GOES-15 6.5 µm water vapor channel images (above; click image to play animation; also available as an MP4 movie file) showed the development of a train of stratospheric intrusion vortices over the East Pacific Ocean during the 07 August – 08 August 2014 period. These vortices formed along a middle to upper tropospheric wind shear axis, and propagated toward the northeast.

The corresponding GOES sounder Total Column Ozone product (below; click image to play animation) revealed ozone values as high as 375 Dobson Units (lighter green color enhancement) within the more well-defined stratospheric intrusion vortices, due to the fact that ozone-rich stratospheric air was descending as the tropopause heights were lowered within the cyclonic vortex circulations.

Other examples of stratospheric intrusion vortices can be found here, here, here, and here.

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GOES-14 (positioned over the Equator at 105º West Longitude) Imager and Sounder instruments have been activated to support of SRSO-R operations, which are scheduled to begin Thursday 14 August. The first image acquired was shortly after 1530 UTC on 5 August; Image Navigation and Registration start-up was scheduled for 7-9 August, and the image above along the Gulf Coast shows that the navigation today is very accurate. Infrared imagery for the same time shows coldest cloud tops (over eastern Arkansas) near -65º C.

After a north-south maneuver on the 12th, GOES-14 1-minute imagery will begin to flow. The satellite is scheduled to return to standby mode on 29 August.

Satellite messages from NOAA, including those pertaining to GOES-14, can be viewed here.

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Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 23:47 UTC on 07 August 2014 (above) showed Category 1 Hurricane Iselle just east of Hawai’i, exhibiting a convective burst within the northern semicircle and cloud-top IR brightness temperatures as cold as -82º C. With the approach of Iselle, the Central Pacific Hurricane Center issued its first Hurricane Warning for a portion of Hawai’i since 1993.

An animation of GOES-15 0.63 µm visible channel images during daylight and 10.7 µm IR images at night (below; click to play animation; also available as an MP4 movie file) revealed a deteriorating satellite signature as the hurricane approached the Big Island of Hawai’i — and Iselle was downgraded to a Tropical Storm around 08 UTC on 08 August. However, abundant moisture and orographic effects led to some locations receiving over 10 inches of rainfall in a 24-hour period. In fact, one final convective burst could be seen developing after about 11:00 UTC, moving over the southeastern portion of the Big Island after about 12:45 UTC.

The period of deteriorating satellite signature and weakening intensification were due to the storm encountering increasing deep layer wind shear (below).

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GOES-15 visible imagery from after sunrise on 7 August 2014 shows the approach of Pacific Hurricane Iselle towards the ‘Big Island’ of Hawai’i. Orographically-forced clouds are apparent on the northern shores of the entire Island chain, and significant rains are possible as the storm passes — Flash Flood Watches are up for the entire state until 6 AM (HST) Saturday.

There are products available to assess how much rain could potentially fall. For example, the Orographic Rain Index (ORI) uses Total Precipitable Water, 850-mb winds from the Global Forecasting System (GFS) Model and high-resolution topography to determine how much rain might occur if winds are orthogonal (or nearly so) to topography. A real-time display of the product is here.

The moisture environment surrounding Iselle appears to be less hostile today. The water vapor imagery from 1200 UTC, 6 August, showed significant dry air between the storm and Hawaii. That dry air is not so pronounced today (above). Both images cover the same domain and use the same enhancement. Hurricane Julio is apparent in the eastern part of the image from 7 August, above; that storm is forecast to remain north of the island chain.

GOES-15 Infrared Channel (10.7 µm) imagery from 7 August shows periodic deep convection forming in the northern half of Iselle’s circulation, north of an eye-like structure in the infrared. The plot of overshooting tops around Iselle (here) shows that overshoots are being detected again after a relatively quiescent period yesterday and the day before.

Microwave data can be used to measure the intensity of precipitation in/around a tropical cyclone, and the MIMIC-TC pages show animations for active storms. The animation above shows Iselle’s slow weakening — as measured by the intensity of the precipitation in the eyewall.

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