Hurricane Hermine

September 1st, 2016

GOES-13 Visible (0.63 µm) images, with surface/buoy/ship reports plotted in yellow [click to play animation]

GOES-13 Visible (0.63 µm) images, with surface/buoy/ship reports plotted in yellow [click to play animation]

Hermine was upgraded to a Hurricane over the Gulf of Mexico around 20 UTC on 01 September 2016. GOES-13 (GOES-East) Visible (0.63 µm) images (above) showed improvement in the appearance of curved banding structures around the eye late in the day. The GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5-7 minutes. Note that Hurricane Hermine developed from Tropical Invest 99L, which was sampled by 1-minute GOES-14 imagery beginning on 25 August; unfortunately, the 1-minute Super Rapid Scan Operations for GOES-R (SRSO-R) test period ended at 1115 UTC on 29 August (however, imaging of the evolution of Tropical Depression 9 to Hurricane Hermine continued at 15-minute intervals).

The corresponding GOES-13 Infrared Window (10.7 µm) images (below) revealed the eventual formation of a distinct eye, with bursts of convection exhibiting cloud-top IR brightness temperatures in the -75º to -80º C range (shades of white to violet pixels) in the western and southern semicircles of the eyewall region. Hermine became the first hurricane to make landfall in Florida since Wilma in 2005.

GOES-13 Infrared Window (10.7 µm) images, with surface/buoy/ship reports plotted in yellow [click to play animation]

GOES-13 Infrared Window (10.7 µm) images, with surface/buoy/ship reports plotted in yellow [click to play animation]

A Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image visualized using RealEarth (below) provided a detailed view of the curved banding around the western and southern portion of the eye.

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

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

A comparison of DMSP-17 SSMIS Microwave (85 GHz) and GOES-13 Infrared Window (10.7 µm) images around 2315 UTC (below) depicted a much larger eye presentation on microwave vs infrared — the microwave image showed the curved banding structure around an eye that was still not well-organized.

DMSP-17 SSMIS Microwave (85 GHz) and GOES-13 Infrared Window (10.7 µm) images [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) and GOES-13 Infrared Window (10.7 µm) images [click to enlarge]

While Hermine passed over waters exhibiting warm Sea Surface Temperature values in the eastern Gulf of Mexico, the Ocean Heat Content values were only modest (below).

Sea Surface Temperature and Ocean Heat Content values [click to enlarge]

Sea Surface Temperature and Ocean Heat Content values [click to enlarge]

The high values of Total Precipitable Water (TPW) associated with Hermine were evident on hourly composites of morphed TPW from MIRS sensors (below). Rainfall amounts exceeded 22 inches in Florida (WPC storm summary)

Morphed Total Precipitable Water derived from MIRS sensors [click to play animation]

Morphed Total Precipitable Water derived from MIRS sensors [click to play animation]


===== Post-landfall Update, 02 September =====
 

Suomi-NPP overflew Hermine shortly after 0700 UTC on 02 September, after its 0530 UTC landfall near St. Mars FL. The toggle below shows the VIIRS 0.7 µm Day/Night Band and the 11.45 µm Infrared Window imagery. Both show the asymmetric nature of the storm. Rain and clouds extend quite a distance to the south and east of the storm, but not far to the west. The infrared imagery shows cold cloud tops surrounding the storm center southeast of Tallahassee, with very cold cloud tops also over Tampa FL and near Savannah GA with bands associated with the storm. Cloud detail is missing in the Day/Night Band image because of the lack of lunar illumination — a New Moon occurred early on 01 September — however, high-altitude mesospheric airglow waves (references: 1 | 2 | 3) can be seen off the east coast of Florida and Georgia, excited by Hermine’s bands of strong thunderstorms.

