Heavy snow across southern Minnesota, northern Iowa and southern Wisconsin

April 18th, 2018 |

24-hour snowfall ending at 12 UTC on 19 April [click to enlarge]

24-hour snowfall ending at 12 UTC on 19 April [click to enlarge]

A band of heavy snow fell across southern Minnesota (as much as 11.0 inches), northern Iowa (as much as 12.0 inches) and southern Wisconsin (as much as 9.4 inches) on 18 April 2018.

Animations of 1-minute Mesoscale Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm), “Clean” Infrared Window (10.3 µm) and “Low-level” Water Vapor (7.3 µm) images (below) showed the formation of convective elements and banding along the southern edge of the colder cloud shield — snowfall rates were enhanced when these convective features moved overhead, and thundersnow was noted at some locations.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly surface weather type plotted in cyan [click to play MP4 animation]

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly surface weather type plotted in yellow [click to play MP4 animation]

GOES-16

GOES-16 “Low=level” Water Vapor (7.3 µm) images, with hourly surface weather type plotted in cyan [click to play MP4 animation]

In south-central Wisconsin, Madison (KMSN) received 7.2 inches of snowfall, which set a new record for daily snowfall (and helped to make April the snowiest month of the 2017/2018 winter seeason). In addition, the daily maximum temperature was only 33 ºF, which was a record low maximum for the date. Over the southwestern part of the city, a cluster of GOES-16 Geostationary Lightning Mapper (GLM) Groups was detected from 1918 to 1919 UTC (below; courtesy of Dave Santek, SSEC) — the GOES-16 Visible image at that time did display a textured cloud top appearance characteristic of embedded convection across southern Wisconsin.

GOES-16 GLM Groups [click to enlarge]

GOES-16 GLM Groups [click to enlarge]

===== 20 April Update =====

GOES-16 true-color (daytime) and Infrared Window (10.3 µm, nighttime) images [click to play MP4 animation]

GOES-16 natural-color RGB (daytime) and Infrared Window (10.3 µm, nighttime) images [click to play MP4 animation]

A fast animation of GOES-16 natural-color Red-Green-Blue (RGB) images (above) revealed the rapid rate of snow melt — especially on 19 April — along the southern edge of the snow cover (where lighter amounts of snow fell). The effect of the high late-April sun angle also played a role in the rapid snow melt.

Large grass fires continue to burn in the southern Plains

April 17th, 2018 |

GOES-16 Shortwave Infrared (3.9 µm) images, with hourly plots of surface reports [click to play MP4 animation]

GOES-16 Shortwave Infrared (3.9 µm) images, with hourly plots of surface reports [click to play MP4 animation]

1-minute Mesoscale Sector GOES-16 (GOES-East) Shortwave Infrared (3.9 µm) images (above) showed a number of “hot spot” signatures (dark black to red pixels) associated with grass fires that began burning in southeastern Colorado, southwest Kansas and the Oklahoma/Texas Panhandles on 17 April 2018. These fires spread very rapidly with strong surface winds (as high as 81 mph at Wolf Creek Pass CO) and very dry fuels due to Extreme to Exceptional drought. In addition to these new fires, hot pixels from the ongoing Rhea Fire in northwest Oklahoma (which began burning on 12 April) were still apparent.

During the subsequent nighttime hours, a strong cold front plunged southeastward across the region (surface analyses) — and on a closer view of GOES-16 Shortwave Infrared images (below), 2 different behaviors were seen for 2 of the larger fires. As the cold front moved over the Badger Hole Fire that was burning along the Colorado/Kansas border, an immediate decreasing trend in hot spot intensity and coverage was noted. Farther to the southeast, when the cold front later moved over the Rhea Fire in northwest Oklahoma a flare-up in hot spot intensity and coverage was evident.

GOES-16 Shortwave Infrared (3.9 µm) images, with hourly plots of surface reports [click to play MP4 animation]

GOES-16 Shortwave Infrared (3.9 µm) images, with hourly plots of surface reports [click to play MP4 animation]

===== 18 April Update =====

A nighttime comparison of (Preliminary, Non-Operational) NOAA-20 VIIRS Day/Night Band (0.7 µm), I-Band Shortwave Infrared (3.75 µm), M-Band Shortwave Infrared (4.05 µm), and M-Band Near-Infrared (1.61 µm and 2.25 µm) images (below; courtesy of William Straka, CIMSS) showed a variety of fire detection signatures associated with the Rhea Fire (283,095 acres, 3% contained) in northwest Oklahoma.

NOAA-20 Day/Night Band (0.7 µm), I-Band Shortwave Infrared (3.75 µm), M-Band Shortwave Infrared (4.05 µm), M-Band Near-Infrared (1.61 µm and 2.25 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm), I-Band Shortwave Infrared (3.75 µm), M-Band Shortwave Infrared (4.05 µm), M-Band Near-Infrared (1.61 µm and 2.25 µm) images [click to enlarge]

The early afternoon 1-km resolution Aqua MODIS Land Surface Temperature product (below) indicated that LST values within the Rhea burn scar (which covered much of Dewey County in Oklahoma) were as high as 100 to 105 ºF (darker red enhancement) — about 10 to 15 ºF warmer than adjacent unburned vegetated surfaces.

