Yet another powerful storm strikes the British Isles

February 5th, 2014 |
Meteosat-10 0.635 µm visible channel images (click to play animation)

Meteosat-10 0.635 µm visible channel images (click to play animation)

McIDAS images of EUMETSAT Meteosat-10 0.635 µm visible channel data (above; click image to play animation) showed the cloud structure associated with a powerful midlatitude cyclone that was moving northeastward toward the British Isles on 04 February 2014. This storm — the latest in a series of intense North Atlantic Ocean storms to batter the region during the winter of 2013/2014 — produced very strong winds (gusting to 92 mph on the Isle of Scilly), heavy rain, and flooding; power was cut to over 40,000 customers, and rail service was disrupted.

The evolution of the storm could be seen on hourly composites of geostationary and polar-orbiting satellite water vapor channel imagery covering the 03-05 February period (below), visualized using the SSEC RealEarth web map server. As the large storm began to dissipate, another system could be seen developing upstream over the North Atlantic Ocean. Also of note are the subtle wave structures that could be seen in the water vapor imagery downwind of the Azores, caused by strong winds interacting with the high terrain of the islands (the tallest point is Pico, at 2,351 meters or 7,713 ft).

Composite of water vapor channel imagery (click to play animation)

Composite of water vapor channel imagery (click to play animation)

Tropical Storm Washi (27W) strikes the Philippines

December 17th, 2011 |
MTSAT-1R 10.8 µm IR images (click image to play animation)

MTSAT-1R 10.8 µm IR images (click image to play animation)

MTSAT-1R 10.8 µm IR images from the CIMSS Tropical Cyclones site (above; click image to play animation) showed a fairly compact cluster of cold convective cloud tops associated with Tropical Storm Washi as it moved westward toward the Philippines during the 15-16 December 2011 period.

A closer view using MIMIC microwave imagery (below) also showed a relatively small area of enhanced brightness temperatures (representing heavy precipitation) crossing Mindanao Island in the southern Philippines on 16 December.

MIMIC microwave imagery

MIMIC microwave imagery

However, AWIPS images of the MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) revealed that Tropical Storm Washi was embedded within a long fetch of very rich tropical moisture, with TPW values in excess of 60 mm or 2.4 inches (darker red color enhancement). This abundance of moisture helped to fuel over 10 hours of heavy rainfall, which resulted in widespread flash flooding and reports of over 900 deaths in the Philippines.

MIMIC Total Precipitable Water product (click image to play animation)

MIMIC Total Precipitable Water product (click image to play animation)

EF-4 tornado strikes the St. Louis, Missouri area

April 23rd, 2011 |
GOES-13 10.7 µm IR image (click image to play animation)

GOES-13 10.7 µm IR image (click image to play animation)

AWIPS images of GOES-13 10.7 µm IR data (above; click image to play animation) showed a large line of severe thunderstorms that moved eastward across the middle Mississippi River Valley region during the evening of 22 April 2011. This storm produced a significant number of large hail, damaging wind, and tornado reports (including one that did damage to the St. Louis airport). The initial storm damage survey has found EF-4 damage in the northern St. Louis county area.

A 1-km resolution POES AVHRR image very close to the time that the tornado was moving through the St. Louis area is shown below, with an overlay of the SPC hail, damaging winds, and tornado reports. Though the time stamp of the AWIPS image was “01:00 UTC”, the actual time that the NOAA-16 satellite was making its overpass of that region was about 01:12 UTC. Note that the storm exhibited a very well-defined “enhanced-v” signature near St. Louis (with a minimum cloud top IR brightness temperature of -83º C) — this enhanced-v IR storm top signature is often observed with areas of strong convection that are producing (or are about to produce) either large hail, damaging winds, or tornadoes.

POES AVHRR 12.0 µm IR image + severe weather reports

POES AVHRR 12.0 µm IR image + severe weather reports

On a larger-scale view, a comparison of the 1-km resolution POES AVHRR 12.0 µm IR image with the corresponding 4-km resolution GOES-13 10.7 µm IR image (below) demonstrated two things: (1) how an improvement in spatial resolution can aid in the detection of small-scale cloud top features and signatures, and (2) the parallax shift of the high cloud top features on the GOES-13 image (features are shifted farther to the northwest compared to the POES AVHRR image, due to the large viewing angle from GOES-13). In spite of the AWIPS time stamps of the 2 images being different, the times of the images are actually about the same: the GOES image began scanning southward from southern Canada at 01:10 UTC, while the Miami ground station began to receive to NOAA-16 AVHRR image over the Gulf of Mexico at 01:00 UTC. Both images are scanning the St. Louis region around 01:12 UTC.

POES AVHRR 10.8 µm IR image + GOES-13 10.7 µm IR image

POES AVHRR 10.8 µm IR image + GOES-13 10.7 µm IR image

As the line of convection was organizing across western Missouri during the afternoon hours, GOES-13 sounder derived product images (below) of Convective Available Potential Energy (CAPE), Lifted Index (LI), and Total Precipitable Water (TPW) showed that the air mass south of the warm frontal boundary across eastern Missouri was moist (TPW values of 30-40 mm or 1.2 to 1.6 inches) and unstable (CAPE values exceeding 4000 J/kg and LI values of -5 to -9 C).

GOES-13 sounder Convective Available Potential Energy derived product image

GOES-13 sounder Convective Available Potential Energy derived product image

GOES-13 sounder Lifted Index derived product image

GOES-13 sounder Lifted Index derived product image

GOES-13 sounder Total Precipitable Water derived product image

GOES-13 sounder Total Precipitable Water derived product image

Remnants of Hurricane Ike

September 14th, 2008 |
GOES-12 visible images + surface reports

AWIPS images of the GOES-12 visible channel + surface reports

The remnants of Hurricane Ike moved rapidly northeastward across the Ohio River Valley region on 14 September 2008. AWIPS images of the GOES-12 visible channel (above) with an overlay of METAR surface reports showed that a large number of locations reported very strong wind gusts just to the south of the cluster of convection that marked the core of Ike’s remnants. Winds gusted to 43 knots (49 mph) at Pahucah, Kentucky (KPAH) at 14 UTC, 49 knots (56 mph) at Evansville, Indiana (KEVV) at 16 UTC, 65 knots (75 mph) at Lousiville, Kentucky (KSDF) at 18 UTC, 64 knots (74 mph) at Cincinnati, Ohio (KCVG) at 20 UTC, and 57 knots (66 mph) at Port Columbus, Ohio (KCMH) at 21 UTC. The highest unofficial wind gust reported was 73 knots (84 mph) at West Chester, Ohio (NWS WIlmington, Ohio summary).

An animation of a mosaic of US radar reflectivity (105-MB QuickTime movie, courtesy of the UW-Madison Department of Atmospheric and Oceanic Sciences) allows one to follow the progression of the remnants of Ike after the hurricane made landfall along the Texas coast. A large swath of heavy rain resulted, with a maximum amount of 11.02 inches reported in La Porte County, Indiana. In addition, an unusual tropical-type tornado outbreak occurred on 13 September in southern Michigan — a total of 5 tornado touchdowns occurred, producing significant damage in Paw Paw and Plymouth.