NOAA/CIMSS ProbSevere with a tornadic cell in Kansas/Oklahoma

April 26th, 2016 |
GOES-14 Visible (0.63 µm) Imagery, 26 April 2016. An orphan anvil is indicated by the Green Arrow at the start of the animation (click to play animation)

GOES-14 Visible (0.63 µm) Imagery, 26 April 2016. An orphan anvil is indicated by the Green Arrow at the start of the animation (click to play animation)

April 26 2016 was a day of well-anticipated severe weather (even a week out!) over the central and southern Plains, with a Moderate Risk of Severe Weather predicted for parts of Nebraska, Kansas, Oklahoma and Texas. The GOES-14 visible animation, above, shows the development of strong thunderstorms in north-central Oklahoma that propagated into south central Kansas, producing hail around 2000 UTC. Note the presence of an orphan anvil just downstream of the developing convection (to the south of the Green Arrow) at the beginning of the GOES-14 SRSO-R animation (that unfortunately has a 15-minute data gap starting at 1900 UTC).

How did the NOAA/CIMSS ProbSevere product perform with this severe cell? ProbSevere provides a probabilistic estimate of whether a cell will produce severe weather within the next 60 minutes. The animation below shows the quick development of the radar feature that became the hail producer. The Satellite Growth of this particular storm was not observed to be strong. Moderate satellite growth and weak glaciation was diagnosed. However, ProbSevere values became very large because of the environment in which the cell developed, because of the presence of large MRMS MESH observations, and active lightning. ProbSevere exceeded a 50% threshold at 1912 UTC, 6 minutes before the Severe Thunderstorm Warning was issued.  The Table at the bottom shows the ProbSevere components as a function of time.

According to SPC storm reports, the cell produced a brief rope tornado at 2058 UTC in far southern Kansas. This storm was blogged about at the Hazardous Weather Testbed. Click here and here for blog posts on the environmental instability.

NOAA/CIMSS ProbSevere Output, 1824-1946 UTC on 26 April 2016 (click to play animation)

NOAA/CIMSS ProbSevere Output, 1824-1946 UTC on 26 April 2016 (click to play animation)

A zoomed-in animation of the Visible Imagery shows the orphan anvil developing around 1740 UTC. (A rocking animation is here).

GOES-14 Visible (0.63 µm) Imagery, 26 April 2016. The orphan anvil is indicated by the Cyan Arrows through the animation (click to play animation)

GOES-14 Visible (0.63 µm) Imagery, 26 April 2016. The orphan anvil is indicated by the Cyan Arrows through the animation (click to play animation)

 

Time (UTC) ProbSevere MUCAPE Env. Bulk Shear MRMS MESH (Inches) Satellite Growth Satellite Glaciation # Flashes
1854
1858 20% 4739 41.9 0.29 1.9% (Moderate) 0.02 (Weak) 0
1900 29% 4702 41.8 0.45 1.9% (Moderate) 0.02 (Weak) 0
1908 34% 4640 40.9 0.54 1.9% (Moderate) 0.02 (Weak) 5
1910 47% 4628 40.7 0.65 1.9% (Moderate) 0.02 (Weak) 13
1912 59% 4623 40.4 0.65 1.9% (Moderate) 0.02 (Weak) 24
1914 58% 4619 40.1 0.65 1.9% (Moderate) 0.02 (Weak) 24
1916 58% 4614 39.8 0.65 1.9% (Moderate) 0.02 (Weak) 24
1918 54% 4614 39.8 0.60 1.9% (Moderate) 0.02 (Weak) 24
1920 60% 4592 39.4 0.74 1.9% (Moderate) 0.02 (Weak) 20
1922 65% 4591 39.1 0.80 1.9% (Moderate) 0.02 (Weak) 20
1924 73% 4591 39.1 0.80 1.9% (Moderate) 0.02 (Weak) 25
1926 75% 4572 38.8 0.84 1.9% (Moderate) 0.02 (Weak) 26
1928 88% 4578 38.7 1.01 1.9% (Moderate) 0.02 (Weak) 31
1930 89% 4578 38.7 1.01 1.9% (Moderate) 0.02 (Weak) 36
1932 97% 4580 38.6 1.24 1.9% (Moderate) 0.02 (Weak) 49
1934 97% 4560 38.3 1.24 1.9% (Moderate) 0.02 (Weak) 58
1936 97% 4544 38.1 1.24 1.9% (Moderate) 0.02 (Weak) 58
1938 97% 4543 38.0 1.24 1.9% (Moderate) 0.02 (Weak) 58
1940 97% 4540 37.8 1.26 1.9% (Moderate) 0.02 (Weak) 58
1942 98% 4528 37.7 1.53 1.9% (Moderate) 0.02 (Weak) 56
1944 99% 4516 37.5 1.71 1.9% (Moderate) 0.02 (Weak) 56
1946 99% 4507 37.4 1.71 1.9% (Moderate) 0.02 (Weak) 56

