Heavy rain in Florida

October 26th, 2017 |

Aided in part by precipitation associated with Hurricane Irma, some areas of Florida have received record rainfall during the June-October 2017 period:

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

GOES-16 Visible (0.64 µm, left), Near-Infrared

GOES-16 Visible (0.64 µm, left), Near-Infrared “Vegetation” (0.86 µm, center) and Near-Infrared “Snow/Ice” (1.61 µm, right) images [click to play animation]

A comparison of GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Vegetation” (0.86 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) showed that water was a strong absorber of radiation at 0.86 µm and 1.61 µm wavelengths — therefore wet ground, rivers, lakes and the oceans appeared dark in those images. This makes those two GOES-16 ABI spectral bands useful for identifying areas of flooding.

Two areas in Florida are noteworthy on the images: the St. Johns River in the northeast part of the state (where Moderate Flooding had been occurring), and parts of South Florida (which had just received an additional 1-5 inches of rain on  the previous day).

A closer look at those 2 areas using Terra MODIS Visible (0.65 µm) and Near-Infrared “:Snow/Ice” (1.61 µm) images are shown below.

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice” (1.61 µm) images, showing central and northeastern Florida [click to enlarge]

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice" (1.61 µm) images, showing southern Florida [click to enlarge]

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice” (1.61 µm) images, showing southern Florida [click to enlarge]

In stark contrast to the periods of heavy rain, a strong cold front brought clear skies and very dry air over Florida, as seen in MIMIC Total Precipitble Water product (below).

MIMIC Total Precipitable Water product [click to enlarge]

MIMIC Total Precipitable Water product [click to enlarge]

This dry air evoked enthusiasm in least one South Florida resident:


Santa Ana winds in Southern California

October 24th, 2017 |

GOES-16 Land Surface Temperature product, with hourly surface reports plotted in white [click to enlarge]

GOES-16 Land Surface Temperature product, with hourly surface reports plotted in white [click to enlarge]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

The GOES-16 Land Surface Temperature product (above, courtesy of Jordan Gerth, CIMSS) revealed a dramatic increase in the land surface temperature (or surface “skin temperature”) following the onset of easterly/northeasterly Santa Ana winds in Southern California’s Ventura County during the overnight and early morning hours of 24 October 2017. Between 06-14 UTC (11 PM-7 AM local time), the surface air temperature increased from 66-91ºF at Oxnard (KOXR), 75-90ºF at Point Mugu (KNTD) and 77-91ºF at Camarillo (KCMA). Surface wind gusts of 32 mph were recorded at Camarillo during this period, although 64 mph was reported at South Mountain (elevation 2350 feet)..

A warming trend in that same area was also evident in the MODIS Land Surface Temperature product (below), during the time between the Terra (0539 UTC) and Aqua (0951 UTC) overpasses — LST values ranged from the low 60s F (lighter shades of yellow) to the upper 80s and low 90s F (darker shades of red) in the higher elevations.

Terra and Aqua MODIS Land Surface Temperature product [click to enlarge]

Terra and Aqua MODIS Land Surface Temperature product [click to enlarge]

A similar warming signature was seen over Ventura County on GOES-16 Shortwave Infrared (3.9 µm) images (below) — although an even more pronounced Santa Ana wind warming signal was evident farther to the southeast over Orange County (where winds gusted as high as 69 mph); note how the warmer orange-enhanced infrared brightness temperatures surged southwestward toward the coast.

GOES-16 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

GOES-16 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

A number of record high temperatures resulted from this Santa Ana wind event:


Record high temperatures in the San Diego, California

Record high temperatures in the San Diego, California area

In fact, the highest temperature in the Lower 48 states that day was 108ºF at Miramar Naval Air Station and San Luis Obispo, California.

National Temperature extremes

National Temperature extremes

Ex-hurricane Ophelia over Ireland and the United Kingdom

October 16th, 2017 |

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

After reaching Category 3 intensity over the eastern Atlantic Ocean on 14 October, Hurricane Ophelia (storm track) rapidly underwent transition to an extratropical storm which eventually spread high winds across much of Ireland and the United Kingdom on 16 October 2017. EUMETSAT Meteosat-10 upper-level Water Vapor (6.25 µm) (above) and lower-level Water Vapor (7.35 µm) images (below) revealed the familiar “scorpion tail” signature of a sting jet (reference). Hourly wind gusts (in knots) from primary reporting stations are plotted in red.

Meteosat-10 Water Vapor (7.35 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Meteosat-10 Water Vapor (7.35 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Two sites with notable wind gusts were Cork, Ireland (67 knots at 0930 UTC) and Valley, UK (70 knots at 1500 UT), shown below. In fact, a wind gust of 103 knots (119 mph or 191 km/hour) was reported at the Fastnet Rock Lighthouse off the southwest coast of Ireland.

Time series plot of surface data from Cork, Ireland [click to enlarge]

Time series plot of surface data from Cork, Ireland [click to enlarge]

Time series plot of surface data from Valley, United Kingdom [click to enlarge]

Time series plot of surface data from Valley, United Kingdom [click to enlarge]

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Terra and Aqua MODIS true-color images [click to enlarge]

Terra and Aqua MODIS true-color images [click to enlarge]

In a toggle between Terra MODIS (overpass time around 1159 UTC) and Aqua MODIS (overpass time around 1345 UTC) true-color Red-Green-Blue (RGB) imagery (above), a somewhat hazy appearance was seen over the Irish Sea on the Terra MODIS image. This was due to an airborne plume of sand from the Sahara Desert (UK Met Office story).

In fact, blowing sand was observed about 3 hours later at Isle of Man, from 1520-1620 UTC — during that time period their surface winds gusted to 68 knots (78 mph), and surface visibility was reduced to 2.2 miles (below).

Time series plot of surface data from Isle of Man [click to enlarge]

Time series plot of surface data from Isle of Man [click to enlarge]

Increase in Turbidity near the Texas Gulf Coast following Hurricane Harvey

August 30th, 2017 |

Terra MODIS True-Color imagery off the Texas Gulf Coast on 23 and 30 August, 2017 (Click to enlarge)

MODIS Today imagery from 23 August (pre-Harvey) (cropped) and 30 August (post-Harvey) (cropped), above, show an enormous increase in turbidity in the nearshore waters off the coast of Texas. Further, many of the rivers change their appearance to brown and flooding in the post-Harvey image. (River gauges in flood stage; Source)

A similar toggle using Suomi NPP VIIRS Imagery, from this site, also from 23 August and 30 August, is shown below. The increase in turbidity was due to a combination of strong winds and runoff from very heavy rainfall associated with the hurricane.

Suomi NPP True-Color imagery off the Texas Gulf Coast on 23 and 30 August, 2017 (Click to enlarge)

Suomi NPP VIIRS Products include a River Flood estimate, developed by Sanmei Li and others at George Mason University. The toggle below from RealEarth shows Suomi NPP VIIRS True Color at 1904 UTC, and the River Flood Product for the same time.

Suomi NPP VIIRS True-Color imagery off the Texas Gulf Coast, 1904 UTC on 30 August, 2017, and the Suomi NPP River Flood Product at the same time (Click to enlarge)

(Thanks to Bill Taylor and John Stoppkotte, NWS in N. Platte NE, for noting this!)