Rapid cyclogenesis off the coast of Japan, with an aircraft experiencing severe turbulence

December 16th, 2014
COMS-1 6.95 µm water vapor channel images (click to play animation)

COMS-1 6.95 µm water vapor channel images (click to play animation)

McIDAS images of KARI COMS-1 6.95 µm water vapor channel data (above; click image to play animation; also available as an MP4 movie file) showed the tell-tale signatures — well-formed dry slot; distinct comma head — of rapid cyclogenesis for a pair of storms off the west and east coasts of Japan on 16 December 2014. An American Airlines passenger jet flying from Seoul, South Korea (RKSO) to Dallas/Fort Worth, Texas experienced severe turbulence at an altitude around 27,000 feet over the eastern portion of Honshu Island, Japan (media report); several passengers and crew members were injured (with some requiring hospitalization), forcing the aircraft to divert from its course and turn back to make a landing at Tokyo Narita airport (RJAA). The turbulence encounter likely occurred near the center portion of the red square which was drawn on the images whose times were within about 30 minutes of the 10:35 UTC turbulence encounter  (FlightAware track log) — note the development of a “transverse banding” signature along the western edge of the southern storm comma head feature (10:00 UTC image).  After the multi-layered clouds of the comma head departed, lee waves or “mountain waves” could be seen downwind of the high terrain of Honshu Island. It should also be noted that the flight path was in the left exit region of an intensifying upper-tropospheric jet streak (250 hPa winds).

In the Turbulence Risk product shown below, the blue to violet colored areas are the Tropopause Fold Turbulence Product (an algorithm developed at CIMSS which uses geostationary water vapor channel data). These colored areas identify the sections of the upper-tropospheric air mass boundaries that are the most likely to have turbulence. However, it does not attempt to show all areas of turbulence. The transverse band formation over Japan was a signature of intense instability along the jet stream axis, which was probably the cause of the major turbulence event for American Airlines Flight 280.

Turbulence Risk product

Turbulence Risk product

A dry slot exhibiting much warmer brightness temperatures (brighter yellow to orange color enhancement) was seen with the more southern of the two storms, which became the dominant system as it moved northeastward and rapidly intensified from a central pressure of 998 hPa at 06 UTC to 971 hPa at 18 UTC (below). The storm was forecast to produce a large area of hurricane-force winds over the far northwestern Pacific Ocean.

MTSAT-2 6.75 µm water vapor channel images with surface analyses at 06, 12, and 18 UTC

MTSAT-2 6.75 µm water vapor channel images with surface analyses at 06, 12, and 18 UTC

An AWIPS image of MTSAT-2 water vapor channel data with overlays of the NWS Ocean Prediction Center surface analysis and Metop ASCAT scatterometer winds showed surface wind speeds as high as 55 knots (63 mph) with the southern storm and 53 knots (61 mph) with the northern storm at 11:48 UTC (below). During the day wind gusts as high as 81 knots (93 mph) were reported at the Izu Islands south of Tokyo Bay.

MTSAT-2 6.75 µm water vapor channel image, with Metop ASCAT scatterometer surface winds and surface analysis

MTSAT-2 6.75 µm water vapor channel image, with Metop ASCAT scatterometer surface winds and surface analysis

GOES-15 Rapid Scan Operations for Hawai’i

November 5th, 2014
GOES-15 6.5 µm water vapor images and atmospheric motion vector (AMV) winds

GOES-15 6.5 µm water vapor images and atmospheric motion vector (AMV) winds

As seen on a sequence of 3-hourly GOES-15 (GOES-West) 6.5 µm water vapor images with satellite-derived atmospheric motion vector (AMV) winds from the CIMSS Tropical Cyclones site (above), a weak but persistent trough aloft over the Hawai’i region was acting to destabilize the atmosphere and create an environment conducive to the development of widespread showers and thunderstorms — some of which were producing heavy downpours over parts of the island chain — during the 04-05 November 2014 period.

Due to radar outages, the NWS forecast office in Honolulu HI requested that the GOES-15 satellite be placed into Rapid Scan Operations (RSO) mode (NOAA/NESDIS bulletin), providing 10 images per hour (compared to only 4 per hour during routine operations). An animation of GOES-15 0.63 µm visible channel images (below; click image to play animation) begins at 17:30 UTC with routine 15-minute interval images, and then after 21:30 UTC transitions into the RSO images to demonstrate how the development and motion of features can be more carefully monitored with improved temporal resolution.

GOES-15 0.63 µm visible channel images (click to play animation)

GOES-15 0.63 µm visible channel images (click to play animation)

Additional details on GOES-15 RSO sectors which were implemented during October 2014 can be found here.

Hurricane Gonzalo moves towards Bermuda

October 16th, 2014
GOES-13 0.63 µm visible channel images (click to play animation)

GOES-13 0.63 µm visible channel images (click to play animation)

Small and intense Hurricane Gonzalo is moving north-northeastward out of the western tropical Atlantic towards Bermuda (Bermuda is located at 32.3º N, 64.8º W). (See the National Hurricane Center Website for the latest Advisories on Gonzalo) GOES-13 Visible imagery (0.63 µm) from the morning of 16 October shows a well-defined eye, intense convection and good outflow in all quadrants. Mesovortices within the eye are also apparent as shown in a storm-centered animation of the eye, below, until mid- and high-level clouds develop near the end of the animation.

GOES-13 0.63 µm visible channel images, centered over the eye of Gonzalo (click to play animation)

GOES-13 0.63 µm visible channel images, centered over the eye of Gonzalo (click to play animation)

Gonzalo’s track will take it over sea surface temperatures that are not quite so warm (see image below, taken from the CIMSS Tropical Cyclones site). Cooler SSTs argue against any further strengthening, and the official forecast suggests peak intensity has already occurred.

