GOES-13 10.7 µm infrared imagery on 13 August 2014; The Islip airport (KISP) is at the violet square (click to animate)

The system that caused flooding in Detroit, MI on 11 August and in Baltimore/Washington on 12 August has moved eastward: Islip, NY, on central Long Island, had historically heavy rainfall early in the morning on 13 August as more than 13″ of rain fell (9.71″ in two hours, and 5.34″ in one hour!!), smashing the New York state record for 24-hour rainfall (Record Event Report).

The GOES-13 animation above shows the satellite presentation of the storms that produced the heavy rainfall (the heaviest rain fell between 0900 and 1100 UTC). It is immediately apparent that the deepest convective clouds were not responsible for the heavy rains: cloud-top IR brightness temperatures over Islip were only near -30º C (per the 1200 UTC OKX sounding, that was around 300 hPa; the tropopause was closer to 150 hPa) and cloud-to-ground lightning was not detected. Winds at the Islip airport shifted from easterly/northeasterly to southeasterly as the heavy rains ended (time series plot of surface weather): an approaching frontal boundary may have helped force the heavy rains.

The animation shows continual cold cloud redevelopment at/near Islip, suggesting that training shower development was an important factor in the flooding.

Although the region was generally cloudy, holes in the cloud cover revealed GOES-13 sounder Total Precipitable Water values (below; click image to play animation) of 45-50 mm or 1.8-2.0 inches over Long Island just ahead of the advancing frontal boundary. The Blended Total Precipitable Water product showed a sudden jump to over 50 mm or 2.0 inches around 10 UTC over Long Island, and these TPW values were around 150% of normal for that location and time of the year.

GOES-13 sounder Total Precipitable Water derived product images (click to play animation)

The MIMIC Total Precipitable Water product (below) showed a northward surge of tropical moisture into the region on 13 August.

MIMIC Total Precipitable Water (11-13 August)

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MIMIC Total Precipitable Water for the 72 hours ending at 1800 UTC 12 August 2014 (click to enlarge)

Very heavy rain has fallen during the day on August 12th in and around Baltimore (with rainfall rates as high as 2.70″ per hour at KBWI) and Washington DC, with reports of up to 10″. Where has this moisture come from? There are a variety of products available to diagnose total precipitable water in the atmosphere. The animation above, taken from the MIMIC Total Precipitable Water page (link), shows an influx of tropical moisture from the south-southeast has surged northward up to the east coast of Maryland on August 12. A mesoanalysis from SPC also suggests a link to the moisture east and south of Cape Hatteras. The GOES Sounder Total Precipitable Water derived product image at 1800 UTC, below, (from this website) showed very high total precipitable water amounts just south of Baltimore and Washington DC with values exceeding 60 mm or 2.4″. Soundings at 1200 UTC also showed high values of precipitable water: 48.5 mm or 1.90″ at Wallops Island, VA, and 44.7 mm or 1.76″ at Washington Dulles. Finally, the Blended Total Precipitable Water Product from NESDIS showed values around 51 mm or 2″ as well. (Values did not quite reach the 200% of normal threshold, however).

GOES Sounder Total Precipitable Water derived product image at 18 UTC

The animation of GOES-13 Infrared (10.7 µm) imagery, below, suggests some training was occurring in the thunderstorm development: thunderstorms continually redeveloped and moved over the same region. Training thunderstorms in moisture-rich air is a recipe for flooding.

GOES-13 10.7 µm infrared imagery on 12 August 2014 (click to animate)

Comparisons of Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 17:16 UTC and 18:54 UTC (below) showed that the convection exhibited cold cloud-top IR brightness temperatures (as cold as -77º C), and subtle shadowing on the visible imagery suggestive of overshooting tops. Using GOES-13 IR imagery,  the CIMSS/NASA Langley Automated Overshooting Tops / Thermal Couplets product displayed one distinct overshooting top (blue square symbol) over the Baltimore area at 18:45 UTC.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 17:16 UTC

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 18:54 UTC

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GOES-15 6.5 µm water vapor channel images (click to play animation)

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.

GOES sounder Total Column Ozone product (click to play animation)

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

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GOES-14 Visible Channel (0.62 µm) imager (click to enlarge)

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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