Aqua MODIS Land Surface Temperature product [click to enlarge]

Aqua MODIS Land Surface Temperature product [click to enlarge]

===== 19 April Update =====

A 30-meter resolution Landsat-8 false-color image from RealEarth (below) provided a detailed view of the Badger Hole Fire, which had burned 48,400 acres along the Colorado/Kansas border.

Landsat-8 false-color image [click to enlarge]

Landsat-8 false-color image [click to enlarge]

Grass fires in northwest and southwest Oklahoma

April 12th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top) and Shortwave Infrared (3.9 µm, bottom) images, with hourly plots of surface reports [click to play MP4 animation]

1-minute Mesoscale Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the development and rapid spread of grass fires in northwest Oklahoma on 12 April 2018. Hot fire pixels are highlighted as red on the Shortwave Infrared images — and the rapid northeastward run of the larger fires was very evident. The intense heat of the fires produced pyrocumulus clouds, which could be seen on the Visible images. Additional images are available on the Satellite Liaison Blog.

SPC had highlighted parts of New Mexico, Colorado, Texas and Oklahoma as having conditions favorable for Extreme wildfire behavior due to strong winds, hot temperatures and very dry air behind a dryline boundary (below). Note that the surface temperature / dew point depression at Woodward, Oklahoma (KWWR) at 2255 UTC on 12 April was 100 ºF (temperature = 97 ºF, dew point = -2 ºF), with southwesterly winds gusting to 35 knots or 40 mph.

SPC Day 1 Fire Outlook [click to enlarge]

SPC Day 1 Fire Outlook [click to enlarge]

===== 13 April Update =====

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.9 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.9 µm) images [click to enlarge]

The fires in northwestern Oklahoma continued to burn into the following night — Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.9 µm) images at 0837 UTC or 3:37 AM local time (above) revealed the bright glow and hot fire pixels associated with the 2 large fire complexes in Woodward County (34 Complex Fire) and Dewey County (Rhea Fire). At least 2 fatalities (Wildfire Today | media report) have been attributed to the larger and longer-burning Rhea Fire in Dewey County (which had burned an estimated 241,280 acres by mid-day on 14 April).

During the following daytime hours of 13 April, GOES-16 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (below) showed the smoke plumes and hot pixels of the northwestern Oklahoma fires. The surface cold front moved over these fires around 18 UTC, with smoke transport transitioning more toward the east then southeast.

GOES-16

GOES-16 “Red” Visible (0.64 µm, top) and Shortwave Infrared (3.9 µm, bottom) images, with hourly plots of surface reports [click to play MP4 animation]

Farther to the southwest, new grass fires which began burning west of the Texas/Oklahoma border after 17 UTC quickly raced eastward and crossed the border into southwestern Oklahoma after 20 UTC (below).

GOES-16

GOES-16 “Red” Visible (0.64 µm, top) and Shortwave Infrared (3.9 µm, bottom) images, with hourly plots of surface reports [click to play MP4 animation]

===== 14 April Update =====

Three nighttime comparisons of (Preliminary, non-operational) NOAA-20 and Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.75 µm) images — each image pair separated by 50 minutes — (below; courtesy of William Straka, CIMSS) showed the bright glow and thermal hot spots of the ongoing Rhea fire complex.

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.75 µm) images at 0737 UTC [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.75 µm) images at 0737 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.75 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.75 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.75 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.75 µm) images [click to enlarge]

===== 15 April Update =====

250-meter resolution Terra MODIS true-color and false-color Red-Green-Blue (RGB) images from MODIS Today (below) showed the burn scars from the 34 Complex and the larger Rhea Fire at 1719 UTC on 15 April 2018.

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

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

Severe thunderstorms in South Florida

April 10th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.3 µm, bottom) images, with SPC storm reports plotted in red and airport identifiers plotted in yellow [click to play MP4 animation]

1-minute Mesoscale Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the southward propagation of a pre-cold-frontal trough axis (surface analyses) which appeared to play a role in enhancing ongoing convection — some thunderstorms then produced weak tornadoes, damaging winds and hail over parts of South Florida during the afternoon hours on 10 April 2018 (KMFL PNS). SPC storm reports are plotted on the GOES-16 images.

The NOAA/CIMSS ProbSevere All Hazards product (from this site) for the 1934 UTC tornado is shown below, at two-minute intervals from 1926-1946 UTC. ProbWind for this storm jumped as the tornado began, and the storm had the highest ProbWind values of those on the map.

NOAA/CIMSS ProbSevere All Hazards read-out from 1926-1946 UTC on 10 April 2018 (Click to enlarge)

The NOAA/CIMSS ProbSevere All Hazards product (from this site) for the 2025 UTC tornado is shown below, at two-minute intervals from 2012-2034 UTC. ProbTor increased from 1% to 10% between 2020 UTC and 2028 UTC with this storm.  ProbWind exceeded 90%.

NOAA/CIMSS ProbSevere All Hazards read-out from 2012-2034 UTC on 10 April 2018 (Click to enlarge)