GOES-14 SRSO-R: heavy snow in the Upper Midwest, severe thunderstorms in the Deep South

February 2nd, 2016

GOES-14 Visible (0.63 µm) images [click to play MP4 animation]

GOES-14 Visible (0.63 µm) images [click to play MP4 animation]

A strong occluded mid-latitude cyclone moved from the central Plains northeastward across the Upper Midwest on 02 February 2016 (surface analyses). This storm produced a variety of precipitation, most notably heavy snow — exceeding 12 inches at some locations in Nebraska, Iowa, Minnesota, Wisconsin, and the Upper Peninsula of Michigan (map) — and blizzard conditions. One-minute interval Super Rapid Scan (SRSO-R) GOES-14 Visible (0.63 µm) images (above; also available as a large 151-Mbyte animated GIF) showed the cloud-top shadows and textured appearance that is indicative of embedded convection — in fact, many sites in Iowa and southern Wisconsin reported thundersnow which produced snowfall rates of 1-2 inches per hour.

Farther to the south, as moisture from the Gulf of Mexico was drawn northward (GOES-14 sounder Total Precipitable Water derived product images) in advance of the eastward-moving cold frontal boundary (surface analyses) associated with the aforementioned Upper Midwest storm, areas of strong to severe thunderstorms developed across the Mississippi River and Tennessee River Valley regions during the afternoon and evening hours. GOES-14 Infrared Window (10.7 µm) images (below; also available as a large 208-Mbyte animated GIF) showed the cold cloud-top IR brightness temperatures (orange to red color enhancement) exhibited by the widespread convective activity.

GOES-14 Infrared Window (10.7 µm) images [click to play MP4 animation]

GOES-14 Infrared Window (10.7 µm) images [click to play MP4 animation]

GOES-14 Visible (0.63 µm) images [click to play MP4 animation]

GOES-14 Visible (0.63 µm) images [click to play MP4 animation]

Taking a closer look at the severe thunderstorms which produced multiple tornadoes from eastern Mississippi  into far western Alabama (SPC storm reports), GOES-14 Visible (0.63 µm) images (above; also available as a large 66-Mbyte animated GIF) revealed numerous overshooting tops; the counties where tornadoes were reported are indicated by their dashed red outlines. Another visible image animation from RAMMB/CIRA is available here. NWS storm damage surveys (Jackson MS | Birmingham AL) found EF-1 to EF-2 damage in both Mississippi and Alabama.

The corresponding GOES-14 Infrared Window (10.7 µm) images (below; also available as a large 37-Mbyte animated GIF) indicated that the coldest cloud-top IR brightness temperatures were in the -50º to -60º range (darker orange to red color enhancement), which was at or above the tropopause level according the Jackson MS and Birmingham AL rawinsonde data.

GOES-14 Infrared Window (10.7 µm) images [click to play MP4 animation]

GOES-14 Infrared Window (10.7 µm) images [click to play MP4 animation]

Widespread severe weather outbreak

December 24th, 2015

SPC preliminary storm reports [click map for complete listing]

SPC preliminary storm reports [click map for complete listing]

As shown above, a widespread outbreak of severe weather occurred on 23 December – 24 December 2015 (surface analysis maps), centered on the Mississippi Valley and Ohio Valley regions of the US. There were at least 14 fatalities in Mississippi, Tennessee, and Arkansas — and storm damage surveys (NWS Memphis PNS) showed that there were two long-track tornadoes in the Mid-South region: one EF3-rated that was on the ground for 63 miles in northwestern Mississippi, and another EF4-rated that was on the ground for 75 miles from northern Mississippi to far southwestern Tennessee (below).

Preliminary tornado damage paths [click to enlarge]

Preliminary tornado damage paths [click to enlarge]

Daytime GOES-13 (GOES-East) Visible (0.63 µm, 1-km resolution) images on 23 December (below) showed the development of several lines of severe thunderstorms — some with bowing segments earlier in the day — with many storms exhibiting signatures of well-defined Overshooting Tops and having strong Cloud-Top Cooling rates.

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

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

Longer animations of GOES-13 Infrared (10.7 µm, 4-km resolution) and Water Vapor (6.5 µm, 4-km resolution) images that extended into the nighttime hours of the severe weather outbreak are shown below.

GOES-13 Infrared (10.7 µm) images [click to play animation]

GOES-13 Infrared (10.7 µm) images [click to play animation]

GOES-13 Water Vapor (6.5 µm) images [click to play animation]

GOES-13 Water Vapor (6.5 µm) images [click to play animation]

Tornado in central California

November 15th, 2015

GOES-15 Visible (0.63 µm) images [click to play animation]

GOES-15 Visible (0.63 µm) images [click to play animation]

An EF-1 tornado was on the ground for about 20 minutes near Denair (Local Storm Report | Facebook post) in central California on 15 November 2015. 1-km resolution GOES-15 Visible (0.63 µm) images (above) showed that clusters of small thunderstorms rapidly developed in an environment of instability along and just behind a fast-moving cold frontal boundary. The location of the tornado is indicated by a red “T” on the 2145, 2200, and 2211 UTC images. Very strong southwesterly winds aloft allowed the upwind portion of the highly-tilted thunderstorms to be brightly illuminated by the low sun angle of late afternoon in mid-November.

The corresponding 4-km resolution GOES-15 Infrared (10.7 µm) images (below) revealed that cloud-top IR brightness temperatures quickly cooled from -23º C at 2130 UTC to -42º C at 2200 UTC.

