GOES-14 in SRSO-R Scanning

May 18th, 2015

GOES-14 0.62 µm visible imagery [click to play animation]

GOES-14 0.62 µm visible imagery [click to play animation]

GOES-14 is producing imagery at 1-minute intervals as part of Super-Rapid Scan Operations for GOES-R (SRSO-R). Sectors that are scanned change each day and are determined by likely weather events. The animation above, in the southwest corner of the Monday May 18 sector shows strong convection over northern Louisiana. (A similar animation in mp4 format is available here (YouTube)) A benefit of 1-minute imagery is that it can capture the entire lifecycle of overshooting tops, cloud-top features that typically form and decay in less than 10 minutes.

GOES-R is scheduled to launch in March 2016. It will have the capability to provide routine 1-minute imagery over mesoscale-sized domains such as those sampled in the next three weeks by GOES-14. Real-time GOES-14 SRSO imagery is available through the SSEC RealEarth web map server and the GOES-14 SRSOR Imagery site.

Rapid Scan Operations allow the eye to distinguish between upper- and lower-level clouds that typically move at different speeds or in different directions. In the animation below (similar mp4 available here), high clouds over western Pennsylvania are moving over dissipating river fog in the central part of the state. Upper level clouds over southern New York are moving southward; low clouds are moving westward behind a back-door cold front: winds at White Plains, Newark, Trenton (and other stations) have all switched to easterly.

GOES-14 0.62 µm visible imagery [click to play animation]

GOES-14 0.62 µm visible imagery [click to play animation]

Another feature of interest was a thin layer of lake fog that was streaming northward across Lake Michigan during the morning hours, as seen in the animation below (also available as an mp4 movie file). Note the appearance of an undular bore propagating southeastward through the northern portion of the fog at the end of the animation; this may have been caused by an internal reflection of the strong southerly flow impinging upon the rugged southern coastline of the Upper Peninsula of Michigan. According to buoy data and the Terra MODIS Sea Surface Temperature product, Lake Michigan waters were still in the upper 30s to low 40s F — it was the pre-cold-frontal southerly flow of much warmer air with dew point values in the 50s and 60s F that led to the formation of the lake fog.

GOES-14 0.62 um visible channel images (click to play animation)

GOES-14 0.62 um visible channel images [click to play animation]

Rounds of deep convection persisted over parts of the Gulf Coast states during the day, which can be seen in the sunrise-to-sunset animation of GOES-14 visible images below (also available as an MP4 movie file). In Louisiana, some of these storms produced heavy rainfall and flash flooding, with a few water rescues necessary.

GOES-14 0.62 µm visible channel images (click to play YouTube animation)

GOES-14 0.62 µm visible channel images (click to play YouTube animation)

A mid-tropospheric atmospheric bore viewed by GOES-15, GOES-14, and GOES-13

May 16th, 2015

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 6.5 µm water vapor channel images [click to play animation]

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 6.5 µm water vapor channel images [click to play animation]

An elongated north-to-south oriented atmospheric bore was observed on GOES-15 (GOES-West), GOES-14, and GOES-13 (GOES-East) 6.5 µm water vapor channel images (above; click to play animation; also available as an MP4 movie file) on the morning of 16 May 2015. This bore feature was located in the area where strong westerly to southwesterly mid-tropospheric winds were impinging upon a consolidating dryline — this dryline later moved eastward and acted as the focus for severe thunderstorms across Texas (SPC storm reports). GOES-14 had been activated to perform Super Rapid Scan Operations for GOES-R (SRSOR) duties beginning on 18 May.

Note that there were no parallel cloud rolls present on the corresponding GOES-15/14/13 0.63 µm visible channel imagery (below) — so this gravity wave bore feature was forming in clear air.

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.63 µm visible and 6.5 µm water vapor channel images

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.63 µm visible and 6.5 µm water vapor channel images

A comparison of 12 UTC El Paso, Texas (yellow) and Midland, Texas (cyan) rawinsonde data (below) showed the differences in vertical moisture profile to the west and to the east of the bore feature — especially in the 500-600 hPa layer, where a good deal of the signal contributing to the overall water vapor brightness temperature was originating from.