 

NOAA/CIMSS ProbSevere with a Nebraska Hailstorm

September 22nd, 2015 |
GOES-13 Visible (0.63 µm) images [click to play rocking animation]

GOES-13 Visible (0.63 µm) images [click to play rocking animation]

A severe hail-producing thunderstorm moved over northeast Nebraska before noon on 22 September (SPC Storm Reports). The region hit was just south of a Marginal Risk of Severe Weather (The update at 1630 UTC included the region of severe weather). The GOES-13 visible animation, above, shows the initial development occurring along a subtle cloud line aligned mostly east-west.

The NOAA/CIMSS ProbSevere model produces a probability that a developing thunderstorm will initially produce severe weather within the next sixty minutes. It consistently supplies information with a good lead time, and the storm on 22 September was no exception. The animation below shows the product for about an hour before the first storm report at 1408 UTC. The storm out of which the hail dropped was, at 1300 UTC, flagged as having a ProbSevere under 10%; values exceeded 10% at 1314 UTC and then jumped to 60+% at 1336 UTC (the first time that the value exceeded 50%) Values fluctuated between 60 and 80% between 1336 and 1400 UTC. After 1400 UTC, values increased into the mid-80s. The first report of hail was at 1408 UTC, 32 minutes after ProbSevere jumped above 50%. A severe thunderstorm warning for hail was issued at 1412 UTC.

NOAA/CIMSS ProbSevere values, 1300-1412 UTC on 22 September 2015 [click to play animation]

NOAA/CIMSS ProbSevere values, 1300-1412 UTC on 22 September 2015 [click to play animation]

The GOES Sounder Lifted index product, below, (also available here) showed the instability that was present over the central Plains.

GOES-13 Sounder DPI Values of Lifted Index [click to play animation]

GOES-13 Sounder DPI Values of Lifted Index [click to play animation]

NOAA/CIMSS ProbSevere Product and storms over Texas

April 24th, 2015 |
NOAA/CIMSS ProbSevere Output from AWIPS on 24 April, 1902, 1908, 1912, 1930, 1938, 1944, 1948, 1950, 1954 and 1958 UTC (click to play animation)

NOAA/CIMSS ProbSevere Output from AWIPS on 24 April, 1902, 1908, 1912, 1930, 1938, 1944, 1948, 1950, 1954 and 1958 UTC (click to play animation)

Severe thunderstorms moved across central Texas on April 24th (Link). The NOAA/CIMSS ProbSevere product can be used with storms like this to alert a forecaster to when severe weather will develop. ProbSevere output tells you the probability that a given storm cell will first produce severe weather in the next 60 minutes. (The type of severe weather — hail, high winds or tornado) are not specified by the product. In the animation, a strong thunderstorm is just entering Coke county from Sterling county to the north of Tom Green county. The list below shows ProbSevere values with the three storms shown in the animation above.