GOES-15 Infrared (10.7 µm) images [click to play animation]

GOES-15 Infrared (10.7 µm) images [click to play animation]

There was a 30-minute gap in GOES-15 coverage from 2100 to 2130 UTC (due to a full disk scan), but a comparison of 1-km resolution NOAA-19 AVHRR Visible (0.63 µm) and Infrared (10.8 µm) caught the very early growth of the tornado-producing storm at 2115 UTC (below). The cloud-top IR brightness temperatures were as cold as -23º C at that time, indicating a high probability that cloud glaciation had begun.

NOAA-19 Visible (0.63 µm) and Infrared (10.8 µm) images [click to enlarge]

NOAA-19 Visible (0.63 µm) and Infrared (10.8 µm) images [click to enlarge]

A timely overpass of the Suomi NPP satellite allowed a comparison of 375-meter resolution VIIRS Visible (0.64 µm) and Infrared (11.45 µm) images during the time that the tornado was srill on the ground (below). Once again, the strong slant of the storms due to increasing wind speeds aloft allowed the western/southwestern sides of the thunderstorm clouds to be brightly illuminated on the visible image. The coldest cloud-top IR brightness temperature was -51º C (yellow color enhancement), which was just shy of the -53º C tropopause temperature reported on the Oakland rawinsonde report at 12 UTC.

Suomi NPP VIIRS Visible (0.64 µm) and Infrared (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared (11.45 µm) images [click to enlarge]

A VIIRS true-color image of the storm visualized using RealEarth is shown below. The actual satellite overpass time was around 2151 UTC.

Suomi NPP VIIRS true-color image [click to enlarge]

Suomi NPP VIIRS true-color image [click to enlarge]

GOES-15 sounder Lifted Index (LI) derived product images (below) showed the pockets of post-frontal instability over central California — LI values less than -4 C were seen (yellow color enhancement).

GOES-15 sounder Lifted Index derived product images [click to play animation]

GOES-15 sounder Lifted Index derived product images [click to play animation]

Updated Criteria for GOES RSO Calls

November 11th, 2015
<strong>GOES-13 Water Vapor (6.5 µm) infrared imagery with Day 1 Convective Outlook and rawinsonde 850 hPa and 300 hPa observations (Click to enlarge)</strong> (Click to enlarge)

GOES-13 Water Vapor (6.5 µm) infrared imagery with Day 1 Convective Outlook and rawinsonde 850 hPa and 300 hPa observations (Click to enlarge) (Click to enlarge)

The Storm Prediction Center has revised its criteria for initiating GOES Rapid Scan Operations (RSO) calls. Previously, RSO was automatically activated when a Moderate Risk (MDT) appeared in the SPC Day 1 Convective Outlook. On October 1st that was changed per a September email from SPC:

Starting October 1, the SPC Lead Forecaster will contact the NCO/SDM to request GOES RSO whenever a Day 1 Convective Outlook includes an ENH Risk area. Data from the first six months of 2015 suggests SPC would request RSO on approximately 10-20 more days compared to the current MDT Risk criterion. Activating RSO on a more frequent basis using the ENH Risk criterion would improve NWS forecaster situational awareness on convectively active days and help prepare users for much higher temporal frequency GOES-R data.

An Enhanced Risk was issued on 11 November 2015 as a strong extratropical cyclone was developing over the midsection of the country. The image above shows the GOES-13 Water vapor imagery from 1145 UTC on 11 November. A strong jet extends from the southwestern United States northeastward. On the previous day (10 November, at 12 UTC) Albuquerque reported 135-knot winds at 300 hPa (and no winds at all at 200 hPa as the balloon was lost to the tracker); at 00 UTC on 11 November, winds were 162 knots just above the 250 hPa level. Strong veering, indicating warm advection, is apparent over the mid-Mississippi River Valley. Low-level warm advection is forecast to increase as the extratropical cyclone intensifies.

Update: GOES-East began RSO at 1545 UTC on 11 November 2015 — a few image animations are shown below.

GOES-13 Water vapor (6.5 µm) images [click to play animation]

GOES-13 Water vapor (6.5 µm) images [click to play animation]

Of particular interest on 6.5 µm water vapor imagery, above, was the tightly-wrapped signature of the middle-tropospheric vorticity center moving northeastward along the Kansas/Nebraska border.

GOES-13 Infrared (10.7 µm) images [click to play animation]

GOES-13 Infrared (10.7 µm) images [click to play animation]

The 10.7 µm Infrared images, above, showed the development of thunderstorms across Iowa which exhibited cloud-top IR brightness temperatures in the -50 to -60º C range (yellow to red color enhancement). Hail, damaging winds, and tornadoes were produced by these areas of deep convection (SPC storm reports).

GOES-13 Shortwave Infrared (3.9 µm) images [click to play animation]

GOES-13 Shortwave Infrared (3.9 µm) images [click to play animation]

3.9 µm Shortwave Infrared images, above, displayed numerous “hot spots” (black to yellow to red color enhancement) due to fire activity in parts of northeastern Oklahoma and southeastern Kansas.

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

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

Finally, 0.63 µm Visible channel images, above, showed the hazy signature of smoke plumes from these Kansas/Oklahoma fires (along with a separate plume of blowing dust). In addition, as clouds cleared along the western edge of the storm, swaths of fresh snow cover could be seen over portions of Wyoming, Colorado, South Dakota, Nebraska, and Kansas. As much as 12.5 inches of snow was reported in northeastern Colorado, with wind gusts of 75 mph creating blizzard conditions.