moderate Risk). GOES-14 1-minute Visible Imagery for the 30 minutes ending at 2230 UTC, available here, shows a line of strong convection from the Piedmont of North Carolina northward to metropolitan Washington DC.

Visible SRSO-R Imagery from GOES-14, above, shows the strong storms moving rapidly to the northeast along a line stretching from Washington DC south to central North Carolina as the sun set on 24 February. (Animation available here as an mp4). Another animation of GOES-14 visible images centered on Virginia and North Carolina (covering the period from 1300-2159 UTC) with plots of station identifiers is available as an MP4 or an animated GIF.

====================================================The NOAA/CIMSS ProbSevere model combines information about the storm environment (from the Rapid Refresh) with satellite indicators of cloud growth and with radar estimates of hail size. It is designed to predict when a developing convective cell will first produce severe weather. In the animation above, a growing cell has developed over South Carolina. At the start of the animation, 2134 UTC, the cell is displaying moderate growth rate, and weak glaciation. Two minutes later, at 2136 UTC, ProbSevere has jumped to 62% as the MRMS MESH (Maximum Expected Size of Hail) has jumped from 0.32 to 0.67 inches. By 2144 UTC, ProbSevere exceeds 90%, and it retains that value through the end of the animation at 2250 UTC. This cell produced wind damage three miles northwest of Brownsville SC at 2130 UTC. (SPC Storm Reports). The cell was associated with other wind events in Robeson County, NC at 2155 UTC.

View only this post Read Less

The Australian icebreaker Aurora Australis was resupplying at Mawson Station along the Indian Ocean coast of Antarctica (map) when a strong storm (surface analysis) producing blizzard conditions — with winds as high as 86 knots gusting to 98 knots at 0936 UTC — caused it to break free from its mooring lines and run aground on 24 February 2016 (news release). Antarctic infrared composite images (using data from both geostationary and polar-orbiting satellites), above, showed the evolution and movement of the storm as it intensified close to Mawson Station early in the day on 24 February.

View only this post Read Less

JMA Himawari-8 Visible (0.64 µm) images (above) revealed the presence of mesovortices within the large and well-defined eye of Category 5 Severe Cyclone Winston as the storm approached the largest Fiji islands of Vanua Levu and Viti Levu during the 19-20 February 2016 period.

A longer animation of Himawari-8 Infrared Window (10.4 µm) images (below) showed a degradation of the eye as it moved over the slightly rugged terrain of Viti Levu, suggesting a slight decrease of intensity (ADT plot | SATCON wind | SATCON pressure). However, when Winston initially made landfall on that island with sustained winds of 185 mph it tied as the second strongest landfalling tropical cyclone on record — and Winston could also be the strongest tropical cyclone on record in the Southern Hemisphere (Capital Weather Gang blog). The images include plots of surface observations from Nadi (NNFN) and Nausori (NNFA) on the island of Viti Levu.

Nighttime comparisons of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images showed Cyclone Winston as the storm was well east of Fiji on 18 February, and just west of Fiji on 20 February (below). With abundant illumination from the Moon in the Waxing Gibbous phase (from 82 to 95% of full), the “visible image at night” capability of the Day/Night Band was effectively demonstrated.

As Winston began to decrease in intensity from a Category 4 to a Category 2 storm after 12 UTC on 21 February, a large eye was still present in DMSP-16 SSMIS Microwave (85 GHz) imagery from the CIMSS Tropical Cyclones site (below).

View only this post Read Less