Suomi NPP Day/Night Band Visible (0.70 µm) and Infrared Window (11.45 µm) images at 0723 UTC on 2 September [click to enlarge]

Suomi NPP Day/Night Band Visible (0.70 µm) and Infrared Window (11.45 µm) images at 0723 UTC on 2 September [click to enlarge]

A toggle between before-landfall (0319 UTC Terra MODIS) and after-landfall (0814 UTC POES AVHRR) Infrared images, below, shows the expected trend of warming cloud-top IR brightness temperatures and a consolidation into a more compact storm circulation.

11.0 µm Terra MODIS (0319 UTC) and 12.0 µm POES AVHRR (0814 UTC) Infrared images [click to enlarge]

11.0 µm Terra MODIS (0319 UTC) and 12.0 µm POES AVHRR (0814 UTC) Infrared images [click to enlarge]

===== 03 September Update =====

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0707 UTC on 03 September (above; courtesy of William Straka, SSEC) showed that Hermine — still being classified as a Tropical Storm — continued to produce mesospheric airglow waves as it moved off the East Coast of the US. Numerous bright white streaks were also evident on the Day/Night Band image, due to cloud illumination from intense lightning activity.

During the following daylight hours of 03 September, GOES-13 (GOES-East) Visible (0.63 µm) images (below: also available as an MP4 animation) showed the circulation of post-tropical cyclone Hermine. In eastern North Carolina, winds gusts as high as 80 mph were recorded, with rainfall amounts as great as 8.54 inches (NWS Newport/Morehead City); the storm also produced a few tornadoes (SPC Storm Reports). In southeastern Virginia, winds gusted to 73 mph (NWS Wakefield). A few of the heavier rainfall amounts for individual states are listed here.

GOES-13 Visible (0.63 µm) images, with surface and buoy wind barbs plotted in yellow and wind gusts (knots) plotted in red [click to play animation]

GOES-13 Visible (0.63 µm) images, with surface and buoy wind barbs plotted in yellow and wind gusts (knots) plotted in red [click to play animation]

A Suomi NPP VIIRS true-color image visualized using RealEarth (below) showed the clouds associated with Hermine at 1827 UTC.

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

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

Detection of River Flooding in Alaska

August 31st, 2016
Google Maps of west central Alaska, the JPSS River Flood Product and Landsat-8 False Color Imagery, 30 August 2016 [click to enlarge]

Google Maps of west central Alaska, the JPSS River Flood Product and Landsat-8 False Color Imagery, 30 August 2016 [click to enlarge]

Swampy conditions near the meandering Innoko River, a tributary to the Yukon River in Alaska, have been diagnosed by the JPSS River Flood Product near the Innoko’s mouth on the Yukon. (August has been very wet over parts of Alaska) A timely Landsat-8 overpass, in clear skies, on 30 August 2016 allows for excellent validation of the Flood Product. The animation above (using Images from RealEarth) cycles between the Google Maps terrain and satellite views of the region, the JPSS Flood Product (developed by a group led by Sanmei Li at George Mason University, which product uses reflective channels on JPSS (I01, I02, and I03, 0.64 µm, 0.86 µm and 1.61 µm, respectively) and I05, the 11.45 µm channel) and the Landsat-8 False Color overpass. Diagnosed floods in the JPSS Product are distinctly captured in the Landsat-8 False Color product.

Flooding in Louisiana

August 12th, 2016

Morphed MIRS observations of total precipitable water (TPW), 1500 UTC 11 August - 2100 UTC 12 August [click to play animation]

Morphed MIRS observations of total precipitable water (TPW), 1500 UTC 11 August – 2100 UTC 12 August [click to play animation]

Persistent convection in an atmosphere rich in moisture has led to life-threatening flooding over many Parishes in southern Louisiana. The animation above, taken from images at this site that morphs MIRS estimates of Total Precipitable Water (with values valid over both land and water) shows values around three inches over much of southeastern Louisiana. These TPW values agree with in situ observations such as the radiosonde from New Orleans at 1200 UTC on 12 August, where 2.70″ was observed. 24-hour rainfall totals ending at 1200 UTC on 12 August (Link) show a widespread region of more than 6″; raingauge observations of 6-hour totals at 1200 and 1800 UTC, below, show that the rain continued into the day on 12 August.

