Mesoscale Convective Vortex over Arizona

July 18th, 2017 |

Terra MODIS Infrared Window (11.0 µm) image, with SPC storm reports of severe winds plotted in cyan [click to enlarge]

Terra MODIS Infrared Window (11.0 µm) image, with SPC storm reports of severe winds plotted in cyan [click to enlarge]

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

Strong summer monsoon season thunderstorms developed over Arizona in the pre-dawn nighttime hours on 17 July 2017, producing damaging winds across the Phoenix area (SPC storm reports). A Terra MODIS Infrared Window (11.0 µm) image (above) revealed cloud-top brightness temperatures as cold as -77º C at 0508 UTC.

GOES-16 “Clean” Infrared Window (10.3 µm) images (below) showed the development and eventual dissipation of the overnight convection.

GOES-16 Infrared Window (10.3 µm) images, with station identifiers plotted in yellow and SPC storm reports plotted in cyan [click to play animation]

GOES-16 Infrared Window (10.3 µm) images, with station identifiers plotted in yellow and SPC storm reports plotted in cyan [click to play animation]

During the following daytime hours, GOES-16 “Red” Visible (0.64 µm) images (below) displayed the circulation of a Mesoscale Convective Vortex (MCV) as it propagated west-southwestward. Note that surface dew point temperatures were in the upper 60s  to low 70s F across southern Arizona.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly surface reports [click to play animation]

GOES-16 ABI Mesoscale Sector imagery and GLM data with strong thunderstorms over Wisconsin

July 12th, 2017 |

GOES-16 ABI Band 13 (“Clean Window”) 10.3 µm Imagery, every minute from 1000 – 1359 UTC on 12 July 2017, with GLM Lightning Flash locations for each minute (yellow circles) superimposed (Click to animate)

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

Strong morning thunderstorms with a few severe weather reports, and abundant heavy rain (24-h totals ending 1200 UTC on 12 July 2017, from here), spread over the northern part of the GOES-16 default western Mesoscale Sector on the morning of 12 July 2017. The animation above shows the GOES-16 Advanced Baseline Imager (ABI) 10.3 µm imagery with Geostationary Lightning Mapper (GLM) Lightning Flash event locations superimposed, at 1-minute timescales. The top of the default Mesoscale Sector cuts through central Wisconsin.

Click here to see a graphic with the GLM Flashes for the 3 different hours.

1-minute GOES-16 images: severe thunderstorms in North Dakota, South Dakota and Minnesota

July 11th, 2017 |

GOES-16 Visible (0.6 µm, left) and Infrared Window (10.3 µm, right) images, with SPC storm reports plotted in red (on Visible) and black (on Infrared) [click to play MP4 animation]

GOES-16 Visible (0.6 µm, left) and Infrared Window (10.3 µm, right) images, with SPC storm reports plotted in red (on Visible) and black (on Infrared) [click to play MP4 animation]

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

Severe thunderstorms developed in the warm sector of a mid-latitude cyclone that was moving eastward along the US/Canada border on 11 July 2017.  GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the storms that produced tornadoes, wind gusts to 80 mph and hail as large as 2.00 inches (SPC storm reports) across far eastern North Dakota and far northwestern Minnesota (NWS Grand Forks summary). Time-matched SPC storm reports are plotted on the images — the report locations are parallax-corrected to match the location o the cloud-top features. Overshooting tops were very evident on the Visible and Infrared imagery; in addition, pronounced cold/warm Thermal Couplets and/or Enhanced-V signatures were seen in the Infrared images.

Farther to the south, other storms (below) produced hail as large as 3.00 inches and wind gusts to 75 mph across northeastern South Dakota (NWS Aberdeen summary).

GOES-16 Visible (0.64 µm, top) and Infrared Window (10.3 µm, bottom) images, with SPC storm reports plotted in red (on Visible) and black (on Infrared) [click to play MP4 animation]

GOES-16 Visible (0.64 µm, top) and Infrared Window (10.3 µm, bottom) images, with SPC storm reports plotted in red (on Visible) and black (on Infrared) [click to play MP4 animation]

Using GOES-16 Baseline Products to anticipate where heavy rain might fall

July 10th, 2017 |

GOES-16 10.3 µm “Clean Window” Superimposed on the Clear-Sky Baseline Total Precipitable Water Product, 0107 – 1337 UTC on 10 July (Click to play large animated gif)

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

Very heavy rain (4-5″) fell over parts of southwestern Wisconsin early on 10 July 2017 as a Mesoscale Convective System traversed the Upper Midwest (0831 UTC VIIRS Infrared vs Day/Night Band). The animation above blends the Clean Window (10.3 µm) from GOES-16 with the Total Precipitable Water Baseline Product (This product is available online — with a time delay — here). Note that the largest values of Precipitable Water are diagnosed to be over southern and western of Wisconsin. Looking at the animation of the 10.3 µm imagery, can you decide where the heaviest rain fell?

A screen capture from this website, below, shows 24-hour precipitation over the Upper Midwest, with a northwest-to-southeast oriented maximum near the northwest-to-southeast gradient of diagnosed total precipitable water field shown in the animation above. (This summary from the National Weather Service in Milwaukee shows accumulated precipitation ending at 0900 Central Time).

The Hazardous Weather Testbed at the Storm Prediction Center evaluates GOES-16 (and other satellites, such as Suomi NPP) products. There have been many instances that noted convection was most intense along the gradient of the moisture (See this summary, for example, or this one.) When GOES-16 Baseline Products indicate a gradient, pay close attention when strong convection develops upstream.

24-hour Precipitation over the Upper Midwest ending at 1200 UTC on 10 July 2017 (Click to enlarge)

Added: One day later, again, convection initiated (and/or persisted) north of the diagnosed Total Precipitable Water maximum over Illinois and Iowa (link), i.e., in the gradient of Total Precipitable Water.