  1. 1902 UTC  (Northern Cell)  ProbSevere 46%
  2. 1908 UTC (Northern Cell) ProbSevere 50%
  3. 1912 UTC (Northern Cell) ProbSevere 85%
  4. 1930 UTC (Northern Cell) ProbSevere 95%
  5. 1932 UTC (Northern Cell) ProbSevere 95% (Severe Thunderstorm Warning active)
  6. 1948 UTC (Southern Cell) ProbSevere 23%
  7. 1950 UTC (Southern Cell) ProbSevere 50%
  8. 1954 UTC (Middle Cell) ProbSevere 57%
  9. 1956 UTC (Middle Cell) ProbSevere 70%

So, the northern cell crossed the 50% ProbSevere threshold at 1908 UTC, the southern cell crossed the 50% ProbSevere threshold at 1950 UTC, and the small middle cell had a >50% ProbSevere from the start, at 1954 UTC.

Severe hail (1.25″ in diameter) was reported at 1928 UTC (20 minutes after ProbSevere crossed the 50% threshold) 8 miles west (31.89 N, 100.62 W)of Robert Lee, TX (the county seat of Coke County). At 1957 UTC, 1.75″ Hail was reported four miles north (31.94 N, 100.30 W) of Bronte, TX (also in Coke County).

The middle cell in the animation above eventually merged with the southern cell, and intensified. The animation from 1958 through 2014 UTC is below. ProbSevere with the middle storm (that merges with the southern cell) is 70%, rising to 98% at 2014 UTC.

NOAA/CIMSS ProbSevere Output from AWIPS on 24 April, 1958, 2000, 2008, 2010, 2012, 2014 UTC (click to play animation)

NOAA/CIMSS ProbSevere Output from AWIPS on 24 April, 1958, 2000, 2008, 2010, 2012, 2014 UTC (click to play animation)

At 2015 UTC, the National Weather Service issued a Severe Thunderstorm Warning. At this time, 2.75″ Hail was falling five miles northwest of Tennyson in Coke County. (31.79N, 100.35W). The 2016 UTC ProbSevere output is here.

The ProbSevere product is something that distills many bytes of information: model output that describes the environmental conditions, satellite data that describes the initial growth of convection, and MRMS radar data that captures the present state of a storm. The distilled data can be used to increase the confidence that a severe event will occur within the next 60 minutes.

An animation of the 10.7 µm imagery from 1800 through 2015 UTC is shown below. The locations of the severe hail reports noted above are included on the relevant images.

GOES-13 10.7 Brightness Temperature 1800-2015 UTC on 24 April 2015;  Coke County is highlighted (click to play animation)

GOES-13 10.7 Brightness Temperature 1800-2015 UTC on 24 April 2015; Coke County is highlighted (click to play animation)

NOAA/CIMSS ProbSevere for an isolated storm in Nebraska

July 9th, 2014 |
NOAA/CIMSS ProbSevere product, and National Weather Service Warning Polygons, 2302-2334 UTC 9 July 2014 (click to enlarge)

NOAA/CIMSS ProbSevere product, and National Weather Service Warning Polygons, 2302-2334 UTC 9 July 2014 (click to enlarge)

The storm in the animation above produced baseball-sized hail in Nebraska (Visible animation is here, courtesy Dan Lindsey from NOAA at CIRA) although MRMS Mesh Hail sizes were “only” in the 1-inch range (that is, nickel to quarter size). How did the ProbSevere product, which product includes MRMS Mesh size as a predictor, perform?

The visible and infrared satellite animation, below, shows quick development in the absence of cirrus obscuration, and the ProbSevere Satellite components from 2230 UTC are both characterized as ‘Strong’. The model components of ProbSevere (MUCAPE around 2000 J/kg, shear exceeding 30 knots) are also strong. Probabilities increased from 40% to >80% before the warnings for the cell were issued.

MRMS values in this case were not extreme; indeed, when the first warning was issued, MESH was still less than 1″ (but ProbSevere was >80%). Satellite growth rates and environmental information in this case compensated for the modest MRMS Mesh values.

GOES-13 Visible (0.63 µm, top) and Infrared (10.7 µm, bottom) from 2200 UTC 9 July through 0200 UTC 10 July (click to animate)

GOES-13 Visible (0.63 µm, top) and Infrared (10.7 µm, bottom) from 2200 UTC 9 July through 0200 UTC 10 July (click to animate)