GOES-14 Visible (0.62 µm) images, with METAR observations of 6-hour precipitation, 1200 and 1800 UTC on 12 August 2016 [click to enlarge]

GOES-14 Visible (0.62 µm) images, with METAR observations of 6-hour precipitation, 1200 and 1800 UTC on 12 August 2016 [click to enlarge]

The flood-producing thunderstorms were very slow-moving, as evidenced in the animation of Infrared Window (10.7 µm) images from GOES-14, below (GOES-14 is in SRSO-R mode this month). Very little motion occurs in the two hours of this loop (using images at 5-minute time steps).

GOES-14 Infrared Window (10.7 µm) Imagery, 1625-1830 UTC on 12 August 2016 [click to play animation]

GOES-14 Infrared Window (10.7 µm) Imagery, 1625-1830 UTC on 12 August 2016 [click to play animation]

The entire sequence of 1-minute interval GOES-14 Infrared Window (10.7 µm) images from 0001-2358 UTC on 12 August is shown below.

GOES-14 Infrared Window (10.7 µm) images, with surface weather symbols plotted in yellow [click to play MP4 animation]

GOES-14 Infrared Window (10.7 µm) images, with surface weather symbols plotted in yellow [click to play MP4 animation]

This event is also discussed at the Satellite Liaison Blog, where the focus is on 1-minute visible imagery from GOES-14 and 1-minute lightning data.

===== 13 August Update =====

GOES-14 Infrared Window (10.7 µm) images, with hourly surface weather symbols plotted in yellow [click to play MP4 animation]

GOES-14 Infrared Window (10.7 µm) images, with hourly surface weather symbols plotted in yellow [click to play MP4 animation]

The heavy rainfall continued into 13 August, with storm total accumulations exceeding 31 inches in Louisiana (WPC storm summary). The entire sequence of 1-minute interval GOES-14 Infrared Window (10.7 µm) images spanning the period 1115 UTC on 11 August to 2159 UTC on 13 August, above, shows the development of multiple clusters of slow-moving thunderstorms, some of which exhibited cloud-top IR brightness temperatures of -80ºC or colder (violet color enhancement).

Heavy rainfall and flash flooding in Maryland

July 30th, 2016

GOES-13 0.63 µm Visible (top) and 10.7 µm Infrared Window (bottom) images [click to play animation]

GOES-13 0.63 µm Visible (top) and 10.7 µm Infrared Window (bottom) images [click to play animation]

A 2-panel comparison of GOES-13 (GOES-East) Visible (0.63 µm) and Infrared Window (10.7 µm) images (above) showed a band of thunderstorms oriented southwest-to-northeast across northern Virginia and northern Maryland late in the day on 30 July 2016. Cells within this band produced very heavy rainfall and extreme flash flooding at Ellicott City, Maryland — located northwest of Baltimore/Washington International Airport KBWI, and marked with a cyan * symbol — with a total of 6.60 inches of rain in just over 2 hours (NWS Baltimore/Washington Public Information Statement | Event summary). The coldest cloud-top IR brightness temperature was -67º C at 0045 UTC on 31 July (8:45 pm local time).

The MIMIC Total Precipitable Water product at 3-hour intervals (below) indicated the presence of TPW values in the 2.0 to 2.5 inch range over parts of the region.

MIMIC Total Precipitable Water product [click to enlarge]

MIMIC Total Precipitable Water product [click to enlarge]

Upstream rawinsonde data profiles from Washington Dulles International Airport in northern Virginia (below) showed TPW values of 46.8 mm or 1.83 inches at 12 UTC on 30 July, and 49.2 mm or 1.94 inches at 00 UTC on 31 July (although the later data looks suspect, given the balloon was launched as strong thunderstorms were approaching).

Washington Dulles VA rawinsonde profiles [click to enlarge]

Washington Dulles VA rawinsonde profiles [click to enlarge]