Tornado near Eureka, California

January 25th, 2018 |


A waterspout moved inland near the NWS Eureka forecast office during the late afternoon hours on 25 January 2018. The brief tornado caused some EF-0 damage (interestingly, it was the only report of severe weather in the US that day, and the first tornado in the Eureka forecast area since 1998).

A comparison of GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (below) showed the line of convection as it moved across the area (Eureka and the location of the 0040-0041 UTC tornado are a few miles south-southwest of the airport KACV) — the coldest cloud-top infrared brightness temperatures on the 0037 UTC and 0042 UTC GOES-16 images were -30.7ºC (dark blue color enhancement). Note: there were no western US images available from GOES-15 (GOES-West) between 0030 and 0100 UTC, due to a routine “New Day Schedule Transition” and a 0051 UTC Southern Hemisphere scan.

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.3 µm, right) images, with plots of hourly surface reports [click to play animation]

There was an overpass of the NOAA-19 satellite about 2 hours prior to the Eureka tornado, at 2251 UTC. If we compare the NOAA-19 Visible (0.63 µm) image to the corresponding GOES-16 Visible (0.64 µm) image (below), a parallax shift to the west is evident with GOES-16 (which was scanning that same scene only 24 seconds later than NOAA-19: 22:52:23 UTC vs 22:51:59 UTC).

NOAA-19 and GOES-16 Visible images at 2252 UTC, with plots of 23 UTC surface reports [click to enlarge]

NOAA-19 and GOES-16 Visible images at 2252 UTC, with plots of 23 UTC surface reports [click to enlarge]

In the corresponding Infrared Window images from NOAA-19 (10.8 µm) and GOES-16 (10.3 µm) (below), the parallax shift was also apparent — and the coldest cloud-top infrared brightness temperatures associated with the convection just northwest of KACV were -36.2ºC and -35.2ºC, respectively. Given the very high viewing angle for GOES-16 (about 67 degrees over Eureka), the qualitative and quantitative satellite presentation compared quite favorably to that seen from the more direct overpass of NOAA-19.

NOAA-19 and GOES-16 Infrared Window images at 2252 UTC, with plots of 23 UTC surface reports [click to enlarge]

NOAA-19 and GOES-16 Infrared Window images at 2252 UTC, with plots of 23 UTC surface reports [click to enlarge]

As mentioned in the afternoon Area Forecast Discussion, offshore Sea Surface Temperature (SST) values were in the 50-55ºF range; this was also seen in a comparison of the nighttime and daytime MODIS SST product (below). With the presence of cold air aloft and relatively warm water at the surface, the lower troposphere was unstable enough to support the development and growth of showers and thunderstorms.

MODIS Sea Surface Temperature product [click to enlarge]

MODIS Sea Surface Temperature product [click to enlarge]

Lake Michigan Mesovortex

December 31st, 2017 |

1-minute GOES-16

1-minute GOES-16 “Red” Visible (0.64 µm) images, with hourly surface reports plotted in yellow [click to play MP4 animation]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed a well-defined mesoscale vortex (or “mesovortex”) moving southward across southern Lake Michigan on 31 December 2017. The default western GOES-16 Mesoscale Sector provided images at 1-minute intervals. This feature was responsible for brief periods of heavy snow at locations such as South Haven, Michigan KLWA (beginning at 1455 UTC), Benton Harbor, Michigan KBEH (beginning at 1625 UTC) and La Porte, Indiana KPPO (from 2055 to 2115 UTC).

Comparisons of POES AVHRR/Terra MODIS/Suomi NPP Infrared (10.8 µm/11.0 µm/11.45 µm) and Visible (0.86 µm/0.65 µm/0.64 µm) images along with an overlay of the corresponding Real-Time Mesoscale Analysis (RTMA) surface winds (below) provided views of the mesovortex at 1522 UTC, 1714 UTC and 1852 UTC, respectively.

POES AVHRR Infrared (10.8 µm) and Visible (0.86 µm) images at 1522 UTC, with 15 UTC RTMA surface winds [click to enlarge]

POES AVHRR Infrared (10.8 µm) and Visible (0.86 µm) images at 1522 UTC, with 15 UTC RTMA surface winds [click to enlarge]

Terra MODIS Infrared (11.0 µm) and Visible (0.65 µm) images at 1714 UTC, with 17 UTC RTMA surface winds [click to enlarge]

Terra MODIS Infrared (11.0 µm) and Visible (0.65 µm) images at 1714 UTC, with 17 UTC RTMA surface winds [click to enlarge]

Suomi NPP Infrared (11.45 µm) and Visible (0.64 µm) images at 1852 UTC, with 19 UTC RTMA surface winds [click to enlarge]

Suomi NPP Infrared (11.45 µm) and Visible (0.64 µm) images at 1852 UTC, with 19 UTC RTMA surface winds [click to enlarge]

During the preceding nighttime hours, a comparison of Suomi NPP VIIRS Infrared (11.45 µm) and Day/Night Band (0.7 µm) images at 0729 UTC along with an overlay of 07 UTC RTMA surface winds (below) showed in spite of patchy thin cirrus clouds over the region, ample illumination from the Moon (which was in the Waxing Gibbous phase, at 96% of Full) enabled a signature of the early stage of mesovortex formation to be seen on the Day/Night Band (DNB) image. Ice crystals within the thin cirrus clouds were responsible for the significant scattering city light signatures on the DNB image.