Sea Surface Temperatures and Gonzalo's projected (and past) track and intensity (click to enlarge)

Sea Surface Temperatures and Gonzalo’s projected (and past) track and intensity (click to enlarge)

Suomi NPP overflew the storm at 0536 UTC in 16 October. A toggle between the VIIRS Day/Night Band and the 11.45 µm imagery is below. Note that lunar illumination is dropping as the Moon phase wanes so visible features are less distinct than they would be during a more Full Moon. A ragged eye is obvious in both images, however, and there is evidence of a lightning streak well east of the eye in the Day/Night Band.

Suomi NPP Day/Night Band Visible Imagery and 11.45 µm Infrared Imagery (click to enlarge)

Suomi NPP Day/Night Band Visible Imagery and 11.45 µm Infrared Imagery (click to enlarge)

Both Aqua and Metop-A overflew Gonzalo during the day on 16 October. The Aqua True-Color image (from the MODIS Today website) shows the storm and the cold front that will help guide Gonzalo’s future path. The ASCAT scatterometer data from METOP-A, below, showed a tight region of hurricane-force winds.

METOP-A ASCAT Scatterometer winds, 1353 UTC 16 October 2014 (click to enlarge)

METOP-A ASCAT Scatterometer winds, 1353 UTC 16 October 2014 (click to enlarge)

===== 18 October Update =====

Suomi NPP VIIRS 11.45 µm IR channel images

Suomi NPP VIIRS 11.45 µm IR channel images

A sequence of Suomi NPP VIIRS 11.45 µm IR channel images during the 15-17 October period (above) showed the pattern of very cold cloud-top IR brightness temperatures at various times as the storm curved northward toward Bermuda (station identifier TXKF); IR brightness temperatures of -80º C and colder (violet color enhancement) were seen on 15 and 16 October. A close-up view shows Gonzalo on 2 consecutive VIIRS IR images (16:38 and 18:18 UTC) on 17 October.

The MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) showed a plume of high TPW ahead of a cold front moving off the East Coast of the US, which was then reinforced by a northward surge of high TPW from Ganzalo. As a result, the TPW value calculated using the morning rawinsonde data from Caribou, Maine (station identifier KCAR) was 1.68 inches — the highest for so late in the season.

MIMIC Total Precipital Water product (click to play animation)

MIMIC Total Precipital Water product (click to play animation)

Around 20:15 UTC on 17 October, a comparison of GOES-13 10.7 µm IR channel and SSMIS 85 GHz microwave images from the CIMSS Tropical Cyclones site (below), the microwave image revealed the very large size of the eye of Hurricane Gonzalo (which was not as apparent on conventional IR imagery).

GOES-13 10.7 µ IR image and SSMIS 85 GHz microwave image

GOES-13 10.7 µ IR image and SSMIS 85 GHz microwave image

A close-up view of GOES-13 10.7 µm IR channel images with overlays of wind barbs and wind gusts from Bermuda International Airport (below; click image to play animation) showed the development of a convective burst just as the eye of Gonzalo was approaching the island. The airport observations (text listing | time series plot) showed a wind gust to 83 knots (96 mph) as the northern eyewall passed, and a stronger gust to 98 knots (113 mph) as the southern eyewall passed over Bermuda.

GOES-13 10.7 µm IR channel images, with overlays of wind barbs and wind gusts at Bermuda (click to play animation)

GOES-13 10.7 µm IR channel images, with overlays of wind barbs and wind gusts at Bermuda (click to play animation)

The Bermuda Weather Service launched a rawinsonde balloon at 00 UTC on 18 October; winds at the surface were from the southeast at 64 knots (74 mph), which carried the instrument package into the eye of Gonzalo for a portion of its ascent. Note the the temperature profile was nearly moist adiabatic from about 700 hPa to 200 hPa (below).

Bermuda rawinsonde report and GOES-13 10.7 µm IR image

Bermuda rawinsonde report and GOES-13 10.7 µm IR image

Tropical Invest 97L in the western Atlantic Ocean

September 29th, 2014
GOES-13 0.63 µm visible channel images with METAR surface reports (click to play animation)

GOES-13 0.63 µm visible channel images with METAR surface reports (click to play animation)

Tropical Invest 97L formed near Bermuda during the pre-dawn hours on 29 September 2014. After sunrise, AWIPS II images of GOES-13 0.63 µm visible channel data (above; click image to play animation) revealed a well-defined low-level circulation spinning just to the west of Bermuda. It is interesting to note that at 12:55 UTC a waterspout was reported 4 km to the east of the Bermuda International Airport (station identifier TXKF), associated with a band of deep convection that was moving northward (below).

GOES-13 0.63 µm visible channel image with Bermuda METAR observation

GOES-13 0.63 µm visible channel image with Bermuda METAR observation

An overpass of a Metop satellite at 14:38 UTC provided a good view of the surface wind field with data from the ASCAT scatterometer instrument (below). There was one wind vector with a speed around 30 knots (green) just to the east of the center of circulation.

GOES-13 0.63 µm visible channel image with Metop ASCAT scatterometer surface winds

GOES-13 0.63 µm visible channel image with Metop ASCAT scatterometer surface winds

A comparison of Terra MODIS 0.65 µm visible channel and 11.0 µm IR channel images at 15:25 UTC (below) showed that the coldest cloud-top IR brightness temperatures of -55º C (orange color enhancement) were located to the north of the circulation center.

Terra MODIS 0.65 µm visible channel and 11.0 µm IR channel images

Terra MODIS 0.65 µm visible channel and 11.0 µm IR channel images