El Paso and Midland, Texas rawinsonde data profiles

El Paso and Midland, Texas rawinsonde data profiles

Dolphin acquires an eye

May 15th, 2015
Himawari-8 11.22 µm infrared channel images (click to play animation)

Himawari-8 11.22 µm infrared channel images (click to play animation)

Himawari-8 infrared imagery (above, at 2.5-minute time steps and available here as an mp4) shows the development of an eye in Typhoon Dolphin shortly after 1400 UTC when the storm was northwest of Guam. With the subsequent arrival of daylight, mesovortices were clearly seen within the eye on 2.5-minute interval rapid scan visible images (animated gif | mp4 movie file).

About 2 hours prior to eye formation, a Metop satellite overpass allowed the ASCAT instrument to provide surface scatterometer winds of Typhoon Dolphin, overlaid on a MIMIC Total Precipitable Water (TPW) image (below; TPW animation). The maximum TPW values were in the 60-65 mm or 2.4-2.6 inch range, and the highest ASCAT wind value was 68 knots in the eastern eyewall region of the storm.

MIMIC TPW product, with an overlay of Metop ASCAT surface scatterometer winds

MIMIC TPW product, with an overlay of Metop ASCAT surface scatterometer winds

During the preceding daylight hours as Category 2 intensity Typhoon Dolphin was approaching Guam, rapid-scan (2.5-minute interval) 0.5-km resolution Himawari-8 0.64 µm visible channel images (below; click image to play animation; also available as an mp4 movie file) revealed a number of large convective bursts — but no eye was yet apparent. As the center of Dolphin passed between the islands of Guam and Rota, the peak wind gust was 70 knots at Agana, Guam (PGUM) and 92 knots at Anderson Air Force Base, Guam (PGUA).

Himawari-8 0.64 µm visible channel images (click to play animation)

Himawari-8 0.64 µm visible channel images (click to play animation)

Typhoon Dolphin approaches Guam

May 14th, 2015
Himawari-8 11.22 µm infrared channel images (click to play animation)

Himawari-8 11.22 µm infrared channel images (click to play animation)

The animation above (available here as an mp4, and here on YouTube) shows 11.22 µm infrared imagery at 2.5-minute time steps (bottom) and 10-minute time steps (top) from Himawari-8 on 14 May 2015. Category 2 intensity Typhoon Dolphin is approaching Guam, seen at the left edge of both panels in the frame. The 2.5-minute imagery gives a much better indication of the quick rise and decay of overshooting tops (IR brightness temperatures of the storm tops approach -95º C!). A 10-minute time step cannot fully resolve the evolution of these features. The 2.5-minute time step also better captures the divergent flow (and outward-propagating gravity waves) at the top of the central dense overcast. No eye was yet apparent in the infrared imagery, or on DMSP SSMI 85 GHz microwave imagery.

A similar animation from the previous day, 13 May, is shown here: gif, mp4, YouTube. The better organization of the storm on 14 May is readily apparent.

How high are the clouds in the Central Dense Overcast (CDO)? Cloud Heights are available from CLAVR-x (Clouds from AVHRR Extended). Data from Geostationary Satellites are processed and are available to download here. Values from COMS-1 and from MTSAT-2 (displayed with McIDAS-V) suggest maximum cloud heights near 55,500 feet.

The MIMIC Total Precipitable Water (TPW) product, below, showed that Typhoon Dolphin was able to tap rich moisture from the Intertropical Convergence Zone (ITCZ) during the 13-14 May period; TPW values within the tropical cyclone circulation were often in the 60-65 mm or 2.5-2.6 inch range (darker red color enhancement).

MIMIC Total Preciptable Water product (click to play animation)

MIMIC Total Preciptable Water product (click to play animation)

Visible Imagery from Himawari-8, just after sunrise on 15 May, show continuous development of short-lived overshooting tops to the east of Guam. More information on the storm is available at the CIMSS Tropical Cyclones site, the JMA Tropical Cyclone site and the Joint Typhoon Warning Center.

Himawari-8 0.6363 µm visible channel images (click to play animation)

Himawari-8 0.6363 µm visible channel images (click to play animation)