Suomi NPP VIIRS Infrared (11.45 µm) and Day/Night Band (0.7 µm) images at 0729 UTC, with 07 UTC RTMA surface winds [click to enlarge]

Suomi NPP VIIRS Infrared (11.45 µm) and Day/Night Band (0.7 µm) images at 0729 UTC, with 07 UTC RTMA surface winds [click to enlarge]

As an aside, it is interesting to note that ice could be seen in the nearshore waters of Lake Michigan — both in the western part of the lake, off the coast of Wisconsin and Illinois, and in the eastern part of the lake off the coast of Lower Michigan. The lake ice appeared as darker shades of cyan in the 250-meter resolution Terra MODIS false-color (Band 7-2-1 combination) Red-Green-Blue (RGB) image from the MODIS Today site (below).

Terra MODIS true-color and false-color images over southern Lake Michigan [click to enlarge]

Terra MODIS true-color and false-color images over southern Lake Michigan [click to enlarge]

Alaska’s first -40º temperature of the 2017-2018 winter season

November 19th, 2017 |

NOAA-18 Infrared Window (10.8 mm) image, with surface identifiers and air temperatures plotted in red [click to enlarge]

NOAA-18 Infrared Window (10.8 mm) image, with surface identifiers and air temperatures plotted in red [click to enlarge]

Alaska’s first (official) surface air temperature of -40º or colder for the 2017-2018 winter season was reported by the Cooperative Observer at Chicken (-43ºF) on 19 November 2017. A NOAA-18 Infrared Window (10.8 µm) image at 0320 UTC (above) showed cold air drainage into river valleys, with the coldest infrared brightness temperatures around -40ºC/-40ºF (darker blue color enhancement). Chicken is located about midway between Eagle (PAEG) and Northway (PAOR), where 03 UTC surface air temperatures were -17ºF and -24ºF, respectively. However, PAEG reached their minimum temperature around 11 UTC after additional hours of cloud-free radiational cooling.

An automated RAWS site at Chicken reached a minimum temperature of -34ºF at 1120 UTC — the dew point at that time was -42ºF. However, a MesoWest map (below) shows that the RAWS tower is located on a small hill (at an elevation of 2060 feet) — and the Cooperative Observer instrument shelter was likely located in the lower elevations of the settlement.

MesoWest map showing the location of the Chicken RAWS site [click to enlarge]

MesoWest map showing the location of the Chicken RAWS site [click to enlarge]

For comparison, note the 2011-2012 and 2010-2011 winter seasons.

Pyrocumulonimbus clouds in British Columbia, Canada

August 12th, 2017 |

GOES-16 Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images, with hourly surface reports plotted in yellow [click to play animation]

GOES-16 Visible (0.64 µm, top) and Shortwave Infrared (3.9 µm, bottom) images, with hourly surface reports plotted in yellow [click to play animation]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing*

GOES-16 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) along with “Red” Visible and “Clean” Infrared Window (10.3 µm) images (below) showed the formation of 3 pyrocumulonimbus( pyroCb) clouds late in the evening on 12 August 2017, within the cluster of ongoing intense wildfires in British Columbia, Canada.

GOES-16 Visible (0.64 µm) and Infrared Window (10.3 µm) images, with hourly surface reports plotted in yellow [click to play animation]

GOES-16 Visible (0.64 µm, top) and Infrared Window (10.3 µm, bottom) images, with hourly surface reports plotted in yellow [click to play animation]

A toggle between NOAA-18 AVHRR Visible (0.63 µm), Near-Infrared (0.86 µm), Shortwave Infrared (3.9 µm) and Longwave Infrared Window (10.8 µm) images is shown below. The coldest cloud-top IR brightness temperature was -70º C (associated with the northernmost pyroCb).

NOAA-18 Visible (0.63 µm), Shortwave Infrared (3.9 µm) and Longwave Infrared Window (10.3 µm) images, with surface station plots in yellow [click to enlarge]

NOAA-18 Visible (0.63 µm), Shortwave Infrared (3.9 µm) and Longwave Infrared Window (10.3 µm) images, with surface station plots in yellow [click to enlarge]

In a daytime Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image (from RealEarth) with VIIRS-detected fire locations plotted in red (below), a very large pall of exceptionally-dense smoke from the BC fires could be seen drifting northward as far as the Northwest Territories of Canada.

Suomi NPP VIIRS true-color image, with VIIRS-detected fire locations plotted in red [click to enlarge]

Suomi NPP VIIRS true-color image, with VIIRS-detected fire locations plotted in red [click to enlarge]

The Suomi NPP OMPS Aerosol Index (AI) product (below; courtesy of Colin Seftor, SSAI) displayed AI values as high as 17.18 within the thick BC fire smoke pall.

Suomi NPP OMPS Aerosol Index [click to enlarge]

Suomi NPP OMPS Aerosol Index [click to enlarge]

===== 13 August Update =====

Suomi NPP OMPS Aerosol Index product [click to enlarge]

Suomi NPP OMPS Aerosol Index product [click to enlarge]

On 13 August, a maximum OMPS AI value of 39.91 was seen at around 21:13 UTC over the Northwest Territories of Canada (above) — according to Colin Seftor and Mike Fromm (NRL), this value surpassed the highest pyroCb-related AI value ever measured by TOMS or OMI (whose period of record began in 1979).

The north-northeastward transport of BC fire smoke — as well as a prominent increase in smoke from fires across northern Canada and the Prairies — was evident in an animation of daily composites of Suomi NPP VIIRS true-color images from 07-13 August (below).

Daily Suomi NPP VIIRS true-color image composites (07-13 August), with VIIRS-detected fire locations plotted in red [click to play animation]

Daily Suomi NPP VIIRS true-color image composites (07-13 August), with VIIRS-detected fire locations plotted in red [click to play animation]